[Hirsutism and multinodular goiter in a 40-year-old female watchmaker]. / Hirsutismus und Struma multinodosa bei einer 40-jährigen Uhrmacherin.

This article presents the case of a female patient with acromegaly caused by ectopic production of growth hormone-releasing hormone (GHRH) secretion. In the presence of typical clinical features of acromegaly but a lack of evidence for a pituitary adenoma the results of somatostatin receptor scintigraphy were indicative of a typical carcinoid of the lungs as the cause of the ectopic secretion of GHRH and the stimulation of pituitary gland growth hormone secretion resulting in acromegaly. Finally, the patient underwent curative surgical treatment.

Recurrence rate, time to progression and facial nerve function in microsurgery of vestibular schwannoma.

OBJECTIVE: Recurrence rate, time to progression, and facial nerve function were analysed by comparing patients with complete and near total tumor removal after suboccipital craniotomy for vestibular schwannoma surgery. METHODS: From 1996 to 2004, 118 patients with vestibular schwannoma were operated with an interdisciplinary approach. Fifty patients fulfilled the inclusion criteria and were included in the study. Progression was defined as an increase of ⩾2 mm in the largest diameter in the magnetic resonance imaging. Preoperative tumor size, facial nerve function estimated using the House-Brackmann score (HBS), time to progression, and recurrence rate were analysed and related to the extent of resection. RESULTS: In 28 cases (group I), a capsular remnant was left. In 22 cases (group II), tumor removal was complete. In group I, nine patients (32·1%) showed progression. In group II, two patients (9·1%) developed a recurrent tumor, no significance (P = 0·085). In groups I and II, 53·6 and 59·6% had a good function of the facial nerve (HBS I+II), 28·6% in group I and 13·5% in group II had a moderate disturbance (HBS III+IV), and 17·9% in group I and 27·7% in group II had a poor function (HBS V+VI). There was no significant difference between median preoperative tumor size and facial nerve function within patients with HBS III and IV. CONCLUSION: Complete tumor removal may be associated with a risk of functional loss, whereas near total tumor removal may be associated with a higher risk of progression.

Cerebrospinal fluid leak after microsurgical surgery in vestibular schwannomas via retrosigmoidal craniotomy.

OBJECTIVE: Cerebrospinal fluid (CSF) leak is still a common complication in surgery of vestibular schwannoma, increasing morbidity and prolonging hospital stay. Our single center study was performed to determine the incidences of CSF leaks after microsurgical removal of vestibular schwannoma via a retrosigmoidal approach with two different surgical closure techniques. METHODS: Between January 2003 and December 2009 in 81 patients, microsurgical tumor resection using a suboccipital, retrosigmoidal approach was performed with an interdisciplinary ENT and neurosurgical management was performed. In 41 cases, the dural closure was done using a sandwich technique: subdural closure with TissuFleece® respectively Spongostan®, and after that dural suture and epidural Tachosil® were fixed on. In 40 cases, the dura was sealed epidurally with Tachosil after suture. In 65 cases, the posterior wall of the petrous bone was drilled. The closure was performed using muscle and FibrinGlue®. All patients had a minimal follow-up of 1 year. RESULTS: Seven patients (8.6%) developed a CSF fistula. Three patients (3.7%) underwent surgical procedure because of persisting CSF fistula while in four cases (4.9%) spontaneous closure under lumbar drain was observed. Comparing the different techniques of dural sealing, we found in 41 patients with sandwich technique three CSF leaks (7.3%) while there were four CSF leaks (10%) in 40 patients with a single epidurally sealed dural closure (P=0.69). No rhinorrhea or otorhinorrhea was observed. No intracranial infection or meningitis in case of CSF leak occurred. CONCLUSION: Suture and occlusion of the dura is an important step to prevent CSF leak and postoperative infection. By comparing sandwich technique and single-layer dural sealing, no significant difference could be shown.

Meningiomas involving the sphenoid wing outcome after microsurgical treatment--a clinical review of 73 cases.

