PubMed Health⌕ Search

Biomedical subjects

P Cinquin

Publications and source records attributed to P Cinquin.

At least 19 recordsLinked to original sources
PubMed1997

Computer assisted spine surgery.

When inserting screws into a vertebral pedicle, the surgeon usually exposes the back part of the vertebra and uses his or her anatomic knowledge to align the drill in the proper direction. A slight error in direction may result in an important error in the position of the tip of the screw. This is done with no direct visibility of crucial structures (spinal cord, pleura, vessels). Statistical analysis of a series of surgical procedures has shown that 10% to 40% of the screws are not installed correctly. To reduce the risk of complication, a computer assisted method is proposed that enables the surgeon to place a screw at a position preoperatively defined in 3 dimensions using computed tomography images. This allows the surgeon to align a standard surgical drill with the optimal position and direction. The depth of the pilot hole during drilling also is monitored by the system to prevent penetration of the anterior cortex of the vertebral body. Using this procedure, in vitro tests were performed and showed that an accuracy of less than 1 mm can be obtained. Clinical trials were done in 10 patients who suffered severe scoliosis or spondylolisthesis. The trajectory of the holes drilled in L2, L3, L4, and L5 vertebrae were checked for all clinical tests. Postoperative radiographs and computed tomography scans showed that the screws were well inserted in each plane for each pedicle. This technique also can be used to perform osteosynthesis at the thoracic and cervical levels.

Adult↗
PubMed1996

[Medical imaging and computer-assisted interventions].

Computer science can assist the physician or the surgeon in defining an optimal strategy for an intervention, and then in performing it. This implies introducing new sensors, then processing all the data gathered about the patient, and finally operating systems for guidance of the very act of intervention.

Diagnostic Imaging↗
PubMed1996

Computer-assisted mandibular condyle positioning in orthognathic surgery.

PURPOSE: The correct placement of the mandibular condyle in the glenoid fossa during the osteosynthesis after the sagittal ramus osteotomy is often a problem. This article describes a computer-assisted positioning device. METHODS: The procedure is based on the use of a three-dimensional optical localizer to establish the condylar segment position. The operative procedure is only slightly different from the usual. RESULTS: The system is very easy to use, it does not require preoperative data acquisition, and the accuracy obtained is in fractions of a millimeter.

Bone Nails↗
PubMed1996

Three-dimensional fetal cephalometry.

Craniofacial growth has been the subject of numerous studies in which different techniques have been elaborated aiming to model this dynamic phenomenon in a rational manner. One of the methods employed is cephalometric analysis applied to the fetus. Generally, however, these studies are confined to the exploration of a single spatial plane (sagittal plane), whose orientation is never defined in a rigorous and perfectly reproducible manner. Thus, none of these analyses offers a formal growth model. This has led us to propose a new method of fetal cephalometric study taking into account criteria for proper reproducible analysis: spatial exploration of the head performed through three-dimensional tomodensitometric images and precise location of landmarks and reproducibility of the orientation of each image, which is assured by reference to the vestibular orientation (based on the external semicircular canals), as has been described by Girard and Perez and further developed by Fenart. When the labyrinth is developed, this orientation does not change during the growth stages of the head, even with craniofacial deformities. This permits application of this orientation on fetuses and the superposition of images of different subjects. The methodology is presented using two normal human fetuses, and the advantages of this computerized tool are discussed.

Cephalometry↗
PubMed1995

Computer-assisted knee anterior cruciate ligament reconstruction: first clinical tests.

Anterior cruciate ligament reconstruction is a delicate task. The procedure of choice is the patellar tendon bone autograft, but an anisometric position of this tendon often leads to failure. We allows positioning of the central part of the ligament graft at the least anisometric sites. The system uses a workstation and a three-dimensional optical localizer to create images that represent knee kinematics. The surgeon uses these images to guide the surgery. This technique has been validated on eight cadavers and 12 patients.

Anterior Cruciate Ligament↗
PubMed1995

Computer-assisted spine surgery: a technique for accurate transpedicular screw fixation using CT data and a 3-D optical localizer.

The computer-assisted spine surgery system presented in this paper follows the basic ideas which have been developed for computer-assisted medical interventions (CAMI) in our lab since 1985. There are three steps to insert a linear tool inside vertebral pedicles. First, the surgeon defines an optimal trajectory on pre-operative computed tomography. Second, this trajectory is reported in the operating room coordinate system using an intra-operative sensor and a registration algorithm. Third, a guiding system helps the surgeon follow the selected trajectory. In this paper, we present an implementation of this method that uses only a 3-dimensional optical localizer. Results on cadaver specimens and on the first seven patients are presented.

Bone Screws↗
PubMed1995

Patient setup optimization for external conformal radiotherapy.

The aim of conformal radiotherapy is to deliver precisely a specific dose of radiation to a planning target volume, concurrently radiating as little healthy tissue and organs as possible. This can be accomplished only with the accurate positioning of the patient with respect to the radiotherapy system. In this paper, we describe a system to achieve a higher overall accuracy in the delivery of a prostatic radiation boost for treatment of carcinoma of the prostate. The system is based on the use of ultrasound images for measuring the actual position of the patient's prostate just before the radiation. Since these images are registered with pretreatment computed tomography or magnetic resonance imaging, the position and orientation of the planning target volume are computed with respect to the radiotherapy system and can be corrected as needed. This system is under clinical evaluation.

