Transport Health-Information Network Project in Bulgaria

D. Baltadjiev¹, D. Tcharaktchiev²

¹Department of Medical Informatics, Transport Medical Institute, Sofia, Bulgaria

²University Hospital of Endocrinology and Gerontology, Sofia, Bulgaria

Transport workers' health promotion in Bulgaria is under the supervision of the Ministry of Transport and Communications. The Transport Medical Institute (TMI) serves as an occupational health service for transport workers of all kinds of transport- railway, road, water and air transport. The Institute is situated in Sofia. There are Regional Transport Hospitals in seven big towns of the country.

The aim of the Transport Health-Information Network (THIN) Project is to integrate, validate and demonstrate systems and services that provide teleconsultation and remote cooperative diagnostic work between transport hospitals at different locations by using applications and services to transmit patient's diagnostic information (data, biological signals and images). The network will be developing as WAN using Frame Relay and TCP/IP communication protocols. The THIN Project supports comprehensive and integrated sets of health care telematic services - teleconferencing, telepathology, teleradiology, telecardiology, etc. between TMI as a center of reference and regional hospitals for the exchange of information and expert advice.

At present, the Transport Medical Institute is also connected to the Bulgarian Medical Network and the satellite terminal of the GALENOS Project - TEN 45592 (FS) via a leased line and high-speed SDSL 2 Mbit/s modem. Completing the health-information network would reduce the transportation costs, increase efficiency through block scheduling of consults and increase effectiveness of patient record tracking.

Investigation on an MR Antenna Stent Prototype with Reversible Size Shift

T. Bertsch^1,2, A. Melzer^1,2,3, C. Trepanier⁴, M. Busch¹

¹ SiMAG GmbH, Berlin, Germany

² Department of Physical Engineering, University of Applied Sciences Gelsenkirchen, Gelsenkirchen, Germany

³ Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

⁴ NDC, Fremont (CA), USA

Introduction

MRI examination of stents is hampered by susceptibility artifacts created by the stent materials and the mesh-like designs are shielding signal emission from the lumen. The use of wireless RF (Radio Frequency) antennas (resonators) in MR Imaging is a new approach to the design of active MRI stents for the evaluation of stent functioning and patency. (*1) Hitherto, the design of active MRI stents has been limited to a predetermined diameter and length. In order to overcome these limitations, we developed an MRI stent that provides defined elastic and plastic deformation and expansion.

Subjects & Methods

For the prototypes, we used copper (plastic) or Nitinol (elastic) wire and commercial SMD (surface-mounted device) capacitors. We investigated the different possibilities to compress the antennas (coils) in order to place them on a commercially available balloon catheter introduction system as either balloon-expandable or on a delivery system for self-expanding stents. In theory, the inducted potential in a single loop exclusively depends on (the 1^st derivative in time of) the circumvented area, orthogonally projected to the magnetic field.

Thus we were able to build a structure with parts that work in accordance with this rule, and some that work against. As long as the first ones predominate, there will be sufficient signal intensity.

(Parts of the loop that are parallel to the magnetic field do not contribute) The interaction of these two parts makes it possible to fold the coil closely to the introduction catheter.

The design of the foldable coils consists of a wire wound in a serpentine form with a dimension of 1.0*1.2mm up to 1.8*1.8mm in steps of 0.2mm. After being brought into serpentine shape, the wire was wrapped upon a kernel to give it the correct coil shape. We evaluated the operativeness of the antennas in a SIEMENS MAGNETOM OPEN (0.2 Tesla) open magnet configuration.

Results

We were able to construct several prototypes of balloon-expandable coils using copper wire plated with silver or tin. We covered the arrangement with a clear varnish coating for insulation. After expanding, the coil demonstrated a sufficient signal. Using superelastic Nitinolwire it was possible to construct a self-expanding coil.

Discussion/Conclusion

We were able to demonstrate that resonating MR antennas could be folded and re-expanded again. This is the fundamental prerequisite for using these antennas in the human body. For the prototypes, we used SMD (surface-mounted device) capacitors. If a resonator is to be introduced into the human body, the capacitor will have to be built with the wire arrangement.

(*1) A.Melzer et al.: Signal Enhancement of Stents in Magnetic Resonance Imaging, ISMRM’2000

Simulation Of Moving Artifacts In Magnetic Resonance Imaging

T. Bertsch², D. Boll, A. Melzer^1,2, R. M. M. Seibel¹

¹ Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

² Department of Physical Engineering, University of Applied Sciences Gelsenkirchen, Gelsenkirchen, Germany

Background

A typical problem of MR (magnetic resonance) Imaging is that every movement of the patient inside the magnet will cause artifacts in the picture. All frequently appearing movements, such as breathing and blood pulsation, will give rise to consecutive misinterpretations of the incoming data and so to multiple appearances throughout the picture. We have developed a simulator with blood pulsation and breathing movements, which enables us to study the influence of movements to the different imaging sequences.

Methods

The simulator consists of two parts, a driving unit and a phantom human thorax, both connected via 5m plastic tubes. The driving unit contains a power supply, a centrifugal pump, two magnetic valves, a car wiper motor and a computer interface. The phantom human thorax comprises plastic ribs, mounted to a wooden base plate, furthermore a small network of smooth plastic hoses to create a vascular system, and finally some dummy organs made of a special silicone / fat emulsion.

The dummy organs are moved up and down by a hydraulic system that transmits the breathing movements from the wiper motor in the driving unit. The pump circulates a special blood substitute, using the two magnetic valves to create a two-step pulsation. The blood substitute consists of a physiologic saline solution, dotted with 2 mmol/l gadolinium contrast agent, a very small amount of dishwashing detergent to prevent bubbles and a silver-saline-based disinfectant.

The silicone/fat organs give an appropriate MR signal that could be further enhanced by using a special silicone rubber inlet, containing animal organs or meat. With a little computer program we can transmit data from a PC to the driving unit via the built-in interface in order to realize different rates of blood pulsation and breathing.

Results

The simulator was tested in a horizontal 0.2 Tesla open magnet configuration, Siemens Magnetom OPEN. It was necessary to experiment with a great variety of pulse and breathing rates to achieve perceptible artifacts. The decrease in the pressure of the liquid caused by the length of the connecting pipes did not turn out easy to handle. We used pipes with a rather large inner width and stiff walls to optimize the transmission of pressure. The electromagnetic shielding of the driving box, realized by a thin copper sheet, turned out to be less problematic than predicted. To optimize the signal-to-noise ratio, longer transmission pipes can be used and the driving unit can be placed outside the MR cabin.

Conclusion

We were able to demonstrate that phantoms of the human body with artificial blood supply and simulated breathing movements provide adequate signal characteristics under MR imaging. It is likewise possible to examine artifact behavior of new MR sequences or to test new surgical instruments, endoscopes or interventional devices.

Overview of Task Analyses of the Minimally Invasive Surgical Process

K.T. den Boer^1,2, J. Dankelman¹, L.T. de Wit², D.J. Gouma², C.A. Grimbergen^1,3

¹ Man-Machine Systems Group, Faculty of Design, Engineering and Production,

Delft University of Technology, Delft, The Netherlands

² Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands

³ Department of Medical Physics, Academic Medical Center, Amsterdam, The Netherlands

A quantitative method was developed to evaluate the quality and efficiency in minimally invasive surgery. Task analysis was used to evaluate the complex minimally invasive surgical technique. In surgery, there is hardly any quantitative method for the pre-operative assessment of the quality and efficiency of skill performance or the functionality of instruments. The method was used to evaluate the surgical process, to get an insight into the laparoscopic skills of a resident and to investigate the differences between alternative surgical techniques.

Evaluation method (1,2):

To record the operations, a wide-angle CCD camera was used to get an overview of all actions performed by the surgeon. This overview image with sound was recorded simultaneously with the images of the laparoscope and, where available with other diagnostic images, using a video-mixing device. The instrumentation for recording the procedures was portable, allowing instant use in any operating theatre as well as placement outside the range of the actions of the operating team, thereby not interfering with the peroperative process. Afterwards, the procedures recorded were analyzed outside the operating theatre. For each protocol, an action list was developed and the procedure was subdivided into phases (e.g. opening phase, dissection phase). The time needed per phase, the time to perform an action and the number of actions were determined.

Surgical process in general (3):

Task analysis was applied to evaluate the peroperative surgical process and the technical equipment during diagnostic laparoscopy with laparoscopic ultrasonography (DLLU). The current standard of DLLU was calculated from the mean time and number of actions determined for each phase. The time for each phase, efficient actions and limiting factors (e.g. technical problems, time spent waiting) were determined. Of the actions performed, 52% were qualified as efficient, 17% as time spent waiting for personnel, 13% for instrument positioning and 10% for unnecessary instrument exchanges. Critical evaluation of the results led to advice to the operating team, resulting, for instance, in a significant reduction in delay times. Evaluation of the functional problems with the biopsy instruments led to new design criteria for improved biopsy instruments. The current standard enables the peroperative evaluation of the learning of laparoscopic skills and of new instruments.

Learning of laparoscopic skills:

Training programs are available to acquire laparoscopic skills in the operating room or in a laboratory setting. However, no quantitative method exists to assess the actual efficiency level or correctness of skill performance, during the peroperative procedure. The quantitative task analysis method was used to evaluate the learning of laparoscopic skills. The first 25 DLLUs performed by a resident were analyzed with respect to number of actions, correctness and speed of skill performance for each sub-task of the prescribed protocol. The experienced surgeon evaluated the quality of the peroperative tasks. The postoperative complications and outcome correctness were compared to the outcomes of the experienced surgeon. The skills were performed correctly in 93.4% of the sub-tasks, partially in 1.0%, not at all in 3.5%, and using the wrong technique in 2.1% of the sub-tasks. Postoperative complications and outcome correctness did not differ between the resident and experienced surgeon. The resident's efficiency for most specific diagnostic skills remained significantly lower as compared with those of the surgeon (p<0.001). The results show that time-action analysis is a powerful method for evaluating the efficiency and quality of skill performance, enabling personal feedback and a quantitative measurement of the correctness of skill performance, and efficiency of learning skills in laparoscopic operations.

Evaluation of surgical techniques (4):

Three surgical dissection techniques were analyzed to demonstrate the application of the quantitative evaluation method on surgical techniques. In an open procedure, standard dissection with ligation of vessels, bipolar scissors, and monopolar coagulation were consecutively applied to dissect four meters of small bowel mesentery of pigs. The actions of the surgeon were recorded using a finger-sized head-mounted camera, and all actions were analyzed using a standard action list. The efficiency of each technique was expressed in terms of mean dissection time and number of actions, and the safety in terms of the number of complications and severity of microscopic damage. Bipolar scissors were significantly more efficient than the standard ligation technique and monopolar coagulation (p<0.01). Furthermore, bipolar coagulation required significantly less recoagulation of an oozing vessel than did monopolar coagulation and the zone with microscopic cell damage was significantly smaller. Significantly less time was spent waiting or exchanging instruments with bipolar scissors than with the standard technique. Bipolar scissors were more efficient and they coagulated vessels more safely than monopolar coagulation. These results show that task analysis can be used to compare different surgical techniques objectively.

Conclusion:

We have developed a quantitative method for evaluating the complex minimally invasive surgical process. We showed that task analysis provide detailed insight into the peroperative surgical process. Furthermore, the analysis resulted in improvements of the surgical process, insight into the learning of skills of a resident and an objective evaluation of different surgical techniques.

(1) Claus G.P., Sjoerdsma W., Jansen A., Grimbergen C.A. Quantitative standardised analysis of advanced laparoscopic surgical procedures. Endoscopic Surgery and Allied Technologies 4: 209-213, 1995

(2) W. Sjoerdsma. Surgeons at work, time and actions analysis of the laparoscopic surgical process. PhD-thesis Delft University of Technology, 1998.

(3) K.T. den Boer, L.T. de Wit, J. Dankelman, D.J. Gouma. Peroperative time-motion analysis of diagnostic laparoscopy with laparoscopic ultrasonography. British J. of Surgery 86: 951-955, 1999

(4) K.T. den Boer, I.H. Straatsburg, A.V. Schellinger, L.T. de Wit, J. Dankelman, D.J. Gouma. Quantitative analysis of the functionality and efficiency of three surgical dissection techniques. A time-motion analysis. Journal of Laparoendoscopic & Advanced Surgical Techniques 9: 389-295, 1999

LAHYSTOTRAIN – Advanced Training Environment for Laparoscopy and Hysteroscopy

U. Bockholt¹, W. Müller², P. Oppelt¹, J. Stähler², G. Voss¹

¹ Fraunhofer Institute IGD, Darmstadt, Germany

² Berchtold GmbH & Co., Tuttlingen, Germany

Problem/Background

Rapid developments in the medical field, expanding knowledge bases and new technologies require continuing medical education to achieve a life-long learning process and keep surgeons up to date. This means that specific training is necessary to guarantee qualification of the surgeons. To overcome the current drawbacks of traditional training systems (on-the-job training, plastic models etc.) for laparoscopy/hysteroscopy, an intelligent adaptable training environment has been realized.

Tools&Methods

The LAHYSTOTRAIN training system is an advanced training system for laparoscopic/hysteroscopic procedures combining virtual reality (VR), multimedia (MM) and intelligent tutoring techniques (ITS). Based on ESHRE (European Society of Human Reproduction and Embryology), the user requirements are specified. Starting with diagnostic procedures and ending with complex therapeutic interventions, the whole educational process is covered. In general, owing to the various levels in difficulty and complexity, the training course can be individually adapted to the level of the trainee addressing all potential "learners" as students, novices and experts. The training environment is divided into two scenarios: The basic training system consists of a Web-based training system, where intelligent tutoring techniques are used to address novice users, focusing on the theory and conceptual aspects of laparoscopy/hysteroscopy. The advanced training system using VR technology addresses more experienced surgeons who want to acquire or improve their skills in minimally invasive techniques. It provides a realistic training environment for rehearsing the various interventions and gives a more intuitive 3D interaction. The intelligent tutoring architecture detects superficial errors and infers their cause. A tutor proposes different training sessions and exercises in keeping with the user's expertise.

Results

The first prototype of LAHYSTOTRAIN includes the treatment of ovarian cysts. The WWW component provides the learning environment for knowledge acquisition, and the VR simulation system is suitable for skill training. The VR training environment contains virtual anatomical structures and simulates an endoscope, surgical instruments and object behavior (collision detection, deformation, cutting). In addition, a force-feedback device is integrated into the training system; thus, the trainee is able to feel the give and resistance of the anatomical structures via instruments. The intelligent tutor system functions as a "surgical expert" guiding the trainee through the various levels of the training process.

Conclusion

The integrative adaptable training environment provides new opportunities in medical education. Combining intelligent tutor, VR, WWW, and multimedia, this approach shows that the entire educational process can be covered considering the individual training level of the trainee. This concept is generally applicable to other medical specialties.

Task Analysis of Instrument Positioners Used During Laparoscopic Cholecystectomy

M. Bruijn², K.T. den Boer^1,3, J.E. Jaspers², L.P.S Stassen⁴, W.F. van Erp, A. Jansen⁴, P.M.N.Y.H. Go,

J. Dankelman³, D.J. Gouma¹

¹ Department of Surgery, Academic Medical Center, Amsterdam, The Netherlands

² Department of Medical technological Development, Academic Medical Center, Amsterdam,

The Netherlands

³ Man-Machine Systems Group, Faculty of Design, Engineering and Production, Delft University of Technology, Delft, The Netherlands

⁴ Minimally Invasive Surgery and Interventional Techniques, Delft University of Technology, Delft,

The Netherlands

Introduction

Laparoscopic surgical techniques are applied to an increasing degree because of their advantages for the patient, such as reduced pain, shorter hospital stay and quicker convalescence, compared to conventional open surgery. However, the absence of direct hand-tissue contact and the absence of a direct 3D view on the operative field require more complex surgical skills on the part of the surgeon. Various (supporting) instruments, such as instrument positioners, have been developed to facilitate laparoscopic surgery with the intention to increase efficiency. Normally, a surgical assistant controls the laparoscope during laparoscopic operations and when needed, an additional grasper. Unfortunately, the surgeon thereby loses direct control over his viewing direction and the image is often unstable due to tremors and sudden movements of the surgical assistant. Furthermore, the surgical assistant's task is relatively static and tiresome. Instrument positioners return camera-control to the surgeon and stabilize the laparoscopic image. They could dispense with the need for a surgical assistant in laparoscopic procedures. Instrument positioners are divided into two main groups: passive positioners, which the surgeon has to reposition manually, and active positioners, which are repositioned by a robotic device.

Clinical testing of new surgical instruments and techniques normally focuses on post-operative complications, total operation time and subjective appreciation by the surgeon. Laboratory experiments with instrument positioners have shown that both the surgeon's observation and manipulation tasks improve when he has direct control over his viewing direction (1). Clinical experiments demonstrated that the use of an instrument positioner instead of a human camera assistant does not increase the time needed for surgery and is subjectively preferred by surgeons (2). To our knowledge, however, there is no objective information available as to their actual per-operative use. Recently, task analysis has been introduced as a technique capable of objectively evaluating the efficiency, functionality and limiting factors of surgical instruments and techniques during per-operative use (3).

The aim of this study is to evaluate, by means of task-analysis methods, whether instrument positioners enable surgeons to safely and efficiently perform laparoscopy without a surgical assistant. The influence of instrument positioners on the per-operative process is evaluated in terms of the time required for each operation phase, the number and type of actions performed, positioning accuracy and subjective appreciation by the surgeon.

Methods

Patients undergoing elective laparoscopic cholecystectomy on symptomatic, radiologically confirmed cholelithiasis, were included in this study. Patients with foreseen complicating factors, such as extreme obesity, previous upper-abdominal surgery, and suspicion of cholestasis or infection, were excluded. Laparoscopic cholecystectomy was selected for this study because it is performed frequently and in accordance with a standard protocol. Four different hospitals participated in the study. 72 Laparoscopic cholecystectomies were performed by four experienced surgeons (thus with a fully acquired, non-variable surgical technique) and one resident. The laparoscopic cholecystectomies were randomly performed with a surgical assistant controlling the laparoscope (group A) or with instrument positioners (group B). All surgeons performed as many operations in group A as in group B to compensate for variations caused by differences in individual surgical techniques and OR procedures. In group B, either the active voice-controlled AESOP or a recently developed passive instrument positioner called pASSIst was used to position the laparoscope. pASSIst is a manually controlled mechanical arm, capable of positioning the laparoscope or an additional grasper. pASSIst is slender and can be placed next or opposite to the surgeon. It allows movements in four degrees of freedom; all three rotations around the incision point in the abdominal wall and one translation through this incision. When needed, two pASSIst devices can be used at the same time. When pASSIst was used, the task of retracting the gall bladder was performed by an additional pASSIst and not by the surgical assistant.

During the surgical procedures, images from the laparoscope and images from two additional external CCD-camera's were recorded simultaneously, using a 4-channel mixing device and a Super-VHS video-recorder. The small CCD-cameras were placed next to the operation lights to guarantee a central overview of the surgical procedure. In addition, sound was recorded using an omni-directional microphone. Recorded procedures were analyzed outside the operating theatre so as not to interfere with the per-operative procedure. The procedures were subdivided into three phases - setup, dissection, and closure. For each phase, the time and actions needed were analysed using a strictly defined list of actions. The positioning accuracy was analysed for the dissection phase; for each tissue-touching action the position of the tip of the instrument in the image was determined - in the center of the image, at the border of the image or outside the monitor. In addition, the surgeons completed a questionnaire regarding their per-operative contentment after each procedure.

Results

There was no significant difference in patient characteristics (age, gender) or complications (arterial bleeding and gall-bladder leakage) between groups A and B (20 versus 15, p=0,42). In group B, 31 operations were performed with Passist and 5 with AESOP. The resident performed eight operations in each group. The resident's results were analysed separately from those of the experienced surgeons to reduce dispersion.

There was no significant change in total operation time between groups A and B. The total operation time was on average 41 minutes in group A (SD=21) and 48 minutes in group B (SD=23, p=0,26). However, the setup phase was significantly longer in group B than in group A - 14 instead of 9 minutes (p<0,001).

There was no significant difference in total actions needed between groups A (640, SD=259) and B (640, SD=272, p=0,99). However, the laparoscope was significantly more often repositioned in group A (115 times, SD=56) than in group B (48 times, SD=27, p<0,001).

There was no significant difference in positioning accuracy between groups A and B. In group A 49% (SD=26%) of the electro-surgical dissections was performed within the defined center, in group B this was 46% (SD=21%, p=0,69). 38% of the other dissection or grasping actions was performed inside the defined center in group A (SD=16%) and in 42% in group B (SD=14%, p=0,42).

The questionnaire showed that the surgeons preferred to operate with an instrument positioner instead of a surgical assistant.

The task-analysis results didn't differ between the operations with AESOP and those with pASSIst. There was no difference between pASSIst and AESOP in their influence on the individual surgeon in terms of time and actions needed.

Neither was there any significant difference in total time and actions performed between group A and B for the operations performed by the resident. Naturally, the average total time and actions needed were above the average of the experienced surgeons.

Conclusions

This study shows that the use of pASSIst enables surgeons to perform laparoscopic cholecystectomy without a surgical assistant. Furthermore, the instrument positioners tested enable surgeons to perform laparoscopic cholecystectomy without a significant change in time and the number of actions needed. The use of instrument positioners reduces laparoscope repositioning without significantly changing positioning accuracy. Surgeons subjectively prefer to operate with an instrument positioner rather than a surgical assistant.

References

1. Voorhorst F, Meijer D, Overbeeke&Smets C. Depth perception in laparoscopy through perception-action coupling, Min Invasive Therapy and Allied Techn 1998; 7:325-34.

2. Omote K, Feussner H, Ungeheuer A, et al. Self-guided robotic camera control for laparoscopic surgery compared with human camera control, Am J Surgery 1999; 177:321-4.

3. Claus GP, Sjoerdsma W, Jansen A, Grimbergen CA. Quantitative standardised analysis of advanced laparoscopic surgical procedures, End Surg 1995; 3:210-3.

Chronic Plantar Fasciitis treated by ESWT

Results of a prospective, multicenter, randomized, placebo-controlled, double blind clinical study

Buch, M. ; Knorr, U.; Siebert, W.E.

Introduction:

We report about the results of gait analysis and MRI that have been gained in the pre-investigation and at three months follow up of patients taking part in a multicenter, randomized, placebo-controlled, prospective, double blind clinical study to proof safety and effectiveness of extracorporeal shock wave therapy for plantar fasciitis in patients who failed to respond to conservative treatment.

Material and method:

A total of 150 patients at six sites (3 US American, 1 Canadian, 2 German) are to be treated, randomized in a 1:1 allocation ratio: a group receiving Extracorporeal Shock Wave Therapy (ESWT) with the Epos Ultra and a control group receiving sham treatment (realized by a thin air cushion). Defined eligibility criteria have to be fulfilled by the patients in order to take part in the study.

Both active and sham patients will receive an injection of local anesthetic for pain

An ultrasound image of the point where the first shock waves will be delivered will be obtained for all patients immediately prior to the release of the shock waves in order to document the therapy site. The therapy head will be coupled tangentially on the medial aspect of the foot.

The single therapy will be delivered by administering approximately 50 shock waves (±10) at levels 1 - 6 until level 7 is reached. Approximately 3500 shock waves (±10) will be administered at level 7 to reach an approximated total energy delivery of 1300mJ/mm². Shock wave frequency will begin at a setting of 60 shocks per minute and is increased in increments of 30 shocks per minute. During treatment, the frequency of release of the shock waves will begin at 60 shocks/minute at level 1 and will be increased by one level of 30 shocks per minute at each energy level until 240 shocks per minute at level 7 is reached.

Prior to treatment and at 3 months follow up a MRI and a gait analysis are obtained.

Patients initially being randomised to placebo treatment were treated as a cross over group if eligible after 3 months.

Protocol Overview

	Pre-Tx	Tx/ Post-Tx	3-5 Day	6 Wk	3Mo	6Mo	12Mo
History & Physical: · Symptom Assessment	X		X	X	X	X	X
· Inspection	X		X	X	X	X	X
· Pulse Assessment	X		X	X	X	X	X
· Capillary Refill Assessment	X		X	X	X	X	X
· Measurement of ankle/foot sensation	X		X	X	X	X	X
· Pain during palpation with Pressure Threshold Meter	X		X	X	X	X	X
X-ray: calcaneus lateral view	X
VAS Pain Questionnaires	X		X	X	X	X	X
Roles & Maudsley Pain Evaluation	X			X	X	X	X
SF 12 Health Survey	X			X	X	X	X
AOFAS Ankle - Hindfoot Scoring System Questionnaire	X			X	X	X	X
Pain medication diary		X	X	X	X	X	X
Adverse Effects		X	X	X	X	X	X
Determination of/Changes in Medications	X		X	X	X	X	X
Ultrasound image of crosshair position prior to shock wave release		X
Pain during & immediately post-treatment		X
Unblinding and evaluation of control patients for crossover treatment					X

Endovascular Graft Placement to the Thoracic Aorta: Current Challenges and Future Opportunities

M. D. Dake, C. P. Semba, S. T. Kee, M.K. Razavi, S. M. Slonim, S. L. Samuels, D.Y. Sze, R. S. Mitchell, D. C. Miller

Cardiovascular and Interventional Radiology and Cardiovascular and Thoracic Surgery, Stanford University Medical Center, Stanford (CA), USA

Thoracic aortic aneurysms are potentially life threatening. The majority are caused by atherosclerosis, most commonly of the descending aorta; clinical manifestation are due to the compression of adjacent structures, dissection, or rupture. Rupture of a thoracic aneurysm is almost always rapidly fatal. Several reports have estimated the risk of rupture in patients with untreated thoracic aortic aneurysms to range from 46% to 74%, with actuarial five-year survival rates being estimated to range from 9% to 13%. This prognosis is worse than the five-year survival rate for patients with untreated abdominal aortic aneurysms.

The traditional treatment of thoracic aortic aneurysms is the surgical placement of a graft. Although substantial advances in the operative care of patients with thoracic aortic aneurysm have been achieved over the past 30 years, the variety of underlying diseases, the frequency of coexistent cardiovascular diseases and the unpredictable need for emergency surgical intervention continue to pose vexing challenges. The difficulty presented by this problem is underscored by studies documenting a mortality rate of more then 50% in patients requiring emergency operative treatment and in those with particular characteristics or coexisting conditions such as advanced age or the presence of congestive heart failure. The risk associated with elective surgical repair is lower, with a mortality rate of 23% reported in one large contemporary series.

Transluminally placed endovascular stent-graft prostheses offer an alternative approach to treatment that is potentially less invasive and less expensive, with a lower risk than standard operative repair. The clinical feasibility of transluminal endovascular grafting has been recently described for the treatment of abdominal aortic aneurysms, subclavian-artery aneurysms, arteriovenous fistulae, and femoral occlusive disease. The following represents our current experience with transluminally placed endovascular stent-grafts for the repair of descending thoracic aortic aneurysms.

Aim

To evaluate the safety and effectiveness of a transluminally placed stent-graft device for the treatment of descending thoracic aortic aneurysms.

Method

Custom-fabricated, self-expanding stent-grafts composed of a stainless steel endoskeleton consisting of Z-shaped elements and woven polyester graft material were implanted in 132 patients, and commercially manufactured stent-grafts (TAG EXCLUDER, W.L. Gore, Inc., Flagstaff, AZ) made of a self-expanding Nitinol stent lined with an ultra-thin wall of polytetrafluoroethylene (PTFE) graft material were placed in 18 patients with thoracic aortic aneurysms (94 true and 56 false aneurysms). A variety of etiologies included atherosclerosis (107), dissection (13), trauma (16), anastomotic (6), mycotic conditions (6), tumor-related (1), and Marfan’s Syndrome (1). Eight patients had stent-grafts placed for multiple thoracic aneurysms. Sixteen patients had acute aortic ruptures. The mean age of the patients treated was 67.9 years (ranging between 16 and 88 years), with 37 patients older than 75 years. Follow-up CT and angiography were performed in all patients.

Results

The deployment of the prosthesis was technically successful in all but one case. Forty-four patients required multiple stent-grafts to cover the aneurysm completely. Complete thrombosis of the aneurysm was achieved in 134 (89%) of the patients. Nine patients died within 30 days of the procedure. Paraplegia occurred in four patients. Stroke was a complication in four cases. There were no instances of infection or distal embolization. One case required immediate surgical conversion. The mean follow-up interval was 2.1 years and the maximum was 6.2 years.

Conclusions

In our mid-term clinical experience, transluminally placed stent-grafts appear to represent a feasible alternative to standard surgical procedures for the management of highly selected patients with descending thoracic aortic aneurysms.