OBJECTIVE: Sphenoid wing meningiomas represent a difficult to access subtype of intracranial meningiomas involving important neurovascular structures such as the optic nerve, cavernous sinus or carotid artery. They cause neurological compromises by direct compression of adjacent cranial nerves. Insidious and aggressive dural, bony, and orbital involvement produces several difficulties for adequate resection leading to higher rates of recurrence. METHODS: This retrospective case analysis consists of 73 patients who were surgically treated for meningiomas involving the sphenoid wing, where a pterional approach was performed between April 2001 and February 2006. 51 women and 22 men with a mean age of 59.4 years were operated on. The follow-up period ranged from 3-75 months (mean 29.8 months). Patients were divided into the following groups based on the site of the tumor: group 1: outer part of the sphenoid ridge (lateral, n=16); group 2: middle part of the sphenoid ridge (intermediate, n=5); group 3: inner part of the sphenoid ridge (medial, n=22); and group 4: spheno-orbital meningioma (n=30). RESULTS: The majority of patients presented with visual impairment (55%), followed by generalized headaches (36%) and visual field defects (33%). Total microscopic tumor resection was achieved in 35 patients (47.9%). Visual acuity improved in 58% of the patients, with 23% returning to normal vision. Preexisting cranial nerve deficits remained unchanged in the majority of patients (79%) and improved in 18%. Temporary new cranial nerve deficits occurred in 6 cases, and 1 patient (1%) developed permanent third nerve palsy. The mortality rate was 3% (2 patients) and the rate of permanent nonvisual morbidity was 7% (5 patients). 12 patients (16%) received postoperative radiotherapy. In 6 of 7 patients who were observed for at least 1 year after radiotherapy, stable tumor volume was noted at the follow-up review (mean 30.2 months, range 16-50 months), which provides a tumor growth control rate of 86%. The overall recurrence rate was 15% (11 of 73 patients). CONCLUSION: The result of this study affirms the safety of microsurgical treatment strategies, so that sufficient tumor control can be achieved with minimal morbidity and satisfying functional results in most cases.

Evaluation of a navigated and power controlled milling system "navigated control spine" for spinal surgery.

PURPOSE: The aim of this work was the evaluation of a navigated and power controlled milling system for spine surgery (navigated control spine). The navigation is based on a set of intraoperatively taken fluoroscopic images from different angles. A manually planned workspace limits the power of the mill and assures a higher automatisation degree than any other established navigation system for spine surgery. METHODS: Both a technical study in workspace planning from fluoroscopic images and a milling study on a spine phantom were performed with participants with different level of knowledge of spinal surgery. RESULTS: In the region of interest the workspace planning could be performed with a maximum excess of 1.40 mm for surgeons. In the study performing the milling of a standardised workspace the remnant bone after milling had a mean difference from the planned workspace margin of 1.96-2.12 mm in the region of most interest. Accurate handling of the mill still required a certain level of medical knowledge and experience. In both studies the time needed for application of the system proved acceptable for clinical purposes. DISCUSSION: This concept of navigated and power controlled spinal surgery has proven feasible in an experimental study. This navigation system seems therefore promising for clinical application.

[Virtual endoscopy of the nose and paranasal sinuses in real-time. Surgical planning system "Sinus endoscopy" (SPS-SE)]. / Virtuelle Echtzeit-Endoskopie der Nase und Nasennebenhöhlen. Surgical-Planning-System "Sinus Endoscopy" (SPS-SE).

