External validation of a prostate biopsy simulator.

INTRODUCTION: Simulation-based training has proven to be a promising option allowing for initial and continuous training while limiting the impact of the learning curve on the patient. The Biopsym simulator was developed as a complete teaching environment for the prostate biopsy procedure. This paper presents the results of an external validation of this simulator, involving urology residents recruited during a regional teaching seminar. METHODS: Residents from 4 academic urology departments of the French Auvergne Rhône-Alpes region, who did not take part in the previous simulator validation studies, were enrolled. After a short presentation and standardized initiation session, residents carried out a simulated systematic 12-core biopsy procedure and were asked to fill in a questionnaire collecting their expectations and evaluation of the Biopsym simulator. The number of biopsies reaching each targeted sector, the total score provided by the simulator and the duration of the procedure were recorded. RESULTS: Twenty-three residents were recruited. The overall added value (/100) for learning was rated at a median of 100 (interquartile range 83-100), overall realism of the biopsy procedure at 80 (65-89). The median percentage of biopsies reaching the targeted sector was 66.7% (62-75). The median score provided by the simulator was 50% (37-60). For both, the difference between residents with or without prior biopsy experience was not statistically significant. The median duration of the simulated biopsy procedure was 4:58 (minutes: seconds) (3:49-6:00). Resident with prior experience required less time to complete the biopsy procedure 3:53 (3:39-4:56) vs. 5:10 (4:59-7:10), P=0.01. CONCLUSION: This external validation study confirms a high acceptance of the simulator by the target audience. To our knowledge, the Biopsym simulator is the only prostate biopsy simulator that demonstrated such validity as evaluated by clinicians, outside the center involved in its early development. LEVEL OF EVIDENCE: 3.

Validating the Transfer of Skills Acquired on a Prostate Biopsy Simulator: A Prospective, Randomized, Controlled Study.

OBJECTIVES: To evaluate the ability of students to reproduce the skills acquired on a prostate biopsy simulator in a real-life situation. DESIGN: A prospective randomized controlled study was conducted. Medical students with no experience of prostate biopsy were randomized between arm A « conventional training ¼ and arm B « simulator-enhanced training. ¼ The training was performed for both groups on the simulator. The students in arm B were provided with visual and numerical feedback. The transfer of skills was assessed by recording the position of the 12 biopsies performed by each student on an unembalmed human cadaver using a 3D ultrasound mapping device. SETTING: The study was conducted in an academic urology department and the cadaver experiments in the adjoining anatomy laboratory. RESULTS: Twenty-four students were included, and 22 completed the study. The median score obtained on the simulator at the end of the training was 57% (53-61) for arm A and 66% (59-71) for arm B. The median score obtained on the cadaver by students trained with the simulator was 75% (60-80), statistically superior to the score obtained by students trained conventionally of 45% (30-60), p < 0.0001. The median score obtained by all students when performing biopsies in a real-life situation was 63% (50-80) versus 60% (56-70) for their last training on the simulator. CONCLUSION: These results support the transfer of skills acquired on the simulator, and the superiority of a training curriculum integrating simulation, and performance feedback.

Simulation-based training for prostate biopsies: towards the validation of the Biopsym simulator.

Objectives: The Biopsym simulator, a virtual-reality simulator for prostate biopsies, was designed to offer enhanced teaching of the biopsy procedure. The objectives of the present article are to describe the new version of the simulator and report the results of a new validation study.Material and methods: A prospective validation study was conducted between January and March 2017. The new version of the simulator, with improved physical realism, ultrasound image deformation, and a new scoring system, was evaluated by novice and confirmed users.Results: Twenty-one users evaluated the simulator, including ten novices and 11 confirmed users. The overall realism of the biopsy procedure was rated at 7.7/10 (IQR 5.7-9). The differences between the rates given by confirmed users and novices were not statistically significant. The median overall score obtained for the performance of 12 systematic ultrasound-guided biopsies was 43% (IQR 33-55). The median score obtained by confirmed users was 54% (IQR 46-62), and the median score obtained by novices was 31% (IQR 20-35). The difference between the scores was statistically significant (p = 0.005).Conclusions: This study allowed us to gather evidence towards the validation, and particularly towards the construct validation of the new version of the Biopsym simulator.

