[Simulation-based training in urology: A systematic literature review]. / Formation par la simulation : de quels outils disposons-nous en urologie ? Revue systématique de la littérature.

CONTEXT: Simulation-based training is taking an increasingly important place in surgical training and is becoming mandatory with the latest reform of the French medical studies. OBJECTIVES: The objectives of this work were to report the various simulation tools available for the surgical training in urology, along with their validation level, through a systematic literature review. DOCUMENTARY SOURCES: A search was conducted using Medline® with the terms "urology" and "simulator". Articles in English and French were selected. STUDY SELECTION: Two hundred and ninety-one abstracts were read, allowing for the selection of 154 articles read to assess their eligibility. Studies whose main objective was not the validation of a simulator, studies describing animal models or studies whose full text was not available were excluded. RESULTS: One hundred and six studies were analyzed in this review. The simulators described were classified in 7 categories: laparoscopic surgery, robotic surgery, ureteroscopy, percutaneous nephrolithotomy, endoscopic bladder and prostate surgery, basic skills in urology, and ultrasound-guided prostate interventions simulators. Apparent and content validity were demonstrated for most simulators, but construct and predictive validity were often lacking. LIMITATIONS: We did not consider the use of simulators as competency evaluation tools. Besides, the latest terminology proposed to define the various validation steps was not taken into account. CONCLUSION: Many simulators are available in the field of urology and allow the reproduction of a large variety of urological procedures. However, their validation level is inconsistent, and has to be taken into account when choosing a simulator for surgical training, along with its cost, the eagerness of students to use the simulator and its availability.

Modeling the impact of prostate edema on LDR brachytherapy: a Monte Carlo dosimetry study based on a 3D biphasic finite element biomechanical model.

Prostate volume changes due to edema occurrence during transperineal permanent brachytherapy should be taken under consideration to ensure optimal dose delivery. Available edema models, based on prostate volume observations, face several limitations. Therefore, patient-specific models need to be developed to accurately account for the impact of edema. In this study we present a biomechanical model developed to reproduce edema resolution patterns documented in the literature. Using the biphasic mixture theory and finite element analysis, the proposed model takes into consideration the mechanical properties of the pubic area tissues in the evolution of prostate edema. The model's computed deformations are incorporated in a Monte Carlo simulation to investigate their effect on post-operative dosimetry. The comparison of Day1 and Day30 dosimetry results demonstrates the capability of the proposed model for patient-specific dosimetry improvements, considering the edema dynamics. The proposed model shows excellent ability to reproduce previously described edema resolution patterns and was validated based on previous findings. According to our results, for a prostate volume increase of 10-20% the Day30 urethra D10 dose metric is higher by 4.2%-10.5% compared to the Day1 value. The introduction of the edema dynamics in Day30 dosimetry shows a significant global dose overestimation identified on the conventional static Day30 dosimetry. In conclusion, the proposed edema biomechanical model can improve the treatment planning of transperineal permanent brachytherapy accounting for post-implant dose alterations during the planning procedure.

Results of a cohort of 200 hormone-naïve consecutive patients with prostate cancer treated with iodine 125 permanent interstitial brachytherapy by the same multidisciplinary team.

PURPOSE: To report survival and morbidity of a cohort of 200 hormone-naïve consecutive patients with localized prostate cancer, treated by low-dose rate brachytherapy within the frame of multidisciplinary approach. PATIENTS AND METHODS: Between 2001 and 2011, 200 patients were treated by the same team with 125 iodine seeds: 167 low-risk and 33 intermediate risk according to the d'Amico classification; eligible patients had clinical stage T1/T2a-b, Gleason score 3+3 or 3+4, baseline prostate-specific antigen level below 15ng/mL, prostate volume less than 60cm(3). The median number of random biopsies was 12 (range 6-32) and the breakdown of positive cores was as follows: 1 (29%), 2 (35%), 3 or more (36%). Acute morbidity was assessed according to the Common Terminology Criteria for Adverse Events and late toxicity according to the EORTC/RTOG scale. Data were prospectively collected. RESULTS: The median follow-up was 69 months (range 16 to 135). The 5- and 10-year biochemical relapse free survivals were 95.6% (95% confidence interval [CI]: 91-98) and 89.7% (95% CI: 79.4-95.0). The 5-year and 10-year overall survival were respectively 96.4% (95% CI: 92-98.4) and 89.7% (95% CI: 80.8-94.6%) and the 10-year disease specific survival, 99.1% (95% CI: 93.0-99.9). The 5- and 10-year grade 3 acute toxicity cumulative rate were respectively 3.3% (95% CI: 1.4-6.6) and 4% (95% CI: 1.4-6.6) and the 5- and 10-year grades 3 cumulative late toxicity 2.5% (95% CI: 2.0-5.9) and 4% (95% CI: 2.0-5.9). CONCLUSION: Brachytherapy managed within the frame of a multidisciplinary approach - from diagnosis to evaluation - may offer optimized results with a reduced late toxicity rate, while remaining opened to dosimetry and technical improvements.