PROBLEM: The aim of this study was the development and clinical evaluation of a new method for virtual endoscopy of the nose and paranasal sinuses. MATERIAL AND METHODS: The surgical planning system "sinus endoscopy" (SPS-SE) was completely newly developed. The surfaces of the CT images are represented with direct volume rendering (raycasting) which allows a sufficiently high image repetition frequency with the movement of the virtual endoscopy and material effects for a natural appearance were added. Detail accuracy of the virtual illustrations was examined with the help of a picture-statistic comparison between optical and the virtual endoscopy. The evaluation of the system by the patients and physicians was made with a validated questionnaire. RESULTS: The deviations from defined landmarks of virtual in comparison to optical endoscopy are between 1.4 mm and 11.1 mm. Manoeuvering the virtual endoscope was found to be better than with the optical endoscope but the important parameters for visualization were similar. The accuracy of volume rendering, the high variability of scaling of the anatomical borders and orientation were judged to be negative factors. Altogether there was a balanced opinion from the ENT surgeons but without exception patients judged the system positively. DISCUSSION: This investigation proved the efficiency of SPS-SE for three-dimensional real time reconstruction of high-resolution CT data of the nose and paranasal sinuses. However, some modifications are necessary before introduction into routine use.

Automation in surgery: a systematic approach.

This chapter proposes a classification of surgical assistance systems with respect to their type and level of automation. This classification is based on previous work in the field of human factors and takes two aspects into consideration, the type of information-processing function of the surgeon that is supported by the system, as well as the type of function allocation between surgeon and systems. With respect to the former, three basic functions are distinguished, referred to as information acquisition and analysis, decision making and planning, and execution of surgical action. With respect to the type of function allocation, the status of being either "passive" or "active" comes into consideration for both objects of reference (i.e. the surgeon and the machine), depending on whether a given function is mainly performed by the surgeon, by the system, or collaboratively by both. Hence, a classification results for intraoperative assistance systems in six categories, each of these representing a different degree of automation. The classification scheme is explained and illustrated on the basis of examples of surgical assistance systems from various fields.

[Manipulator assisted endoscope guidance in functional endoscopic sinus surgery: proof of concept]. / Ein Konzept für eine automatisierte Endoskopführung für die Nasennebenhöhlenchirurgie.

BACKGROUND: Functional endoscopic sinus surgery (FESS) is characterized by single-handed preparation and guidance of the endoscope by the nondominant hand. This results in an additional extension of operation time by up to 15% and ergonomic deficits. The aim of this study is the conception of an automated assistance system for FESS in view of the following questions: (1) Which degree of surgical automation is suitable for FESS? (2) Which design is suitable? (3) What are the properties of the technical system (planning, time, accuracy, precision) of the selected system? (4) Does the system offer potential for a clinical application? METHODS: In all 49 FESS were analyzed for surgical workflows. Measurement of the maximum forces within FESS was performed with 40 trials on an anatomical model. Three different mechanical systems were used in ten FESS and evaluated using the ICCAS Human-Machine Evaluation Scale. For realization of automated endoscope guidance an engine-driven and -braked manipulator (PA10-6c, Mitsubishi, Japan) was used. The technical parameters determined were expenditure of time for the preoperative planning of workspace, surgical accuracy and precision of the intraoperative endoscope positioning, maximal forces, and time. RESULTS: Concept-conditioned instrument changes amount to an average of 41.1 and 18.9% (5.21 min) time requirement for each FESS side. Maximum forces on the mucous membrane during a conventional FESS were measured at 9.8 N (5.9-9.8). Usability of the mechanical endoscope holder was estimated in 18 of 20 cases to be inferior to the standard procedure. The time needed for segmenting the intranasal workspace was 15.2 min (10.0-23.0). The maximum deviation of the automatically driven endoscope from a planned position amounted to 0.85 mm (manually 4.64 mm). The maximum force was measured with 1.1 N in the z direction (manually 9.8 N). Automated guidance of the endoscope to an intranasal position needed 7.25 s (6.4-7.9); manually 12.64 s (5.9-43.0). CONCLUSION: Guidance of the endoscope for FESS by an automated motor-driven system is possible. The conception which is based on workflow analysis favors a system with automatic definition of the workspace and a manual movement of the endoscope. The examined system offers a potential for clinical application. Definition of the automation level and development of a man-machine interface is more important than selection or reconstruction of a special manipulator for endoscope guidance in FESS from a surgical point of view.