Hybrid 2D-3D ultrasound registration for navigated prostate biopsy.

PURPOSE: We present a hybrid 2D-3D ultrasound (US) rigid registration method for navigated prostate biopsy that enables continuous localization of the biopsy trajectory during the exam. METHODS: Current clinical computer-assisted biopsy systems use either sensor-based or image-based approaches. We combine the advantages of both in order to obtain an accurate and real-time navigation based only on an approximate localization of the US probe. Starting with features extracted in both 2D and 3D images, our method introduces a variant of the iterative closest point (ICP) algorithm. Among other differences to ICP, a combination of both the euclidean distance of feature positions and the similarity distance of feature descriptors is used to find matches between 2D and 3D features. The evaluation of the method is twofold. First, an analysis of variance on input parameters is conducted to estimate the sensitivity of our method to their initialization. Second, for a selected set of their values, the target registration error (TRE) was calculated on 29,760 (resp. 4000) registrations in two different experiments. It was obtained using manually identified anatomical fiducials. RESULTS: For 160 US volumes, from 20 patients, recorded during routine biopsy procedures performed in two hospitals by six operators, the mean TRE was [Formula: see text] mm (resp. [Formula: see text] mm). CONCLUSION: This work allows envisioning further developments for prostate navigation and their clinical transfer.

Initial validation of a virtual-reality learning environment for prostate biopsies: realism matters!

BACKGROUND AND PURPOSE: A virtual-reality learning environment dedicated to prostate biopsies was designed to overcome the limitations of current classical teaching methods. The aim of this study was to validate reliability, face, content, and construct of the simulator. MATERIALS AND METHODS: The simulator is composed of (a) a laptop computer, (b) a haptic device with a stylus that mimics the ultrasound probe, (c) a clinical case database including three-dimensional (3D) ultrasound volumes and patient data, and (d) a learning environment with a set of progressive exercises including a randomized 12-core biopsy procedure. Both visual (3D biopsy mapping) and numerical (score) feedback are given to the user. The simulator evaluation was conducted in an academic urology department on 7 experts and 14 novices who each performed a virtual biopsy procedure and completed a face and content validity questionnaire. RESULTS: The overall realism of the biopsy procedure was rated at a median of 9/10 by nonexperts (7.1-9.8). Experts rated the usefulness of the simulator for the initial training of urologists at 8.2/10 (7.9-8.3), but reported the range of motion and force feedback as significantly less realistic than novices (P=0.01 and 0.03, respectively). Pearson r correlation coefficient between correctly placed biopsies on the right and left side of the prostate for each user was 0.79 (P<0.001). The 7 experts had a median score of 64% (59%-73%), and the 14 novices a median score of 52% (43%-67%), without reaching statistical significance (P=0.19). CONCLUSION: The newly designed virtual-reality learning environment proved its versatility and its reliability, face, and content were validated. Demonstrating the construct validity will necessitate improvements to the realism and scoring system used.

Using CamiTK for rapid prototyping of interactive computer assisted medical intervention applications.

Computer Assisted Medical Intervention (CAMI hereafter) is a complex multi-disciplinary field. CAMI research requires the collaboration of experts in several fields as diverse as medicine, computer science, mathematics, instrumentation, signal processing, mechanics, modeling, automatics, optics, etc. CamiTK is a modular framework that helps researchers and clinicians to collaborate together in order to prototype CAMI applications by regrouping the knowledge and expertise from each discipline. It is an open-source, cross-platform generic and modular tool written in C++ which can handle medical images, surgical navigation, biomedicals simulations and robot control. This paper presents the Computer Assisted Medical Intervention ToolKit (CamiTK) and how it is used in various applications in our research team.