VASCULAR STENT-GRAFTS

I. (A) Applications

I. Aneurysms

(a) Thoracic aorta

(b) Abdominal aorta

II. Occlusive Disease

III. Vascular Injury

(a) Transection

(b) Rupture

(B) Design Considerations

I. Flexible or rigid stent

II. Deployment: Balloon-expandable, self expanding or

combination

III. Stent location: proximal, proximal & distal or throughout

IV. Attachments: Hooks or friction seal

V. Graft material: Woven Dacron, knitted Dacron or PTFE

VI. Delivery system: Balloon catheter, sheath/pusher, capsule

(C) Graft Material

I. Characteristics

(a) Porosity

(b) Capacity for radial expansion

(d) Pliability

(e) Dilation with time

II. Other Considerations

(a) Crimping

(b) Velour coating

(D) Graft Material

I. Woven Dacron

II. Knitted Dacron

III. PTFE - 30, 60, 90 micron fibril length

(a) Reinforced

(b) Non-reinforced

(E) Technical Problems

I. Device delivery to target

II. Misplacement of prosthesis

III. Reliable deployment

IV. Migration

(F) Anatomical Factors

I. Route of Delivery - Iliac Arteries

(a) Tortuosity

(b) Significant atherosclerosis

II. Target Vessel Measurements

(a) Absolute diameter of aneurysm neck

(b) Mismatch between proximal and distal diameter

III. Target Vessel Morphology

(A) Thoracic

I. Aortic arch curvature

II Proximity to great vessels

(B) Abdominal

I. Short or absent aneurysm neck

II. Marked angulation between aneurysm and its neck

III. Proximity to renal arteries

IV. Accessory renal arteries

V. Extension to aortic bifurcation or into iliac arteries

REFERENCES

1. Parodi JC, Palmaz JC, Barone HD. Transfemoral Intraluminal Graft Implantation for Abdominal Aortic Aneurysms. Ann Vasc Surg 1991;5:491-499.

2. Laborde JC, Parodi JC, Clem MF, Tio FO, Barone HD, Rivera FJ, Encarnacion CE, Palmaz JC. Intraluminal Bypass of Abdominal Aortic Aneurysm: Feasibility Study. Radiology 1992; 184:185-190.

3. Palmaz JC, Windeler SA, Garcia F, Tio FO, Sibbitt RR, Reuter SR. Atherosclerotic Rabbit Aortas: Expandable Intraluminal Grafting. Radiology 1986; 160:723-726.

4. Yoshioka T, Wright KC, Wallace S, Lawrence DD, Gianturco C. Self-Expanding Endovascular Graft: An Experimental Study in Dogs. AJR 1988; 151:673-676.

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3D Visualization of Multimodal Images using Registration, Filtering and Segmentation

Das M^1,2, Mamisch C^1,2, Kolvenbach C^1,2, Jolesz F¹ , Kikinis R¹, Seibel R²

¹ Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

² Surgical Planning Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston (MA), USA

Introduction

The visualization of medical images of different modalities has become more and more important over the past few years. New technologies and software were developed to make the three-dimensional visualization more effective and detailed. This gives e.g. neurosurgeons new powerful possibilities for diagnostic, surgical planning and intraoperative navigation. But also three-dimensional models of different regions of the body to show the complexity of the anatomy for teaching purposes or further use are possible. New concepts and terminologies such as image-guided therapy, computer-assisted surgery, surgical robotics and telesurgery have emerged. A few years ago, however, direct visibility of exposed anatomy was restricted to the surfaces. Surgeons, with or without the use of microscopes or endoscopes, were unable to see beyond surfaces. To overcome this limitation, imaging modalities have been utilized to help surgeons to expand their vision. Various imaging modalities can be distinguished by comparing their ability to represent the body as a three-dimensional 3D structure.

Material and Methods

We developed different methods and tools to use medical data of different modalities. In the Surgical Planning Laboratory we produce three-dimensional images by reconstructing data from CT, MR, MRA and other.

We use methods like filtering, registration and segmentation to gain three-dimensional models of high details.

The filtering is a method that is used to improve the results of segmentation and to get more accurate 3D models. The filtering uses an adaptive filtering algorithm to emphasize structures of interest in CT data to make the segmentation of the bone easier.

Registration is a process to align medical image data by using the mutual information. Nonlinear registration is the set of techniques that allow the alignment of data sets that are mismatched in a nonlinear or non-uniform manner. For surgical planning, intraoperative imaging or the building of three-dimensional models it is important to register different images together, to gain a new set of images with both information or to align the images in the same coordinate system.

Filtered, registrated and normal images can be used to generate three-dimensional models. A set of semi automated computer procedures was used to label the anatomic parts represented by each voxel in the data set. Sometimes the results of the thresholding are still not good enough and further methods of manual renderings were used. Different structures were labeled and VTK models were generated out of the labels by using the marching cubes algorithm.

Results

With these methods we are able to build high detailed three-dimensional models, which integrate the information of medical image datasets of different modalities. The different methods enable the user to gain models, which are based on different datasets what leads to better details. The three-dimensional models can provide important information of different steps during diagnostic, surgical planning and intraoperative surgery.

Conclusion

The three-dimensional imaging has become more and more important. Further developments of better imaging that improve the quality of the image data will lead to even better three-dimensional visualization and will make it easier to develop fully automated segmentation techniques. Our methods provide already very helpful tools to generate high detailed three-dimensional models.

Nonrandomized Comparison of Standard Open-Flank Versus Laparoscopic Nephrectomy

C. Doehn, P. Fornara, D. Jocham

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

Objectives

We report the results from a comparative nonrandomised study between standard open-flank versus laparoscopic nephrectomy for benign renal disease.

Materials

Between 1993 and 1998, we performed a total of 249 nephrectomies for benign renal diseases. There were 118 patients in the standard open-flank nephrectomy group (median age 59 years, range 8 to 89 years) and 131 patients in the laparoscopic nephrectomy group (median age 40 years, range 16 to 73 years). Various clinical data were compared between the two groups.

Results

The median operative time in the standard open-flank nephrectomy group was 90 minutes (ranging between 30 and 240 minutes) and also 90 minutes in the laparoscopic nephrectomy group (ranging between 41 and 210 minutes). In the laparoscopy group, 8 patients had a conversion to open surgery (6.1%). There were 27 complications (20.6%) in the laparoscopic nephrectomy group compared to 30 complications (25.4%) in the standard open-flank nephrectomy group. Postoperatively, patients in the laparoscopic nephrectomy group required less morphine sulphate equivalent (median 12 mg. vs. 20 mg.) for pain control and they had a shorter hospital stay (4 days vs. 10 days) and shorter duration of convalescence (24 days vs. 36 days). These results were statistically significant.

Conclusions

Laparoscopic nephrectomy results in similar operative results but in a significantly briefer postoperative course when compared to standard open flank nephrectomy. Laparoscopy is an attractive treatment option for patients with benign renal diseases, and an appreciated supplement to the spectrum of operative techniques for nephrectomy.

Novel Approach to Exclude Upper Urinary Tract Malignancy in Patients with Analgesic Nephropathy

C. Doehn, P. Fornara, L. Fricke, D. Jocham

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

Objectives

Analgesic abuse is still an essential cause of end-stage renal disease. Such patients bear an elevated risk of developing malignancies, predominantly transitional cell carcinoma. We report our experience with laparoscopic unilateral nephroureterectomy before a scheduled renal transplantation, carried out on patients with analgesic nephropathy in order to exclude transitional cell carcinoma of the upper urinary tract.

Materials

Since 1996, 10 patients (8 women and 2 men) with a long-term history of analgesic abuse underwent laparoscopic unilateral nephroureterectomy in our department. The median age was 60 years (ranging between 51 and 70 years). All patients had developed end-stage renal failure due to heavy analgesic abuse with a median duration of 14 years (ranging between 7 amd 40 years).

Results

The median operative time was 93 minutes (ranging between 55 and 125 minutes). There were no conversions. Two complications occurred and three patients required blood transfusions. The median hospital stay lasted 5 days (ranging between 2 and 12 days) and median reconvalescence was 20 days (ranging between 6 and 44 days). None of the patients had a transitional cell carcinoma. In one patient, however, a renal cell carcinoma was detected.

Conclusions

Patients with analgesic nephropathy bear an elevated risk for the development of transitional cell carcinoma or renal cell carcinoma. In these patients, laparoscopic nephroureterectomy combines minimal invasiveness with a maximum of diagnostic safety.

Prospective Nonrandomized Comparison of Laparoscopic Transperitoneal, Open Transperitoneal, and Open Retroperitoneal Nephrectomy

C. Doehn, P. Fornara, M. Hagen, D. Jocham,

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

Objectives

Since 1990, laparoscopic nephrectomy has been adopted by many centres as an operative alternative for patients requiring kidney removal. Only a few series comparing the laparoscopic and open approaches have been reported. We carried out a prospective comparison between laparoscopic, open transperitoneal, and open retroperitoneal nephrectomy.

Materials

Between October 1998 and April 2000, 116 patients underwent nephrectomy at our hospital. There were 45 patients who underwent laparoscopic nephrectomy (group 1), 52 patients who had an open transperitoneal nephrectomy for renal cancer (group 2) and 19 patients who had an open retroperitoneal nephrectomy for benign diseases (group 3). Various operative and postoperative parameters were investigated.

Results

In the laparoscopy group, the median operative time was less when compared to open nephrectomy (80 vs. 158 vs. 140 minutes). Complication rates were comparable for all groups (18.8 vs. 21.8 vs. 25%). Patients in the laparoscopy group had less pain and analgesic consumption, earlier mobilisation and oral intake. Furthermore, these patients had a shorter duration of hospital stay (5 vs. 10 vs. 10 days) and reconvalescence (28 vs. 49 vs. 46 days) when compared to the open nephrectomy groups.

Conclusions

Laparoscopic nephrectomy results in an improved postoperative course when compared to open nephrectomy. Patients after open retroperitoneal nephrectomy do worse in terms of pain, appetite loss and other gastrointestinal symptoms when compared to open transperitoneal nephrectomy.

Laparoscopic Bilateral Nephrectomy: Indication and Outcome

C. Doehn, N. Kirac, P. Fornara, L. Fricke, D. Jocham,

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

Objectives

Hypertension is an important risk factor for the development of chronic allograft failure and decreased graft and patient survival following renal transplantation. Despite the availability of potent antihypertensive drugs, a few patients still suffer from severe hypertension. Bilateral nephrectomy has been shown to be effective in lowering the blood pressure in 60% to 80% of such patients. We report our experience with laparoscopic bilateral nephrectomy for the treatment of severe hypertension following renal transplantation.

Materials

From August 1994 to July 1999, 36 patients underwent laparoscopic bilateral nephrectomy for severe hypertension following successful renal transplantation. The age range was between 23 and 59 years. In all patients, the laparoscopic bilateral nephrectomy was performed via the transperitoneal approach. A point system for the measurement of antihypertensive drug potencies and dosages was developed.

Results

Parameters such as operative time, complications and conversions, analgesic consumption, start of ambulation and oral intake, and durations of hospitalisation and reconvalescence were comparable to those obtained in non-transplant patients undergoing laparoscopic unilateral nephrectomy. Postoperative blood pressure improved significantly in 31 out of 36 patients (86%). Moreover, a significant reduction of the number of antihypertensive drugs was achieved.

Conclusions

In our experience, bilateral nephrectomy is effective in reducing blood pressure in renal transplant patients with severe blood pressure. The laparoscopic approach offers not just a brief postoperative period but also an appreciated outcome for the risk group of renal

Laparoscopic Nephroureterectomy

C. Doehn, P. Fornara, L. Fricke, D. Jocham

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

Objectives

Nephroureterectomy is indicated for upper urinary tract transitional cell carcinoma and certain benign conditions. We report our experience with laparoscopic nephroureterectomy for benign diseases.

Materials

Since 1994 22 patients (16 women and 6 men) with a mean age of 50 years (range 22 to 70) underwent a laparoscopic nephroureterectomy at our hospital. Indications for an operation were non-functioning kidneys due to vesicoureteral reflux (n=11) or ureteral obstruction from a calculus (n=2) with recurrent episodes of pyelonephritis or analgesic nephropathy (n=9) prior to a planned renal transplantation.

Results

The mean operative time was 98 minutes (range 40 to 165 minutes). The mean blood loss was 140 ml. (range 50 to 550 ml.). A conversion to open surgery was not necessary. Six complications (27%) occurred and included a postoperative elevations of the body temperature and flank haematomas. Analgesic consumption for postoperative pain control was 12 mg. of morphine equivalent (range 0 to 30 mg.). The mean hospital stay was 5.7 days (range 2 to 12 days) and the mean reconvalescence 21 days (range 6 to 44 days).

Conclusions

Laparoscopic nephroureterectomy results in similar operative results and an improved postoperative course when compared to open operative techniques. Therefore, this is the preferred technique in our department for patients with benign disease who require a nephroureterectomy.

Percutaneous Fixation of Pelvic Fractures With CT Control

P. Eude, C. Trojani, G. Eude, S. Piche, C. Avidor, C. Aboulker, F. De Peretti

Hôpital Saint-Roch – Centre Hospitalier Universitaire de Nice, Nice, France

We present a series of 45 fractures operated on over a period of 26 months. Among the injuries were 31 to the sacroiliac joint (69%), 11 acetabular injuries (24%) and 2 associations. The causes were mainly road accidents in 26 cases (58%) and falls in 17 (38%). Most of the patients were young; 34 (75%) were under 50 years of age but six (13%) were older than 70 (max 83).

A spinal anesthesia was performed in 40 (89%). The operator was a surgeon, a radiologist or in case of bilateral injuries, both were present, operating simultaneously on both sides. The approach was strictly percutaneous through a centimetric incision allowing introduction of the screw. In some cases, two screws could be driven through one same opening. A cautiously introduced guide pin allows introduction of a drill and then a screw, with the direction of the various devices being controlled by CT slices. Usually it takes between 20 and 35 minutes for each screw and the total occupation time of the CT room for such an operation does not usually exceed two and a half hours including anesthesia, preparation of table, patient and operators. We did not notice any operative complications.

The pain relief begins after 24 to 36 hours after the operation. The problem is obviously specific for some patients with lower-limb or spine injuries, whose comfort is, however, improved. Most of the patients are able to sit up the day after and as often as possible, they begin to stand up and walk right on this same day. They most often exit the surgery department after 3 to 5 days towards rehabilitation units or even home. Another interest of this technique is therefore the highly significant savings due to all these factors.

Percutaneous Transvascular Aortic Valve Replacement with Self-Expanding Stent Valve Device

M. Ferrari¹, I. Tenner¹, H.R. Figulla¹, C. Damm², T. Peschel², C. Weber²

¹ Clinic of Internal Medicine, Jena University Medical Center, Jena, Germany

² Fraunhofer Institute IOF, Jena, Germany

Besides surgical replacement for the treatment of aortic valve stenosis or insufficiency, there is still a lack of sufficient alternatives. Due to high risks of open-heart operation especially in elderly and multi-morbid patients, a minimally invasive therapeutically approach would be favorable.

A possible solution of these problems can be seen in a transvascular implantation of a so-called bio valve which is made of porcine heart valve by chemical fixation. This bio valve is attached to the distal end of a Nitinol stent. The stent valve device can be implanted with a catheter by folding it to a diameter of 6 mm. The self-expanding stent deflates the bio-valve in an orthotopic position in the left outlet tract pushing the old valve into the aortic vessel wall.

A newly designed self-expanding Nitinol stent was designed as the result of a cooperation of the Friedrich Schiller University and the Fraunhofer Institute in Jena. This Nitinol stent provides high flexibility and stiffness for optimal placement in the outlet tract of the beating heart. For correct placement of the commissures, the coronary ostials should be marked by guiding catheters. Fluoroscopy and transesophageal echo are useful for optimal implantation of the valve-stent device. The design of the stent stabilizes the bio valve after deflation in a physiological manner. We tested the self-expanding stent valve device in an artificial circulation model achieving the following results:

· no dislocation occurred up to a pressure load of > 200 mmHg

· the maximum transvavular pressure gradient was < 22 mmHg under flow rate of 5 l/min

· leakage flow was < 500 ml/min under pulsatile pressure load of 120 / 80 mmHg

Because of these promising results in vitro we intend to perform animal experiments with the self-expanding stent-valve device.

Robotics in Combination with Imaging Systems

H. Fischer¹, J. Vagner¹, A. Felden¹, A. Hinz¹, A. Schäf¹, H. Baltschun¹, W. A. Kaiser²

¹ Institute of Medical Technology and Biophysics, Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

² Institute of Diagnostic and Interventional Radiology, Jena University Medical Center, Jena, Germany

In cooperation with the Institute of Diagnostic and Interventional Radiology of the Friedrich-Schiller-University of Jena, the Forschungszentrum Karlsruhe (Karlsruhe Research Center) developed a manipulator that allows for biopsy and subsequent therapy directly in the ISO center of the MRT. The system includes a control and driving unit for the three axes of motion, and a gripping unit for charging the manipulator with instruments for biopsy removal. Movement along the x- and y- axes takes place by means of US (Ultra Sound) motors. To measure the actual position of the manipulator optical rotation code transducers are used.

Thus, tissue specimens can be taken from smallest tumors under imaging control. Following the immediate histological investigation of this biopsy specimen, a minimally invasive therapy with e.g. laser technology or cryotechnology can be initiated immediately in case of malignant findings.

After completion of numerous experiments and test runs, the manipulator is intended for use in the combination of diagnostics, biopsy and therapy in a single examination step. Whole interventions shall take place within a relatively short period of time without causing too much strain on the patient, i.e. in a routine setting to be developed within a period of about 45 -60 minutes in total. As a consequence, the patient can leave the hospital immediately after the ambulant diagnosis and removal of the breast cancer. Follow-up examinations should control the success of the treatment. Thus, the high total costs for the operation, anesthesia, hospital stay and inability to work can be reduced significantly. Furthermore, the patient does not experience any significant scar-related complications. Within the framework of the present research project, various therapy forms shall be studied with regard to their suitability for the elimination of breast cancers.

NiTi Applications for MIT

H. Fischer, B. Vogel, M. Kaiser, K. Britzel

Institute of Medical Technology and Biophysics, Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

Shape Memory Alloys, such as Nickel Titanium (NiTi) undergo a phase transformation in their crystal structure when cooled from the high temperature phase (Austenite, strong mechanical behavior) to the low temperature phase (Martensite, weak mechanical behavior). This inherent phase transformation is the basis for unique properties such as thermal shape memory and superelasticity. Its widespread use can be attributed not only to those remarkable properties, but also to lesser known but equally important properties, such as constant stress and stress hysteresis as well as their temperature dependence. Because of its excellent biocompatibility and high corrosion resistance, NiTi has become the material of choice for many implants, instruments and accessories for minimally invasive therapies, mainly in endoscopic surgery and interventional radiology. This paper explains the thermal shape memory effect and the mechanical shape memory effect, which is known as superelasticity. It also gives an overview of the NiTi applications, developed in the Forschungszentrum Karlsruhe: A flexible distal tip for a steerable endoscopic camera system was formed, welded and structured. In order to perform bypass operations on the beating heart, stabilizers must be used causing a regional immobilization of the heart. If this operation is carried out entirely endoscopically with a robot system, the stabilizer must also be inserted endoscopically. Using the effect of the constant force (strain), an endoscopic stabilizer for minimally invasive cardiac surgery, which applies a constant force onto the heart over a wide range of positions, was developed. Constant force and superelasticity were also used on a spreader for the fatty tissue of the heart in order to make anastomosis easier. And finally, the kink resistance is shown on guide wires, dilatators and retrieval baskets in all kinds of different variations.

– Minimally Invasive Urogynecology –

7 Years Experience with Laparoscopic Burch Colposuspension

V. Frank, V. Koch and E.H. Schmidt

In 1991 the laparoscopic Burch colposuspension was first described by Vancaillie and Schüssler and since than has gained increasing popularity.

Study objective:

Evaluation of the laparoscopic Burch procedure with transperitoneal entry to the space of Retzius.

Methods:

In a prospective observational study women with genuine stress incontinence underwent a laparoscopic colposuspension according to the open procedure described by Burch 1961. The patients were examined prior and 6 months to 7 years after laparoscopic colposuspension.

Results:

Since 1993 306 women with genuine stress incontinence had a laparoscopic Burch procedure. An interims analysis in 1999 of 231 women showed the following results: Age ranged from 27 to 78 years (average 54.8 years). 66.7% of the women presented with moderate (II°) and 25.9% with severe (III°) stress incontinence. In 60.2% concomitant procedures such as hysterectomies and/or surgical procedures for pelvic floor defect were performed. The mean follow-up was 19.3 months (3 to 52 months). The overall success rate was 84.2%. Women with hypotonic urethra had a clinical success rate of 73.3%. Postoperative de novo detrusor instability was observed in 3.8%. The most frequent complication observed was injury of the bladder during dissection of the space of Retzius (6.9%).

Conclusion:

Laparoscopic Burch colposuspension is an effective method for the treatment of genuine stress incontinence. The overall success rate is 84.2% and therefore comparable with the open Burch procedure.

Cardiac intervention in a new century

Erik Fosse, MD

The Interventional Centre, Rikshospitalet, Oslo, Norway.

The development of modern treatment for cardiac disease is based on a continuous chain of achievements in imaging technology, extracorporeal circulatory technology and surgical techniques.

The development of modern angiography has made invasive accurate diagnostics of cardiac anomalities possible.

The development of echocardiography has made non invasive diagnostics of valve disease and congenital disease possible.

The development of extracorporeal circulation allowing intracardiac surgery was started by C. Walton Lillehei when he did the first cross-circulatory operation closing an atrial septal defect in a 1 year old boy, using his mother as the “heart lung machine” 26. march 1954. 13. May 1955 Lillehei performed ASD closure in a three year old child using the De Wall oxygenator.

A rapid improvement in heart lung machines and the development of membrane oxygenators, biocompatible surfaces etc has made open cardiac surgery into safe procedure associated with low morbididty and mortality.

In 1979 Andreas Grüntzig published a series of 50 coronary patients treated with percutaneous transluminal coronary angioplasty. Later angioplasty was further developed by the construction of stents. Today 60-70% of patients with coronary disease are treated by angioplasty.

The new technologies also lead to new complications. Angiography is associated with serious cerebrovascular complications in 0.2% of cases. The cerebrovascular complications of extracorporeal circulation is also well known. In 1967 Kolessov and coworkers reported successful direct anastomosis of the mammary artery to the left anterior descending artery on a beating heart. By 1968 coronary revascularization was a widespread technique performed on extracorporeal circulation. In the beginning of the nineties Bennetti and Buffolo published large series on beating heart coronary revascularization with good results.

During the nineties new technology has made beating heart coronary revascularization into a safe procedure, avoiding the heart lung machine altogether.

During the nineties development of visualization techniques has made minimal access surgery an option in most surgical disciplines. Attempts to perform minimal access cardiac surgery was made in the mid-nineties. And several centers routinely use endoscopic LIMA harvesting or video assisted valve reconstruction and replacement.

By the end of the nineties robots were introduced to facilitate total endoscopic bypass surgery.

During the last two decades transluminal stenting techniques developed further making interventional closure of persisting ductus arteriosus into a radiological procedure. During the nineties several devices was developed to close atrial septal defects, and ventricular septal defects.

Imaging technology is in rapid development by the beginning of the new century. New technologies for image acquisition such as CT, ultrasound and MRI together with new image guided therapies have made images to a very important source of information in both diagnostics and treatment. In radiological departments more and more examinations are done by magnetic resonance imaging (MRI).

Development of radiological technology and MRI systems can make reflected light visualization superfluous. Surgery may be performed just by percutaneous insertion of the instruments.

Robotic systems may increase dexterity in minimally invasive procedures and was introduced in cardiac surgery by the late nineties. By the beginning of this century more than 300 cardiac operation had been performed with either the Zeus (Computer Motion, Goleta CA) or the Da Vinci (Intuitive,CA) robotic systems.

Robots for surgery are in an early stage. The development of microrobots and “intelligent” catheters may change the whole concept of cardiac intervention.

An Approach for the OR of the Future

Erik Fosse, MD

The Interventional Centre, Rikshospitalet, Oslo, Norway.

In order to meet the organisational and technical challenges invoked by the introduction of new technology in the hospitals, The Interventional Centre at Rikshospitalet was established in 1996 in a provisional building, as the hospital was moving to a new location in May 2000. The centre is a research and development department within the field of image guided and minimal invasive therapy, with the following tasks: to develop new procedures, develop new treatment strategies, make comparative studies between existing strategies and new strategy and study the social, economical and organisational consequences of new techniques.

The department was cross-disciplinary organised and included two completely merged operation theatres/radiology suites. In one room there was an open Signa 0,5 Tesla magnet (General Electric Medical Systems, Milwaukee), the other room was a combined angiography and operation suite.

From the opening June first 1996 until the moving of the hospital in May 2000, 1800 patients and healthy test persons where treated or examined at the centre, 140 animal procedures and 120 technical tests were performed in the same period.

The main advantages of the centre were:

New procedures may be developed outside the normal hospital routines

Cross-disciplinary work is encouraged

Advanced, expensive technical equipment with a competent operating staff is made available to all the departments in the hospital.

During the summer of year 2000 the centre was installed in new location in the new Rikshospitalet. The centre now has a treatment area of 700 square meters with three ORs. In a addition a communication centre with fiberoptic lines to the three ORs of the centre and four ORs in the general operation department for transmission to the lecture rooms inside the hospital and for communication with external locations on ISDN lines, ATM lines and via satellite. The centre also contains a technical laboratory for dry-lab robot training, simulator development and image processing research.

Modern interventional treatment will require specially designed rooms with integrated imaging solutions. The development of microtechnology will increase the use of robots and biosensors in interventional procedures. Voice controlled or operator control of different functions in the OR will reduce the need for personnel, although cross-disciplinary approach to treatment will be increasingly important.

Objective Assessment of Perceptual Skill that Predicts Laparoscopic Performance in Three Separate Studies

A. G. Gallagher, R. Cowie, I. Crothers, J.-A. Jordan, J. McGuigan, N. McClure

Northern Ireland Centre for Endoscopic Training and Research and The Queen's University of Belfast, Belfast, Ireland

Aims

The loss of the third dimension in laparoscopic surgery is not resolved by the use of contemporary 3D camera systems, and it is therefore crucial to find ways of measuring differences in aptitude for recovering a 3D structure from 2D images, and assessing its impact on performance. Our aim was to test empirically for a relationship between laparoscopic ability and the perceptual skill of recovering information about 3D structures from 2D monitor displays.

Methods

Participants in three studies completed a simulated laparoscopic cutting task as well as the Pictorial Surface Orientation Battery (PicSOr) Test.

In studies 1 (n = 48) and 2 (n = 32) both groups were laparoscopic novices and among the participants in study 3 (n = 32), 16 of the subjects were experienced laparoscopic surgeons.

Results

All three studies showed that PicSOr consistently predicted the laparoscopic performance of participants on the laparoscopic cutting task (study 1, r = 0.497, p < 0.0003; study 2, r = 0.495, p < 0.004 and study 3, r = 0.417, p = 0.017). Furthermore, the test was also a significant predictor of the performance of laparoscopic surgeons (r = 0.537, p = 0.047).

Conclusions

This is the first objective perceptual psychometric task to reliably predict laparoscopic ability. PicSOr may provide the means of assessing which trainees have the potential to learn minimal access surgery.

Keywords: Laparoscopic, objective assessment pictorial perception,

MR Monitoring and Prediction of Laser Lesion Size in Liver and Breast Using SE and CBASS3D Sequences

D. Germain^1,2, P. Chevallier³, H. Saint-Jalmes⁴, E. Vahala⁵, G. Ehnholm⁵, C. Becker⁶, F. Terrier⁶, M. Wassef⁷, A. Laurent^1,7.

¹ Cr2i, APHP-INRA, Jouy en Josas, France

² Marconi Medical Systems France, Chatenay-Malabry, France

³ Hôpital de l'Archet 2, Nice, France

⁴ Laboratoire de RMN, Université Lyon 1, Villeurbanne, France

⁵ Marconi Medical Systems Finland, Vantaa, Finland

⁶ University Hospital of Geneva, Geneva, Switzerland

⁷ Hôpital Lariboisière, Paris, France

Objective

To use MRI for monitoring the temperature during laser ablations of animal liver and breast tissues in vivo, and to study the feasibility of lesion size prediction, both in a low-field open magnet.

Materials and methods:

Two temperature measurement studies were conducted: one in vivo using Spin Echo (SE), the other in vitro using 3D Completely Balanced Steady State (CBASS3D) sequences. The imaging was done in a 0.23 T open magnet (Marconi Medical Systems Finland, Vantaa, Finland). 1- For the first study, a single-loop coil with a diameter of 14 cm was used. The ablator consisted of an 810 nm diode laser. It was applied, in vivo, for 300-400 s at 3-5 W on six pig livers and one sheep breast, the animals being under general anaesthesia. During liver experiments, the temperature was measured with thermocouples as well as with MRI, using SE sequences. Image acquisition took 29 s with a voxel size of 30 mm3 for the livers and 56 s with a voxel size of 40 mm3 for the breast. The values were chosen so as to allow calculation of temperature maps using sensitivities of T1 and M0 to the temperature. Calibration of the sensitivities was performed ex vivo, prior to the experiment. Images predicting damaged tissue were computed during the experiment by integrating temperature over time using Arrhenius's law. T2-weighted sequences were acquired at the end of the treatment. For imaging of the liver, all sequences were acquired while the animal was in apnoea. Animals were sacrificed at the end of the procedure in the liver experiments and 16 days after the ablation in the breast experiment. Lesion sizes were confirmed histologically and compared with the estimates from MRI sequences and temperature maps. 2- For the second study, a single-loop coil of diameter of 17 cm was used. The ablator was an Nd-YAG laser with a cooled tip probe. The laser was applied for 15 min at 25W on extracted pig liver tissue. A CBASS3D sequence was used for MRI temperature measurement. Acquisition time was 34 s with a voxel size of 19.5 mm3, resulting in a SNR of 40 in liver tissue. Mathematica (Wolfram Research, Inc., IL, USA) was used to simulate the behaviour of the MRI signal and to estimate the precision in the temperature measurement.

Results

1. In the pig liver, in vivo, a correlation exists between temperature measurements with SE MRI sequences and thermocouples (rho=0.875 p<0.001 Spearman test; cf. graph). Mean surface of predicted tissue damage is consistent with mean necrosis seen on macroscopic photos of the lesions. In the breast, in vivo, visualisation of temperature distribution is possible with SE sequences. 2. Temperature images were calculated with CBASS3D images during laser application (cf. image). In the liver, CBASS3D images should yield a temperature precision of approximately 3°C.