[MRI-guided targeted prostate biopsies in the diagnosis of prostate cancer: a systematic literature review]. / Biopsies prostatiques ciblées guidées par IRM dans le diagnostic du cancer de prostate : revue de la littérature.

INTRODUCTION: Advances in MRI technology for detection of prostate cancer allow targeted biopsies of suspicious areas. MATERIAL AND METHODS: A systematic literature review was performed on Medline(®) with the keywords "targeted", "prostate biopsy" and related articles. We studied 65 abstracts and 102 related abstracts, read 38 articles and selected 27 articles. RESULTS: Mental reconstruction gives way for targeted biopsies by direct MRI guidance inside the MRI, and MRI-TRUS fusion. The first option offers high precision targeting but is limited by the accessibility, cost and duration of the procedure. MRI-TRUS image fusion is a promising compromise. Cancer detection rates vary from 15 to 64 %. CONCLUSION: Biopsies targeting suspicious areas on MRI are promising to improve the sensitivity and performance of prostate biopsies.

Assessment of a percutaneous iliosacral screw insertion simulator.

BACKGROUND: Navigational simulator use for specialized training purposes is rather uncommon in orthopaedic and trauma surgery. However, it reveals providing a valuable tool to train orthopaedic surgeons and help them to plan complex surgical procedures. PURPOSE: This work's objective was to assess educational efficiency of a path simulator under fluoroscopic guidance applied to sacroiliac joint percutaneous screw fixation. MATERIALS AND METHODS: We evaluated 23 surgeons' accuracy inserting a guide-wire in a human cadaver experiment, following a pre-established procedure. These medical trainees were defined in three prospective respects: novice or skilled; with or without theoretical knowledge; with or without surgical procedure familiarity. The screw insertion in the human cadaver was performed in two different settings: either without prior training for a first group (G1) or after simulator guidance in the second group (G2). Analysed criteria for each tested surgeon included the number of intraoperative X-rays taken in order to achieve the surgical procedure as well as an iatrogenic index reflecting the surgeon's ability to detect any hazardous trajectory at the time of performing said procedure. RESULTS: An average number of 13 X-rays was required for wire implantation by the G1 group. G2 group, assisted by the simulator use, required an average of 10 X-rays. A substantial difference was especially observed within the novice sub-group (N), with an average of 12.75 X-rays for the G1 category and an average of 8.5 X-rays for the G2 category. In the second sub-group of operators devoid of procedural knowledge (P-), a significant difference was found, since 12 X-rays appeared on average required in the G1 group versus six in the G2 group. Finally, within the sub-group of operators with technical knowledge (T+), a significant difference also was found since an average of 16 X-rays was required in the G1 versus an average 10.8 X-rays in the G2 group. As far as the iatrogenic index is concerned, we were unable to observe any significant difference between the groups. DISCUSSION: Despite some methodological variations, we were able to demonstrate the simulator's efficiency in familiarizing the operator with the use of a 2D imaging system as a first step facilitating the procedure conduct in the real 3D patient environment. Novice surgeons (N) having a good lumbosacral joint anatomy knowledge although devoid of specific surgical technique knowledge were the ones who most benefited from this guiding tool. Analysis of the training data collected during simulator's use helps orientating the prospective surgeon toward possession of not yet acquired learning points. This educational program can easily be extended to any other percutaneous technique requiring fluoroscopic control guidance. LEVEL OF EVIDENCE: Level III prospective diagnostic study.