Application of intraoperative 3D ultrasound during navigated tumor resection.

Intraoperative 3D ultrasound (3D-iUS) may enhance the quality of neuronavigation by adding information about brain shift and tumor remnants. The aim of our study was to prove the concept of 3D ultrasound on the basis of technical and human effects. A 3D-ultrasound navigation system consisting of a standard personal computer containing a video grabber card in combination with an optical tracking system (NDI Polaris) and a standard ultrasound device (Siemens Omnia) with a 7.5 MHz probe was used. 3D-iUS datasets were acquired after craniotomy, at different subsequent times of the procedure and overlaid with preoperative MRI. All patients underwent early postoperative 3D MRI including contrast agent within 24 hours after surgery. Acquisition of 3D iUS and the fusion with preoperative MRI was successful in 22/23 patients. The expenditure of time was at least 5 minutes for one intraoperative 3D US dataset. The technique was used three to seven times during surgery. The quality of the ultrasound images was superior in cases of metastasis, meningeoma and angioma over those in malignant glioma. Brain shifting ranged from 2-25 mm depending on localization and kind of tumor. A resection control was possible in 78%. All six neurosurgeons demonstrated a learning curve. The introduction of 3D ultrasound has increased the value of neuronavigation substantially, making it possible to update several times during surgery and minimize the problem of brain shift. Configuration of both the 3D iUS based on a standard ultrasound system and the MR navigation system is time- and especially cost-effective. Faster navigational datasets and more intuitive image-guided surgery enable novel and user-friendly display techniques.

[Clinical efficiency and the influence of human factors on ear, nose, and throat navigation systems]. / Ist der Vorteil eines Navigationssystems in der HNO-Chirurgie messbar? Ein Konzept zur Evaluation ergonomischer und chirurgischer Erfolgsparameter.

BACKGROUND: The aim of this study was to evaluate the Navibase navigation system for ear, nose, and throat (ENT) surgery. A new methodology for evaluating surgical and human factors is developed. PATIENTS AND METHODS: The evaluation is based on 102 ENT surgical applications, including 89 cases of functional endoscopic sinus surgery (FESS). The evaluation of surgical and human factors was performed by seven ENT surgeons. To evaluate surgical performance, level of quality (LOQ) in the 89 cases of FESS was determined, comparing the surgeon's own impressions with those of the navigation system on a scale from 0 to 100 and further comparing them with clinical results. Intraoperative changes in surgical strategy were documented. The human factors of total confidence (trust), situation awareness, skill set requirement and workload shift were recorded as level of reliance (LOR). RESULTS: The maximum deviation amounted to 1.93 mm. Averaging the quality of information resulted in an LOQ of 63.59. Every second application of the navigation system (47.9%) led to a change in surgical strategy. Total confidence showed a positive evaluation of 3.35 points in LOR. CONCLUSION: Application-relevant information relevant to the application beyond only technical details permits comparison with other assisting systems.

[Accuracy and precision in the evaluation of computer assisted surgical systems. A definition]. / Genauigkeit und Präzision in der Bewertung von chirurgischen Navigations- und Assistenzsystemen. Eine Begriffsbestimmung.