Conclusions

Temperature monitoring during laser ablation in liver and breast is possible, in vivo, in a low-field open scanner. Prediction of lesion size from MR images seems very promising. CBASS3D sequences should permit us to obtain 3D temperature maps with a better temperature precision and spatial resolution than SE sequences.

Operating room of the Future

Distributed Medical Intelligence and the EU Project GALENOS

G. Graschew, P. M. Schlag*

Surgical Research Unit OP 2000, Robert-Roessle-Clinic at the Max-Delbrueck-Center for Molecular Medicine (MDC), Academic Hospital Charité of the Humboldt University at Berlin, Lindenberger Weg 80, D-13122 Berlin, Germany.

*Director of the Clinic for Surgery and Surgical Oncology, Robert-Roessle-Clinic at the MDC, Academic Hospital Charité of the Humboldt University at Berlin, Lindenberger Weg 80, D-13122 Berlin, Germany.

and A. Melzer**,

* *Mülheimer Radiologie Institut, Schulstraße 10, D-45468 Mülheim an der Ruhr, Germany

The Surgical Research Unit "OP 2000" (Operating room of the Future) of the Robert-Roessle-Clinic at the Max-Delbrueck-Center for Molecular Medicine (MDC), Academic Hospital Charité of the Humboldt University at Berlin has developed and tested several modern interactive telecommunication components in close cooperation with worldwide leading academic and non-academic institutions as well as industrial partners. At present, the operating room of the future in the Robert-Roessle-Clinic does not merely serve to demonstrate the functioning of the new technologies, but at the same time optimizations with respect to ergonomic design and human-machine interfaces are elaborated.

Modern video-, communication- and computer-technologies have enabled the realization of extended competence networks, which allow physicians, although distributed over several different locations, to work in an collaborative way. These competence networks may play a key role in ensuring the quality of medical care in the future.

In the GALENOS project (Generic Advanced Low-cost trans-European Network Over Satellite) such a European competence network via satellite, dedicated to telemedical applications, has been realized. Owing to the participation of industrial partners in integrating the communication network and getting satellite transmission capacity available, several telemedical services (e.g. offline access to archived data, live consultation of experts, etc.) have become available in a unified and low-cost technology. This distributed medical intelligence in the competence network enables e.g. local physicians or local hospitals that are confronted with unexpected test results to get online advice from the nearest academic hospital.

This possibility to get support from external experts, the improvement of the precision of the surgical treatment by means of computer-assisted surgery and manipulator- and/or robot-assisted systems, and last but not least, online documentation and hence improved analysis of the available data of a patient, will contribute to a continuous improvement in treatment and care of patients.

Sofia/Bulgarien - Institut für Endokrinologie

Firenze - Hospital Careggi - alle Spezialisten vorhanden - Radiologie ?

Athen - Demokritos Research center - Naturwissenschaftler

Berlin Charité - alle Spezialisten vorhanden - Ultraschall, Endoskopie,

pathologie

Physically Based Tissue Models for Surgery Simulations

J.Gross¹ , M.Hauth² , B. Eberhard² , O. Etzmuss² , L. Schnieder¹ , G.Buess¹

¹Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Medical Center, Tübingen, Germany

² Computer Graphics Lab, Wilhelm Schickard Institute for Computer Science, Tübingen University

Up to now, the mechanical properties of tissues for surgical simulation were seldom determined on physical grounds. Usually, the elastic moduli are roughly chosen as to reflect typical values of real organs. Damping terms are adjusted to yield stable simulations and give some kind of resemblance to real organs. The result are models with a limited degree of realism at least from the physical point of view. We have therefore started to develop a physically correct model for tissues that uses measured elastic and relaxation data in order to produce a more realistic organ simulation.

The most obvious drawback of current tissue simulations is the exponential relaxation behavior of the simulated tissue. This produces damping centered to a specific frequency, which makes the model react realistically on a single time scale, but not for faster or much slower deformations. In reality, tissues exhibit a very wide spectrum of relaxation frequencies. This makes it necessary to approximate the mechanical relaxation behavior by a superposition of multiple standard exponential terms. As it turns out, however, only three exponential terms with appropriate weights and frequencies are sufficient to reproduce the relaxation function over more than two orders of magnitude in time scale - which is enough to produce a much better impression of the organ deformation during surgery simulation.

In the organ model, the weights and frequencies of the tissue are adjusted by choosing appropriate damping terms parallel to the springs in the mass-spring system. The key is to use several different damping terms dispersed in a statistical manner over the organ.

The simulation will be as fast as any standard mass spring (or finite element) simulation because no additional computations are necessary. Moreover, no explicit modeling of hysteresis is necessary, because the correct relaxation behavior entails realistic hysteresis of the tissue automatically.

In order to acquire the information necessary to do the modeling, time-dependent shear measurements were performed on tissues (since there are virtually no published data on soft tissues). In our current setup, a slice of liver is glued between aluminum plates using cyanide glue. The plates are mounted in a mechanical testing machine in a way that ensures pure shear deformation for the sample. Then the sample is loaded and unloaded repeatedly for about 20 min. The resulting data are fitted using a mathematical model, from which the exponential relaxation terms can be determined.

Currently, the experimental data are being used to set up a simple organ model. This organ will then be virtually deformed in several ways to ensure that it conforms to the experimental data. Finally, the simulation will be assessed by surgeons in terms of realistic deformation in typical surgical tasks, such as grasping.

The Totally Extraperitoneal Approach of Bilateral and Recurrent Inguinal Hernias

I. Grote

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Patients

Since the beginning of 1998, we have conducted a prospective non-randomized study of 589 patients who had received a totally extraperitoneal (TEP) repair of inguinal hernias. 107 of these patients had bilateral inguinal hernias, 68 of them showed recurrent inguinal hernias.

Method

The dissection of the preperitoneal space starts with a subumbilical, retromuscular approach with the help of a reusable balloon dissector. We use two 10 mm-trocars for the preparation of the inguinal region, especially the hernial sac. The hernial orifice is closed with a 12 cm x 15 cm non-resorbable mesh.

Results

During the whole period, we repaired 683 inguinal hernias. Beside this method we performed 45 Lichtenstein repairs and in 49 cases a Shouldice procedure. All bilateral hernias were repaired at the same time. The conversion rate of the endoscopic repair is beyond 1%. Major complications did not occur. Minor complications (

(two infections of the umbilicus, three preperitoneal heatomas, two nerve irritations and five seromas) were treated conservatively. Until now, we have not observed any early recurrences.

Conclusion

The TEP hernia repair is feasible for bilateral and recurrent hernias with the use of sufficient large meshes. The complication and recurrence rate is low. The repair of primary inguinal hernias is part of the training program for residents, whereas the closure of recurrent hernias should be done by a surgeon who is familiar with the endoscopic operation technique.

Microvascular Anastomosis Observing an Endoscopic Image in the Microscopic Field of View

A. Hayashi, Y. Maruyama, M. Osaki, E. Okada

Department of Plastic and Reconstructive Surgery, Toho University Hospital, Tokyo, Japan

Surgical microscopes have come a long way during the past few years. Rapid advances in optical, electrical and mechanical technology have made it possible to design microscopes that are easier to use and more precise than ever before.

For the purpose of performing a safe and precise microsurgical operation, we used OME-8000 (OLYMPUS, Tokyo) for microvascular dissection and anastomosis. The surgeon can observe an endoscopic image in the field of view. Thus, the surgeon can observe views from the opposite side or different angle during microsurgical operations.

An in-field monitor provides surgeons with greater flexibility and precision by displaying a live endoscopic image or a transmitted image taken before the operation (CT or MRI) within the microscopic imaging field. The monitor image is displayed in the top left corner during microscopic observation and can be switched on and off by simply pressing the foot switch.

The OME-8000's optical system allows the surgeon's assistant to simultaneously observe the same three-dimensional image, in any position relative to the operating surgeon, with the same axial relations and magnification. During high-magnification observation by the operating surgeon, the magnification of the assistant's image can be independently reduced for a macroscopic observation. A coaxial illumination system provides bright, even illumination throughout the field of view. An upgraded zoom system with greater local depth provides both the operating surgeon and assistants with clearer, more precise images.

Six-month results obtained in patients with osteochondritis dissecans treated with high-energy extracorporeal shock-wave therapy (ESWT)

S. Heidersdorf, S. Lauber, H.-J. Lauber

The objective of this study is to test the effectiveness of high-energy shock waves for the treatment of osteochondritis dissecans (OD). For this purpose a prospective multi-center study was carried out in the form of a cooperative venture involving the ESWT Center in Hattingen (Germany), the Division of Radiology of Velbert-Niederberg Hospital and the Division of Orthopedic Surgery at University Hospital Bochum.

Between 10/97 and 7/98 ten patients suffering from OD (/ x OD of the femoral condyle, 3 x OD of the talus) were treated with high-energy shock waves using an Ossatron unit (HMT Company).Following a standardized initial examination, an identical clinical examination and MRI examination were formed two weeks, six weeks, three months and six months after the high-energy shock-wave therapy. The clinical course was evaluated on the Visual Pain Analog Scale and the clinical scales developed by Brückl and Larson.

The results obtained from 8 patients (6 x OD of the femoral condyle and 2 x OD of the talus) were analyzed. A distinct improvement or even recovery was observed in six patients. In two patients, the initial findings remained unchanged six month after the administration of high-energy shock-wave therapy.A worsening of the findings was not observed in any of the cases documented. The score achieved on the Visual Pain Analog Scale improved from 7.0 to 2.7. The average score on the Brückl Scale decreased from 8.2 to 3.0 on the average, whereas the score on the Larson Scale climbed from 48 to 83 points.

Both the clinical and MRI results after 6 month shows that good results were achieved with this method. This is an indication that use of high-energy shock waves represents a non-invasive, low-risk and reasonably priced treatment for OD. The one-year results will be analyzed in a future study.

Virtual Neuronavigation Using Virtual Reality and Deformable Tissue Simulation

D. Hellwig, T. Riegel, H. Bertalanffy

Department of Neurosurgery, Marburg University Medical Center, Marburg, Germany

Objectives

Modern computer technology opens new tracks to the examination of the ventricular system. By using computerized flight-through simulations, minimally invasive examinations of patients' ventricular system can be performed with the help of virtual neuronavigation technology

Material and Method

MRI data were collected using a GE Helical Scanner (1.5 Tesla Sigma Highspeed) and were stored in the Dicom file format. The data were transferred to a Sun workstation running the GE Navigator software provided by GE Medical Systems. The Navigator software automatically converted this series of MRI images to a three- dimensional model by using the Dicom-specific information of location and slice thickness of each MRI image. Within this three-dimensional model, virtual operative approaches can be simulated navigating freely through the ventricular system.

Results

Eight patients with different pathologies of the ventricular system - aqueductal stenosis (3), colloid cysts (3), solid tumors (4) - have been examined preoperatively using virtual neuronavigation. The size of the ventricles, intraventricular vessels, as well as the three-dimensional extension of the cysts and the tumors could be clearly identified. With the help of this model, it was possible to decide whether the CSF pathways were blocked or if there was normal CSF circulation. Free navigation within the ventricular system was possible in flight through sequences. Unfortunately, textures and colors are still missing at the moment.

Conclusion

Virtual neuronavigation provides important information about the intraventricular pathology before the operative procedure. The planning of the operative approach can be carried out with greater precision, as it is possible to visualize structures that lie behind the operative field. Once the technical limitations have been overcome, virtual neuronavigation will become an integral part of operative planning as well as a useful tool for education and training.

Using High Energetic Shock Wave Therapy for the Treatment of Pseudarthrosis

C. Herbert

Berlin Center of Shockwave Therapy, Berlin, Germany

Using high-energy acoustical waves (shock waves) in therapy is not new. Urologists have used shockwaves successfully for years to disintegrate kidney stones. The advantage is that there is no intensive surgery with any risk to the patient. In orthopedics and traumatology Valchanaou (1991), Michailov and Sokul et al. (1992) introduced high energetic shockwave therapy for the treatment of non-healing fractures (pseudarthrosis) or delayed union.

For nearly 10 years, numerous articles have been written on the positive experience in using shockwave therapy. We know about indications for atrophic, oligotrophic and hypertrophic non-union. Limiting factors of ESWT for expanded and instable non-healing fractures are well known.

Receiving only one general or one regional anesthetic the impact of shockwaves causes micro fractures and bleedings into the bone, thus stimulating osteogenesis. Osteosynthetic material does not disturb the treatment. Under conditions of usual fracture therapy, the non-union will be completely stabilized in three months after shockwave therapy.

The advantages of ESWT in comparison to operating are obvious. Patients who had surgical treatment several times don’t need any further risky operations, attended by a well known rate of complications like osteomyelitis and wound infection.

Having clear indications and appraising all risks for the patient, shock wave therapy should be appreciated as a gentle and low-risk therapy and it should be accepted as an effective and alternative to surgical management.

Musculoskeletal Shock Wave Therapy for the Treatment of Tendinosis Calcarea, Follow-Up of 1483 Patients Between 1995 and 1998 (4 Years)

C. Herbert, R. Thiele, T. Hartmann, K. Helbig

Berlin Center for Shockwave Therapy, Berlin, Germany

Between January 1995 and December 1998, we treated 1483 patients with tendinosis calcarea in our Center of Shockwave Therapy in Berlin. On these patients, we performed a total of 3017 shoulder treatments with an average of 2.03 treatments per patient. Treatment followed the guidelines set by the German Society of Shockwave Therapy. All patients were treated conventionally at least between 6 and 24 months prior to shockwave therapy. The follow-up investigation was performed 6 months after the last treatment. The results: motility – 68 % success; pain – 76 % success; X-ray-resolving or improvement - 72 % success. For the future another follow-up investigation is planed fall all these patients to get results for a period of 1 1/5 until 5 years after treatment.

Shockwave therapy of pseudoarthrosis

(org.: Pseudarthrosenbehandlung mit Stosswellen)

C. Herbert

In Orthopedics and traumatologic medicine Valchanaou (1991), Michailov and Sokul et al. (1992) inaugurated high energetic shockwave therapy on the treatment of non-healing fractures (pseudarthrosis) or delayed union.

For nearly 10 years numerous articles on positive experience using shockwave therapy have been written. We know about indication between atrophic, oligotrophic and hypertrophic non-union. Limiting factors of ESWT for expanded and instable non-healing fractures are well known.

Receiving only one general or one regional anaesthetic the impact of shockwaves causes micro fractures and bleedings into the bone. Osteogenesis will be stimulated. Osteosynthetic material does not disturb the treatment. Under the condition of usual fractures therapy, the non-union will be completely stabilized in three months after shockwave therapy.

The advantages of ESWT in comparison to operating are obvious. Patients, who had surgical treatment on several times, don’t need any further risk operations, attended by a well known rate of complications like osteomyelitis and wound infection.

Having clear indications and appraising all risks for the patient, shock wave therapy should be appreciated as a gentle and small risk therapy and it should be accepted as an effective and alternative for surgical management.

Principles of Musculoskeletal Shockwave Therapy for the Treatment of Soft Tissue

C. Herbert

Extracorporal shockwave therapy in orthopedic subject has been established in clinic since 1988. Since 1994 orthotripsy is used in ambulant medicine. The main indications till now are 1. Soft tissue diseases with and without calcifications 2. Pseudarthrosis or delayed healing fractures.

Tendinosis calcarea: Degenerative calcification is formed directly at the major tubercle. Typically, the calcific deposit of calcifying tendonitis is found in the rotator tendon. The calcification of hydroxyapatite is usually formed by fibrocartilage cells through an unknown stimulus. We know a two-phase disease, the chronic initial phase with type I and the acute phase with type 3 calcification. From our Berlin Extracorporal Shockwave Center 1750 treatments of shoulders can be presented. According to the results of other authors, there is a success rate of 85 %.

Epicondylitis: The success rate of ulnar side orthotripsy is lower, compared to the radial side of epicondylitis. There are better results in more chronic pain groups with duration of disease more than 3 month. In sports medicine some groups reported very good results in early stage of pain.

Heel spur: Best results are considered on heel spur or plantar fasciitis shockwave application. It’s shown, that high energy shockwave therapy leads to better results than low energy treatment

Achillodynia and Knee Tendinopathies: Until now there are no sufficient studies about shockwave therapy in chronic pain stage. It may be useful for treating acute pain after sports injuries.

Duypuytren: As reported in London, shockwave therapy can’t be adviced in the therapy of Dupuytren or Ledderhose’s contracture.

Musculoskeletal shockwave therapy for the treatment of tendinosis calcarea,follow up of 1483 patients between 1995 and 1998 ( 4 years)

C. Herbert MD, Richard Thiele MD, Thomas Hartmann MD, Karin Helbig MD, Berlin Center of shockwave therapy

From 1/1995 until 12/1998 in our Center of shockwave therapy Berlin, we treated 1483 patients with tendinosis calcarea of the shoulder. We did for these patients 3017 shoulder treatments with an average of 2,03 treatments per patient. The treatment was done under the guideline conditions of the German Society of Shockwave Therapy. All the patients were treated before shockwave therapy conventionally at least 6 until 24 months. The follow up investigation was done 6 months after the last treatment. The results: motility – 68 % success; pain – 76 % success; X-ray-resolving or improvement - 72 % success. For the future another follow up- investigation is planed fall all these patients to get results for a period of 1 1/5 until 5 years after treatment.

Repetitive CT-Guided Minimally Invasive Periradicular and Epidural Therapy in 92 Patients: One-Year Follow-UP

S. A. Hengst, J. C. Boeck, M. T. Pflaesterer-Schoensiegel, R. Felix

Clinic of Nuclear Medicine, Charité Campus Virchow Medical Center, Medical Center of the Humboldt University Berlin, Berlin, Germany

Aim

The aim of this clinical study was to evaluate the benefit of repeated periradicular and epidural therapies.

Methods

Ninety-two patients suffering from lumbar and/or sciatic pain, or chronic cervicobrachial syndrome (n=21). The patients were placed in a CT scanner (Somatom Plus 4, Siemens, Erlangen, Germany). After initial imaging in prone (lumbar interventions) or supine position (cervical interventions), skin disinfection, and local anesthesia, a 20 G spinal cannula (Becton-Dickinson (Franklin Lakes, NJ, USA) was advanced towards the treatment target under CT-fluoroscopic control (Care Vision, Siemens). In cervical interventions, 4 mg of dexamethasone-21-palmitate (Lipotalon, Merckle, Blaubeuren, Germany) were administered periradicularly. In lumbar interventions, 40 mg of triamcinolone-acetonide (Volon A, Bristol-Myers Squibb, Munich, Germany) were administered either in the periradicular or in the epidural space. In all procedures, 0.5 ml of bupivacaine-HCl 0.5 (Bupivacain-RPR, Rhone-Poulenc Rorer, Cologne, Germany) and 0.5 ml of iotrolane (Isovist 300, Schering, Berlin, Germany) were added to the corticosteroid. The procedure was repeated up to five times at monthly intervals, as requested by the patient or the referring physician. Pain was assessed before (interview), one week after every intervention (interview), and five months after the first intervention (correspondence). In those patients with clinical benefit at the five-month follow-up, a last assessment was obtained one year after the initiation of the treatment (interview). Pain was assessed using a Numeric Analogous Pain Scale (NAS) ranging from zero to ten, by subjective evaluation of the change in pain intensity or frequency, and other parameters including undesired effects.

Results

In cervical interventions, NAS was 6.6 before the first intervention, 4.6 after the first, 3.8 after the second, 4.3 after the third, and 4.8 after five months. A decrease in pain intensity or frequency was indicated by 65% after the first, 78% after the second, 57% after the third intervention and 50% five months after the start of the study. In lumbar interventions, NAS was 6.1 before the first intervention, 4.3 after the first, 3.9 after the second, 3.8 after the third, and 4.7 after five months. A decrease in pain intensity or frequency was indicated by 77% after the first, 77% after the second, 70% after the third intervention and 51% five months after the start of the study. The one-year follow-up results are incomplete as yet because of the ongoing nature of the study. The pooled results of cervical and lumbar interventions suggest that approximately one third of the patients with improvement after five months continued to have decreased pain intensity or frequency after three interventions and did not require any further interventional therapy since our third intervention. Another 20% continued to feel better but required repeated CT-guided periradicular or epidural treatments. The remainder required other specific pain therapies.

Conclusions

CT-guided periradicular and epidural are efficacious in approximately 50-80% of the patients one week up to two months after the intervention. However, our yet incomplete long-term follow-up results indicate that only approximately 15% of the initial study population did not require any further interventional treatment (except oral pain medication) one year after three interventions at one month intervals.

Biomedical Microdevices - 2000 And Beyond

S.-P. Heyn

Enhanced efficiency for the support of medical diagnosis and therapy, reliable and improved methods of therapy support and control, minimal-invasive procedures for the patient's ambulant treatment and home care are major trends in modern health care.

Within these trends, microtechnologies and microdevices substantially contribute to biomedical product innovations. Improved products as well as completely new types of devices will be of benefit for the patient as well as for the health care professional. In the fields of instrumentation for MIT,catheter systems, implantable devices and diagnostics & pharma screening, new business and market opportunities already exist or will be created on the basis of microtechnologies. To support the innovation process, interdisciplinary teams that bring together expertise in medical application, technology and health care markets are an essential factor.

The presentation will summarise:

---examples of recent developments,

---trends & market forecasts and

---"biomedical activities" within the European Network NEXUS

Design and Feasibility of pASSIst, a Passive Instrument Positioner, in Minimally Invasive Surgery

J.E.N. Jaspers¹, K.T. den Boer^1,2, W. Sjoerdsma², M. Bruijn¹, J. Dankelman², C.A. Grimbergen^1,2

¹ Department of Medical Technological Development, Academic Medical Center, Amsterdam, The Netherlands

² Man-Machine Systems Group, Faculty of Design, Engineering and Production, Delft University of Technology, Delft, The Netherlands

Abstract

In laparoscopic cholecystectomy, the camera is controlled by an assistant most of the time instead of by the surgeon himself. The indirect way of controlling and manipulating complicates the observation and manipulation actions and disturbs eye-hand co-ordination. This can lead to communication problems between the surgeon and the assistant and to an unsteady and inaccurate viewpoint when the assistant has to maintain a fixed posture for a long time. Generally, the same assistant has to control the laparoscopic grasper that is used to retract and present the gall bladder, which is a purely static task. The negative effects of the static tasks and the indirect viewpoint adjustment might be reduced by replacing the assistant by instrument positioners. Commercially available remote or voice-controlled active positioners (Robots) such as AESOP and EndoAssist cannot get "tired". Although they function properly, these "Robots" are relatively slow, need a lot of space, are expensive, not sterile and only control the camera. Passive positioners are also available. These positioners are relatively large or not stiff enough and not easy to handle. At the Medical Technological Development department of the Academic Medical Centre (AMC) in Amsterdam, we designed and produced passive instrument positioners for positioning the camera and the laparoscopic grasper. These slender but stiff positioners, placed opposite or next to the surgeon on the table rail, hardly interfere with the actions of the surgeon. The parallelogram mechanism of the positioners is designed in such a way as to allow only movements in four degrees of Freedom (DOF), three rotations around the incision in the abdominal wall as well as one translation through this incision. The positioners are manually controlled, allowing a simple mechanical construction. The positioners can be autoclaved completely. By manually adjusting just one knob, the friction in all the joints of the positioners is increased, stabilizing the instrument in a fixed position. The camera positioner is spring-loaded to compensate for the weight of the camera, therefore only a low level of friction in the joints is needed, enabling easy single-hand repositioning of the camera without adjusting the knob. A surgeon using two passive positioners would be able to perform solo surgery, controlling the viewpoint himself and locking the camera or the laparoscopic grasper in the desired position, resulting in a steady viewpoint and facilitating dissecting actions. The surgeon has to release a laparoscopic instrument when he wants to move the camera or the gall bladder into another position. However, it turned out that this was only a disadvantage when frequent movements were needed. The pASSIst has been tested in three different procedures - laparoscopic cholecystectomy, laparoscopically assisted vaginal hysterectomy and laparoscopic spondylodesis. In all these procedures, the surgeon was able to manipulate all his instruments on his own so that the assistant could be satisfactorily replaced. This feasibility study showed that a surgeon is able to perform these minimally invasive solo surgeries, resulting in an accurate, steady viewpoint. A prospective randomized controlled trial has been performed in three hospitals by comparing laparoscopic cholecystectomies with and without instrument positioners, by an experienced surgeon, to evaluate the functionality, efficiency and viewpoint accuracy of stabilising the camera and grasping forceps during the per-operative process of laparoscopic cholecystectomy. Time-motion analysis was used to evaluate the advantages and disadvantages in daily clinical use of two passive positioners in terms of action and time reduction, reduction in the amount of assistance, and reduction of viewpoint inaccuracy.

Surgery Planning with 3D Sonography and Intraoperative Endoscopic Sonography

J. Jürgens¹, B. Klemm²

¹ Department of Obstetrics and Gynecology, Helios-Klinik Neustadt, Neustadt, Germany

² Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

3D sonography can be used for more exact preoperative diagnosis as compared with 2D sonography, for free examination of all possible planes in the registrated block even in those layers which cannot be examined in two-dimensional sonography, especially for endocavitary sonography, where probe movement is limited. Furthermore, the combination of 3D sonography with other techniques such as powerangiomode or hysterocontrast sonography can yield other important pieces of information for the surgeon, such as three-dimensional imaging of blood perfusion (localization of major blood vessels of solid tumors) and abnormalities of endocavitary proliferation. The registration can by done in the moment of maximal cavum dilatation. Even an exact three-dimensional topography of myoma to myometra is possible. All pieces of information are saved, so full examination in a second time and by other persons (such as operative physician) are possible.

The second topic of this lecture shows the first pictures of a new 10mm Ultrasonic probe which can be inserted through a common trocar and provides excellent pictures of the intraabdominal organs. This method allows detection of the exact position of tumors behind adhesions or other processes under the normal surface of solid organs such as the ovaries, uterus or liver.

The Tübingen Balloon: On-Line Assessment of the Wrap Characteristics During Laparoscopic Nissen Fundoplication

D. Kalanovic, G.F. Buess

Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Medical Center, Tübingen, Germany

An adequate fundic wrap is fundamental to the success of conventional and laparoscopic Nissen fundoplication. With the support of Rüsch (Kernen, Germany), we developed a measurement balloon for laparoscopic application. The balloon allows the surgeon to define the width of the wrap and predetermine its length, as well as to measure its tension. Depending on the measured balloon pressure, the surgeon can perform fundic sutures more or less tightly. Currently the optimal intraoperative balloon pressure is being investigated in a prospective clinical study. We have contributed 30 procedures to this international study. The video shows an intraoperative measurement with the Tübingen Balloon during a laparoscopic fundoplication.

The "Overview Telescope"

B. Kappeler

Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Medical Center, Tübingen, Germany

Introduction

The conventional rigid endoscope often has to be brought near the operative field for exposing anatomical structures and make an optimal view of details possible. In this setting, only a small part of the body cavity is visible. Overview, orientation and control of all instruments are aggravated. In response to these facts, an overview telescope was developed.

Material and methods

A 7 mm detail telescope is brought through a shaft (outer diameter: 15mm). The right and left sides of this shaft contain respectively one far-sighted overview telescope. The entire unity is inserted through a 15 mm trocar. The shaft is slid to the front until the two overview optics appear at the end of the trocar. The detail telescope is brought near the operative field as usual. One gets three simultaneous video signals, which are shown on three monitors.

Result

With the help of the overview telescope it is possible to retain orientation within the anatomical structures and their order. During changing of instruments the detail telescope does not have to be removed because the change can be seen on the two monitors of the overview telescope. Thus, a relatively stable camera position is guaranteed. This overview makes possible to bring instruments to the operative field without touching or injuring other organs. The other trocar and neighboring organs can be supervised. The assistants can, for instance, see their fixation pliers and check their position, which is not possible with the detail telescope.

Discussion

The use of three complete video systems is complicated, expensive and prolongs set-up time. The weight of the telescope requires the use of a camera fixation system. At the moment, the overview telescope is not applicable in routine yet. However, the prototype shows that an overview telescope is possible and offers additional information, overview and safety for the surgeon. The receipt of additional information is very useful for teaching and training of surgical activities. Permanent moving of the telescope is almost discontinued. Developments in future could lower the costs of a new generation of endoscopes. These developments should be more similar to human eye regarding dissolving and overview.

Who Will Manage the Technique in the OR 2000?

