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Jocelyne Troccaz

Publications and source records attributed to Jocelyne Troccaz.

At least 37 records · Page 2Linked to original sources
arXiv2008

Urologic robots and future directions

PURPOSE OF REVIEW: Robot-assisted laparoscopic surgery in urology has gained immense popularity with the daVinci system, but a lot of research teams are working on new robots. The purpose of this study is to review current urologic robots and present future development directions. RECENT FINDINGS: Future systems are expected to advance in two directions: improvements of remote manipulation robots and developments of image-guided robots. SUMMARY: The final goal of robots is to allow safer and more homogeneous outcomes with less variability of surgeon performance, as well as new tools to perform tasks on the basis of medical transcutaneous imaging, in a less invasive way, at lower costs. It is expected that improvements for a remote system could be augmented in reality, with haptic feedback, size reduction, and development of new tools for natural orifice translumenal endoscopic surgery. The paradigm of image-guided robots is close to clinical availability and the most advanced robots are presented with end-user technical assessments. It is also notable that the potential of robots lies much further ahead than the accomplishments of the daVinci system. The integration of imaging with robotics holds a substantial promise, because this can accomplish tasks otherwise impossible. Image-guided robots have the potential to offer a paradigm shift.

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arXiv2008

Atlas-Based Prostate Segmentation Using an Hybrid Registration

Purpose: This paper presents the preliminary results of a semi-automatic method for prostate segmentation of Magnetic Resonance Images (MRI) which aims to be incorporated in a navigation system for prostate brachytherapy. Methods: The method is based on the registration of an anatomical atlas computed from a population of 18 MRI exams onto a patient image. An hybrid registration framework which couples an intensity-based registration with a robust point-matching algorithm is used for both atlas building and atlas registration. Results: The method has been validated on the same dataset that the one used to construct the atlas using the "leave-one-out method". Results gives a mean error of 3.39 mm and a standard deviation of 1.95 mm with respect to expert segmentations. Conclusions: We think that this segmentation tool may be a very valuable help to the clinician for routine quantitative image exploitation.

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arXiv2008

Framework for 3D TransRectal Ultrasound

Prostate biopsies are mainly performed under 2D TransRectal UltraSound (TRUS) control by sampling the prostate according to a predefined pattern. In case of first biopsies, this pattern follows a random systematic plan. Sometimes, repeat biopsies can be needed to target regions unsampled by previous biopsies or resample critical regions (for example in case of cancer expectant management or previous prostatic intraepithelial neoplasia findings). From a clinical point of view, it could be useful to control the 3D spatial distribution of theses biopsies inside the prostate. Modern 3D-TRUS probes allow acquiring high-quality volumes of the prostate in few seconds. We developed a framework to track the prostate in 3D TRUS images. It means that if one acquires a reference volume at the beginning of the session and another during each biopsy, it is possible to determine the relationship between the prostate in the reference and the others volumes by aligning images. We used this tool to evaluate the ability of a single operator (a young urologist assistant professor) to perform a pattern of 12 biopsies under 2D TRUS guidance.

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arXiv2008

3D-Ultrasound probe calibration for computer-guided diagnosis and therapy

With the emergence of swept-volume ultrasound (US) probes, precise and almost real-time US volume imaging has become available. This offers many new opportunities for computer guided diagnosis and therapy, 3-D images containing significantly more information than 2-D slices. However, computer guidance often requires knowledge about the exact position of US voxels relative to a tracking reference, which can only be achieved through probe calibration. In this paper we present a 3-D US probe calibration system based on a membrane phantom. The calibration matrix is retrieved by detection of a membrane plane in a dozen of US acquisitions of the phantom. Plane detection is robustly performed with the 2-D Hough transformation. The feature extraction process is fully automated, calibration requires about 20 minutes and the calibration system can be used in a clinical context. The precision of the system was evaluated to a root mean square (RMS) distance error of 1.15mm and to an RMS angular error of 0.61 degrees. The point reconstruction accuracy was evaluated to 0.9mm and the angular reconstruction accuracy to 1.79 degrees.