Fluoroscopy-based navigation system in spine surgery.

The variability in width, height, and spatial orientation of a spinal pedicle makes pedicle screw insertion a delicate operation. The aim of the current paper is to describe a computer-assisted surgical navigation system based on fluoroscopic X-ray image calibration and three-dimensional optical localizers in order to reduce radiation exposure while increasing accuracy and reliability of the surgical procedure for pedicle screw insertion. Instrumentation using transpedicular screw fixation was performed: in a first group, a conventional surgical procedure was carried out with 26 patients (138 screws); in a second group, a navigated surgical procedure (virtual fluoroscopy) was performed with 26 patients (140 screws). Evaluation of screw placement in every case was done by using plain X-rays and post-operative computer tomography scan. A 5 per cent cortex penetration (7 of 140 pedicle screws) occurred for the computer-assisted group. A 13 per cent penetration (18 of 138 pedicle screws) occurred for the non computer-assisted group. The radiation running time for each vertebra level (two screws) reached 3.5 s on average in the computer-assisted group and 11.5 s on average in the non computer-assisted group. The operative time for two screws on the same vertebra level reaches 10 min on average in the non computer-assisted group and 11.9 min on average in the computer-assisted group. The fluoroscopy-based (two-dimensional) navigation system for pedicle screw insertion is a safe and reliable procedure for surgery in the lower thoracic and lumbar spine.

[Accuracy measurements of acetabular cup positioning using CT less navigation]. / Protocole d'évaluation du risque d'erreur dans le positionnement cotyloïdien par navigation sans imagerie tomodensitométrique préopératoire.

PURPOSE OF THE STUDY: Standard methodology is lacking for evaluating the accuracy of surgical navigation systems. The purpose of the present study was to propose a new approach to error measurements of an image-free navigation system used for total hip arthroplasty. MATERIAL AND METHODS: This new approach evaluates the overall accuracy of the system and quantifies the influence of clinical application on this global error. The majority of hip navigation systems use the anterior pelvic plane as part of the reference system. With image-free systems, anatomic pelvic landmarks must be acquired intraoperatively in order to define the anterior pelvic plane. This step could potentially introduce a significant error for navigation. Two studies were performed to measure this error, one on patients and the other on pelvic phantoms. Both used the difference between the intraoperative cup orientation, as displayed by the navigation system and the postoperative cup position, measured on computer tomography (CT) data. The CT measurements used the same reference system as the navigation system. RESULTS: The intraobserver measurement variability ranged from 48.4 degrees to 49.5 degrees for cup abduction and from 12 degrees to 13.5 degrees for anteversion. The interobserver variability ranged from 47.5 degrees to 19 degrees for cup abduction and from 11.8 degrees to 13.8 degrees for anteversion. Overall errors were calculated for cup abduction and anteversion. Cup navigation was accurate on pelvic bone phantoms. The anteversion error ranged from 0 degrees to 2.5 degrees (mean 0.9 degrees, standard deviation 0.7 degrees). For the clinical study, abduction errors ranged from 2.1 degrees to 16.7 degrees. The mean abduction error introduced by the acquisition of anatomic landmarks was 7.2 degrees. DISCUSSION: The proposed simple clinical end-to-end accuracy evaluation model provides the surgeon with sufficiently accurate information. The evaluation model was able to identify and more importantly to quantify the clinically induced error. This study proves that ameliorating the reference system acquisition would improve the system's overall accuracy.

Towards a realistic echographic simulator.

Echography is a useful tool to diagnose a thrombosis; however, since it is difficult to learn to perform this procedure, the objective of this work is to create a simulation to allow students to practice in a virtual environment. Firstly, a physical model of the thigh was constructed based on experimental data obtained using a force sensor mounted on a robotic arm. We present a spring damper model consisting of both linear and non-linear elements. The parameters of each of these elements are then fitted to the experimental data using an optimization technique. By employing an implicit integration to solve the dynamics of the system we obtain a stable physical simulation at over 100 Hz. Secondly, a haptic interface was added to interact with the simulation. Using a PHANToM force-feedback device may touch and deform the thigh in real-time. In order to allow a realistic sensation of the contact we employ a local modeling technique allowing to approximate the forces at much higher frequency using a multi-threaded architecture. Finally, we present the basis for a fast echographic image generation depending on the position and orientation of the virtual probe as well as the force applied to it.