B. Kipfmüller¹, A. Melzer^1,2

1 Department of Physical Engineering, University of Applied Sciences Gelsenkirchen, Gelsenkirchen, Germany

2 Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

The rapid development of new technologies in medicine is even a challenge for the staff in the OR and the surgeon. They are confronted with complicated equipment such as video endoscopy, high-frequency surgery, instrument navigation, intraoperative imaging and robotics. The know-how of these techniques is not part of the training of physicians. The systems of the modern OR require the knowledge of an engineer, so that even at the choice and purchase of new technologies you can profit from that know-how. In keeping with this demand, a new course of studies in Health Technology was conceived since 1996 in interdisciplinary round-tables between engineers and medical doctors at the University of Applied Sciences Gelsenkirchen. For the first time engineering students are trained by medical professors of surgery and radiology, who continue their clinical work in the half of the week. The first course started in 1998 with 12 students. Meanwhile we take care of 35 students. For the best modern education of the students, an OR is equipped with the most modern technologies such as MRT and CT. The knowledge gap in the technical know-how in the OR should be closed by the engineer of health technology. The content of this presentation will be the educational course of the students, the presentation of the equipment of our new OR for research and education and the overview of the perspectives of the engineer of Health

A New Single-Knot Suture Technique for Endoscopic Surgery – First Experiences

B. Kipfmüller¹, K. Kipfmüller²

¹ Department of Physical Engineering, University of Applied Sciences Gelsenkirchen, Gelsenkirchen, Germany

² Clinic of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Suturing and knotting in endoscopic surgery are difficult and time-consuming. Since 1999, a new endoscopic suturing system called Quickstitch has been available. It consists of a 5 mm reusable stainless steel handle, a 2,1 mm reusable stainless needle driver and a unique patented suture spool with a pre-tied slip knot and a straight taper point needle. We tested the new system in 40 cases of conventional endoscopic surgery (cholecystectomy and herniorrhaphy) as well as in 30 cases of advanced endoscopic surgery (colon resection and NISSEN fundoplication). Our results showed that there are no complications involved in the technique. We saw a safe closure of the knot. Because of the pre-tied slip knot the time especially for laparoscopic fundoplication was reduced by 15 minutes as compared to a handmade slip knot. With the new system the control of the force exerted on the tissue during suturing is much more better. The reusable product is a less expensive alternative to clips and tackers. A new type has been produced from Titanium and Nitinol and makes the system suitable for MR-guided surgery. The Quickstitch is a new system for endoscopic suturing and is simple to use especially for those not used to endoscopic suturing. It is potentially time-saving and economical. Its versatility will be tested in further clinical studies.

Transanal Endoscopic Segmental (TEM) Resection of Rectal Tumors

K. Kipfmüller

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Sessile and extended adenomas are predominantly localized in the rectum and lower sigma. They show a high tendency for malignant transformation and frequently recur after snare resection, requiring complete removal. Curative local excision can be performed on "low risk"-pT1-carcinomas. The transanal endoscopic microsurgical method (TEM) (BUESS's Technique) reaches the whole rectum and lower sigma using mechanical dilation of the rectal cavity by CO2-insufflation and magnification by a stereoscopic endoscope. According to the preoperative findings, localization and size, tumors can be removed by mucosectomy or full-thickness excision up to complete segmental resection. Since April 1989, we have used the new technique in 325 patients, including 102 patients with rectal carcinoma. We performed 285 full-thickness excisions. In eighteen of these patients, a segmental resection was necessary. The average area of the resected rectal segments was 79,3 cm2; the average tumor size was 58,6 cm2. Operating time depended on the size of the tumor, being at an average of 166min (range between 90min and 240min). Intraoperative blood loss was minimal (average 97,9ml).

Limited, sphincter-saving surgery is important in the management of rectal tumors. Benign tumors or nearly low-risk carcinomas are suited for local excision. Compared to conventional surgical techniques for the local treatment of rectal tumors, we are able to reach the whole rectum with the technique of transanal endoscopic microsurgery. Endoscopic preparation is more precise and the method is less invasive.

The Laparoscopic Repair of Large Diaphragm Lesions

K. Kipfmüller

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Patients

This presentation shows the laparoscopic repair of large diaphragm lesions in three patients: A 83-year-old female patient with therapy-resistant esophageal reflux disease and large paraesophageal hernia with displacement of one half of the stomach into the thoracic cavity, a 65-year-old male patient with a large diaphragm defect after nephrostomy with displacement of the left colony flexure into the left thoracic cavity, and a 35-year-old male patient with upside-down-stomach.

Method

The positioning of the trocars and the camera is similar to that in laparoscopic fundoplication. The first step is the replacement of the stomach or colon into the abdomen. The diaphragm lesions were closed with non-resorbable sutures and mesh. The patient with the reflux disease underwent NISSEN fundoplication.

Conclusion

In three cases, the procedure was done completely laparoscopically. There were no complications during the operation and the postoperative follow-up. The stay in hospital was beyond 10 days.

The use of AESOP 3000 in laparoscopic colon resection

K. Kipfmüller

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Since the beginning of 1999, we have used the voice- controlled computer system AESOP 3000 for camera guidance. After the use of AESOP in over 200 endoscopic operations, we examined the feasibility and time reduction during 15 endoscopic colon resections.

Method

After positioning of the trocars, the AESOP 3000 was installed. It was used during the whole operation time except the time of the saving of the resected tissue.

Results

We had no complications due to the AESOP system. The frequency of the cleaning of the optic was reduced to the fifth part. The time-reduction was 15 minutes.

Conclusion

The AESOP 3000 is a voice-controlled camera guidance system that allows a laparoscopic colon resection with one surgeon and one assistant. The guidance of the camera is quiet and free of fatigue. The lower frequency of lens cleaning is time saving. The presentation will show the use and the results of AESOP 3000 during laparoscopic sigmoid resection.

Retroperitoneoscopic Adrenalectomy After Previous Major Abdominal Operations

K. Kipfmüller

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Patients

Since 1997, we have operated on 17 patients with adrenal tumors. Two patients had previous major abdominal operations: 1. A female patient (69 years old) had a left hemicolectomy and a splenectomy in 1992 because of a stenotic colonic carcinoma. (UICC: pT4 pN0 pM0-R0). In 1995, a hemihepatectomy and a partial gastrectomy followed because of a metachrone liver metastasis. In 1998, CT staging revealed a 5cm left adrenal tumor. A CT-guided biopsy gave the result of a benigne adrenal adenoma. 2. A female patient (50 years old) with former chronical alcohol abuse had an aldosteron-producing adrenal adenoma. In 1995, the patient had had a Whipple operation after alcohol-induced chronical calcifying pancreatitis.

Material and Methods

With the patient in a lateral decubitus position, a 2 cm incision was made below the 12th rib and 5 cm lateral from the spine. The retroperitoneal dissection was performed by a balloon catheter. After changing into a camera catheter a pneumoperitoneum was created. Three further small preparing catheters were placed. After using small metal clips the vasal dissection was done in toto. In both cases the operation time was 1455 min. The postoperative procedure was without any complications.

Conclusion

Retroperitoneoscopic adrenalectomy is a suitable minimally invasive technique especially for patients with possible intraabdominal adhesions after extended abdominal surgery such as resections of the colon, liver, or pancreas. Dorsal retroperitoneoscopic adrenalectomy is less invasive as compared to the transperitoneal laparoscopic or open transperitoneal operation.

Modern Techniques of Tissue Ablation Illustrated by Endometrium Ablation

B. Klemm¹, A. Melzer²

¹ Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

² Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

One of the future trends in minimally invasive therapy will be the search for forms of energy that only take effect on the tissue the surgeon wants to remove. A typical indication is uncontrolable bleeding.

Usually, the coagulation or removal of the bleeding tissue would be sufficient as a treatment. In gynecology, various procedures were developed to destroy or remove the endometrium as the inner layer of the uterus. These various procedures will be introduced and rated according to their ability to exclusively remove one specific layer of the organ. The application of various forms of energy (such like heat, light, laser, electricity, mechanical energy) cause different complications and failure rates. Therefore, these minimally invasive methods have not yet replaced open surgery (hysterectomy). Reasons for complications are the use of high energy, which is hardly specific to the endometrium.

A new method, which is still in experimental state, will be introduced. According to the future trend, it uses low energy but is highly selective to the endometrium. Thus, the removal of the inner layer of the organ is easy and safe to perform while the other layers remain completely intact. Results of in-vitro-experiments and animal tests will be presented.

Minimally Invasive Gynecology - Use Gyn Experiences For Your Own Work

B. Klemm

Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

In various fields of medicine, minimally invasive interventions have been developed to highly specialized techniques. Most procedures are adapted to certain organs only. These specialized techniques are often presented exclusively on congresses for specialists of this field. Sometimes, however, the know-how could be applied in other fields of medicine or the idea behind it could inspire other surgeons to develop modified techniques for other regions of the body. Interdisciplinary congresses such as SMIT are predestined to go beyond the limits of each discipline. Thus, the exchange of knowledge becomes an additional benefit.

The focus session on Minimally Invasive Gynecology will present the highlights of current developments while the emphasis lies on lectures, which I hope will be interesting and inspiring for other specialists too.

Main Topics

- Neural anatomy of the pelvis and laparoscopy (Possover, Jena)

The development of laparoscopic techniques for retroperitoneal lymph-node sampling was the prerequisite for the minimally invasive treatment of carcinomas of the pelvis. Beyond the advantage of minimal access, the enhanced visualization by laparoscopy allows blood saving procedures. Another advantage is better detection and maintenance of nerve structures, which is important for the function of inner organs in order to improve the quality of life for patients after radical cancer surgery. PD Possover will also demonstrate his technique of testing the intactness of the exposed pelvic nerves by neurostimulation during operation. This technique could also gain importance for the treatment of motorically paralyzed patients.

- Endoscopic axillary lymphadenectomy after fat suction and sentinel nodes sampling (Suzanne, Clermont-Ferrand)

Minimally invasive surgery is performed in natural cavities or in a cavity formed by a distention medium. How about the idea of creating your own cavity, for example by liposuction? Professor Suzanne will show his technique of creating a cavity in the axilla for the removal of lymph nodes. Another topic of his lecture is about marking the sentinel nodes to minimize the trauma further.

- Laparoscopic procedures: Is pregnancy a contraindication? (Mettler, Kiel)

Many experienced surgeons have already performed minimally invasive interventions during pregnancy. However, we have few data about the risks of such interventions, e.g. premature birth or negative effect of CO2-Pneumoperitoneum to the fetus. Many colleagues perform these interventions according to their intuition. But can we already find an agreement about the question which procedures are allowed and which are critical? Professor Mettler will report about the data she has collected and give her estimation.

- Surgery planning with 3D-songraphy and endoscopic intraoperative sonography (Jürgens, Neustadt)

To avoid bleeding is important in laparoscopy especially in the extirpation of major tumors. When looking at the two-dimensional screen an experienced surgeon creates a 3D image of the organ in his mind while manipulating and dissecting it. Preoperative 3D Sonography enhances this mental process and gives the surgeon an image of the anatomy from the beginning. Especially the localization of major blood vessels surrounding the tumor before the operation is very helpful. This advantage will be demonstrated by the example of a myoma very near the uterine artery. The second topic of this lecture will show first pictures of a new 10-mm ultrasonic probe that can be inserted through a common trocar and provides excellent pictures of the intraabdominal organs. This method allows detecting the exact position of tumors behind adhesions.

- Minimally invasive urogynecology - 5-year experience with Burch´s procedure (Frank, Bremen)

Burch´s procedure for bladder-neck suspension has become the golden standard for incontinence treatment. Normally, this operation is performed preperitoneally by transverse incision. During recent years, a transperitoneal approach and special knot techniques have been developed to perform this operation during laparoscopy. The hospital in Bremen has the largest number of such cases world-wide. Dr. Frank will give a report on their technique and long term results.

- Modern techniques of tissue ablation illustrated by endometrium ablation (Klemm, Leer)

To stop bleeding within hollow organs plays an important role in various fields of endoscopic therapy. Various forms of energy with different advantages and risks are used. For the treatment of uncontrollable uterine bleeding numerous techniques have been developed during the last years. The lecture will present an overview and give a rating of the energies (such as heat, light, laser, electricity, mechanical) according to their ability to exclusively remove the bleeding tissue without destroying surrounding layers of the organ. The author will also introduce a new method in experimental state that uses low energy to reduce complications and is highly specific to the endometrium.

The Medical Engineering Program of Forschungszentrum Karlsruhe – an Overview.

Dr. U. Knapp, Forschungszentrum Karlsruhe

The actual r&d-program on medical engineering and biophysics at Forschungszentrum Karlsruhe was established beginning of 1997. An overview will be given on the main activities of this program which focuses on three main research fields. Points of main interest in the first field are either complex operation systems for minimally invasive surgery, above all for cardiac surgery, and systems for interventional radiology which can be used in the magnetic field of an MRI. Furthermore training systems for endoscopic interventions are being developed. In biophysics, the second research area, the efforts aim mainly at developing therapies for degenerative diseases applying so-called interferential current. An actual example will be presented. Finally an insight will be given into the activities of our cyclotron where short living radionuclides for diagnostics are being produced and new applications for them are being developed.
A Tool for Visualization and Teaching Anatomy of the Human Body

C. Kolvenbach^1,2, C. Mamisch^1,2, M. Das^1,2, R. M. M. Seibel², R. Kikinis¹, F. A. Jolesz¹

¹Institute of Diagnostic and Interventional Radiology, University of Witten Herdecke, Mülheim/Ruhr, Germany

² Surgical Planning Laboratory, Brigham and Women’s Hospital, Harvard Medical School, Boston (MA), USA

Introduction

With the newest imaging technologies it is possible to obtain isotropic data sets within a short period of time. Furthermore, improvements in the quality of images have made possible the use of 3D segmentation and 3D visualization techniques to develop true three-dimensional atlases of several anatomic regions of the human body. Consequently, anatomic details can be appreciated in 3D instead of being restricted to 2D images of 3D structures.

Material and Methods

We developed three-dimensional (3D) digitized atlases of several anatomic regions of the human body to visualize the tremendous amount of detail and complexity in the interrelationship among anatomic structures. The use of 3D anatomic models can greatly facilitate the learning of the human anatomy because they provide the student with important information not only about the shape of a structure but also its spatial relationship to surrounding structures. Other important features of 3D graphical models are the ability to manipulate the models by removing or making transparent various structures, and the ability to zoom in to examine the structure in detail.

Unfortunately, the computer hardware necessary to access the large databases required for such 3D models is expensive and limited to a small number of people who have access to a graphics workstation. In addition, the major users of 3D atlases - medical professionals and medical students - are likely to want to access anatomic information from remote sites at times convenient to them, rather than only from inside a specially equipped center.

Umans and colleagues have employed a method to overcome these obstacles by using representations of 3D models that take less time to transmit and require less intensive computations than 3D computer graphics renderings. This technique belongs to the category of image-based techniques, such as QuickTime VR, which generally provide navigational capabilities but little interaction. However, the technique of Umans et al. allows the user to interact with the model in several ways, such as by turning structures on and off, adjusting opacity, and changing colors. These modes of interaction are particularly useful when working with large medical data sets.

Results

Our "Anatomy Browser" utilizes the technique of Umans et al. to allow interactive manipulation of 3D models of the human brain on personal computers without high transmission costs or the need for specialized graphics hardware. The main features of the browser include the ability to do the following:

· Display various views of the model

· Select structures to be annotated

· Remove or make structures transparent

· Zoom in on structures

· Collapse and expand a hierarchical description of the structures to control the level of detail displayed

· Cross-reference with cross-sectional slices.

Conclusion

We have used the atlases in several ways over the last few years. On the one hand, a limited number of students have been using the atlases to learn anatomy. In addition, the atlases have been used to provide reference information on anatomical structures in a selected number of surgical cases. Furthermore, we have used the atlases as a template for the automated segmentation of new images into anatomical structures.

Anatomical Analysis and Preoperative Planning of Correctional Osteotomies in Patients with Slipped Capital Femoral Epiphysis (SCFE)

J. Kordelle², C. Mamisch^1,2, R. Kikinis², R. M. M. Seibel¹, J. Richolt²

¹ Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

² Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston (MA), USA

SCFE is defined as the slippage of the femoral head relative to the femoral neck along the proximal femoral growth plate. The femoral head shifts and rotates along the proximal end of the femoral neck usually posteriorly and inferiorly. The pathoanatomical findings are characterized by the changed relationship between the femoral head and femoral metaphysis and between the femoral head and the acetabulum. Furthermore, a reduced femoral anteversion, a varus deformity of the femur, a shortening of the femoral metaphysis and an anterior metaphyseal prominence is regularly observed. This may lead to an impingement between the femoral metaphysis and the acetabular rim. Potential consequences of this complex three-dimensional deformity are pain, a reduced range of hip motion and an early degenerative joint disease. In moderate and severe cases, redirectional femoral osteotomy is recommended. Different techniques as subcapital, base-of-neck, intertrochanteric and subtrochanteric osteotomies are described. These correctional osteotomies aim towards a reconstruction of the hip-joint geometry to prevent early arthritic degeneration. Currently, the planning of surgical treatment of these cases is based on measurements on anterio-posterior and lateral plain radiographs. The relevant angle for the planning of correctional osteotomies is the physis-shaft angle determined in both plains. These angles describe the degree of slippage and thereby help the surgeon to indicate and plan a correctional osteotomy. Plain radiographs, however, are projectional images and therefore carry inaccuracies caused by the overlay of anatomical structures and incorrect positioning of the patient. 3D reconstructions are more accurate and provide the surgeon with additional information, for instance regarding the anteversion of the acetabulum. The authors developed an interactive three-dimensional software to measure projected angles to analyze the geometry of the proximal femur, and to determine the orientation of the acetabulum on the basis of three-dimensional reconstructions of CT data sets. Furthermore, a program was developed to simulate different techniques of osteotomies and to evaluate the postoperative range of hip motion and the hip joint geometry. Accurate three-dimensional measurements, additional anatomical information, the possibility to simulate different techniques of osteotomies and to evaluate the simulated postoperative result enable the surgeon, with regard to the clinical findings, to decide for the optimal surgical treatment.

Augmented Reality (AR) Systems for Real-Time Guidance in Surgery

K. Koushik

INTRODUCTION TO AR SYSTEMS

Augmented Reality (AR) is a technology in which a computer-generated image is super-imposed onto the user's vision of the real world, giving the user additional information generated from the computer model. This technology is different from virtual reality in which the user is immersed in a virtual world generated by the computer. Rather, AR systems bring the computer into the world of the user by augmenting the real environment with virtual objects. With the help of an AR system, the user's view of the real world is enhanced. This enhancement may be in the form of labels, 3D-rendered models or shaded modifications. In this paper, we review the applications of the AR system to surgery and touch upon the requirements of an interventive system, which can help guide surgeons in executing a surgical plan. It will be seen that minimal tissue invasion would be a natural corollary to the application of AR systems in medicine.

Typically, AR systems are applied in various areas like repair and maintenance of complex systems, facilities modification, interior design, etc. In medical applications, a computer-generated virtual organ will be superimposed onto the surgeon's view of the patient, giving spatial information of the organ relative to the patient's body or simply 'X-ray vision'.

During a surgical procedure, computed tomography, magnetic resonance imaging etc. are used to obtain information to aid in surgical planning. These medical images are usually two-dimensional and are obtained pre-operatively. The drawback of these preoperatively obtained data is that they can be used only as a reference for planning prior to the actual operation and that they do not provide spatial information of the organ relative to the patient's body though 3D reconstruction is possible using images of different planes.

The obvious advantage of intraoperative images is that they provide real-time interaction as well as spatial information for the surgeon. However, most ultrasonic images are 2D and the surgeon is required to scan across the targeted area in order to 'see' the organ in different planes, after which he can only try to visualize the 3D volume and complete his surgical plan before proceeding with the operation. This is not always possible because of the geometries involved and since accurate spatial information is still not available to the surgeon, the effectiveness of treatment is compromised.

AR systems focus mainly on ultrasonography as an imaging technique, as it is the only method that can be used intraoperatively and is free from radiation hazards. With the aid of the AR system, the surgeon's vision will be enhanced, giving good spatial information of the observed volume. By superimposing the virtual organ into the surgeon's view of the patient, the 3D volume of the organ can be seen, tissue that needs to be treated can be identified and sensitive healthy areas can be avoided.

The data regarding the tissue of interest obtained from ultrasonography are used to get the internal organ configuration and position. These results are processed along with surgeon's actual viewpoint to give an actual AR output that has the features as mentioned above. Thus, the surgeon can identify organs or tissue that need to be treated and avoid healthy or sensitive areas.

SYSTEM CONFIGURATION

The basic configuration of AR system consists of video cameras, a six degree-of-freedom motion-tracking system, a head mounted display (HMD) or other display technology, a frame grabber, a personal computer/workstation and graphics accelerator. The main differences in the systems are the types of the HMD used. HMD's are equipped with see-through capability, on which computer generated graphics can be superimposed. Two types of HMD are generally used, namely optically see-through and immersive type. The optical see-through type uses optical combiners where computer generated graphics are optically super-imposed onto directly viewed real-world scenes. The immersive type uses a video camera to view the outside world. Subsequently, the image of the real world is electronically mixed with the computer-generated image and displayed on the LCD screen of the HMD. When using the immersive type HMD, an accurate 1:1 orthoscopic mapping between the proportion of the displayed images and the surrounding real world environment must be maintained. This will ensure that the user's view of the real world through the video see-through HMD is exactly the same as the directly viewed real world, thus creating a 'video see-through' system analogous to an optical see-through system. Presently, AR systems are using workstations for processing data. This is mainly due to the complex imaging data required to be processed and displayed. However, the use of PC's in medical AR applications is possible because organs of relatively simple geometry, such as kidneys, liver and prostate, can be generated. Although this may seem to be a step back in minimizing the lag time of the system, the cost and portability of a PC system is more desirable in operating theater applications.

APPLICATION IN MEDICAL SCIENCE

Presently, AR systems in medical applications are focused on enhancing visualization, which is important in surgical planning. Commonly used visualization techniques are CT, MRI, PET and ultrasonography. These images are, however, two-dimensional. Therefore, reconstruction of the scanned target into a 3D image is performed and this is used for AR display. Comparing these medical imaging methods, all except for ultrasonography expose the surgical staff and the patient to a radiation risk when used excessively. As mentioned before, ultrasonography is the only method that can be used intraoperatively. This is the cheapest of the imaging methods and has no known side effects. When used below a certain intensity there is no biological interaction. These are some of the reasons that researchers are focusing on the use of ultrasonography in AR systems.

In applying AR to neurosurgery, three-dimensional MRI and CT images must be used because of the data required to be displayed to the neurosurgeon. In medical applications, such as puncturing the kidneys for the removal of pus and kidney stones or for delivering drugs to affected organs (for example, radioactive seed implantation), simple graphical representations of the organs should suffice for AR display, since these organs are basically ellipsoids. Despite this difference in the amounts in data to be displayed, accuracy of the image registration process cannot be compromised. Generally, the organ of interest is not rigid but deforms according to the rhythm of the beating of the heart and respiration or when physically probed. The real-time deformation of the target organ is not reflected in its graphical representation; thus, the virtual organ is only an approximation of the real one. AR systems can be accurately used for the treatment of organs which are relatively undisturbed by the patient's heartbeat or respiration (such as prostate, etc). Nonetheless, as long as these approximations are within stipulated tolerances, AR systems can prove to be a valuable tool for enhancing visual information.

AN INTERVENTIVE AR SYSTEM

If the AR system which enhances the field of surgeon's vision is coupled with an interventive tool to aid in surgical procedures, the system not only provides the surgeon with eyes with which he can see through the patient, but also with a 'third hand' which acts as an assistant. The third hand will thus perceive what the human natural touch will not perceive. Due to concerns such as safety and minimizing device sophistication, this tool must be passively driven by the surgeon. The use of an interventive tool in conjunction with an AR system is possible only on the premise that the user's hand-eye coordination is preserved despite the use of an immersive-type head-mounted display. Although the use of optical see-through HMDs preserve the hand-eye coordination by direct viewing of the real world, the user cannot perceive the depth of the virtual object relative to its environment. An alternative for the user is to adapt to the new pair of 'eyes' and condition himself to coordinate his hands with his new vision. An interventive tool is a sensorized tool that is equipped with internal or external tracking sensors and, for safety reasons, is passively driven by the surgeon. With the additional involvement of the tool, the system can be termed an interventive augmented reality system. These interventive tools are also called 'synergistic devices' because they connect the world of images, plans and computers to the physical world of the surgeons, patients and tools. In these systems, a surgical plan is elaborated on the basis of diagnostic images, and the systems hence will guide the surgeons in the accurate execution of his surgical plan.

APPLICATION TO MINIMALLY INVASIVE THERAPY

The application of AR to minimally invasive therapy is a mere restatement of what has been described before. During a surgery or a drug delivery process, the spatial information of the tissue of interest (TOI) with respect to other tissues, is displayed in the AR system display. Using this information, one can surgically plan an access trajectory which least affects other tissues before accessing the TOI. In this way, we can make sure that healthy and sensitive areas are not affected, and we can also determine a way of minimizing tissue invasion by taking advantage of the enhanced faculties of vision and touch bestowed by the interventive AR system. Thus, in conclusion it can be said that, with the progress in image processing and device fabrication techniques, interventive AR systems will become more accurate and will aid the surgeon in performing precise and accurate incisions.

A New Device for In Vitro Functional Testing of PTCA Catheters

M. Kraft

VANGUARD GmbH, Berlin, Germany

In-vitro methods for testing PTCA catheters are the only way in which relevant and former unknown properties during the intervention and after reprocessing can be quantified. A very complex, completely new multifunctional testing device, which uses a multitude of sensors integrated into an anatomically correct model of the coronary system, was developed. It is the first test device, to quantify the interaction between PTCA catheter, arterial wall, guide wire and guiding catheter. The development of the device is based on analytical and experimental studies. To specify the parameters of the testing device, extensive surveys were performed in the USA and Germany. Experimental studied were performed to simulate in-vivo frictional properties between the catheter and the intima. The catheter can be pushed using a specially developed catheter drive. Analogous to the cardiologist's manual advancement, the catheter is pushed into the model vasculature in an alternating motion, with advancement forces being simultaneously measured. The computer-controlled testing device can measure various frictional advancement and reaction forces at different locations in the coronary vasculature. Furthermore, balloon pressure/diameters relationships can be measured as well. Over 3000 measurements, performed with the new testing device including 31 PTCA catheters, showed previously unknown relationships and significant differences in product characteristics among PTCA catheter designs. The trackability, i.e. the capability of a PTCA catheter to cross a tortuous stenosis, can be analyzed by measuring the force transfer perpendicular to the arterial wall. In this study, wall reaction forces at a force sensor located 60 mm distally of the ostium were measured along with their corresponding advancement and pull-back forces in an in-vivo friction RCA model. To sum up, there are significant differences in the reaction forces that are transferred from the PTCA catheter to the arterial wall. Guide wire dislocation can occur when PTCA catheters are exchanged or maneuvered through stenosed coronary arteries. This is generally due to frictional forces in the guide wire lumen of catheters. In this study, using of in vivo frictional properties in an anatomically correct model of the circumflex coronary artery, and the advancement and pull-back forces of PTCA catheters were measured. In addition, the frictional forces on the guide wires were measured with a force sensor located 65 mm distal of the ostium. In summary, there are significant differences in frictional forces transferred from PTCA catheters to guide wires, which may lead to guide wire dislocation in the proximal direction. The required backup of PTCA catheters within guiding catheters can determine the success of the intervention. In the worst case, high support forces could cause the tip of the guiding catheter to slip out of the ostium. Using the anatomically correct RCA model, the support forces exerted on the distal end of the guiding catheter were measured. In summary, the required advancement forces of PTCA catheters increase after balloon inflation in contrast to the support forces, which decrease when the PTCA catheters are maneuvered through the peripheral vasculature. Manufacturers of balloon catheters indicate the safety of their products by defining the ratio of the balloon pressure to the corresponding balloon diameters. These ratios, however, do not consider time and stress dependent creep of the balloon material. With the help of optical techniques (laser micrometer), the pressure and time dependent balloon diameters were measured in two orthogonal axes. In summary, the manufacturer's specifications of balloon diameters are only estimates of the actual balloon diameters, which are dependent upon the number of inflations and their duration.

Endoscopic Surgery Training using Virtual Reality and Deformable Tissue Simulation

U. Kühnapfel, H.K. Çakmak, H. Maaß

Institute of Applied Informatics, Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

Virtual reality (VR) is a technology that can teach surgeons new procedures and can determine their level of competence before they operate on patients. Surgical training systems based on VR and simulation techniques for tissue deformation may represent a more cost-effective and efficient alternative to traditional training methods. At the Forschungszentrum Karlsruhe (FZK), we developed a virtual reality training system for minimally invasive surgery based on the simulation software KISMET. An overview of the current state of development for the "Karlsruhe Endoscopic Surgery Trainer" is presented. The MIS trainer provides several surgical interaction modules for deformable objects such as grasping, application of clips, cutting, coagulation, injection and suturing. It is possible to perform irrigation and suction in the operation area. For quick and easy creation of surgical scenes containing deformable anatomical organ models, the spline-based modeler KisMo has been developed, which generates beside the geometry also a spatial mass-spring network of the objects for the elastodynamic simulation in KISMET. Active deformable objects are used for the morphodynamic simulation of the stomach and intestines. Furthermore, a hierarchical pulse simulation in virtual arterial vessel trees has been realized, which enables the palpation of the pulse with a force-feedback device. The pulse simulation is coupled with an arterial bleeding simulation, which is activated by injuries to arteries and stopped by the application of clips. The simulation system has been applied to minimally invasive surgery training in gynecology and laparoscopy. Special attention is addressed to elastodynamically deformable tissue models and geometric modeling techniques for graphical real-time performance.

ESWT Treatment of OD

LAUBER, H.-J.

Center of Extracorporal Shock Wave Therapy Hattingen, Ev. Krankenhaus Hattingen

IFR, Interdisziplinäre Forschungsgesellschaft Rhein Ruhr, Bruchstraße 32, 45525 Hattingen

Osteochondronecrotic lesions as OD (Osteochondrosis Dissecans) in adults and adolescents invariably exhibit the same kind of pathomorphological changes. Frequently, the underlying condition is a circulatory disorder accompanied by the successive destruction of bone cells, although direct damage caused by inflammation, radiation or high-dosage of cortisone may also cause metbolic disorders. The onset of the disease is heralded by micromorphological changes wich are not visible on x-ray. For detection of early stages MRI is the diagnostic tool of 1^st choice.