Accuracy represents the outstanding criterion for navigation systems. Surgeons have noticed a great discrepancy between the values from the literature and system specifications on one hand, and intraoperative accuracy on the other. A unitary understanding for the term accuracy does not exist in clinical practice. Furthermore, an incorrect equality for the terms precision and accuracy can be found in the literature. On top of this, clinical accuracy differs from mechanical (technical) accuracy. From a clinical point of view, we had to deal with remarkably many different terms all describing accuracy. This study has the goals of: 1. Defining "accuracy" and related terms, 2. Differentiating between "precision" and "accuracy", 3. Deriving the term "surgical accuracy", 4. Recommending use of the the term "surgical accuracy" for a navigation system. To a great extent, definitions were applied from the International Standardisation Organisation-ISO and the norm from the Deutsches Institut für Normung e.V.-DIN (the German Institute for Standardization). For defining surgical accuracy, the terms reference value, expectation, accuracy and precision are of major interest. Surgical accuracy should indicate the maximum values for the deviation between test results and the reference value (true value) A(max), and additionally indicate precision P(surg). As a basis for measurements, a standardized technical model was used. Coordinates of the model were acquired by CT. To determine statistically and reality relevant results for head surgery, 50 measurements with an accuracy of 50, 75, 100 and 150 mm from the centre of the registration geometry are adequate. In the future, we recommend labeling the system's overall performance with the following specifications: maximum accuracy deviation A(max), precision P and information on the measurement method. This could be displayed on a seal of quality.

[Workflow analysis to assess the efficiency of intraoperative technology using the example of functional endoscopic sinus surgery]. / Bestimmung der Effizienz von intraoperativer Technologie: Workflow-Analyse am Beispiel der endoskopischen Nasennebenhöhlenchirurgie.

Evaluation of the efficiency of surgical technology systems has to date been largely subjective. The aim of this study was to develop an ontology for surgical procedures usable workflow structures, and the evaluation of surgical workflow analysis using the example of functional endoscopic sinus surgery (FESS). A total of 38 procedures (20 patients) were included. Surgery was carried out by seven different surgeons with different degrees of training. Description of the surgical procedures and resources is based on the standard EN1828/2001 (Structure for Classification and Coding Systems for Surgical Procedures). In addition the requirements of the Workflow Reference Models (document no. Tc00-1003), Workflow Management Coalition (WfMC) were integrated. The workflow recorded the position, frequency of change of position, use time, cleaning time and concept based instrument changes. A total of 293 items were used to define FESS. A total of 1,029 different endoscopic positions were documented. These could be combined into five major endoscopic positions. The frequency of position changes was 27.1 per side, the period spent in an endoscopic position is about 1.31 min. Time for the concept-caused instrument changing was 6.44 min per side. This study demonstrates the need for assistance in guiding the endoscope in FESS. Using the workflow-data, the concept of an assistant system is possible. We offer a basis for discussion of the development of an ontology, recording and analysing surgical workflows and their practical application.

Effect of 3T MRI on the function of shunt valves--evaluation of Paedi GAV, Dual Switch and proGAV.

The MR-compatibility of medical implants and devices becomes more and more important with the increasing number of high-field MR-scanners employed. Until the end of 2004, about twenty 3T MR in Germany will be in clinical practice. Patients with hydrocephalus need frequent follow-up MR-examinations to assure correct functioning of a shunt. We tested three types of gravitational valves: the Paedi GAV, the Dual Switch and as a new programmable valve the proGAV (Miethke Company, Berlin), that have not been evaluated at 3T, yet. In sum, there is strong evidence for maintenance of function of these valves after exposure to 3T. This also implies the programmable valve, as long as the brake mechanism is properly adjusted during MR-examination.

[Navigated control: a new concept in computer assisted ENT-surgery]. / Navigated Control: Ein neues Konzept für die Computer-Assistierte-HNO-Chirurgie.

This work conceived and evaluates a mechatronical system for ORL-surgery by example of a Shaver for Functional Endoscopic Sinus Surgery controlled by navigation. The Shaver is automatically on/off-regulated depending on the current position in relation to the planned working space. This working space is defined on the basis of the individual CT data. Within this area the Shaver reacts to the signal of the surgeon (foot pedal). If the Shaver leaves the working space, an interruption of the drive regulation to the Shaver takes place. The evaluation of the planning software based on 32 patient CT-data sets. The registration accuracy in a anatomical model was examined on 451 measurements of endonasal attached titanium screws. The conversions of the working space were evaluated at 5 different technical models. The average time for segmenting the working space was found at 4.23 minutes per case. An average registration accuracy of the Shaver of 1.08 mm resulted. The pre-defined cavity was to be cleared away without restrictions. The preoperative determined work-space was converted by 3.1 mm over all levels. The study proves the feasibility of a mechatronical assistant system by the example of the navigate-controlled Shaver in paranasal sinus surgery. Contrary to conventional CAS solutions redundancy and cognitive discharge of the surgeon are considered in this conception. We see numerous applications according to the explained principle for power-control of instruments in ORL-surgery in the future such as drilling, high frequency surgery or laser.