MRI/TRUS data fusion for brachytherapy.

BACKGROUND: Prostate brachytherapy consists in placing radioactive seeds for tumour destruction under transrectal ultrasound imaging (TRUS) control. It requires prostate delineation from the images for dose planning. Because ultrasound imaging is patient- and operator-dependent, we have proposed to fuse MRI data to TRUS data to make image processing more reliable. The technical accuracy of this approach has already been evaluated. METHODS: We present work in progress concerning the evaluation of the approach from the dosimetry viewpoint. The objective is to determine what impact this system may have on the treatment of the patient. Dose planning is performed from initial TRUS prostate contours and evaluated on contours modified by data fusion. RESULTS: For the eight patients included, we demonstrate that TRUS prostate volume is most often underestimated and that dose is overestimated in a correlated way. However, dose constraints are still verified for those eight patients. CONCLUSIONS: This confirms our initial hypothesis.

Computer-assisted access to the kidney.

OBJECTIVES: The aim of this paper is to introduce the principles of computer-assisted access to the kidney. The system provides the surgeon with a pre-operative 3D planning on computed tomography (CT) images. After a rigid registration with space-localized ultrasound (US) data, preoperative planning can be transferred to the intra-operative conditions and an intuitive man-machine interface allows the user to perform a puncture. MATERIAL AND METHODS: Both CT and US images of informed normal volunteer were obtained to perform calculation on the accuracy of registration and punctures were carried out on a kidney phantom to measure the precision of the whole of the system. RESULTS: We carried out millimetric registrations on real data and guidance experiments on a kidney phantom showed encouraging results of 4.7 mm between planned and reached targets. We noticed that the most significant error was related to the needle deflection during the puncture. CONCLUSION: Preliminary results are encouraging. Further work will be undertaken to improve efficiency and accuracy, and to take breathing into account.

SURGETICA at Grenoble: from computer assisted medical interventions to quality inspired surgery.

Research on "Computer Assisted Medical Interventions" (CAMI) was initiated in Grenoble in 1984, as an attempt to take up the challenge of "Minimally Invasive Interventions", thanks to the introduction of Information and Communication Techniques in the Operating Room. In a first section, we will describe our initial vision. The corresponding achievements will then be presented. A final section will show that the challenge now is to "invert this movement": instead of moving the computer in the Operating Room, we should embed the surgeon (or at least his or her expertise) into the Information Technology based tools he or she uses.

Model driven therapy - the instance of computer assisted medical interventions.

OBJECTIVES: Taking into account a priori knowledge is a key issue to meet the medical, scientific and industrial challenges of the progresses of Minimally Invasive Surgery. We propose an overview of these challenges. METHODS: Models play a major role in representing the relevant knowledge to plan and realize complex medical and surgical interventions. We analyze the three basic steps of Perception, Decision and Action, and illustrate by some instances how models may be integrated in these steps. RESULTS: We propose a selection of the results obtained in Model Driven Therapy. These results illustrate the issues of Perception (models allow accurate reconstruction of 3D objects from a limited set of X-ray projections), Decision (models allow to take into account elastic and dynamic characteristics of muscles), and Action (models allow to design innovative navigational and robotics aids to the realization of complex interventions). Likewise, models play a major role in the process of surgeon's education, which leads to the concept of Virtual Orthopedic University. CONCLUSIONS: Model Driven Therapy emerges as the way to perform optimal medical and surgical interventions, providing physicians and surgeons with the possibility to augment their capacities of sensing multi-modal information, of combining them to define optimal strategies, and of performing accurate and safe actions.

Bone morphing: 3D morphological data for total knee arthroplasty.