In the joint-preserving surgical treatment of OD the methods are recommended on the basis of the stage of the disease. These methods range from decompression of the medullary space with and without transplantation of spongiosa material to drilling of the OD and pin refixation of loose bodies.

The objective of our prospective study was testing the effectiveness of high-energy ESWT (Extracorporal Shock Wave Therapy) for the treatmant of OD of the knee and the ankle.

Eight patients (six OD of the kneeand two ODof the ankle) were treated by high-energy ESWT with an Ossatron (HMT Swiss) with 2000-3000 impulses and an charging voltage of 20-28 kV. There was a standardized examination including medical history, x-ray and MRI before and 2 weeks 6 weeks 12 weeks and 6 months after ESWT. Five patients had an stable and three patients had an unstable OD. Pain on the visual pain analogical scale decreased from 7.0 to 2.8 within 6 month. The Larson Score increased from 48 points to 83 points within 6 month.

There was no deterioration in syndromes. One patient showed no effect, another slight improvement of the OD. Six patients showed subjectively, clinically and by MRI good or very good effects.

Imhoff et al. (1992) and Pritsch et al. (1986) showed on long-term observations, that a restitution is possible, if the necrotic bone fragent can be revitalized along with preservation of the covering cartilage.

In future ESWT could become a veritable and low-risk treatment of OD, avoiding surgical procedures in early stages. Therefore further investigations and studies are necessary.

MRI controlled results of extracorporal-shockwave-therapy in adult osteonecrosis of the femoral head

S. Lauber / Hattingen, H.J. Lauber / Hattingen, J. Ludwig / Bochum,

H. Hötzinger / Velbert,

referring Author: S. Lauber / Kassel (interdisziplinary research group ruhr-city)

Osteonecrosis can be seen in adults and in younger age, the pathomorphological changing is similar, but the prognoses shown in both ages, due to the activity of the epiphysis gab, are totally different.

In the most cases a vascular osteopathy with following osteonecrosis is the reason.

Other reasons of osteonecroses are inflammation, ray treatment or metabolic interference (high dose cortison therapy). Even traumatic osteonecroses most of the cases are ischaemic.

In the beginning of the osteonecrosis the bone is stable. With beginning of the repairing processes

the bone gets soften and if the process continues the collapse of the surface could be the result.

The aim of this prospective study was, to scrutinise the effect of high energy shockwave-therapy

in treatment of osteonecroses of the femoral head. The carrying out of this study was possible

by means of a co-operation of the ESWT-Centre Hattingen (Dres. Lauber, Platzek) the radiological clinic Velbert-Niederberg (Prof. Hötzinger) and the orthopaedic clinic of the Ruhr-Universität-Bochum (Dr. Ludwig), within the interdisziplinary research group ruhr-city. The osteonecroses were classified by the ARCO- classification, which consider MRI and X-ray, the FICAT- classification and the Brougham- Score.

The evaluation was based on the Harris hip score as well as using a subjective assessment using a

visual pain scale.

The discernment of the Stadium I in X-ray is very difficult or even not possible. With MRI discernment of this stadium is possible in most of the cases. To show the vascular supply

the MRI was made on a special way.

Before treatment with shockwave, the examination was made in mentioned way and a MRI

as well as a X-ray were carried out.

Two weeks after treatment with shockwave a clinical examination was made and six weeks, three month, six month and one year after shockwave-therapy an examination in similar manner like the first one was carried out.

Until now 72 osteonecroses of the femoral head were treated. 21 cases were analysed one year after shockwave-therapy. The Median of Harris-Score improved from 43.0 points at the first examination to 88.0 points after one year. The visual pain scale improved from 8.4 to 2.2.

The analysis of the results after a year shows good successes, which could be interpreted as a sign for form of therapy that has less risk and could help saving costs.

New Technology of Stents

D. Liermann

Clinic of Radiology and Nuclear Medicine, Kath. Marienhospital Herne/Bochum University Medical Center, Herne, Germany

Both angioplasty and stent implantation induce arterial wall expression and release of smooth muscle cell mitogens. As compared with PTA, therefore, stent implantation in peripheral arteries does not appreciably reduce the risk of restenosis resulting from intimal hyperplasia. The new techniques in stenting the arteries comprise endovascular brachytherapy with different sources, radioactive stents or local drug application. Another practicable method to minimize dramatization of the vessels wall seems to be temporary stenting. We developed endovascular brachytherapy with Iridium 192 HDR to prevent restenosis in peripheral arteries in 1990. Now we are able to report on the follow-up in 40 patients treated in this first trial. The results of this observation are encouraging and demonstrate the usefulness of intravascular irradiation. The method now is well established. After recanalization, PTA and stenting of the stenotic segment we positioned a special 9Fr catheter with an inner lumen of 5 Fr into the affected vascular segment. It later accommodated the source of Ir 192 (10Ci) with a diameter of 1.1mm. Using a Nucletron Selectron HDR system for the exact calculation, monitoring and control of the afterloading procedure we applied a surface dose of 12 Gy to the wall of the vessel. The follow-up up to 9 years showed no deterioration of the clinical stage and no restenosis in 30 patients today. Four patients showed restenosis above or below the stented segment. One patient developed acute thrombosis three months after stent implantation. Five patients dropped out. We did not detect any serious complications of radiation therapy such as nerve lesion or malignancy. This means that the afterloading therapy with Iridium 192 HDR is a promising tool to prevent restenosis of peripheral arteries after PTA and stent implantation.

Reprocessing Used Minimally Invasive Surgery Instruments

C. Lösche

Department of Biomedical Engineering, Technical University of Berlin, Berlin, Germany

The demands placed on the reprocessing of used minimally invasive surgery instruments are becoming more stringent due, on the one hand, to the introduction of new functions such as new cutting and coagulation techniques and, on the other hand, due to the increasing miniaturization of such instruments. The motivation for using single-use-only instruments often lies in their special functions, as shows the example of the ultrasonic cutting techniques. Disposable instruments are being used with increasing frequency. The reprocessing of single-use instruments raises two basic questions: firstly the legal question of liability and secondly the question of the technical procedure to be used. The legal question has been settled in Germany. From this aspect, the utilization of reprocessed single-use products is definitely possible. The technical implementation of reprocessing methods for disposable products is often more difficult than for multiple-use products which have been specifically designed for re-use. For instance, much more sophisticated technical equipment is needed in order to optimize the mechanical/physical and chemical or biological parameters (internal high-pressure rinsing, ultrasonic techniques, neutral cleaning agents, chemical disinfection) and permit the monitoring and recording of all essential process parameters (process validation). In the context of guaranteeing functional and hygienic safety, additional extensive testing is required. The reprocessing of instruments comprises the steps of cleaning, disinfection and, where necessitated by the circumstances, sterilization. Here, one should remember that the cleaning process is the only one that removes undesirable substances from the surfaces by mechanical, chemical or biological means. The ensuing steps of the procedure will deactivate any viable micro-organisms present, but do not necessarily remove them. In order to evaluate the success of the complete process, compliance with a given standard will have to be established. Of course, by definition, it is assumed that a product is absolutely free of viable microorganisms after it has been sterilized [PrEN13824]. In practice, this fact cannot be proved, which is why the draft standard mentioned above states that the number of microorganisms surviving a sterilization procedure can only be expressed as a probability value. As for the cleaning process, there are no standard specifications on what level of residual contamination can be tolerated. This poses a considerable problem, since, in practice, reduction of contamination by spores to a specific value is assumed as a basis for the following process step, namely sterilization of the product. Thus, even if a validated sterilization process is applied, it is not possible to conclude that the final products will always be actually sterile. If the residual contamination before the start of sterilization (i. e. after cleaning) was too high, then one may expect a non-sterile instrument even after sterilization has been carried out correctly. Clinical studies of multiple-use products confirm this fact. Thus, determination of the tolerable residual contamination after cleaning and the definition of a generally accepted method of testing for this parameter are urgent fundamental issues. This is the only way of consistently and sensibly introducing validated cleaning processes as the decisive missing element in validation of the overall reprocessing procedure. The current distinction between single-use and multiple-use instruments is a basic issue of dispute. A distinction based on whether product-specific validated methods for reprocessing the respective instruments exist or not makes far more sense. Such processes can be developed and specified by the manufacturer (obligatory in the case of items declared as multiple-use products), but also by third-party service companies.

Degenerative Shoulder Disease

LUDWIG, Jörn

Orthopädische Universitätsklinik im St. Josef-Hospital, Bochum

Gudrunstr. 56, 44791 Bochum, Tel. 0234/5092511, Fax 5092525

IFR, Interdisziplinäre Forschungsgesellschaft Rhein Ruhr, Bruchstraße 32, 45525 Hattingen

Degenerative shoulder diseases are more frequent in the 5^th and 6^th decade of life than many other degenerative orthopedic diseases. In Germany approximately every 10^th patient of an orthopedic surgeon complains of shoulder pain.

Different reasons are responsible for shoulder pain as an intrinsic or an outlet impingement as well as calcium deposits, rotator cuff tears or adhesive capsulitis.

Aside from conservative treatment as physiotherapy, drugs, local injections and surgical treatment ESWT (Extracorporal Shock Wave Therapy) has become one alternative in treatment of degenerative shoulder diseases, especially in Germany and Austria.

In 1992 Dahmen used low-energy ESWT in treatment of painful calcium deposits in the soft tissue of the shoulder and reported about decrease of pain. In 1993 Loew et al. applicated high-energy ESWT to a tendinosis calcarea in 6 patients. After that few casuistries ESWT became a treatment of different syndroms of pain originated from the musculoskeletal system.

Only few controlled studies exist about treatment of degenerative shoulder disease by ESWT reporting about the treatment of tendinosis calcarea with success in reduction of pain between 52 percent and 65 percent. There are no evidenced studies in treatment of all the other degenerative soft tissue diseases of the shoulder as impingement, enthesopathy of the supraspinatus or adhesive capsulitis.

For that reason additional controlled prospective and randomized studies with a high number of patients are necessary before more propagation of this treatment for other indications than tendinosis calcarea at the shoulder will be recommended.

ESWT in treatment of orthopedic diseases is too worth for uncritical and undirected treatment. Only indications proofed by controlled studies with high number of patients should be treated by ESWT.

Impacted Bile-Duct Stones: A Major Cause of Failure in Laparoscopic Exploration

S. Mahmud, A. Nassar

Department of Surgery, Vale of Leven District General Hospital, Alexandria, Dunbartonshire, Scotland

Background

Impacted bile duct stones (IBDS) are occasionally encountered during laparoscopic common bile duct exploration (LCBDE). They are the single most important cause of technical difficulty, increasing the operative time, the cost of equipment and the potential for operative and post-operative morbidity. In experienced hands, IBDS are the commonest cause of failure and conversion of LCBDE.

Aims & Methods:

As it is almost impossible to predict the presence of IBDS preoperatively, this study aims to identify possible risk factors. An analysis of prospectively collected data from a series of 100 LCBDEs was also carried out to evaluate the timing of surgery, the operative technique, the use of consumables and outcome parameters in order to optimise the use of resources on a unit offering laparoscopic treatment to all comers with suspected ductal calculi who are fit for surgery. Stones were considered to be impacted if found at the lower end of the CBD or had a diameter greater than that of the CBD and required repeated manipulation attempts or failed to be dislodged.

Results:

100 cases underwent LCBDE performed by one surgeon over a period of 6 years. 10 patients had stones which were defined as impacted (10%). Eight were females and the median age was 62 years (39-85). All were emergency admissions, eight with jaundice and two with pain and LFT derangement. The ultrasound scans showed dilated ducts in all with stones in seven. ERCP was attempted in an 85-year-old with multiple previous surgery and an aortic aneurysm but failed (2.5 cm. stone in mid-CBD). Five LCBDEs were performed on emergency theatre sessions. Cholangiography showed multiple stones in all but two patients but only five had more than one impacted stone. Transcystic exploration was attempted in three patients, was successful in one and was thought to have caused the impaction of stones in the other two patients. Choledochotomy exploration was successful in three of nine patients (33%). Conversion to open surgery was done in six cases (60%), a bypass procedure being necessary in three patients due to failure of stone removal. The median operating time was 4 hours 45 minutes (2 hrs. 30 mins. - 5 hrs. 45 mins.). The mean duration of hospital stay was eight days (4-16). There was no major morbidity or reoperation but one ERCP was required to remove two retained stones in one patient who had open conversion.

Conclusion:

The presence of risk factors for IBDS (recurrent jaundice and CBD stones on ultrasound) may help plan treatment strategies and optimise the use of operative lists. Emergency operation sessions for LCBDE can reduce disruption to elective lists. The operative technique needs to be tailored to individual cases and the conversion rate will remain high. However, LCBDE remains our method of choice as impacted stones are a recognised cause of ERCP complications and failure. Short video clips will be used to demonstrate successful methods of dealing with IBDS.

Anatomy Browser: Teaching, Surgical Planning and Model Driven Segmentation

Tallal C.Mamisch, Carl P. Kolvenbach, Marco Das, Alexander Y.Lind, Sonja Bonitz, Julian Rathert, Daniel Boll, D-A. Sennst, Arya Nabavi, Joachim Kettenbach, Polina Golland, Ferenc Jolesz, Rainer M.M.Seibel, Ron Kikinis

Objective: We developed a three-dimensional (3D) digitized atlas of different anatomical regions (e.g.:brain, spine, pelvis) to visualize spatial complex structures. It was designed for use with magnetic resonance (MR) ,CT imaging data sets and the VHP(Visible Human Project) dataset. Thus far we have used this atlas for surgical planning, model driven segmentation, and teaching.

Materials and Methods: We used a combination of automated and supervised segmentation methods to define regions of interest based on anatomical knowledge. We also used 3D surface rendering techniques to create a atlas that would allow us to visualize complex 3D structures. We further linked this information to script files in order to preserve both spatial information and anatomical knowledge.

Results: We are presenting an application of the atlas for visualization in surgical planning, for model driven segmentation, and for the teaching human anatomy.

Conclusions: This digitized anatomical structures have the potential to provide important reference information for the planning of surgical procedures. It can also serve as a powerful teaching tool, since spatial relationships among anatomical structures can be more readily envisioned when the user is able to view and rotate the structures in 3D space. Moreover, each element of the brain atlas is associated with a name tag, displayed by a user-controlled pointer. The atlas holds a major promise as a template for model driven segmentation. Using this technique, many regions of interest can be characterized

simultaneously on new brain images.

Computer-Assisted Planning of Surgical Interventions in Patients with Slipped Capital Femoral Epiphysiolysis (SCFE)

T. C. Mamisch^1,2, J. Kordelle¹, J. Richolt¹, M. Das^1,2, R. M. M. Seibel², R. Kikinis¹

¹ Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston (MA), USA

² Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

Purpose

In case of SCFE the capital femoral epiphysis, including the femoral head, is displaced from the metaphysis. Usually the femoral head is tilted in a postero-inferior position in relation to the femoral neck whereas a valgus slip was rarely observed. In general, acute slips are epiphyseal fractures between the epiphysis and the metaphysis of the femoral neck. Shear forces, influenced by body weight, muscle forces, and abnormal femoral angulation, appear to play a major role in the development of SCFE. Some authors reported an association with SCFE and decreased femoral anteversion or varus deformity of the proximal femur. Furthermore, it is conceivable that the abnormal femoral angulation may lead to a maldevelopment of the acetabulum. The goal of the presented study was to investigate the relation between the proximal femur and the orientation of the epiphysis and, furthermore, to determine if the acetabular development is influenced by the femoral neck orientation or the epiphyseal alignment.

Material/Methods

Three-dimensional reconstructed models based on CT data sets of 22 patients with thirty slipped capital femoral epiphysis were reviewed. The computed tomography data sets were achieved with patients in supine position, 2-5 mm contiguous, axial slices through the hip joint. Three-dimensional models were reconstructed based on "The Visualization Toolkit" (VTK, General Electric, Schenectady, NY, USA). Measurement of the hip joint geometry was performed by using a newly developed interactive software to determine projected angles. The measurement tool consists of two elements. The end of the tool is provided with a plane to facilitate the definition of the orientation of the acetabulum and the epiphysis. The axis of the tool is proposed to define the longitudinal axis of an anatomical structure (e.g. femoral shaft axis). The three-dimensional model and the measurement tool can be freely shifted and rotated in all planes. A phantom scan was performed to validate the accuracy of the tool. The mean error rate in a total of 24 measurements was 0.76(Std.Dev. 0.61). The determination of the mentioned angles was performed three times. Calculations were carried out by the use of the mean value.

Results

We found a significant positive correlation between the femur version and the version of the femoral epiphysis (P: 0.02, R: 0.41). Furthermore, there was a highly significant positive interdependence between the shaft-neck-angle (g) and the shaft-epiphysis-angle (d) (P: 0.001, R: 0.6). No correlation was detected between the femoral version and the acetabular anteversion (P: 0.11) or between the shaft-neck-angle (g) and the acetabular inclination (P: 0.48). In addition, there was no correlation between the epiphyseal orientation and the anteversion (P: 0.14) and inclination (P:0.35) of the acetabulum.

Conclusion

The three-dimensional measurement of the hip geometry in cases of SCFE demonstrates a significant correlation between the femoral orientation and the epiphyseal alignment. In addition, we found a reduced femoral anteversion, a normal femoral shaft-neck angle, and normal acetabular orientation. A correlation between the orientation of the acetabulum and the femoral neck, as well as between the alignment of the acetabulum and the epiphysis could not be observed. In response to these results, we suggest that there is an interrelation between the development of the proximal femur and the epiphyseal growth plate.

Present State of Stent Angioplasty of Internal Carotid Artery Stenosis

K. Mathias, H. Jäger (Department of Radiology, Teaching Hospital of Dortmund)

Indications

Carotid atherosclerosis is responsible for about 30% of ischemic strokes. When the degree of carotid stenosis exceeds 70% in symptomatic patients or 80% in asymptomatic patients the indication for stent angioplasty (CSA) is given. In stage IV removal of the carotid stenosis is performed in patients who might suffer from a second stroke. Heavily calcified lesions and larger thrombus in the ICA may be contraindications for stent angioplasty. Recurrent stenosis after CEA is well suited for CSA.

Diagnostic

The diagnostic work-up includes a clinical and neurological examination, color-coded doppler ultrasound of the neck vessels, MRI of the brain, the neck and cerebral arteries and determination of the neurovascular reserve capacity. A four-vessel angiography is performed to evaluate the degree of stenosis and the collateral circulation.

Technique

The intervention is performed in 6 steps: diagnostic angiogram, probing of the stenosis, predilatation with a 3 to 4 mm coronary balloon, placement of a self-expandable stent with a size between 6x20 to 10x30 mm according to the individual arterial diameter, and definitive dilatation with a 5 to 6 mm balloon. The Wallstent is preferred when the stent is placed across the bifurcation, because it adopts well to the different diameters of the common and internal carotid artery. During the procedure continuous monitoring of blood pressure and ECG is necessary. Transcranial Doppler sonography may be helpful. Presently, cerebral protection techniques are evaluated and have shown a reduction of the neurological complication rate. 5,000 IU of heparin and 1.0 mg atropine are given during the intervention; heparin for two days (PTT 60 sec), 75 mg clopidogrel for 6 weeks and 300 mg aspirin for at least 6 months.

Results

From 10/84 to 4/00 869 patients with 1064 carotid artery stenoses were treated, 72% of them being symptomatic. Angioplasty alone was performed in 264, stent angioplasty in 790 arteries with a technical success rate of 99%. Stent angioplasty was combined with cerebral protection in 48 patients. Only self-expandable stents were used. Complications included TIA 3.7%, cerebral hemorrhage 0.1%, amaurosis fugax 0.8%, minor stroke 1.8%, major stroke 1.1%, deaths (30 day mortality) 0.38%. All strokes and deaths amounted to 3.3%. The 6-months restenosis rate was 1.9%. Five-years patency was 92%.

Conclusion

CSA has a technical sucess, complication and patency rate comparable to reported surgical results and better than those of the NASCET and ECST. Preliminary experiences with cerebral protection techniques give some evidence that the rate of permanent cerebral deficits can be reduced below 2%.

Gynecological Laparoscopic Procedures: Is Pregnancy a Contraindication?

L. Mettler,

Department of Obstetrics & Gynecology, University of Kiel Medical Center, Kiel, Germany

Pregnancy is considered to be a contraindication for laparoscopic surgery by many clinicians because no excellent external evidence from systematic research is available. After a literature research of whether pregnancy is a contraindication for laparoscopic surgery and after having spoken to many of my colleagues, I conclude that there are almost no scientific data available on endoscopic surgery during pregnancy; however, everyone is able to cite individual cases that have been performed. Clearly there are limitations to performing endoscopic procedures during pregnancy: The level of uterine fundus, which grows and limits the space of the operative field, the adiposity of the abdominal wall and the risk of anesthesia in general. The following surgical procedures are performed during pregnancies: cholecystectomies, appendectomies, ovarian cystectomies, myomectomies and adhesiolysis. The frequency of non-obstetric surgery during pregnancy is low. The most common procedures are appendectomy and cholecystectomy, which can be performed to a certain level of uterine size by either laparoscopy or laparotomy.

Sonographically Guided Interstitital High-Frequency Thermotherapy (HFTT) with Needle Electrodes – Effects and Applications

W. Müller¹, J. Hänsler², D. Becker², E.G. Hahn²

¹ Berchtold Medizin-Elektronik GmbH & Co., Tuttlingen, Germany

² 1^st Medical Clinic, Erlangen-Nürnberg University Medical Center, Erlangen, Germany

Only approx. 15% up to 30% of all liver malignancies are accessible to curative surgical therapy. In all other cases, palliative methods are used (chemotherapy, laser ablation, alcohol instillation, radio frequency ablation etc.). High-frequency currents and voltages with a frequency of 375 kHz, with capacities of 5 to 60 W and application times of a few seconds up to 10 minutes are converted into heat energy in the target area of the electrolytically conductive bio-tissue via a special HFTT needle applicator. During this procedure, the patient is a constituent part of the high-frequency electric circuit due to a low impedance contact with a large-surface adhesive neutral electrode, which is located as short a distance as possible from the zone of activity.

The biophysical interactions of the HF energy correspond to a soft coagulation or microarcfree coagulation, as has been known and proven in practice for a long time in monopolar surgical electrocoagulation. A heat effect occurs, especially where the electrical HF fields and HF currents are locally condensed. The HF currents have a quadratic influence and the HF application times a linear influence on the heat generation of the HFTT needle in the target area (tumor area).

The HFTT needle applicator, with a diameter of 1.2 mm (18 Gauge), has a special liquid-permeable active electrode that can be between 10 and 25 mm long, on the distal end and a shaft insulated with TEFLON, between 10 and 20 cm long, as well as a connection for the HF cable and flushing liquid. The HFTT needle applicator is autoclavable and is designed for single use. The flow rate of the infusion fluid (isotonic NaCl solution) of 60 to 100 ml/h supplied by an injection pump via infusion set, permanently perfuses the active needle electrode, which contains several micro boreholes and micro water pockets formed using laser technology. During the high-frequency application, the permanent electrode perfusion has the function to increase the electrolytic conductivity for the HF fields and HF currents in the target area, forcing a transfer of heat into the tissue matrix and preventing the tissue from drying out and the electrode from sticking during the coagulation process. The synchronous heating up of the NaCl solution to the maximum temperature on the interface between the interstice and the perforated HFTT needle surface is essential during this process, as is also a favorable parameter ratio of HF power density and flushing liquid flow.

The HFTT method coagulates the target area (tumor area) in the environment of the HFTT needle applicator at temperatures of 56 °C < T £ 100°C. A temperature check can be performed in the interstice by means of a miniature temperature sensor in the HFTT needle applicator. A computer-assisted high frequency generator, the “ELEKTROTOM 106 HFTT”, with special control characteristics, impedance monitor and a digital timer, provides the necessary HF energy. The selectable parameters of HF power, HF application time and flushing liquid flow, as well as the geometry of the metal electrode tips, have a considerable influence on the expansion of the generally rotational-elliptical coagulation zone, whose volume can be a maximum of 50 cm³ (diameter of the coagulation zone up to 40 mm).

Real-time control of the thermal interactions is easily possible with modern ultrasound diagnostic units, as the acoustic impedance of the hyperthermal bio-tissue increases in relation to the temperature and is echoed as a brightened image. In comparison, after post-therapeutic cooling of the coagulated target area, the necrosis zone is no longer echoed. Starting from the distal end of the HFTT needle, microcurrents can easily be recorded by means of a power Doppler during positioning of the applicator in the target area before and after HF activation.

With the use of ultrasound imaging, the minimally invasive procedure can be used both percutaneously and intraoperatively for patients with inoperable liver metastases/tumors and for other indications.

The treatment with HFTT and perfused needle electrodes is a safe and effective technique. No worsening of liver function occurred. Treatment in the direct vicinity of large vessels and the porta hepatis can be carried out safely. The cooling by the blood stream seems to prevent larger vessels from thermal damage.

Image-Guided Neurosurgery - Surgical Planning, Visualization and Intraoperative MRI

A. Nabavi, D. T. Gering, T. C. Mamisch, R. S. Pergolizzi, W. M. Wells, R. B. Schwartz, R. Kikinis, P. Mc Black, F. A. Jolesz

Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston (MA), USA

Image-guided neurosurgery has made enormous progress since the original descriptions in the mid-80s. Image fusion allowed the integration of multimodal image sources into one comprehensive 3D representation of pathology and functional studies. Nevertheless, the major limitations of these conventional neuronavigation systems remain the intraoperative deformations, occurring mainly due to cerebrospinal fluid leakage and tumor resection. Particularly towards the end of surgery, when information regarding the gross total tumor resection is most important, these systems are least reliable. In order to provide means for the compensation of this so-called "brain-shift", various modalities were tested for the acquisition of intraoperative images. We will describe our approach to image guided surgery, the computer assisted navigation as an integral part of an open-configuration MRI system.

Since 1996 the intraoperative SignaSP 0.5 Tesla open-configuration MRI (GE Medical Systems, Milwaukee) was used in over 100 brain biopsies and 350 open craniotomies for tumor removal. A breakdown of the cases yields 76 glioblastomas, 64 oligodendrogliomas, 42 astrozytoma I-II, 38 astrozytoma III, 56 recurrent lesions, 28 metastases, 16 vascular lesions and 30 others. This SignaSP open-bore system has a vertical gap of 56 cm, which allows two surgeons access to the patient positioned in the scanner. Therefore, the patient can remain in the same position for scanning as well as surgery, i.e. it is unnecessary to move the patient in and out of the imaging system during this surgery. Repeated scans for orientation and the identification of residual tumor/signal abnormality can be obtained at the surgeon's discretion, without major preparations. This advantage is also utilized for research, such as in the field of intraoperative brain deformations. Furthermore, we integrated an in-house developed frameless computer-navigation system into the SignaSP. Routinely applied sequences are T1, T2, and SPGR volume acquisitions. Special studies include perfusion images, diffusion-weighted images, heme-sensitive sequences, TOF-angiography and thermosensitive sequences. Although the flexibility of intraoperative imaging is remarkable, presurgical data such as, for instance, functional and diffusion weighted imaging are presently impossible to acquire (fMRI) and qualitatively superior (DWI) to intraoperative studies. These studies can be integrated for the initial approach, or trajectory planning. As the surgery changes the configuration, these initial studies decrease in accuracy. To update the information for navigation, new images are acquired. These images are integrated into our in-house developed navigation system, the 3D Slicer, which provides a navigation tool with fast computer graphics. The surgeon uses this tool to plan approaches, to guide the resection and for the final control for residual tumor. Current research points into the direction of deformable models, i.e. the adaptation of presurgically acquired data and 3D models to the intraoperative changes, and the implementation of improved sequences (DWI and continuous imaging).

The advent of intraoperative MRI with its flexibility and superior image contrast has revolutionized the field of image-guided therapy as a whole, and that of neurosurgery in particular. As an integrated system, with computer-assisted navigation and visualization software and intraoperatively updated images, it provides us with the tools of truly spatial and near-real-time intraoperative guidance for neurosurgery.

Multimodal image information for intraoperative image guidance

resection control after removal of an oligodendroglioma

Thoracoscopic Excision of a Mid-Esophageal Diverticulum

A.H.M. Nassar, D.F. Campbell, S. Mahmud

Department of General Surgery, Vale of Leven District General Hospital, Alexandria, Dunbartonshire, Scotland

The benefits of minimally invasive surgery are well established, yet it is difficult to gain access to the mid esophagus without a muscle-cutting incision to assist the thoracoscopic approach. Thoracotomy and mini thoracotomy incisions are associated with significant post-operative morbidity and discomfort. Esophageal diverticula are encountered occasionally and may require excision when symptomatic. Thoracoscopic excision of epiphrenic diverticula is well documented but the few reports on treating middle third diverticula highlight the difficulty in totally thoracoscopic excision and hence the need for mini-thoracotomy. We present a case report of the resection of a large (7x4cm) symptomatic mid-esophageal diverticulum at 30 cm in a 63-year-old man by a purely thoracoscopic approach. With the patient in the left lateral position and with double-lumen endotracheal intubation, four ports were secured on the right side of the chest (2x10mm,2x5mm). A gastroscope was used to evacuate the diverticulum of food debris and then left in to aid localization by transillumination during sharp and blunt dissection. The neck of the diverticulum was isolated and then transected using an ATB 35 flexible linear stapler, and the diverticulum was removed. The staple line was checked under water with air insufflation through the gastroscope. Post-operative recovery was uneventful and the patient was discharged on the 7th post-operative day having been restored to a normal diet. We believe this to be the first report of the removal of a mid-esophageal diverticulum without thoracotomy in the English literature. A video will demonstrate the technical steps, the precautions, and the anatomy of this difficult area.