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arXiv2008

3D/4D ultrasound registration of bone

This paper presents a method to reduce the invasiveness of Computer Assisted Orthopaedic Surgery (CAOS) using ultrasound. In this goal, we need to develop a method for 3D/4D ultrasound registration. The premilinary results of this study suggest that the development of a robust and ``realtime'' 3D/4D ultrasound registration is feasible.

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arXiv2008

MRI/TRUS data fusion for prostate brachytherapy. Preliminary results

Prostate brachytherapy involves implanting radioactive seeds (I125 for instance) permanently in the gland for the treatment of localized prostate cancers, e.g., cT1c-T2a N0 M0 with good prognostic factors. Treatment planning and seed implanting are most often based on the intensive use of transrectal ultrasound (TRUS) imaging. This is not easy because prostate visualization is difficult in this imaging modality particularly as regards the apex of the gland and from an intra- and interobserver variability standpoint. Radioactive seeds are implanted inside open interventional MR machines in some centers. Since MRI was shown to be sensitive and specific for prostate imaging whilst open MR is prohibitive for most centers and makes surgical procedures very complex, this work suggests bringing the MR virtually in the operating room with MRI/TRUS data fusion. This involves providing the physician with bi-modality images (TRUS plus MRI) intended to improve treatment planning from the data registration stage. The paper describes the method developed and implemented in the PROCUR system. Results are reported for a phantom and first series of patients. Phantom experiments helped characterize the accuracy of the process. Patient experiments have shown that using MRI data linked with TRUS data improves TRUS image segmentation especially regarding the apex and base of the prostate. This may significantly modify prostate volume definition and have an impact on treatment planning.

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arXiv2007

Computer- and robot-assisted urological surgery

The author reviews the computer and robotic tools available to urologists to help in diagnosis and technical procedures. The first part concerns the contribution of robotics and presents several systems at various stages of development (laboratory prototypes, systems under validation or marketed systems). The second part describes image fusion tools and navigation systems currently under development or evaluation. Several studies on computerized simulation of urological procedures are also presented.

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arXiv2007

Medical image computing and computer-aided medical interventions applied to soft tissues. Work in progress in urology

Until recently, Computer-Aided Medical Interventions (CAMI) and Medical Robotics have focused on rigid and non deformable anatomical structures. Nowadays, special attention is paid to soft tissues, raising complex issues due to their mobility and deformation. Mini-invasive digestive surgery was probably one of the first fields where soft tissues were handled through the development of simulators, tracking of anatomical structures and specific assistance robots. However, other clinical domains, for instance urology, are concerned. Indeed, laparoscopic surgery, new tumour destruction techniques (e.g. HIFU, radiofrequency, or cryoablation), increasingly early detection of cancer, and use of interventional and diagnostic imaging modalities, recently opened new challenges to the urologist and scientists involved in CAMI. This resulted in the last five years in a very significant increase of research and developments of computer-aided urology systems. In this paper, we propose a description of the main problems related to computer-aided diagnostic and therapy of soft tissues and give a survey of the different types of assistance offered to the urologist: robotization, image fusion, surgical navigation. Both research projects and operational industrial systems are discussed.

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arXiv2007

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.

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arXiv2007

Towards 3D ultrasound image based soft tissue tracking: a transrectal ultrasound prostate image alignment system

The emergence of real-time 3D ultrasound (US) makes it possible to consider image-based tracking of subcutaneous soft tissue targets for computer guided diagnosis and therapy. We propose a 3D transrectal US based tracking system for precise prostate biopsy sample localisation. The aim is to improve sample distribution, to enable targeting of unsampled regions for repeated biopsies, and to make post-interventional quality controls possible. Since the patient is not immobilized, since the prostate is mobile and due to the fact that probe movements are only constrained by the rectum during biopsy acquisition, the tracking system must be able to estimate rigid transformations that are beyond the capture range of common image similarity measures. We propose a fast and robust multi-resolution attribute-vector registration approach that combines global and local optimization methods to solve this problem. Global optimization is performed on a probe movement model that reduces the dimensionality of the search space and thus renders optimization efficient. The method was tested on 237 prostate volumes acquired from 14 different patients for 3D to 3D and 3D to orthogonal 2D slices registration. The 3D-3D version of the algorithm converged correctly in 96.7% of all cases in 6.5s with an accuracy of 1.41mm (r.m.s.) and 3.84mm (max). The 3D to slices method yielded a success rate of 88.9% in 2.3s with an accuracy of 1.37mm (r.m.s.) and 4.3mm (max).