Computer Simulation↗
PubMed1995

Computer-assisted bronchoscopy: aims and research perspectives.

The introduction of spiral computed tomography (CT) of the thoracic cavity has allowed the development of new visualization tools. These tools provide a three-dimensional (3-D) endoluminal reconstruction of the tracheobronchial tree, as it would be viewed through a fibroscopic instrument. However, 3-D reconstruction techniques cannot replace conventional fibroscopy, which remains indispensable for obtaining histological samples. Furthermore, when CT-detected mediastinal or parenchymal lesions are not seen during fiberoptic bronchoscopy, guiding transbronchial needle biopsy is a major challenge. Computer-guided transbronchial biopsy involves the fusion of image data from both CT slices and bronchoscopic video sequences. This fusion is described in this paper in two parts. First, we present a segmentation process, using mathematical morphology operators, in order to analyze the video sequence and localize the bronchoscopic camera within the tracheobronchial tree. Second, we present tools used to match this localization knowledge with CT data. Finally, we produce images that create a bronchoscopic augmented reality, using elements extracted from the CT examination.

Biopsy, Needle↗
PubMed1995

Mathematical determination of the tibial insertion of the patellar tendon using computed tomography images.

Misalignment of the extensor apparatus is an essential factor in impairment of the patellar-femoral joint. This may be partly or entirely responsible for patellar dislocation or lateral patellar-femoral arthrosis. One surgical method to correct the pathology is medial transposition of the patellar ligament on the tibial tuberosity (anteriorly or posteriorly, distally or ventrally). These interventions correct misalignment of the extensor apparatus relative to statistical norms. We propose a mathematical method based on the use of computed tomography (CT) images to determine the ideal tibial insertion for the patellar tendon. This method is based on biomechanical modeling and the use of equipressure criteria. It is the first step in allowing the use of mathematics to model correctly tibial insertion of the patellar ligament, an entirely new development. This is important because it will allow surgeons greater accuracy in distal correction of extensor apparatus misalignments.

Biomechanical Phenomena↗
PubMed1995

Building a hybrid patient's model for augmented reality in surgery: a registration problem.

In the field of Augmented Reality in Surgery, building a hybrid patient's model, i.e. merging all the data and systems available for a given application, is a difficult but crucial technical problem. The purpose is to merge all the data that constitute the patient model with the reality of the surgery, i.e. the surgical tools and feedback devices. In this paper, we first develop this concept, we show that this construction comes to a problem of registration between various sensor data, and we detail a general framework of registration. The state of the art in this domain is presented. Finally, we show results that we have obtained using a method which is based on the use of anatomical reference surfaces. We show that in many clinical cases, registration is only possible through the use of internal patient structures.

Algorithms↗
PubMed1995

Computer generated visual assistance during retroperitoneoscopy.

In this paper we present a system of computer assisted surgery, the function of which is to enhance the real time feedback between the patient's body, the surgical tools and the surgeon. We show using such a system during some surgical operations--in our case, retroperitoneoscopy. After giving the requirements for such a system, we describe the components currently used in our experiments. We detail the different problems and our current solutions; photographs of an experiment carried out on a cadaver and of classical operations are shown in this paper.

Computer Simulation↗
PubMed1995

Interpretation of multimodal medical images using connectionist and variational methods.

Our medical objective is to match multimodal 3D medical images into a coherent model of the patient, from which diagnosis can be assessed and therapeutics guided. 3D image segmentation is absolutely necessary to reach this objective. We investigate two complementary approaches for segmenting 3D medical images. First we present some definitions, basic properties and recent theoretical results about formal neural networks, and show that these results can be applied to brain tumour segmentation. A variational approach (called the 'snake spline' method) is then detailed. We finally show how segmented 3D images can be used for multimodal image matching.

Algorithms↗
PubMed1995

[Image information systems].

The notion of image information system (IIS) is introducted, based on an on-going experience in Grenoble's university hospital. The objectives and of a IIS are clarified, and the basic principles of its architecture are presented.

Computer Communication Networks↗
PubMed1995

[Place of computer-assisted surgery in the evaluation of lymphatics metastases in pelvic cancers. Exploration by retroperitoneoscopy].

Extraperitoneal pelvioscopy is a surgical endoscopy without insufflation which enables exploration of the extraperitoneal space in order to obtain biopsy specimens of adenopathies and tumors. 189 extraperitoneal endoscopy have been performed since 1976. When made through an iliac approach, the Extraperitoneal Endoscopy explores iliac and pelvic lymph nodes. It is an indication when checking the extension of uterine, prostatic and bladder cancers. Recently, a system of computerized assistance has been added to the initial method. Its aim is to guide the movements of the surgical tool when the indication is difficult: overweight patient, small tumors, risky tumoral environment. The basic principle is to show recalculated RMI or CT scan sections of the patient during the intervention, on which appear in real time the positions of the endoscope and that of the target to biopsy. The authors describe the technical ways of the method, the system of tridimensional localisation included in the operating room and the sort of interface given to the surgeon. In the future, the realisation of a simulator of intervention will allow diffusion and teaching of this intervention.

Equipment Design↗