Prospects of MR-Guided Vascular Interventions

W. R. Nitz¹, C. Manke², A. Oppelt¹

¹ Siemens AG, Medical Engineering Group, Erlangen, Germany

² Regensburg University Medical Center, Regensburg, Germany

Magnetic resonance imaging (MRI) guidance of interventional procedures offer several advantages over x-ray fluoroscopy guided techniques: absence of ionizing radiation, avoiding the potential hazards of iodinated contrast media, multiplanar capability and superior soft tissue contrast. Utilization of ?active? tip tracking has shown promise for easy tracking of guide wires as well as catheters [1-3]. These elegant approaches require sophisticated hardware and software for signal detection and signal display. It has been shown, that using a ?passive? imaging technique, based on the susceptibility artifact created by a commercially available catheter, it is feasible to place stents under MR guidance [4]. Nevertheless the use of a conductive guide wire during the presence of a high frequency electromagnetic field (RF) has to be cautioned and the work presented here will cover the safety aspects of using commercially available guide wires and catheters in combination with a strong static magnetic and an RF field. Results will be shown for stent placements under MR guidance and a speculative outlook will be given with respect to the further development.

Guide wires are mandatory tools utilized in vascular interventions, to guide catheters through stenotic areas to ensure correct placement of stents or PTA approaches. We performed several experiments, demonstrating, that the wire itself is not getting hot, that the heat sensation and the notable temperature increase is solely related to the voltages building up between the tip of the wire and surrounding tissue. Dangerous regions are areas of high resistance like the skin surface or fat layers and situations where the wire is only slightly touching the body. Although our results show no measurable effects below a 30° excitation angle for fast GRE protocols, applications utilizing a higher excitation angle with the guide wire being in place might cause harm to the patient and/or physician. A safe solution would be the use of a non-conducting guide wire.

We evaluated ten commercially available vascular stents with respect to MR safety, MR visibility, feasibility of stent deployment and the capability of identifying a patent inner stent lumen.

We decided for the Memotherm iliac stent (Angiomed Bard, Karlsruhe) to be the most suitable commercially available stent and successfully performed MR guided stent placements in 15 patients. Picture 1 is showing the stenotic lesion using a ceMRA-Roadmap (A), the stent placement (B), the stent release (C) and the balloon dilatation (D).

All experiments were performed on a 1.5T System (Siemens AG, Erlangen, MAGNETOM Symphony) equipped with an In-Room-Monitor (Picture 2).

The conclusion of our work is that a MR guided stent placement is possible utilizing commercially available hardware, software and tools designed for conventional angiography. Critical part of this application is the currently favored conductive guidewire, but there are indications that this safety issue will be solved in the near future.

[1] Wildermuth S, Debatin JF, Leung DA et al. MR imaging guided intravascular procedures: initial demonstration in a pig model. Radiology 1997; 202:578-583

[2] Bakker CJ, Smits H, Bos C et al. MR-guided balloon angioplasty: in vitro demonstration of the potential of MR guiding, monitoring and evaluating endovascular interventions. J Magn Reson Imaging 1998; 8: 245-250

[3] Bücker A, Neuerburg JM, Adam G et al. Stent placement under real time MR control: first experience in an animal model. Fortschr Roentgenstr 1998; 169: 655-657

[4] Manke C, Nitz WR, Lenhart M et al. Stent angioplasty of iliac artery stenoses under MR-control: initial clinical results. Fortschr Roentgenstr 2000; 172: 92-97

Intraoperative Magnetic Resonance Imaging? Problems and Solutions

A. Oppelt, T. Vetter

Siemens Medizinische Technik, Erlangen, Germany

Magnetic Resonance Imaging (MRI) is well suited to guiding surgical procedures because of its excellent tissue contrast, vessel conspicuoucy, and the possibility to position slices with arbitrary orientation, or to establish 3D image volumes. Although MRI is capable of real-time imaging and is a non-contact procedure, space limitations in the magnet and limits of the signal-to-noise ratio during real-time image acquisition have up to now restricted its Intraoperative use to neurosurgery, where the head can be easily immobilized. Intraoperative MRI has been shown to improve accuracy in localization and removing lesions in the brain [1-3]. Hospital charges for MRI guided surgery have been reported to be higher than in standard surgery [4], but first studies show that survival times for patients are prolonged [5]. To follow surgical procedures with MRI in real time requires special magnets allowing access to the patient for operation during imaging. However, compromises have to be made with respect to field strength, imaging volume, weight of the magnet and current consumption, access to the patient and freedom of movement for the surgeon. Costly non-magnetic surgical tools are required, which sometimes lack performance. Modifying standard MR scanners to bring in a patient undergoing surgery is, therefore, an attractive alternative. The surgeon operates outside the magnet with no need to change his routine in positioning the patient on a surgical table, applying a surgical microscope and using navigational equipment, but can acquire intraoperative MR images for monitoring of surgery and update of the navigational data base. Initially development was started with a twin surgical suite, where the patient was moved several meters from the surgical site to the MR scanner. Although the spatial separation of the surgical and the MR site is an advantage when the scanner is also to be used for purely diagnostic imaging, this approach implies a lengthy transport maneuver, during which a patient with an open skull is prone to shocks. State-of-the-art magnets with their rapidly decaying fringe field allow operating with standard instruments close to the MR scanner, and the patient can be broughtfrom the surgical position into the scanning position rapidly and smoothly by rotating the surgical table. In combination with a 0.2 T scanner, this concept has been realized [6], whereby the open construction allows also procedures such as brain biopsies under real-time control. A surgical head holder with an integrated imaging coil (fig. 1) permits craniotomies [7]. To bring the benefits of high-field MRI such as better image quality, spectroscopy, diffusion and functional imaging into the surgical suite, the concept of an integrated surgical table has been consequently developed further (fig. 2). The table is adjustable in height and tiltable from Trendelenburg to anti-Trendelenburg position, as well as around the longitudinal axis. In addition, a head holder for craniotomies has been constructed that fits into a separable head coil. In conclusion, current MR scanners with their high image quality optimized for diagnostic purposes can be combined with a fully functional MR-compatible surgical table to enable image-guided surgery in a fringe field, which is weak enough for the surgeon to stay with his normal routine.

References

[1] P.M. Black, et al: Neurosurgery 41, 831 (1997)

[2] V.M. Tronnier, et al: Neurosurgery 40, 891 (1997)

[3] R. Steinmeier, et al: Neurosurgery 43, 739 (1998)

[4] C. Lycette, et al: Proc. Intl. Soc. Mag. Reson. Med. 8, 65 (2000)

[5] C.R. Wirtz, et al: Neurosurgery 46, 1112 (2000)

[6] M. Wendt, et al: ELECTROMEDICA 67, 98 (1999)

[7] A. Staubert, et al: JMRI 11, 564 (2000)

Square Stent Based Large Vessel Occluder: An experimental pilot study

Pavcnik D, BT. Uchida, H. Timmermans, CL. Corless, M Loriaux , FS. Keller, J Rösch,

Dotter Interventional Institute, Oregon Health Sciences University

PURPOSE: In vitro and in vivo experimental evaluation of a square stent based vascular occlusion device for large vessels.

MATERIALS AND METHODS: Square stent large vessel occluders (LVO) 5mm-50mm in size were constructed from stainless steel square stents covered by porcine small intestine submucosa (SIS). LVOs with 2 backside barbs were delivered through a guiding catheter. The LVOs with 2 backside and 2 frontal barbs were front loaded and delivered coaxially. A pusher with a retention mechanism at its end was used for deployment. In vitro testing for competency was done using a flow model with pressure increases. In an experimental pilot study in 7 swine and 5 dogs, 16 LVOs were placed into the aorta (n=4), common iliac artery (n=2), pulmonary artery (n=4) and medial sacral artery (n=6). Four animals received two LVO in different locations. Angiography was performed before and after placement of each LVO. Animals were followed up to 3 months by angiography, then sacrificed for gross and histologic evaluation.

RESULTS: In vitro LVOs with both 2 and four barbs were easily collapsed and pushed through or front loaded into guiding catheters (6 F for 5mm occcluder to 10 F for 50-mm occluder). A 20-mm LVO adapted to tubular structures from 10 to 15 mm in diameter forming a polygon with a range from 17-mm to 18.5-mm in length respectively. In the flow model, LVOs endured pressure increases up to 300 mm Hg. In vivo the LVOs self-expanded and self-adapted to the vessel without migration in all cases. The locking pusher allowed precise LVO placement and engagement of its barbs into the vessel wall prior to complete deployment preventing dislodgment by blood flow. Complete arterial occlusion occurred within 10-20 minutes and arteries remained occluded to the time of sacrifice in all cases. After two months, histologic evaluation revealed replacement of SIS by host tissue and its remodeling with variable fibrocytes, fibroblasts and some inflammatory cells. Complete endothelialization was seen on both sides of the LVO.

CONCLUSION: The SIS large vessel occluder has proved effective and reliable for acute and chronic occlusion in a high flow model and in experimental animals.

Transcatheter placement of bioprosthetic aortic valve. A feasibility study

Pavcnik D, Uchida B, Timmermans H, Corless C, Rösch J, Keller FS

Dotter Interventional Institute, Portland, Oregon

Purpose:

In vitro and in vivo experimental evaluation of a new, artificial, bicuspid, aortic valve was performed.

Materials and methods: Valves were constructed from square-stents with four barbs covered by porcine small intestine submucosa (SIS). One valve, 15 mm in diameter, was tested in a flow model (2.5 l/min) with pressure measurement proximal and distal to the valve during prograde flow. A 100-ml rubber bag attached to a side arm at lower end of the flow model simulated the heart ejection fraction. In acute (n=6) and longer term experiments (n=3) conducted in 5 swine and 4 dogs, valves ranging from 16 - 28mm in diameter were placed into the ascending aorta through 10 F guiding catheter; 2 subcoronary and 6 supracoronary in position. Function of the valves and their stability was studied with injections of contrast medium and pressure measurement. Two swine were used for longer term testing and then were sacrificed for gross and histologic evaluation at 2 and 2 weeks.

Results:

At rest without flow, the valve was closed by hydrostatic pressure of 101 mm Hg below and 100 mm above the valve. In pulsatile flow, when the valve closed, pressure above it increased to 110( /-5) mm Hg and below it decreased to 79( /-7) mm Hg. In 3 short term animals with valve, placed in the subcoronary position, one of the cusps of the original valve was trapped between the square stent and the aortic wall. This created considerable regurgitation and an appropriate model for evaluating the efficacy of the new device. Both animals maintained systemic pressures of 92/74 ( /-9) mm Hg and 110/80 ( /-11) mm Hg, respectively. Aortogram revealed minimal regurgitation, and no interference with coronary blood flow in all animals. Postmortem examination revealed the valves to be securely anchored. Histologic evaluation at 2 and 4 weeks revealed early remodeling of SIS with fibrocytes, fibroblasts and endothelial cells.

Conclusion:

Pilot study demonstrates that the development of a bio- prosthetic aortic valve for transcatheter placement is feasible.

Percutaneously introduced prosthetic venous valve: an experimental pilot study

Pavcnik D, Uchida B, Timmermans H, Corless C, Rösch J, Keller FS

Dotter Interventional Institute, Portland, Oregon

Purpose: In vitro and in vivo experimental evaluation of a new, homemade, artificial, bicuspid, square-stent venous valve was performed.

Materials and methods: Bicuspid valves were constructed from square-stents covered by porcine small intestine submucosa (SIS). In vitro testing of the valves was done using in a flow model for competency with pressure measurement during prograde and retrograde flow. Calf venous pump input (100ml) was provided by a side arm to the flow model. In an acute experiment in three dogs valves with four barbs were placed into the IVC through an 8 F guiding catheter. Function of the valves and their stability was studied in supine and upright position with injections of contrast medium and pressure measurement. For longer term testing, valves were placed into the IVCs and iliac veins of three young swine. Animals were followed at two weeks by venograms, then were sacrificed for gross and histologic evaluation.

Results: In vitro the valve was closed with a pressure of 61 mm Hg below the valve and 60 mm Hg above the valve. During injection of 100 ml of water the valve opened permitting fluid flow. After injection the valve immediately closed and the pressure below the valve declined to 11 mm Hg with a range 6-16 mm Hg. Above valve pressure was unchanged. Good valve function was observed in all animals. No pressure gradient was observed through the valves in supine position. All veins remained patent at 6 weeks and smooth incorporation of the SIS valves into the vein wall was observed. Histologic evaluation demonstrated early SIS remodeling with variable fibrocytes, fibroblasts and inflammatory cells.

Conclusion: SIS valve is a promising one –way competent valve capable of sustaining high venous back pressure, while allowing forward flow with minimal resistance.

Radiation Exposure in CT-Guided Lumbar Periradicular or Epidural Treatment and in Lumbar Sympathectomy

M. T. Pflaesterer-Schoensiegel, J. C. Boeck, S. A. Hengst, N. Hidajat, R. Felix

Clinic of Nuclear Medicine, Charité Campus Virchow Medical Center, Medical Center of the Humboldt University Berlin, Berlin, Germany

Aim

The aim was to measure the radiation exposure of the patient and interventionalist during lumbar periradicular or epidural treatment and during lumbar sympathectomy. Procedures were performed by experienced interventionalists in a spiral CT scanner (Somatom Plus 4, Siemens, Erlangen, Germany) using CT fluoroscopy (Care Vision, Siemens). Measurements were performed on the patients' and interventionalists' skin using 36 thermoluminescence detectors during routine clinical interventions (periradicular and epidural interventions (pooled): n=18, lumbar sympathectomies: n=17). Male patients' gonads were protected by 1 mm lead, interventionalists wore 0,4 mm lead aprons.

Results

The average radiation exposure in micro-Sievert, presented in table form:

	periradicular/epidural		sympathectomy
	patient	doctor	patient	doctor
R eye	6,4	58,5	12,6	30,3
R hand		40,4		74,2
R thyroid	17,9	13,6	38,5	26,3
gonads	441,6	9,8	546,7	11,3
skin gantry		14790,7		24660,6
R breast	140,6	6,4	135,3	14,0

Conclusion

As compared with other diagnostic and interventional procedures, the radiation exposure of the patient and the interventionalist during CT-guided lumbar periradicular or epidural treatment and in lumbar sympathectomy are reasonable. In our experience, deterministic radiation effects should not occur in either the patient or the interventionalist. However, although the radiation exposure is quite low, stochastic effects cannot be definitively excluded because there may be no threshold exposure.

Assessment of Precision of Blind Sympathectomy (not guided by CT): Experimental Results

M. T. Pflaesterer-Schoensiegel, J. C. Boeck, S. A. Hengst, R. Felix

Clinic of Nuclear Medicine, Charité Campus Virchow Medical Center, Medical Center of the Humboldt University Berlin, Berlin, Germany

The aim of the study was to evaluate the precision of minimally invasive sympathectomy performed without image guidance. Eleven dead pigs were studied in supine position in the CT suite. A 20 cm long 22 G needle using a coaxial 0,73 mm cannula (Seibel/Groenemeyer Interventionelles Coaxiales Kannuelenset, Cook, Bjaeverskov, Denmark) was advanced towards the suspected location of the celiac trunc, the lumbar sympathic chain (right and left), or the superior hypogastric plexus. After that, the trunc of the animals was imaged by spiral CT (Somatom Plus 4, Siemens, Erlangen, Germany). On the images, the deviation of the needle position from the target was measured in all three dimensions.

Results:

In none of the 55 punctures the target was reached. Deviations ranged from 4 to 9 cm. In several cases, the final needle position was within organs such as the kidneys, urinary bladder, and small intestine.

Conclusion:

Minimally invasive sympathectomy not guided by CT is imprecise. Consequently, it usually requires higher doses of sympathicolytic agents, may be less efficient, and is potentially harmful.

Abstract to be presented at the Enervation Congress, Fall 2000

Dr. med. Platzek

Introduction:

In the past few years, advances in pain therapy were achieved in particular via the differentiated use of new combinations of medications. Many patients are deterred from choosing this form of therapy because of the regular consumption of medication, its possible side effects and due to the fact it is not a causal therapy.

In light of this, the discovery that extracorporeal shock wave lithotripsy (ESWL) not only effectuates benefitial morphologic changes of bones but also has clear analgesic effects is a welcome development.

Results:

Altogether there was a definite and significant reduction in pain on average.

Pain during exercise, before therapy (rating according to a VAS) 8,7 - 0,8 After therapy: 4,1 - 1,04

Pain while resting before therapy:(rating according to a VAS) 6,6 - 0,9 After therapy: 2,7 - 0,6

The values on the pain scale only increase insignificantly three months after therapy.

Pain during exercise: (rating according to a VAS) 4,9 - 1,5

Pain while resting: (rating according to a VAS) 2,9 - 1,8

It was very evident that ESWL treatment positively effected the unpleasant concomitant symptom of pain (reported according to the Zersson Index). This improvement persisted even 3 months after therapy was compleded.

On the basis of IT documentation, the study collectively analyzed the patients use of analgesics and other therapeutics. The results revealed that only 5 out of 70 patients occasionally took an analgesic - in most cases an NSAR. This was true of 70 percent of the patients before treatment.

Conclusion:

1. The analgetic efficacy of ESWL treatment for necrosis of the femoral head is very obvious.

2. Additional research on the mechanisms of action is imperative.

3. Clinical results available to us today reveal that the spectrum of pain therapy could greatly benefit from the analgesic effects of high-energy ESWL.

Neurale Anatomie des kleinen Beckens und Laparoskopie

M. Possover,

Department of Obstetrics and Gynecology, Jena University Medical Center, Jena, Germany

Während der letzten zehn Jahre wurden zunehmend endoskopische Techniken zur Behandlung gynäkologischer Tumoren angewandt. Hierbei wurde die laparoskopische Lymphonodektomie etabliert und die radikale vaginale Chirurgie für die Therapie des Zervixkarzinoms wieder eingesetzt. Das laparoskopische Operieren hat hierbei den großen Vorteil der siebenfachen Vergrößerung und des Zwanges zum blutarmen Operieren, welches ein exaktes Studium der Anatomie erlaubt. Für den gynäkologischen Chirurgen ist neben der Topographie auch die funktionelle Anatomie von großer Bedeutung: So weiß er, welche Strukturen für die Blutversorgung lebenswichtiger Strukturen erhalten und welche Nervenstrukturen für die Funktion der Hohlorgane geschont werden müssen, um damit eine gute postoperative Lebensqualität zu gewährleisten. Durch ein gezieltes laparoskopisches nervenschonendes Vorgehen können die nervalen Strukturen teilweise erhalten bzw. deren Integrität intraoperativ mit Hilfe der „Neurostimulation“ geprüft werden. Hier hat die Laparoskopie eine wichtige Erweiterung unseres topographisch-anatomischen Verständnisses des kleinen Beckens gebracht und könnte an Bedeutung gewinnen in der Wiederherstellung bestimmter motorischer Funktionen bei gelähmten Patienten.

MR-Guided Preoperative Needle localization of the Breast

H. Pump, K. Jattke, R. Seibel

Institute of Diagnostic and Interventional Radiology, University of

Witten/Herdecke, Germany

Dynamic MR imaging of the breast is an important method in the evaluation of breast cancer. Contrast-enhanced MR is reported to be highly sensitive for the detection of breast lesions and allows the classification of suspect mammographic findings. The differentiation of malignant and benign masses is possible and even small lesions can be localized with MR. These small lesions often cannot be detected with mammography and a conventional preoperative needle localization is not possible.

The development of MR-compatible instruments and puncture needles in combination with specific coils allows the preoperative needle localization of the breast with MR-guidance. The major advantage of MR-localization is the high accuracy. We will present indications for MR-mammography and MR-guided needle localization and we will demonstrate the technique of dynamic MR imaging of the breast and of MR-guided preoperative needle localization.

Non-Invasive Cardiac Imaging with Electron-Beam Computed Tomography

H. Pump¹, C. Sehnert¹, S. Reznikova¹, S. Möhlenkamp², A. Schmermund², R. Erbel², R. M. M. Seibel¹

¹ Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

² Department of Cardiology, University of Essen, Essen, Germany

The aim of our presentation is to demonstrate various indications of electron-beam computed tomography (EBCT) for non-invasive cardiac imaging. The main indication is the detection of coronary artery calcification. The presence of coronary calcium has a strong correlation with the amount of coronary stenoses, and calcium has been shown to have significance as a predictor of cardiac events. Contrast-enhanced electron-beam CT in the detection of coronary artery stenoses and in the post-interventional evaluation is another important indication. We will present the EBCT technology and compare it with conventional spiral CT and multi-slice scanners. We will describe various scanning protocols and post-processing techniques. We will demonstrate the high sensitivities and specificities of contrast-enhanced EBCT in the assessment of coronary arterial stent patency, of bypass graft patency and in the evaluation of coronary artery stenoses after PTCA.

Dynamic MR Imaging of the Breast As an Important Method in the Evaluation of Breast Cancer

H. Pump, K. Jattke, R. M. M. Seibel

Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

Contrast-enhanced MR is reported to be highly sensitive for the detection of breast lesions and allows the classification of suspect mammographic findings. The differentiation of malignant and benign masses is possible and even small lesions can be localized with MR. These small lesions often cannot be detected with mammography and a conventional preoperative needle localization is not possible. The development of MR-compatible instruments and puncture needles in combination with specific coils allows the preoperative needle localization of the breast with MR guidance. The major advantage of MR localization is the high accuracy. We will present indications for MR mammography and MR-guided needle localization and we will demonstrate the technique of dynamic MR imaging of the breast and of MR-guided preoperative needle localization.

Minimally Invasive Surgery for Hair Transplantation

W. R. Rassman

Hair Transplantation - The Problem

The current approach to hair transplantation is a labor-intensive process. In the most progressive technique, single follicular units are dissected under a microscope and placed one-by-one into small needle-like holes in the bald areas. A large piece of scalp must be surgically removed from the side and/or back of the head and sutured with traditional wound closure techniques. The patient experiences several drawbacks with this approach: (1) it is a surgical procedure taking many hours and resulting in a long incision in the posterior scalp, (2) the procedure is labor-intensive and expensive, and (3) the quality varies significantly between doctors.

From the physician's point of view, the procedure requires multiple highly trained technicians (the manual skills can take a year to develop), and small errors in the surgical procedure by technicians or physicians can result in significant reduction of successfully transplanted hairs. These factors keep the costs high and the number of providers low. With more than 50% of the male population over 40 experiencing balding, it is these factors that limit the growth of the hair transplantation field.

The Solution - Minimally Invasive Hair Transplantation

Enabling technologies can replace labor-intensive procedures and, with proper implementation and deployment, can minimize human error. A technique has been developed using optical systems under high magnification to extract individual follicular units directly from the donor area in the back and side of the head. These follicular unit grafts are then inserted directly into the balding area using another developed technology. This dual process reduces the procedure from a process requiring multiple highly skilled technicians to a standardized procedure that can be performed by one surgeon and one or two assistants.

The procedure reduces the time hair grafts are out of the body to seconds, and damage due to handling (such as the drying and crushing commonly seen in current transplant procedures) will essentially be eliminated. Additionally, training for the new procedure is minimized through design. Furthermore, the patient will experience no surgical incision, will have minimal wound care with little or no swelling, and he or she should see the costs of surgery drop as the new procedure proliferates in physician offerings for cosmetic surgery.

The Role of Robotics in Cardiac Surgery

Hermann Reichenspurner, MD, PhD

Department of Cardiac Surgery, University Hospital Munich-Grosshadern, D-81366 Munich, Germany

The final of minimally invasive cardiac surgery is fully endoscopic, closed-chest surgery. Before this final step is reached, several important steps need to be mastered. The surgeon needs to be experienced in cardiac surgery going through limited incisions. It is important to realize that the whole heart is not visible during the surgical procedure. The surgeon therefore needs to rely on other imaging techniques, such as transesophageal echocardiography. In addition, video-assistance plays a significant role and the surgeon needs to learn to rely on the endoscopic image rather than the direct visual field.

At the University of Munich, we have undertaken several steps before approaching the final goal of fully endoscopic cardiac surgery. The whole minimally invasive program consists of 155 MIDCAB-, 355 OPCAB- (1), 69 minimally invasive mitral valve- (2), 52 minimally aortic valve surgeries, 28 Port-Access ASD closures (3), 32 endoscopic mammary artery take- downs and 29 at least partially endoscopic coronary artery surgeries using a computer enhanced robotic system (ZEUS^TM)(4). Visual assistance was used in all the minimally invasive mitral valve prodecures, Port-Access ASD closures, endoscopic LIMA-take-downs and robotically assisted CABG procedures. A 10 mm stereoscope was used which allowed 3-dimensional visualization using a head-mounted display or specific monitor screens (Vista Cardiothoracic Systems). In all cases of video-assistance, a robotic arm (AESOP^TM) was used to hold the camera which also allowed voice-controlled movement of the camera. This way of camera guidance evolved as an important milestone towards fully endoscopic cardiac surgery.

Partially or completely endoscopic coronary artery surgery was done in 29 cases using the computer-enhanced robotic system ZEUS^TM. The system was first tested in patients (n=6) undergoing full sternotomy and cardiopulmonary bypass with cardioplegic arrest. It was then used in OPCAB cases without cardiopulmonary bypass (n=7)(5). In order to limit the incision, a minithoracotomy was performed in the remaining 16 patients; this incision was decreased continuously to 2.5 cm at the current time. All coronary artery anastomoses were done endoscopically through two left lateral ports. Times required for the endoscopic coronary anastomoses ranged from 14 to 50 minutes. Total time of surgery ranged from 4.0 to 7.5h. Two patients needed to be converted intraoperatively due to a small sized LAD in one case and a small sized LIMA in the other case. All patients recovered well from surgery and were discharged after 4 to 12 days after surgery.

The ultimate goal of endoscopic cardiac surgery can only be reached after several milestones have been mastered such as limited access cardiac surgery, video-assistance, voice controlled camera guidance and computer-enhanced robotic assistance.

REICHENSPURNER, H., BOEHM, D.H., WELZ, A., SCHMITZ, Ch., WILDHIRT, S., SCHULZE, C., MEISER, B., SCHÜTZ, A., REICHART, B.

Minimally Invasive Coronary Artery Bypass Grafting: Port-Access Approach Versus Off-Pump Techniques

Ann Thorac Surg 66: 1036-40, 1998

REICHENSPURNER, H., BOEHM, D.H., GULBINS, H., SCHULZE, C., WILDHIRT, S., WELZ, A., DETTER, C., REICHART, B.:

Three-Dimensional Video and Robot-Assisted Port-Access Mitral Valve Operation

Ann Thorac Surg 69: 1176-1182, 2000

3. REICHENSPURNER, H., BOEHM, D., WELZ, A., SCHULZE, C., ZWISSLER, B., REICHART, B.

3D-Video- and Robot-Assisted Minimally Invasive ASD Closure Using the Port-Access^TM Technique

The Heart Surgery Forum 1 (2): 104-106, 1998

REICHENSPURNER, H., DAMIANO, RJ, MACK, M., BOEHM, D., GULBINS, H., DETTER, C., MEISER, BM, ELLGASS, R., REICHART B.

Use of the Voice-Controlled and Computer-Assisted Surgical System Zeus^TM for Endoscopic Coronary Artery Bypass Grafting

J Thorac Cardiovasc. Surg 118: 11-16, 1999

REICHENSPURNER, H., BOEHM, D.H., GULBINS, H., DETTER, C., DAMIANO, R., MACK, M., REICHART, B.:

Robotically Assisted Endoscopic Coronary Artery Bypass Procedures Without Cardiopulmonary Bypass

J Thorac Cardiovasc Surg 118: 960-961, 1999

Image-Guided Neuroendoscopy: Experiences with the Brain Lab Vectorvision System

T. Riegel, O. Alberti, U. Sure, D. Hellwig, H. Bertalanffy

Department of Neurosurgery, Marburg University Medical Center, Marburg, Germany

Objectives

Neuronavigation systems allow a three-dimensional localization of intracranial lesions using preoperative images. This technique can be used to optimize microsurgical resection as well as to define exact craniotomy. We have combined endoscopy and an optical navigation system in patients selected for endoscopic operation.

Material and Methods

Eleven third ventriculostomies, six cyst evacuations, four biopsies, three cystocisternostomies, two septostomies, two foraminotomies, one ventricular catheter replacement and one tumor removal were performed. For these interventions, we modified head fixation of patients and used a special calibration tool suited for endoscopy.

Results

28 patients were treated with a combination of endoscopy and neuronavigation in a period from 03/98 to 03/00. Exact planning of the procedure and determination of the ideal trajectory was possible in 27/28 cases. The calculated precision was 2.1 mm (0.4- 3.1 mm). The combination of a neuronavigation system with an endoscope provides interactive image guided neuroendoscopy. The system allows real-time display of the endoscope position.

Conclusion:

Image guided endoscopy is helpful in narrow spaces and distorted anatomy, e.g. small or atypical ventricles, narrow foramina or blurred endoscopic view.

Thoracoscopic Procedures at a City Hospital

R. Roth

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Patients and Method

Since the beginning of 1998, we have performed 82 thoracic operations, 32 out of which were done thoracoscopically. The interventions were carried out under endotracheal anesthesia with a double-lumen endotracheal tube. The position of the patient was the standard prone posterolateral thoracotomy position with the arm well abducted and the table split in such a way as to splay out the ribs to the fullest extent possible. Access to the thoracic cavity starts in the 5.ICR with a small skin wound without pneumothorax. The position of the other trocars depends on the localization of the pathological findings. For preparation, we use the thoracoscopic standard instruments including the automatic staplers. Retrieval bags are employed for tissue removal.