OBJECTIVE: The clinical outcome of a total knee arthroplasty (TKA) is mainly determined by the accuracy of the surgical procedure itself. To improve the final result, one must take into account (a) the alignment of the prosthesis with respect to the mechanical axis, and (b) the balance of the soft tissues. Therefore, morphologic data (such as the shape of the epiphysis) and geometric data are essential. We present a new method for performing TKA based on morphologic and geometric data without preoperative images. MATERIALS AND METHODS: The global method is based on the digitization of points with an optical 3D localizer. For the morphologic acquisitions, we use a method based on the registration of sparse point data with a 3D statistical deformable model. To build the mechanical axis, we use a kinematics method for the hip center and digitization of anatomical landmarks for the ankle centers. The knee center is not determined by digitization or kinematics of the knee, as this would not be accurate. The surgical planning relies totally on the soft-tissue balance, which is the key issue for a good kinematics result. RESULTS: We have used this system for 6 months in a randomized clinical trial involving 35 patients to date. For the first 11 patients that could be measured in the navigation group, the postoperative frontal alignment was within the range of 180 +/- 3 degrees. Fluoroscopic assessment of the soft-tissue balancing will be performed at the conclusion of an extended 2-year study to evaluate the results from a functional point of view. CONCLUSION: Bone Morphing is an accurate, fast, and user-friendly method that can provide morphologic as well as geometric data. We have introduced the important notion of soft-tissue balancing into the intraoperative planning step to optimize the kinematics as well as the anatomy. Therefore, this method should be considered as an alternative to the CT-based method.

A methodological tool for computer-assisted surgery interface design: its application to computer-assisted pericardial puncture.

Computer Assisted Surgery systems are becoming more and more prevalent. Design processes currently used, pay only a small attention to the surgeon's interaction. To address this lack in design, we propose the OP-a-S notation: OP-a-S modeling of a system adopts an interaction-centered point of view and highlights the links between the real world and the virtual world. Based on an OP-a-S modeling, predictive usability analysis can be performed by considering the ergonomic property. We illustrate our method on the retro-design of a computer assisted surgical application, CASPER.

Clinical validation of computer assisted pelvic surgery using ultrasound. A percutaneous safe technique with low radiation exposure.

This study presents early results of the clinical experience of computer assisted surgery (CAS) applied to percutaneous iliosacral screwing. The results of these 10 first cases (4 patients) are compared to an historical series of 51 cases (30 patients). The CAS technique shows better screw placement without outside bone screw and a very low radiation exposure.

A six-degree-of-freedom passive arm with dynamic constraints (PADyC) for cardiac surgery application: preliminary experiments.

The purpose of Computer-Assisted Surgery (CAS) is to help physicians and surgeons plan and execute optimal strategies from multimodal image data. The execution of such planned strategies may be assisted by guidance systems. Some of these systems, called synergistic systems, are based on the cooperation of a robotic device with a human operator. We have developed such a synergistic device: PADyC (Passive Arm with Dynamic Constraints). The basic principle of PADyC is to have a manually actuated arm that dynamically constrains the authorized motions of the surgical tool held by the human operator during a planned task. Dynamic constraints are computed from the task definition, and are implemented by a patented mechanical system. In this paper, we first introduce synergistic systems and then focus on modeling and algorithmic issues related to the dynamic constraints. Finally, we describe a 6-degree-of-freedom prototype robot designed for a clinical application (cardiac surgery) and report on preliminary experiments to date. The experimental results are then discussed, and future work is proposed.

Clinical results of percutaneous pelvic surgery. Computer assisted surgery using ultrasound compared to standard fluoroscopy.

This study presents early results of clinical experience with the application of Computer Assisted Surgery (CAS) to percutaneous iliosacral screwing, with comparison to a historical series of patients treated using percutaneous fluoroscopy. Four patients were instrumented using a CAS system, with 10 screws being inserted. Thirty patients were treated by percutaneous fluoroscopic screwing, with 51 screws being inserted. The follow-up assessment included the following criteria; operative time, parameters of radiation exposure, neurological examination, screw placement evaluation on CT-scan, antalgic drug consumption, pain, Majeed grading, and loosening of implants. In the CAS group, the average radiation time was 0.35 min per patient and 0.14 min per screw. No trajectories outside the bone and no postoperative neurological deficits were found. In the fluoroscopic group, the average radiation time was 1.03 min per patient and 0.6 min per screw. Twelve screws had outside-bone trajectories, and iatrogenic neurological deficits were found in seven patients. The average operative time was 50 min in the CAS group and 35 min in the fluoroscopic group. The present CAS technique shows better placement of iliosacral screws, with no outside-bone trajectories and lower radiation exposure.