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arXiv2007

Prostate biopsies guided by three-dimensional real-time (4-D) transrectal ultrasonography on a phantom: comparative study versus two-dimensional transrectal ultrasound-guided biopsies

OBJECTIVE: This study evaluated the accuracy in localisation and distribution of real-time three-dimensional (4-D) ultrasound-guided biopsies on a prostate phantom. METHODS: A prostate phantom was created. A three-dimensional real-time ultrasound system with a 5.9MHz probe was used, making it possible to see several reconstructed orthogonal viewing planes in real time. Fourteen operators performed biopsies first under 2-D then 4-D transurethral ultrasound (TRUS) guidance (336 biopsies). The biopsy path was modelled using segmentation in a 3-D ultrasonographic volume. Special software was used to visualise the biopsy paths in a reference prostate and assess the sampled area. A comparative study was performed to examine the accuracy of the entry points and target of the needle. Distribution was assessed by measuring the volume sampled and a redundancy ratio of the sampled prostate. RESULTS: A significant increase in accuracy in hitting the target zone was identified using 4-D ultrasonography as compared to 2-D. There was no increase in the sampled volume or improvement in the biopsy distribution with 4-D ultrasonography as compared to 2-D. CONCLUSION: The 4-D TRUS guidance appears to show, on a synthetic model, an improvement in location accuracy and in the ability to reproduce a protocol. The biopsy distribution does not seem improved.

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arXiv2007

Development of miniaturized light endoscope-holder robot for laparoscopic surgery

PURPOSE: We have conducted experiments with an innovatively designed robot endoscope holder for laparoscopic surgery that is small and low cost. MATERIALS AND METHODS: A compact light endoscope robot (LER) that is placed on the patient's skin and can be used with the patient in the lateral or dorsal supine position was tested on cadavers and laboratory pigs in order to allow successive modifications. The current control system is based on voice recognition. The range of vision is 360 degrees with an angle of 160 degrees . Twenty-three procedures were performed. RESULTS: The tests made it possible to advance the prototype on a variety of aspects, including reliability, steadiness, ergonomics, and dimensions. The ease of installation of the robot, which takes only 5 minutes, and the easy handling made it possible for 21 of the 23 procedures to be performed without an assistant. CONCLUSION: The LER is a camera holder guided by the surgeon's voice that can eliminate the need for an assistant during laparoscopic surgery. The ease of installation and manufacture should make it an effective and inexpensive system for use on patients in the lateral and dorsal supine positions. Randomized clinical trials will soon validate a new version of this robot prior to marketing.

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arXiv2007

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.

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arXiv2007

Robot-based tele-echography: clinical evaluation of the TER system in abdominal aortic exploration

OBJECTIVE: The TER system is a robot-based tele-echography system allowing remote ultrasound examination. The specialist moves a mock-up of the ultrasound probe at the master site, and the robot reproduces the movements of the real probe, which sends back ultrasound images and force feedback. This tool could be used to perform ultrasound examinations in small health care centers or from isolated sites. The objective of this study was to prove, under real conditions, the feasibility and reliability of the TER system in detecting abdominal aortic and iliac aneurysms. METHODS: Fifty-eight patients were included in 2 centers in Brest and Grenoble, France. The remote examination was compared with the reference standard, the bedside examination, for aorta and iliac artery diameter measurement, detection and description of aneurysms, detection of atheromatosis, the duration of the examination, and acceptability. RESULTS: All aneurysms (8) were detected by both techniques as intramural thrombosis and extension to the iliac arteries. The interobserver correlation coefficient was 0.982 (P < .0001) for aortic diameters. The rate of concordance between 2 operators in evaluating atheromatosis was 84% +/- 11% (95% confidence interval). CONCLUSIONS: Our study on 58 patients suggests that the TER system could be a reliable, acceptable, and effective robot-based system for performing remote abdominal aortic ultrasound examinations. Research is continuing to improve the equipment for general abdominal use.

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