[Virtual training in head- and neurosurgery]. / Moderne Trainingsmethoden für die Kopfchirurgie.

BACKGROUND: Surgical skill requires training at close-to-reality scenarios. Conventional procedures (practical exercises, anatomical or animal cadavers) are increasingly in conflict with objective parameters (costs of OR, quality management, cadavers availability and cost). Surgical procedures can be covered by using Virtual Surgical Reality (VSR). METHODS: We examined the principle of a VSR system and evaluated the results with 30 probands by the example of modified radical mastoidectomy and ventriculocisternostomy. Probands were divided in experienced (A) and non-experienced surgeons (B). The protocol included time of surgery, collisions and fatal injuries at altogether 15 passages (10 passages - break of 14 days - 5 passages). Additionally the Medical Level of Trust (LOT) describes the confidence into the surgical scenario and thus the quality by volume illustration, texture and haptic data feedback to the user. We used a numeric scale between 0 and 100 and the starting point of 50. RESULTS: The learning effect can be confirmed for both virtual scenarios. The mastoid scenario reaches a total confidence index LOT of 75. The ventricle scenario is evaluated with a total confidence index of 84. The necessary time for the opening of the antrum is reduced from 15.0 minutes (group A) and 22.5 minutes (group B) around 37 % to 9, 5 (group A) and around 56 % to 10.0 minutes (group B). The virtual haptic result was evaluated positive in both scenarios. CONCLUSIONS: VSR systems have the potential to revolutionize surgical training. All surgical experienced probands evaluated the VSR-scenario as near-to-reality. "Suspension of Disbelief" is the major condition for effective virtual reality training systems.

[Mechatronic in functional endoscopic sinus surgery. First experiences with the daVinci Telemanipulatory System]. / Mechatronik in der HNO-Chirurgie. Erste Erfahrungen mit dem daVinci-Telemanipulator-System.

BACKGROUND: This study examines the advantages and disadvantages of a commercial telemanipulator system (daVinci, Intuitive Surgical, USA) with computer-guided instruments in functional endoscopic sinus surgery (FESS). METHODS: We performed five different surgical FESS steps on 14 anatomical preparation and compared them with conventional FESS. A total of 140 procedures were examined taking into account the following parameters: degrees of freedom (DOF), duration , learning curve, force feedback, human-machine-interface. RESULTS: Telemanipulatory instruments have more DOF available then conventional instrumentation in FESS. The average time consumed by configuration of the telemanipulator is around 9+/-2 min. Missing force feedback is evaluated mainly as a disadvantage of the telemanipulator. Scaling was evaluated as helpful. The ergonomic concept seems to be better than the conventional solution. DISCUSSION: Computer guided instruments showed better results for the available DOF of the instruments. The human-machine-interface is more adaptable and variable then in conventional instrumentation. Motion scaling and indexing are characteristics of the telemanipulator concept which are helpful for FESS in our study.

Navigated control in functional endoscopic sinus surgery.