Results

Nineteen of the 32 patients had peripheral pulmonary lesions. In seven cases we observed malignant neoplasms (mesothelioma 2, lung metastases of colon tumours 3, primary lung carcinoma 1, Pancoast Tumor 1). Six of these interventions were performed with palliative intention. We removed seven benign lung neoplasms definitively. Two non-anatomical resections occurred in diffuse interstitial pulmonary disorders; in two cases, we saw inflammatory pulmonary diseases. Nine patients received a pleural bullae resection with parietal pleurectomy because of recurrent spontaneous pneumothorax . Four were treated for a large empyema.

Conclusion

The substantial benefit to the patient resulting from thoracoscopic surgery results, to a large extent, from the avoidance of a thoracotomy. The thoracoscopic ligature or resection of bullae with a parietal pleurectomy is a standard procedure. In the case of unknown peripheral pulmonary lesions, the thoracoscopic total biopsy delivers the safe histological diagnosis and is the definitive therapy for benign lung neoplasms.

The Biointelligence Age: Medicine After the Information Age

R.M. Satava

Yale University School of Medicine, New Haven, USA

Laparoscopic and minimally invasive surgery are the hallmarks of the Information Age for surgery. There is the perception that we are in the height of the Information Age revolution and that it is growing exponentially and will continue to do so. However, the Information Age is already a century old (telegraphy, telephony, radio transmission all began at the end of the 19th century). Actually, the spreading of the Internet defines the culmination, and hence waning, of the Information Age. The biotechnology revolution is over 40-50 years old, and is still promising results in genetic engineering, drug delivery and decoding the secret script of life. A new era has been brewing, and for lack of another name, the designation "Biointelligence Age" has been given. This is the combination of the worlds of biology, physics and information - into single entities. One of the earliest and simplest devices is the implanted programmable cardiac pacemaker, imitating the biologic performance of a living pacemaker. Emerging technologies and fields in biosensors and biomaterials (bio physical), biocomputation and bio-informatics (bio information) and MEMS microsensors and distributed networking (physical information) have redefined the direction for the future.

Combining all three areas results in systems and devices that are tiny, adaptable, embedded and intelligent. These microsystems will become ubiquitous, embedded in everything (from food to appliances to our body) and communicate through massively distributed networks. They will be programmable, flexible and transparent to daily living. The result will be to change our world from dumb, unconnected to "smart" and networked. The implication for surgery is that our surgical instruments, operating rooms and even the practice of surgery are about to undergo yet another significant change.

A number of the new technologies that are emerging will be a bellwether for things to come - things like smart materials (the smart tee-shirt), biomimetics (self-assembling and self-adjusting prostheses), tissue engineering (growing programmed stem cells on bioresorbable matrices for artificial organs) and smart, self-repairing medical information networks to guarantee high-quality service. As the technologies evolve further, totally independent microsystems (e.g. implantable diabetes systems with glucose sensor, microprocessors to determine the amount of drug delivery, and microfluidic systems to release the proper amount of insulin - all embedded and autonomous) will take on aspects of non-cognitive artificial life – the systems will seem to have a life of their own. A system such as the diabetes system can help resolve some of our most difficult problems, such as real-time management of diabetes and, even more importantly, compliance. Within surgery, the surgical instruments will be embedded with micro sensors or be constructed of smart material; they may become self-cleaning and self-sterilizing, and will be multifunctional. The operating room will continue to be integrated with information science tools and be networked to the outside world; however, this networking will be enabled by knowledge agents which will anticipate the needs of the surgeon or be capable of finding exactly the piece of information needed. Robotic surgical systems will incorporate image-guided navigation, be laden with numerous biosensors that detect both the functioning and biochemical data of tissues and will have features such as augmented vision into the infrared and other spectral ranges to enhance our perception of anatomy and physiology. The advances in tissue engineering will provide new therapeutic modalities, such as implantation of genetically engineered cells to replace damaged or resected tissues, and the replacement of blood vessels, muscle and even organs with artificially grown and tissue engineered systems.

It will be necessary to continually revise our concepts as new technologies either fail or emerge as dominant factors. These will also be subject to many of the non-technical barriers, such as regulation, reimbursement, litigation and refusal of patient or physician acceptance, which may spell the doom of an otherwise excellent and patient-valuable device. However, with biotechnology screaming that it is the answer to all of medicine's problems and the information and physical sciences declaring the same mantra, it is clear that the coming revolution is bigger and more profound than any single technology.

Comparison of 30 tibial non-unions: conventional treatment versus extracorporal shock wave therapy (ESWT)

W. Schaden, A. Sailler, A. Fischer, I. Kölpl, V. Hagmüller

Trauma Center Meidling,Kundratstrasse 37A, 1120 Vienna

From December 1998 onwards tibial non-unions not requiring surgical correction were treated by means of ESWT. The first 15 of this group are compared to a group of 15 priorly surgically treated tibial non-unions to investigate the efficacy of this new method.

Both groups consisted of 11 men and 4 women. The mean age in the surgical group was 38, in the shockwave group 43 years.

In both groups 4 hypertrophic and 11 atrophic non-unions were treated. The mean age of the non-unions was 12 months (ESWT group 4-43 months, surgerygroup 4-23 months).

Surgery in form of intramedullary nailing with or without bone graft was used in 7 cases, in a further 7 cases plates and screws with or without spongioplasty were used. One case was treated with external fixator and bone graft.

In the shockwave group after the therapy 8 patients received a plaster cast for 4 to 12 weeks. 4 patients were treated without fixation. 3 patients were immobilized with an external fixator for 8 to 12 weeks.

In the shockwave group 13 patients achieved bony healing. In this group the stay in the clinic was between 3 and 30 days with a mean of 7 days, in the surgery group it was 8 to 60 days with a mean of 37 days. The outpatient treatment lasted 3 to 12 months in the shockwave group with a mean of 5,3 months and in the surgery group 4 to 25 months with a mean of 7.8 months.

In the surgery group 8 patients healed after the first operation, complicated by

1 haematoma which had to be drained and by a case of skin necrosis which required grafting. 4 patients needed a secondary surgery before healing. In this group one new infection and one re-infection were observed.

In each group we found 1 patient with pre-existent soft tissue damage, so that after several revision operations, amputations had to be performed.

The two groups were also compared concerning the costs of the treatment:

In our experience the surgical treatment has been 70%-80% less as expensive than the treatment by ESWT, depending on the rates of the different insurances: "General Territorial Health Insurance Scheme" (Gebietskranken-kasse),"Minor Health Insurance Schemes" (Beamtenversicherung, Bundesbahnversicherung etc.) and the "Private Health Insurance Companies".

Comparing these two patient collectives in medical and economical aspects we consider shockwave therapy as the first choice in treatment of tibial non-unions.

New Diagnostic and Therapeutic Possibilities in 2-D and 3-D Mini-Endoscopy

Dipl.Ing. Hansgeorg Schaaf, D-85276 Pfaffenhofen, PolyDiagnost GmbH

In microendoscopy we have reached a state of outstanding picture quality and smallest dimensions with outer diameters of endoscopes reaching

0.25 mm. We believe that it is not important to have one diagnostic tool more or less but to develop new methods for micro-, mini- and noninvasive therapy under microendoscopic control.

I would like to introduce four different product families in microendoscopy with therapeutic possibilities:

1.) flexible, steerable endoscopes with working channels and working lengths up to 180 cm for transpapillary cholangio- and pancreaticoscopy,

2.) rigid endoscopes with irrigation and working channels starting with an outer diameter of 0.6 mm,

3.) rigid endoscopes that are steerable, the thinnest one having an outer diameter of 1.2 mm,

4.) flexible 3-D endoscopes that are steerable, starting with an outer diameter of 2.5 mm in which a working channel is included, and rigid 3-D endoscopes with an outer diameter of 1.2 mm including a working channel.

Having nice instruments with working channels but not having the right tools would not be very helpful. It is one of our goals to develop the instruments for the working channels as well.

Entering microendoscopy and -therapy also means that possibilities are given to use this instruments ambulant and in emergency cases outside of the hospital. For this reason we have developed a complete video-endoscopy-system driven by accumulators and built in into a simple pilot case.

In the following I would like to explain the different possibilities that our microendoscopes and the according tools are offering:

We will touch upon the endoscopic and therapeutic possibilities of:

1.) Transpapillary Cholangio- and Pancreaticoscopy offering the possibilities of:

biopsies, electro hydraulic and laser treatment of stones.

2.) Percutaneous Cholangioscopy, during which there can be made use of ultrasound catheters to conduct ultrasound examinations under microendoscopic control at the same time.

3.) Angioscopy with special flexible microendoscopes that additionally have a balloon at the distal end.

4.) In Neuroradiology special microendoscopes allow examinations and treatments in the spinal canal and the intervertebral disc.

5.) In Orthopaedics for the first time there is the possibility to examine the small joints, that means the joints of the fingers and the toes. For sure there is also the possibility to examine and treat the temporomaxillary joint.

6.) Ophthalmology offers outstanding new areas for treatments under microendoscopic control: ECP (endo-cyclo-photocoagulation) of the ciliary bodies, endoscopy of the Schlemm's canal, diagnosis and treatment of the lacrimal duct system using a micro-drill.

7.) In ENT new possibilities for submandibular endoscopy of the saliva channel and the treatment of salivary calculusses did arise.

In the 3-D endoscopy we have just started clinical trials in ophthalmology using the rigid endoscopes and further projects have started in angioscopy and percutaneous cholangioscopy using the flexible endoscopes.

In our believe physicians and engineers have the chance to learn a lot from each other to create new possibilities in the treatment of patients.

MR Behavior of Vena Cava Filters as a Basis for a new MR-Active Prototype of Vena Cava Filters

G. Schaefers ^1,2, A. Melzer ^1,3, M. Busch³

¹ Department of Physical Engineering, University of Applied Sciences Gelsenkirchen, Gelsenkirchen, Germany

² Mediport Simag GmbH, Berlin, Germany

³ Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

Purpose

The purpose of vena cava filters (VCFs) is to prevent pulmonary embolism by intercepting thrombotic material within the inferior vena cava. VCF implantation requires catheterization and is usually performed under guidance of X-ray angiography, which involves the use of nephrotoxic iodine contrast agents [1]. MR imaging provides the advantages of no radiation exposure and is becoming an interesting technique for monitoring VCF placement [2]. MRI-guided VCF implantation, however, is difficult for two reasons: VCFs are made of metal alloys that produce susceptibility artifacts and the VCF material itself generates no signal, being passively imaged with a negative contrast. To be able to use the advantages of MRI for VCF implantation, we tested the MR behavior of nine commercially available VCFs, developing a new MR-active VCF prototype on the basis of the results.

Materials & Methods

For the evaluation of the VCFs, we used a Siemens Magnetom Open MR scanner with a 0.2 Tesla vertical magnetic field. Prior to testing artifact behavior, we examined the filters in terms of their response to magnetic force of attraction and torque. Subsequently, the filters were placed in an artifact-free plastic tube in a heated container filled with 2 mmol/l Gadopentetacid (Magnevist, Schering)/saline solution. Spin echo (TR=300; TE=26) and gradient echo (flash 2D:TR=93; TE=12,7; FA 20-90°) sequences in coronar and transverse directions (SL=5mm) were used to evaluate the artifacts generated by the filter material. After that test, an artifact-free VCF was selected and equipped with a constructed resonating circuit (RC) consisting of an inductivity (cylinder coil, diam. = 4.5mm, length: 19mm) and an SMD (Surface Mounted Device) capacitor. The frequency of the RC was attuned to the Larmor frequency of the protons (wL), 8.3 MHz in this case. After these tests, we proceeded to build the new prototype. For this purpose, we invented a special coil design, which also forms the filter element. This coil was completed with an SMD capacitor to form an RC and tuned to wL. The modified VCF and the VCF prototype were placed in the test basin and were examined in the MR scanner using the parameters described above.

Results

Our testing of force of attraction and torque revealed that none of the commercially available VCFs was affected by force or torque. The artifact testing yielded a different result within the VCF repertory. The incidence of artifacts was highest in VCFs made from Phynox (an alloy) or stainless steel, while materials such as Titanium or Nitinol demonstrated excellent low artifact behavior. One VCF made of Teflon was even imaged completely without artifacts. We were able to identify the modified VCF by its active signal of the RC in coronar and transverse directions using the gradient sequence with excitation angle below 90°. The tests with the VCF prototype yielded the best results. A very high signal intensity of the special filter coil was imaged by using the same sequence. No significant heating occurred in these tests.

Discussion

The images of the modified VCF proved the theory of an active MR-visible Vena Cava Filter. Localization of the passively imaged VCF is thus possible. Especially the VCF prototype can be easily detected in MRI because of its full integration of RC and filter. The potential of the VCF prototype can still be enhanced further by constructing it as a receive-only coil to obtain images of the filter's inside or surroundings.

[1]C.R. Mohan, J.J. Hoballah, W.J. Sharp, et al.:1995, J Vasc Surg 21:235-246

[2]Ch. Frahm, H.B. Gehl, H. Lorch, et al.: 1998, JMRI 8:105-109

OUTPATIENT LAPAROSCOPIC APPENDECTOMY - A BENEFIT FOR CHILDREN

Dr. med. Jörg Schreiber, Tagesklinik Mettmann

After developing the technique of laparoscopic appendectomy (LA) in 1982 I practiced this method first in hospital, and since 1988 in out-patient technique with the same convincing results in adults and even in pregnant women as well as in children. As the diagnosis of appendicitis is particularly difficult infants, one can therefore decide in favour of a diagnostic laparoscopy with simultaneous appendectomyin the slightest suspicion of appendicitis. Perforation is a typical complication in children with a rate about 34% !

From 1988 until 1999 apart from LA in adults, we performed LA in 20 infants (6 boys, 14 girls) aged from 8 to 16 years. All children were accompanied by family-members and they were discharged in the afternoon of the same day.

Histomorphology: Chronic recurrent appendicitis in 11 cases and acute, subacute, fresh phlegmonous or ulcerous appendicitis in 9 cases. Complications occured in two girls: one pelvis-inflammation was cured by drainage and antibiotics in hospital; the second girl with stump-leak one day postoperative had to undergo laparotomy in hospital as well. The procedure of outpatient laparoscopic appendectomy is demonstrated by video.

Results and Prognostic Factors in CT-Guided Periradicular Therapy

S. Schneck-Henter, J. Plassmann, R. M. M. Seibel

Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

INTRODUCTION

Epidural Steroid Injections are commonly used in lumbar disk herniation. With CT-guided Periradicular Therapy (CT-PRT) position of cannula is controlled before and during medicamental instillation and documented via contrast medium. Using local anesthesia, corticoids and 0,9% saline solution are injected next to the disk pathology.

METHOD:

With 115 patients treated with CT-PRT in 1995, a long-term follow-up with a mean observation time of 26 months (12-33) was performed. Disk herniations in the lumbar spine in only one level were accepted in this study. CT or MRI and clinical neurological examination showed correlation of symptoms and nerve root compression. None of the patients had been operated on before.

There were 50 female and 65 male patients aged 22-79 (mean age 51,44) years. Antecedent pain history lasted from several days up to more than five years, with 42,61% having pain for more than two years and 21,74% of those having pain for more than five years. Patients underwent 1-16 (mean 5) CT-guided epidural or intra foraminal injections of 20-80 mg triamcinolonacetonid every four weeks. 52 patients received additional facet-blocks using local anesthesia and 10-40 mg triamcinolonacetonid.

Decrease of back- and leg pain, lifestyle, resilience and satisfaction with CT-PRT were used to evaluate the therapeutic effect of CT-PRT. Prognostic factors leading to a positive outcome were investigated.

RESULTS

Back pain improved in 90,16% of patients after CT-PRT, in 66% leg pain at the time of follow-up was better than before CT-PRT. Leg pain improved in 86,67% of patients after CT-PRT, in 72,72% leg pain at the time of follow-up was better than before CT-PRT. CT-PRT shows to have a significant effect on leg and back pain due to lumbar disk herniation (p<0,01).

A significant decrease of taking of analgesics was observed (p<0,01). Lifestyle improved in 68,47% of patients while 51,82% stated a higher degree of resilience. 91,07% of patients were satisfied with CT-PRT. Those patients who improved within the first two or four injections showed significant better results at the time of follow-up. There was a significantly higher lifestyle of patients having received additional facet-block (p=0,03). A positive correlation was found between participation in "back-school" and decrease of back- and leg pain as to participation in "back-school" and satisfaction of CT-PRT (p<0,05).

Side effects of steroidal therapy were reported in 52% of cases. The incidence of side effects was significantly higher in women (p<0,01) . 6,96% of patients had to be surgery during follow up. Puncture of an epidural vein was observed in 3 of 575 injections (0,52%).

Positive factors of outcome were short duration of symptoms, high frequency of pain, positive straight leg raise and radicular pain. Negative factors of outcome were long duration of symptoms and non-radicular pain. Gender, age, motor symptoms or sensory disturbances showed to be neutral factors of positive outcome with CT-PRT.

CONCLUSION

CT-PRT is effective in lumbar disk herniation. Some prognostic factors of positive outcome were isolated. These factors should be established in future prospective studies.

Investigation of the Angle-Dependent Size and Position of Needle Artifacts in Low-Field (0.2 T) Magnetic Resonance Tomography

K. Seekamp-Rahn¹, L. Schnieder², F. Schick¹, S. Duda¹, G. Buess², C. D. Claussen¹

¹ Department of Diagnostic Radiology, Tübingen University Medical Center, Tübingen, Germany

² Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Hospital, Tübingen, Germany

During the last few years, an increasing amount of medical interventions (such as biopsies, punctures, topical application of substances or minimally invasive procedures for pain therapy or interstitial tumor therapy) have been performed under guidance of imaging methods such as Computer Tomography (CT) or Magnetic Resonance Tomography (MRT). With the development of open-configuration magnetic resonance scanners giving access to the patient within the apparatus, this imaging modality is gaining in importance in this field. Its main advantages are good visualization of soft tissue, the possibility to arbitrarily position the imaging slices, no exposure to radiation and high sensitivity for pathological tissue alterations.

Due to the interaction of metallic materials with the magnetic fields, the standard instrumentation used for these purposes cannot be used in MR-guided interventions. MR-compatible instruments made of Titanium and Nickel-Titanium alloys are nowadays available. On the one hand, they must allow a secure handling within the strong magnetic field of the MR scanner and on the other hand, they should be visible in the MR image without distorting the imaging process. Most of the commonly used instruments are visualized passively based on susceptibility artifacts.

For the present study, six different MR-compatible needles of size 18G (three puncture needles, two biopsy needles and a tumor localizer) from two manufacturers (Daum and Somatex) were examined. Using a water/Gadolinium (0.2 mmolar) based phantom, MR images of the needles for different sequences (gradient echo and spin echo) were recorded for a number of orientations relative to the static magnetic field. Measurements were done in an open configuration (Magnetom OPEN, Siemens) MR system with a field strength of 0.2 T. The size of the artifacts and the apparent position of the tips were compared with the actual size and position. The size of the artifacts increases monotonically with the angle relative to the static magnetic field, having its maximum at perpendicular orientation. The shape and the position of the needle tips in the images show a complex behavior as a function of the orientation. As a result of this, the straightforward location of the needle tip relative to the structures of interest within the patient becomes very difficult. Furthermore, the artifacts also strongly depend on the sequence and read-out direction used during the imaging process. This means that at present, MR-guided interventions are quite complicated and sometimes dangerous. With the help of numerical simulations, the understanding of the relevant processes will be improved.

Minimally Invasive Cardiac Surgery

M. Selig¹, H. Fischer¹, R. Cichon², M. Cornelius², S. Schüler²

¹ IMB Foschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

² Cardiac and Vascular Center of Dresden Technical University, Dresden, Germany

While minimally invasive or endoscopic surgery has been employed in laparoscopy for several years already, its use in cardiac surgery has become more widespread only recently. Novel guiding systems and remotely controlled instruments have been developed for endoscopic heart surgery by the Karlsruhe Research Center (FZK; Forschungszentrum Karlsruhe) in close cooperation with the Cardiovascular Center of Dresden Technical University. This report presents a survey of the international state of the art as well as an outline of the instruments and surgical equipment developed at FZK, the experience gained during clinical tests, as well as future development plans in endoscopic robot-assisted cardiac surgery.

Endoscopic Axillary Lymphadenectomy After Fat Suction By Sentinel Nodes Sampling

F.Suzanne, S.Jeffrey, D. Gallot

Unity of Senology, University of Auvergne, CHU of Clermont-Ferrand, Clermont-Ferrand, France

Since 1994, we have worked on a new technique of axillary sampling by endoscopic axillary lymphadenectomy (EAL) after fat suction. The EAL makes it possible to remove an average of 14 lymph nodes. After more than 250 cases treated, the advantage of this technique turned out to be a very low morbidity rate and in particular the absence of arm swelling. Since 1998, we have practiced an evaluation of sentinel nodes sampling by endoscopy before performing lymphadenectomy. The advantage of EAL is to see all axillary lymph nodes, and to remove the blue sentinel node, the big lymph node, or a complete axillary sampling.

The results from 30 cases are the following:

- in 6 cases (20%) the sentinel nodes technique was not completely trusted (4 false negatives, 2 cases without blue)

- in 24 cases the results were in agreement (80% for external tumor)

This work demonstrates that endoscopic sentinel nodes sampling is just as appropriate a procedure as endoscopic axillary lymphadenectomy.

System for Localization and Guidance of Catheters

D. Tanase, J. F. L. Goosen, P. J. French, P. J. Trimp

Electronics Instrumentation Lab, Faculty of Electrical Engineering, Delft University of Technology, Delft, The Netherlands

Minimally invasive tools such as catheters are generally used for both diagnosis and therapy. When placing them into the cardiovascular system, it is important to constantly monitor their position, since it cannot be predicted which path they follow along the vessels. So far, the location of a catheter is determined by means of X-rays and a contrast fluid, which is sent through the catheter to visualize the blood vessels and locate the catheter. The repeated exposure of doctors and nurses to radiation and the use of contrast medium, however, create significant health problems. For that reason, other devices and/or new techniques are needed to reduce the extensive use of X-rays. Starting from this general issue and trying to minimize the dosage of X-ray radiation used during catheterization, a relevant X-ray image, taken by the interventional radiologist, will be used as a reference image many times during the procedure. This image will be augmented with a virtual indicator representing the current position of the catheter tip. This way, the need to take additional X-rays will be reduced. In order to display the virtual marker on the X-ray image, the real position of the catheter tip has to be determined. Then the marker, indicating the location and orientation of the tip, can be displayed at the corresponding location in the X-ray image. There will be a real-time correlation between the movement of the catheter inside a blood vessel and the position of the marker on the image. The current location of the catheter tip can be determined using pulsed magnetic fields, generated by means of coils, outside the patient. A magnetic sensor placed on the catheter tip will continuously measure the magnetic field, which depends on the position and orientation of the catheter. The development of an initial test model based on this principle is presently under way. A coil is used as a magnetic source and a Hall magnetic sensor plays the role of the sensor on the catheter tip. A pulsed current is sent through the coil to generate a short-pulse magnetic field. Initial measurements have shown a magnetic field of 300 microTesla at a distance of 30 cm. The next stage of experiments involves two coils and a 3D sensor on the catheter tip. The method described above has the advantage of maintaining the usual structure of a vascular intervention: The clinician will undertake the same actions and will continue to work with the same devices he/she is used to. The radiologist will have a real-time indication of the movements of the catheter tip on the same reference image, without the need for additional images. This substantially reduces the number of X-rays, solving the main concern of medical staff.

MR-Guided Interventional Therapy in Patients with Dyskinetic Symptoms

C. A. Taschner, T. Liebig, K. Maier-Hauff, A. Kupsch, N. Hosten, W. Lanksch, R. Felix

Klinik für Strahlenheilkunde der Charité, Campus Virchow Klinikum, Berlin

Klinik für Neurochirurgie der Charité, Campus Virchow Klinikum, Berlin

Klinik für Neurologie der Charité, Campus Virchow Klinikum, Berlin

PURPOSE:

The purpose of our study was to evaluate the accuracy of MR-guidance in the interventional therapy of dyskinetic patients.

METHOD/MATERIALS:

We performed deep brain stimulation in 12 patients with dyskinetic symptoms (6 Parkinson's Syndromes, 2 axial dystonia, 4 segmental dystonia). The patients operated on for Parkinson's Syndrome received bilateral stimulation of the subthalamic nuclei (STN), while dystonic patients were stimulated in the globi pallidi interni (Gpi) and the nuclei ventrales intermedii thalami (VIM) bilaterally. The interventions were performed using a classical frame-based stereotactical approach. The stereotactical coordinates were obtained in an indirect manner and by direct visualization of the target. The indirect localization of the basal ganglia was based upon Tallairach´s coordinates in relation to the AC-PC line gained by intraoperative ventriculography. Additionally the patients received intraoperative stereotactical MRI, which allowed direct visualization of STN, Gpi, AC and PC. The interventions were planned on the navigation system Stereoplan plus, Release 2.3 (Stryker-Leibinger, Freiburg). MR scans were acquired on a 1,5 T Gyroscan ACS NT (Philips, Best) using T2-weighted TSE (TR 2500, TE 90, TSE Fact. 17, FOV 260, Thk. 3 mm, NSA 4, Matrix 255x512) and a T1 weighted GE sequences after administration of 0,2 ml Magnevist/kg body weight (Schering, Germany). The accuracy of the direct MR-based localization was compared with that of the indirect approach by ventriculography. We compared the stereotactical coordinates of the anterior and posterior commissure, STN and Gpi.

RESULTS:

In the T2-weighted images Gpi, STN, AC and PC could clearly be visualized. The T1-weighted images were helpful for planning the intervention, as the trajectory of the electrode could be chosen avoiding major vessels. We compared 72 stereotactical coordinates in 12 patients. In the x- and y-plane, the difference between the two different approaches was below 2 mm. In the z-plane the deviation was larger (2.7 mm). This is most likely due to the given slice thickness (3 mm) in the T2-weighted MRI.

CONCLUSIONS:

1. MR-guided navigation in interventional therapy provides results comparable to the indirect, ventriculography-based approach.

2. MR-guided localization allows an individualized therapy.

3. MR-guided planning shortens the time required for the intervention.

Application of Telemedicine in Bulgaria

D. Tcharaktchiev¹, D. Baltadjiev²

¹University Hospital of Endocrinology and Gerontology, Sofia, Bulgaria

²Department of Medical Informatics, Transport Medical Institute, Sofia, Bulgaria

In June 1999, the Bulgarian Medical Network (Medicalnet-BG) was launched as a MAN type. University Hospital of Endocrinology and Gerontology, Transport Medical Institute and National Oncology Center are linked to the medical network. The hospitals are connected via leased lines and high-speed SDSL 2 Mbit/s modems. Hospital LANs are integrated in medical network via routers and access servers using Intranet based technology and TCP/IP communication protocol. Telematic services, including teleconferencing, telepathology, teleradiology, etc. are available. It allows doctors from these institutions to exchange information and expert advice, and to realize telemedicine sessions. Conferencing software on H320 standard is used. At the end of September 1999 a satellite terminal Skywan was installed at the Communication center of the Medicalnet-BG. This gives the possibility for the Bulgarian physicians to do telemedicine consultations in pathology and radiology remotely from their places with over 20 European hospitals participating in Generic Advanced Low-cost Trans-European Network Over Satellite (GALENOS Project TEN 45592 (FS)). Until now, three videoconferences with Cannes, Rome and Berlin locations have been held. A telemedicine experiment with Marseille location was realized. PC station, equipped with SAMBA application (developed by Samba Technologies, France) was used. Pathological samples and some other basic data files were transferred. Teleconference with Berlin was done using two processors Pentium III 650 MHz workstation and WINVICOS software. The performance was good and the quality of the transferred images and videoconference was very high. Telemedicine appears as a tool for improvement of healthcare delivery, for better management of public health, permitting dissemination of best practice and promoting regional development.

SHOCK WAVE THERAPY IN ORTHOPAEDICS AND TRAUMATOLOGY

M. Thiel, M. Nieswand, M. Dörffel, R. Schultheiss

HMT High Medical Technologies AG, Kreuzlingerstrasse 5, CH-8574 Lengwil

Extracorporeal generated shock waves have been introduced for medical therapy approximately 20 years ago to disintegrate kidney stones. Since this time shock waves have changed the treatment of urolithiasis substantially. Today shock waves are the first choice to treat kidney and ureteral stones. A new indication in Urology is the shock wave treatment on IPP where first clinical investigations show promising results. Urology is not the only medical field for shock waves in medicine. Meanwhile shock waves have used in Orthopedics and Traumatology to treat insertion tendinitis, non- or delayed unions, avascular necrosis of the head of femur and other necrotic bone alteration. Another field of shock wave application is the treatment of tendons on horses in veterinary medicine. The idea of the shock wave therapy for orthopedic diseases is the stimulation of healing processes in tendons, surrounding tissue and bones. This is a completely different approach compared to urology where shock waves were used for disintegration. This composition tries to give an overview of basic physical principles of shock waves, history and basic research of shock wave application in medicine.