This study designs and evaluates a mechatronic system to assist ENT surgery, taking as an example a navigation controlled shaver as used in paranasal sinus surgery. The on/off status of the shaver is regulated automatically, depending on the current position of the shaver tip. The working space for the navigation controlled shaver is planned preoperatively as a three-dimensional model and is based on the individual patient's CT data. Within this area the shaver reacts to signals from the surgeon. If the tip of the shaver moves outside the predefined working space, the shaver's automatic drive control is interrupted by an electrical pulse. The planning software was evaluated using CT data sets from 32 patients. The accuracy of the registration was analysed on an anatomical model with the aid of 451 measurements on titanium screws attached endonasally, whilst the implementation of the working space was evaluated on 5 technical models. The average time taken for segmenting the working space was found to be 4.23 minutes. The average accuracy of the shaver registration was 1.08 mm. The selected cavity was to be resected without any restrictions. The preoperatively determined working space was implemented with a mean deviation of 3.1 mm over all levels. The study proves the feasibility of a mechatronic assistance system taking as an example the navigation controlled shaver used in paranasal sinus surgery. In contrast to isolated CAS solutions, this conceptual approach provides for the redundancy of the surgeon and eases their cognitive burden. We can foresee numerous applications in ENT surgery of the future following the principle presented here, in the control systems of power tools such as cutters, high frequency scalpels and lasers.

Third ventriculostomy in communicating hydrocephalus in adult patients -- the role of lumbar and cranial cerebrospinal fluid outflow measurement.

OBJECTIVE: To evaluate the value of CSF outflow resistance testing as a criterion for endscopic treatment in case of communicating hydrocephalus. METHODS: 12 patients with communicating hydrocephalus were integrated in a prospective study from 1999 - 2001. Under the assumption of different hydromechanical properties of both spinal and cerebral CSF compartment the resorption capacity was measured. V.-p. shunting, ventriculostomy or conservative treatment were performed dependent on the results and clinical outcome was evaluated. RESULTS: Six patients with pathological lumbar testing underwent primary ventriculo-peritoneal shunting. In 6 of the 12 cases the lumbar CSF resorption capacity was found to be normal and cerebral testing was accomplished. Two patients with normal spinal and cerebral resorption capacity were not operated. In the remaining 4 patients cerebral testing was found to be pathological and ventriculostomy was performed. An improvement of clinical symptoms was observed in patients operated with a v.-p. shunt and in the VCS group as well. CONCLUSIONS: This study demonstrates that there is a subgroup of patients with morphological communicating hydrocephalus that is characterized by a functional dissociation of hydromechanical properties of intracranial and spinal CSF compartment. In cases of regular CSF resorption but restricted CSF outflow from the ventricular system to the subarachnoid space ventriculo-peritoneal shunting may be an efficient therapy, but VCS was proved to be an efficient alternative.

[First clinical experience with extended planning and navigation in an interventional MRI unit]. / Erste klinische Erfahrungen mit einer erweiterten Eingriffsplanung und Navigation am interventionellen MRT.

PURPOSE: To present an advanced concept for patient-based navigation and to report on our first clinical experience with interventions in the cranium, of soft-tissue structures (breast, liver) and in the musculoskeletal system. MATERIALS AND METHODS: A PC-based navigation system was integrated into an existing interventional MRI environment. Intraoperatively acquired 3D data were used for interventional planning. The information content of these reference data was increased by integration of additional image modalities (e. g., fMRI, CT) and by color display of areas with early contrast media enhancement. Within 18 months, the system was used in 123 patients undergoing interventions in different anatomic regions (brain: 64, paranasal sinus: 9, breast: 20, liver: 17, bone: 9, muscle: 4). The mean duration of 64 brain interventions was compared with that of 36 procedures using the scanner's standard navigation. RESULTS: In contrast with the continuous scanning mode of the MR system (0.25 fps), the higher quality as well as the real time display (4 fps) of the MR images reconstructed from the 3D reference data allowed adequate hand-eye coordination. With our system, patient movement and tissue shifts could be immediately detected intraoperatively, and, in contrast to the standard procedure, navigation safely resumed after updating the reference data. The navigation system was characterized by good stability, efficient system integration and easy usability. Despite additional working steps still to be optimized, the duration of the image-guided brain tumor resections was not significantly longer. CONCLUSION: The presented system combines the advantage of intraoperative MRI with established visualization, planning, and real time capabilities of neuronavigation and can be efficiently applied in a broad range of non-neurosurgical interventions.