First Experiences With Transfer of Digital Data to a Head-Mounted Display (HMD) in Head and Neck Surgery

J. Verhey¹, A. Ludwig²

¹Department of Medical Informatics,University of Göttingen, Göttingen, Germany

²Department of Cranio-Maxillofacial Surgery, University of Göttingen Medical Center, Göttingen, Germany

Abstract

A 7.5 MHz linear scanner, combined with a system-independent 3D workstation, was used for the preoperative sonographic detection of soft-tissue tumors as well as for the processing and digital saving of the images. These data were directly transferred to the operating room via Intranet. There, the surgeon was equipped with a head mounted display (HMD) of the type SONY Glasstron. The following criteria were evaluated by the surgeon: image quality, availability of the data, handling of the HMD, and its usefulness for the operation. It was seen as positive that any kind of selected images and animations could be made available to the surgeon with only a few seconds' delay. Visualization of all demonstrations on the HMD was possible without loss of quality. The surgeon's freedom of movement was only slightly restricted by the wires connected to the HMD. The 3D images facilitated spatial orientation and detection of the soft-tissue tumors. The described HMD is a low-cost solution for visualizing all kinds of digital data and using them in the operation room. In practice, this technique is not limited to sonographical data alone. The fitting of the HMD to the head of the surgeon offers the advantage of continuous, uninterrupted work and simultaneous visualization of the data at any time.

Key Words:

Head Mounted Display (HMD), 3D ultrasound, sonographical data transfer, head and neck surgery, visualization

Purpose

The aim of this study was to test in how far digital transfer of 3D volume data to the operating room can be performed in head and neck surgery. In our case we were especially interested in testing a technique which allows us to use preoperatively gained sonographic data during the operation. The clinical procedures were evaluated. The prerequisites are optimal processing and Intraoperative availability of the preoperatively acquired data.

Through the utilization of 3D sonographical techniques single 2D soft tissue layers and 3D volume blocks can be digitally saved and processed. So far, the possibilities have hardly been used so that these 3D data have only been available as 2D prints in the operating room. Obviously, this has to be seen as loss of information. Especially for soft-tissue operations in head and neck an optimized transfer of preoperatively gained sonographical data is desirable but is also interesting for other fields of application.

Materials and Methods

Through the combination of a 7.5 MHz linear Scanner (Toshiba) with a system-independent 3D workstation (View Point) soft-tissue tumors were preoperatively detected and analyzed by means of sonography. The ultrasound 3D volume data were processed and visualized with the graphical analyzing software. The saved ultrasound data can directly be transferred to the operating room via Intranet, which could be done within the hospital’s network without problems.

In the operating room a standard PC was installed which gave a first-hand demonstration of the ultrasound data. The surgeon was equipped with a head mounted display (HMD) of the type SONY Glasstron. Using a video beamer the operation team was able to see the data on a projection screen in the operation room. The sonographical data were selected by the surgeon, while an assistant manipulated the data on the standard PC according to the instructions of the surgeon.

Intraoperatively, the surgeon evaluated the following criteria:

1. quality of the sonographical images

2. availability of the data

3. handling of the HMD

4. the utility for the operation procedure.

Results

Through the digital saving of ultrasound data by a conventional linear scanner and a 3D workstation it was principally possible to save, process and transfer the data. The acquired data then could be transferred to a PC in the operation room. The HMD used in this study (SONY Glasstron) was principally well suited for the visualization of ultrasound data to support the operation procedure. For two reasons, however, the transparent mode of the HMD which can also be selected is not to be recommended for surgical interventions: Firstly, the contrast was not sufficient and secondly, the virtual projection of the HMD was made for a fixed projection distance of about 1.5 meter which was not comfortable for the surgeon and likely to result in headaches.

With the HMD described, a low-cost visualization technique for all kinds of digital data is available in the operating room. The weight of the SONY Glasstron is comparable to that of normal glasses so that the HMD is not felt as disturbing. The HMD is tightly fitted on the head. The field of vision is directed downward to the patient and remains free; simultaneously, the view to the projection of the ultrasound data in the HMD is possible by looking upward. This enables the surgeon to work on the patient undisturbed while simultaneously examining the selected sonographical data.

The surgeon's freedom of movement was only slightly restricted by the wires connected to the HMD. The lack of a device for adjusting the image distance of the HMD to the eye distance was also judged to be a disadvantage.

Discussion

Preoperative tests have already shown that the SONY Glasstron cannot be used in the transparent mode due to the low contrast. This might change of another company's HMD is used. The HMD was adjusted to the surgeon’s forehead which gave the surgeon a free view to the operation field. The position of the head during the operation remains unchanged, which enables the surgeon to work on the patient with concentration and undisturbed. This might also be interesting for other techniques (e.g. endoscopic techniques). Nevertheless it is not possible to use this technique for augmented reality purposes. Therefore, other HMDs will be desirable.

So far, only X-ray, CT or MRT images and image series could be used intraoperatively while 3D sonographical data have hardly been used in head and neck surgery. With the technique described, we were able to show that 3D ultrasound data can be used intraoperatively, so that a processing of the 3D ultrasound data is realizable, useful and the principal visualization procedure to be used in the operating room. This saves time and improves and optimizes the course of the operation as well.

Navigation as a Supplement for an Open MR System

T. Vetter, A. Oppelt

Siemens Medizinische Technik, Erlangen, Germany

The possibility of arbitrary slice orientation is a unique feature of MR tomography, which is a benefit especially for the display of instruments in any orientation during image-guided interventions. However, to find the proper slice position and orientation for the depiction of an instrument, such as a biopsy needle, can be a time-consuming procedure. With the Interactive MR Localizer [1,2], slices can be positioned and angulated in the MAGNETOM Open MR system right on the patient with the help of an optically detected pointer. A fast and simple calibration procedure ensures proper referencing prior to each procedure. Various slice-positioning modes provide the means for fast and convenient procedure planning. Thus, the time required for planning is considerably reduced. Due to patient positioning and/or the limited space between the magnetic poles, there is sometimes no access for an intervention inside the magnet. In such a case, navigation on a previously measured 3D data set outside the magnet still provides the means for image-guided procedure planning. An economic way to implement basic navigation functionality is opened when the Interactive MR Localizer is combined with the 3D post-processing software for Multi Planar Reconstruction (MPR), which is integrated in the system software. With an optical reference attached to the patient table, there is no need to change the calibration procedure. The positioning accuracy is expected to be in the same range as for interactive slice positioning inside the magnet; care, however, has to be taken for precise and reproducible table positioning during calibration and image data acquisition. Using the pointing device as MPR controller, three orthogonal cuts centered at the pointer tip can be simultaneously reconstructed to provide e. g. information about the radicality of tumor tissue resection. Oblique cuts displaying the pointer trajectory can be used for procedure planning, e.g. of a biopsy. Controlling the system integrated 3D post-processing software MPR with an external pointing device appears to be an efficient way to add basic navigation functionality as a supplement to the Interactive MR Localizer. Investigations about the positioning accuracy are under way.

[1] A passive navigation device for interactive slice positioning in interventional MRI. W.R. Lees, A.R. Gillams, S.C. Smart, K.R. Kaczynski ECR 1999, Vienna, Austria, presentation no. 522

[2] A Passive Optical Localization System for MR Guidance of Interventional Procedures Q. Zhang, K. Kaczynski, R. Schulz, T. Vetter, A. Oppelt, M. Wendt, J.S. Lewin, J.L.Duerk; ISMRM 1999, Philadelphia, USA, presentation no. 1960

Clinically Driven Approach to the Design of Laparoscopic Instruments

H. de Visser, P. V. Pistecky, H. G. Stassen

Minimally Invasive Surgery and Interventional Techniques, Delft University of Technology, Delft, the Netherlands

Background

In 1997, a large research program was launched at the Delft University of Technology, concerning the improvement of minimally invasive surgery and interventional techniques (MISIT). Nine PhD students and three Post-Doc's are working, under the supervision of professor H.G. Stassen and several assistant professors, in close collaboration with numerous Dutch surgeons to improve several aspects of minimally invasive surgery, ranging from task analysis to the analysis of eye-hand coordination problems and the design of instruments.

Aims

The work presented here concerns a PhD project that aims at designing and improving instruments used in laparoscopic surgery. Advice is given as to how a fruitful collaboration between engineers and surgeons can be achieved. As an example of the practical application of this advice, a description is given of the way this Ph.D. project was set up to discover the largest needs in laparoscopic surgery as performed presently in the Netherlands.

Methods and results

At any cost, it should be avoided that an engineer designs instruments aiming at technical innovation without considering their usefulness for a surgeon. The demand for new or improved instruments should be clinically driven, meaning that it should originate in the operating room. It should, however, be avoided that an engineer designs and constructs an instrument according to the proposal by a single surgeon without questioning whether or not this proposal is the best solution for a problem experienced by more than one surgeon. To design useful, reliable and safe laparoscopic instruments an optimized, continuous collaboration between surgeons and engineers should be established. As the Delft University has no medical department, input from surgeons from Dutch hospitals is indispensable for our research.

To achieve optimal collaboration, the following actions should be taken:

Firstly, several dozens of laparoscopic operations should be attended to have a first-hand experience of the problems involved in laparoscopic surgery. An effective way to stimulate and improve the interaction between engineers and surgeons is to write a report of each operation and send it back to the surgeon. In our project, these reports have been given a standardized form, which is now used by several of the Ph.D. students within the MISIT program. The reports contain a list of all laparoscopic instruments used, an indication of the trocar placement, the observations made by the engineer during the procedure and the engineer's questions and conclusions following from the observations. Answers and comments from the surgeon are usually received during the next visit to the operating room.

Secondly, practical courses in basic laparoscopic skills should be followed, which, in combination with literature research, allow the engineer not only to increase his insight in laparoscopy-related problems, but also to experience them personally.

Thirdly, several kinds of meetings with surgeons should be held. Meetings with individual surgeons are useful to discuss ideas, arisen from literature research and surgery attendance. Besides these meetings, brainstorm sessions with several surgeons and several engineers at a time should be organized, as they have proven to be a fast and efficient way to gain insight into instrument-related problems in laparoscopy. In our project, besides several meetings with individual surgeons, two brainstorm sessions were held with up to six surgeons at a time. The first session was organized to determine which instrument-related problem in laparoscopy should be chosen as a subject for the PhD project presented here. During the session, several subjects were discussed, including: 1) the combination of several functions, such as cutting and grasping, in a single instrument to reduce the number of instrument exchanges; 2) the design of an instrument to measure the tension in the wrap during Nissen fundoplication; 3) the design of an instrument for safe and easy colon anastomoses; 4) the design of an instrument for safe and easy colon manipulation. The latter subject was chosen because only very little research into this subject has been done so far and only a very small part of operations on the colon are performed laparoscopically at this time. This is so because the procedure is quite difficult and risky and requires an experienced laparoscopic surgeon, since the presently available instruments can easily damage the colon when they are used incorrectly. A second brainstorm session was organized to further clarify the problems involved in colon manipulation and to determine guidelines that should lead to the design criteria that the colon manipulator has to meet.

Conclusion

In order for the engineer to make useful additions and improvements to the presently available set of laparoscopic instruments, a clinically driven design approach should be maintained. To do this, an optimal, continuous collaboration between surgeons and engineers is indispensable. To fully understand the problems involved in laparoscopic surgery, the engineer should experience these problems first-hand by attending laparoscopic operations and participating in practical courses in laparoscopic skills. Furthermore, a continuous interaction with the surgeons should be maintained throughout the design process. Brainstorm sessions have proven to be a fast and efficient way to gain insight into instrument-related problems in laparoscopy.

Endoscope Guidance System for Instrument Tracking on the Basis of Image Analysis

U. Voges, H. Becker, H. Breitwieser, W. Eppler, L. Gumb, R. Mikut, R. Oberle, A. Schäf

Institute of Applied Informatics, Forschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

During normal minimally invasive surgery, the endoscope is held by an assistant who tries to provide the surgeon with the best possible picture. If the surgeon does not only work within a small area, this means that the camera assistant must pay full attention and always follow the surgeon's actions. The main drawbacks of the current situation are the need for an additional person, the possible communication problem between the surgeon and the person assisting in holding the camera, and a picture that might not be stable due to such factors as fatigue and tremor. The Forschungszentrum Karlsruhe developed an endoscope guidance system that is capable of following the tip of the surgical instrument. This automatic instrument tracking is done on the basis of image analysis. The endoscopic image is analysed, the instrument is detected, and depending on the position of the instrument within the image, the endoscope is moved or kept in position. The movement takes only place if the instrument leaves the inner part of the image. For this, the image is divided up into three regions:

· the central part,

· the inner region, including the central part,

· the outer region.

If the instrument is detected within the inner region, no movement of the endoscope takes place. If this inner region is left, the endoscope guidance system moves the endoscope until the instrument tip is within the central part of the image. This hysteresis behavior results in a rather steady picture, since not every movement of the instrument tip results in a movement of the endoscope. The detection of the instrument is based on different means of identification, such as texture, shape, color or movement behavior. Only 2D cameras are needed, but the system works for 3D endoscopes as well. Additional position sensors for the endoscope can provide for fault tolerance features and thus increase the precision of the system. Altogether, the system is designed as a low-cost version of an endoscope guidance system, but with high functionality and quality. The main components of the system are standard components off the shelf. No high-cost 3D system is required. The user interface of the system provides for information on the status of the system, has an optional voice feed back, system configuration is aided, and error reports with solution hints are given.

The advantages of this system are:

· constant reaction time,

· steady picture,

· no fatigue,

· no additional commands necessary.

The endoscope guidance system with instrument tracking has first been realized on the basis of the endoscope guidance system FIPS. It is, however, also possible to link up this function to any other endoscope guidance system fulfilling certain requirements such as open interface for control. Depending on the system, a simple solution without the use of position sensors is available, as well as a more sophisticated one making use of the position sensors of the endoscope guidance system. As a further alternative, the analysis of the endoscopic image can be replaced by position sensors for the surgical instrument, providing the same tracking features. A further option of the endoscope guidance system includes voice control of the endoscope. For safety reasons, the surgeon can always take over control and move the endoscope by hand.

A Computer-Assisted Planning System for Pedicle Screw Insertion

G. Voss¹, U. Bockholt¹, W. Müller²

¹ Fraunhofer Institute IGD, Darmstadt, Germany

² Berchtold GmbH & Co., Tuttlingen, Germany

PROBLEM/BACKGROUND

Robot Assisted Surgery (RAS) systems are gaining more and more recognition in the field of orthopedics. Especially in hip surgery, RAS has proved to be suited for application in medical routine. Often, Robot Assisted Surgery Systems consist of a planning and an intraoperative component. The tools are operated according to specifications elaborated with the planning software. The expected benefit of robot-assisted surgery is higher precision and a better outcome of surgical procedures. In the <93>RoMed<94> (Robots and Manipulators for Medical Application) cooperation project between several Fraunhofer Institutes, an exemplary application of robot aided spine surgery is developed. The planning software used in this context is proposed in the remaining article.

METHODS

The surgeon interacts with the planning system via a graphical user interface. This consists of a display area including three orthogonal views and 3D view, as well as a functional area to get status information and for control of the planning session. The system allows the precise planning of the single preoperative steps needed for pedicle screw insertion. In general, the planning procedure starts with loading and checking of the patient-specific CT data set. Furthermore, the surgeon is able to navigate through the 3D data set and to define planning aids by using graphical primitives. Then, after selection of the appropriate 3D implant models, these components can be accurately positioned and aligned. Hybrid rendering provides the visualization of the corresponding components to be implemented, allowing the checking of the planning result. In this context, additional measurements of distances and angles can be realized. In addition, the possibility of predicting the outcome of the procedure on the basis of the preoperative plan is studied. Finally, the planning data can be exported to the intraoperative manipulator.

RESULTS

Using this preoperative planning system the surgeon is able to precisely specify the intervention, resulting in the selection of appropriate implant components and optimal placement in the patient-specific data set. The system produces the preoperative plan to be used by the surgical robot system.

CONCLUSIONS

This planning system for computer-assisted pedicle screw insertion demonstrates that based on patient specific image data and a catalogue of implants, the use of highly interactive 3-D visualization techniques is appropriate to enhance the accuracy of transpedicular screw placement.

Quantifying Hand-Eye Coordination Problems During Minimally Invasive Surgery: Is the Surgeon Misoriented?

M. Wentink¹, P. A. Wieringa¹, J. J. Jakimowicz², G. N. M. Stultiëns²

¹ Man-Machine Systems Group, Faculty of Design, Engineering and Production, Delft University of Technology, Delft, The Netherlands

² Department of Surgery, Catharina Hospital, Eindhoven, The Netherlands

Aim:

In Minimally Invasive Surgery (MIS), the surgeon's hand-eye coordination is impaired. Although impaired hand-eye coordination is recognized as a major disadvantage of MIS, it is still not fully understood. Furthermore, the effect of impaired hand-eye coordination on the efficiency of an operation (e.g. operating time) has not yet been quantified. The aim of the study presented here is to define the main negative effect that causes hand-eye coordination problems and to describe a method to quantitatively assess this negative effect in the operating room.

Method:

Instead of looking down on his/her hands, as is the case in conventional surgery, the surgeon looks at a monitor during MIS. Furthermore, the natural line-of-sight from a surgeon's eyes to his/her hands is replaced by the line-of-sight of an endoscope. As a result, two negative effects that disturb hand-eye coordination (can) occur:

1. Mislocation: The operating area at which the surgeon is looking is not located underneath the hands of the surgeon. 2. Misorientation: The orientation of the instrument on the monitor does not correspond to the natural orientation of the instrument when the surgeon is looking down on it directly. Misorientation occurs when the direction of movement of the instrument tip on the monitor does not correspond with that of the instrument handle in the surgeon's hand, within the visual field of the surgeon. Figure 1 explains this definition of misorientation. From ergonomics literature and from an experiment conducted at our laboratory it is known that misorientation has a greater negative effect on hand-eye coordination than mislocation. Projection of the 3D world onto the retina (which is approximately flat if you consider only a small area) yields the visual field. Misorientation is defined with respect to the visual field, as information from this field is used as feedback in limb movement control. The misorientation angle is that between the projected instrument tip and the projected instrument handle when the surgeon is looking at the monitor or at his hands, respectively (see Figure 1-C). A method to determine the misorientation angle during MIS has been developed. For this purpose, the surgeon wears a head-mounted camera that films his/her dominant hand during the operation. The images of this camera approximate the visual field of the surgeon when he/she is looking down on his/her hands. The endoscopic images on the monitor approximate the visual field of the surgeon when he/she is looking directly at the monitor. The images from the head-mounted camera and the endoscopic images are synchronized and captured on one videotape. After digitizing the videotape, the misorientation angle is extracted from the images by specialized software.

Results:

The method used to determine the misorientation angle described above has been successfully tested in the operating room during a hernia repair and a cholecystectomy. Preliminary results indicate that the angle of misorientation varies greatly during the course of the operation, reaching angles of up to approximately 60°. The final results concerning the degree of misorientation during hernia repair and cholecystectomy operations will be revealed in the presentation.

Conclusions:

The main negative effect that causes hand-eye coordination problems during MIS is the misorientation between direction of movement of the instrument tip and that of the handle within the visual field of the surgeon. Is the surgeon misoriented? Although a definite answer to this question is not yet available, the study described above provides a method to quantify misorientation during MIS. An experiment is currently being conducted to determine the average misorientation angle during different phases of cholecystectomy and hernia-repair operations. Eventually, the effect of the misorientation angle on hand-eye coordination and operation efficiency in general will be assessed in a standardized experiment.

Figure 1: A: The surgeon is looking at the instrument tip on the monitor. B: Corresponding visual field of the instrument handle obtained (visually and proprioceptively) from past experience with direct sight. C: Misorientation between the instrument tip and handle.

Evaluation of Coronary Arterial Stenoses Using Magnetic Resonance Coronary Angiography

T. Yamada, T. Sawada, T. Yamano, A. Azuma, M. Nakagawa

2nd Department of Internal Medicine, Kyoto Prefectural University of Medicine, Kyoto, Japan

Purpose

X-ray coronary angiography (CAG) has become an indispensable examination tool for assessing coronary heart disease. However, repeated angiography can entail various complications for the patients. Magnetic resonance coronary angiography (MRCA) is a newly developed technology and provides a non-invasive and low-cost examination technique for diagnosing coronary arterial stenoses. The purpose of this study is to investigate the usefulness and limitations of MRCA.

Methods

The study group consisted of serial 213 patients (332 coronary arteries) who underwent CAG and MRCA simultaneously. MRCA performed with an electrocardiographically gated gradient echo sequence with k-space segmentation, using 1.0 Tesla and 1.5 Tesla conventional MRI systems. MRCA imaging quality was divided into four classes (class 3, excellent; class 2, fair; class 1, poor quality to diagnose; class 0, unvisualized). MRCA findings were divided into four grades (grade 3, normal; grade 2, vessel narrowing and reduced intensity; grade 1, break of vessel; grade 0, unable to image). CAG was performed with a conventional system, and percent diameter stenosis of the lesions were calculated using digital calipers. Coronary collateral circulation was evaluated from Rentrop's grading 0(R0), 1(R1), 2(R2), and 3(R3) on cineangiograms.

Results

(1) Out of 332 major coronary arteries in 213 patients, 283 arteries (85.2%) were imaged as class 2 or class 3 by MRCA. In the 283 arteries, the validity for diagnosing over 90% arterial stenosis to grade 0 and 1 was 65% in the sensitivity and 88% in the specificity. The validity for diagnosing over 75% arterial stenosis to grade 0, 1, and 2 was 99% and 70%, respectively. (2) In the 283 arteries imaged as class 2 or 3 by MRCA, 46 stenoses were evaluated the presence of restenosis (more than 50% stenosis by CAG) after percutaneous transluminal balloon angioplasty (PTCA). The validity for diagnosing restenosis by MRCA was 92% in the sensitivity and 33% in the specificity. (3) Furthermore, 18 coronary arteries which had total obstruction or subtotal obstruction in proximal or mid portion of the major coronary arteries were evaluated the presence of collaterals. The collateral circulation was R1 in two cases, R2 in seven, and R3 in nine using CAG. The development of collateral circulation improved MRCA findings in the distal portion of obstructed coronary arteries.

Conclusion

We conclude that MRCA provides useful information as a non-invasive examination technique to image coronary arterial stenoses. There is, however, room for improvement because MRCA overestimates medium stenoses after PTCA owing to the flow void phenomenon.

Minilaparoscopy - A new Tool for Diagnosing and Staging of Liver Diseases

J.M. Zeeh, J.Gschoßmann, Ch. Jochum, M. Rünzi, G.Gerken, U.Treichel

Division of Gastroenterology and Hepatology, Department of Internal Medicine, Essen University Medical Center, Essen, Germany

Introduction

Macro- and microscopic evaluation is essential for the staging and treatment of liver diseases. Minilaparoscopy is a new diagnostic and therapeutic tool for a minimally invasive approach to patients including those with a high risk for extensive bleeding. This study compares macroscopic, microscopic and duplex-sonographic findings and defines the indications and complications of the method.

Patients and Methods:

Within the last 16 months, 156 patients underwent minilaparoscopy (ML) and duplex sonography (DS). In most cases a liver biopsy was performed. The macro- and microscopic results were compared. The diameter of the portal vein, portal blood velocity and spleen size were determined.

Results

The mean examination time for an ML was 22 min. An additional 28 and 19 min. were needed for general set-up, handling and patient care prior to and after the procedure, respectively. Major indications for the work-up (60% of all cases) was chronic hepatitis. Complications occurred in 1,3 % of the cases (vagal reaction with decrease of blood pressure and puncture of the stomach) and could be handled by injection of atropin and antibiotic treatment respectively. Prolonged bleeding after liver biopsy was observed in 11% of the patients and required thermic coagulation. Major diagnoses were cirrhosis (50%) and fibrosis (25%). In two thirds of the cases the micro- and macroscopic diagnoses were identical, in one third there was a discrepancy whereas histology missed more early disease stages when compared to laparoscopy. Macroscopic cirrhosis was associated with splenomegaly, decreased portal blood velocity or increased portal vein diameter in 62, 32 or 10 % respectively.

Conclusion

Minilaparoscopy is a safe, simple and minimally invasive method for the evaluation of liver diseases. In earlier disease stages, minilaparoscopy has a higher diagnostic sensitivity compared to histology and duplex sonography. More studies are needed to further compare laparoscopic diagnoses with histology, sonography and other radiological methods such as computed tomography or magnetic resonance imaging. Furthermore, minilaparoscopic interventions and the use of flexible laparoscopes should be evaluated.

Extracorporeal Shock Wave Therapy (ESWT) in the Treatment of Induratio Penis Plastica (IPP)

J. Zumbé, D. Oeynhausen, K. Oelbracht

Department of Urology, Marienhospital Gelsenkirchen, Gelsenkirchen, Germany

Induratio penis plastica (IPP, Peyronie´s disease) is an idiopathic disorder that mainly affects the tunica albuginea of the penis. IPP is characterized by plaques with often painful erection, deviation and erectile dysfunction. We describe our results with extracorporeal shock wave therapy (ESWT) in the treatment of IPP.

In a prospective study - from March 1999 to February 2000 - 20 patients (age 45 to 65 years) were treated with extracorporeal shock wave therapy (Reflectron/HMT-Kreuzlingen). All patients underwent 3 to 5 treatments (average 4,2) with 2.000 shock waves for each treatment. Neither anaesthesie nor analgesia were necessary during treatment.

Prior to ESWT, all patients underwent a penile dynamic ultrasound, 14 out of 20 had photodocumentation of a physiological erection. 14 out of 20 patients received medical therapy and/or physical-injective treatment before ESWT. 9 out of 20 complained painful erection. 9out of 20 suffered from Dupuytren's disease, 6 out of 20 from diabetes mellitus and 6 out of 20 from hypertonus.

After the treatment all the patients were re-evaluated with clinical examination, autoevaluation questionnaire and penile dynamic ultrasound. 14 out of 20 patients had subjective results, such as improvement of elasticity of the plaques with easier and more satisfactory intercourse, even of the partner. The painful erection disappeared in 7 out of 9 patients, a reduction of recurvation was seen in 14 out of 17 patients and 8 out of 16 patients had a better quality of erection after the treatment.

Conclusions

Extracorporeal Shock Wave Therapy (ESWT) seems to be a successful, non-invasive therapy for Induratio Penis Plastica (IPP, Peyronie´s disease).

Introduction

Subjects & Methods

Results

Discussion/Conclusion

Background

Methods

Results

Conclusion

U. Bockholt1, W. Müller2, P. Oppelt1, J. Stähler2, G. Voss1

Problem/Background

Tools&Methods

Results

Conclusion

Protocol Overview

1 Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

Introduction

Material and Methods

Results

Conclusion

C. Doehn, P. Fornara, D. Jocham

Department of Urology, Lübeck University Medical Center, Lübeck, Germany

V. Frank, V. Koch and E.H. Schmidt

Cardiac intervention in a new century

An Approach for the OR of the Future

Methods

Results

Conclusions

I. Grote

Patients

Method

Results

Conclusion

Objectives

Material and Method

Results

Conclusion

C. Herbert

C. Herbert

Abstract

J. Jürgens1, B. Klemm2

1 Department of Obstetrics and Gynecology, Helios-Klinik Neustadt, Neustadt, Germany

2 Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

D. Kalanovic, G.F. Buess

Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Medical Center, Tübingen, Germany

B. Kappeler

Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Medical Center, Tübingen, Germany

Introduction

K. Kipfmüller

Department of Surgery, St. Marienhospital, Mülheim/Ruhr, Germany

Patients

K. Kipfmüller

K. Kipfmüller

Patients

Material and Methods

Conclusion

B. Klemm1, A. Melzer2

1 Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

2 Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

B. Klemm

Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

Main Topics

Dr. U. Knapp, Forschungszentrum Karlsruhe

1 Institute of Diagnostic and Interventional Radiology, University of Witten Herdecke, Mülheim/Ruhr, Germany

Introduction

Material and Methods

Results

J. Kordelle2, C. Mamisch1,2, R. Kikinis2, R. M. M. Seibel1, J. Richolt2

INTRODUCTION TO AR SYSTEMS

SYSTEM CONFIGURATION

APPLICATION IN MEDICAL SCIENCE

AN INTERVENTIVE AR SYSTEM

APPLICATION TO MINIMALLY INVASIVE THERAPY

M. Kraft

VANGUARD GmbH, Berlin, Germany

ESWT Treatment of OD

C. Lösche

Department of Biomedical Engineering, Technical University of Berlin, Berlin, Germany

Degenerative Shoulder Disease

1 Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston (MA), USA

2 Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

U. Bockholt¹, W. Müller², P. Oppelt¹, J. Stähler², G. Voss¹

¹ Institute of Diagnostic and Interventional Radiology, University of Witten/Herdecke, Mülheim/Ruhr, Germany

J. Jürgens¹, B. Klemm²

¹ Department of Obstetrics and Gynecology, Helios-Klinik Neustadt, Neustadt, Germany

² Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

B. Klemm¹, A. Melzer²

¹ Department of Obstetrics and Gynecology, Borromäus Hospital Leer, Leer, Germany

² Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

¹Institute of Diagnostic and Interventional Radiology, University of Witten Herdecke, Mülheim/Ruhr, Germany

J. Kordelle², C. Mamisch^1,2, R. Kikinis², R. M. M. Seibel¹, J. Richolt²

¹ Surgical Planning Laboratory, Brigham and Women's Hospital, Harvard Medical School, Boston (MA), USA

² Institute of Diagnostic and Interventional Radiology, Ûniversity of Witten/Herdecke, Mülheim/Ruhr, Germany

¹ Department of Diagnostic Radiology, Tübingen University Medical Center, Tübingen, Germany

² Section for Minimally Invasive Surgery, Department of Surgery, Tübingen University Hospital, Tübingen, Germany

¹ IMB Foschungszentrum Karlsruhe GmbH, Karlsruhe, Germany

² Cardiac and Vascular Center of Dresden Technical University, Dresden, Germany

G. Voss¹, U. Bockholt¹, W. Müller²