[Show abstract][Hide abstract] ABSTRACT: Arthroplasty, the implantation of prostheses into joints, is a surgical procedure that is affecting a larger and larger number of patients over time. As a result, it is increasingly important to develop imaging techniques to noninvasively examine joints with prostheses after surgery, both statically and dynamically in 3-D. The static problem is considered here, with the aim to create a 3-D shape model of the bone as well as the prosthesis using a set of 2-D X-rays from various viewpoints. The most important challenge to be addressed is the lack of texture, the most common feature to recover shape from multiple views. In order to overcome this limitation, we reformulate the problem using a novel multiview segmentation approach where an active contours 3-D surface evolution with level-set implementation is used to recover the shape of bones and prostheses in postoperative joints. The recovered shape may then be used to track 3-D motions in dynamic X-ray sequences to obtain kinematic information.
IEEE Transactions on Medical Imaging 04/2009; · 4.03 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper we propose a novel method to recover the 3D shape of the knee and of the prosthesis for the patients that have undergone total knee replacement surgery. We address this using a set of 2D X-Ray images of the knee taken from different viewpoints around it. The problem is then casted to a multiview stereo reconstruction problem and we consider an energy-minimization approach to recover the bone structure. This function is designed to recover a 3D surface which minimizes image and shape-based terms. The cost related to data is defined through the projections of the 3D surface onto 2D image planes while the prior-knowledge is introduced using a 3D model of the knee. The use of Markov Random Fileds as well as recent advances in discrete optimization and in particular the state-of-the-art Fast PD optimization algorithm is considered towards optimal reconstruction. Promising results demonstrate the potentials of our method.
Biomedical Imaging: From Nano to Macro, 2008. ISBI 2008. 5th IEEE International Symposium on; 06/2008
[Show abstract][Hide abstract] ABSTRACT: In total knee replacement surgery, also known as total knee arthroplasty, prosthetics are implanted in the knee joint as treatment for progressive diseases such as arthritis or trauma. In this paper, we aim to recover the 3-D shape of bones and prosthetic devices in patients who have undergone total knee replacement. Such an objective is addressed using a collection of 2-D X-rays acquired from multiple viewpoints. Then, both bone and prosthetic shape recovery are formulated as a multi-view reconstruction process through the minimization of an objective function. The objective function is designed to recover 3-D surfaces, which once projected to 2-D images, minimize edge-based and region-based criteria. The calculus of variations and gradient descent are used to obtain a surface with minimum cost through a 3-D level set implementation. Promising results are given for real X-ray data.
Biomedical Imaging: From Nano to Macro, 2007. ISBI 2007. 4th IEEE International Symposium on; 05/2007
[Show abstract][Hide abstract] ABSTRACT: L’IRM est désormais une technique alternative aux autres outils d’imagerie corps entier — incluant scintigraphies, TEP-TDM
et TDM. Alternative d’abord par la possibilité désormais offerte de couvrir l’ensemble du corps humain en IRM avec des temps
d’imagerie limités; alternative aussi et surtout car des outils d’imagerie fonctionnelle — incluant imagerie de diffusion
et de perfusion — peuvent naturellement se combiner à cette large couverture anatomique, alternative enfin de par l’absence
d’irradiation induite par I’IRM comparativement aux autres techniques citées plus haut. Nous détaillerons ici les progrès
de l’instrumentation IRM qui ont rendu possible cette émergence, avant de citer les premières applications cliniques de ce
MRI now offers an alternative imaging technique that combines functional tools with expanded anatomical coverage. Technical
progress in magnetic resonance has reduced acquisition times, allowed perfusion and diffusion imaging to be combined with
whole body scanning, and made it possible to perform whole body scanning without irradiation. Here we detail the technical
advances in whole body MRI and the emerging clinical applications resulting from this new imaging tool.
[Show abstract][Hide abstract] ABSTRACT: Aneurysmal bone cysts (ABC) are expansile osteolytic lesions with thin wall fluid-filled cystic cavities. We report the MR demonstration of delayed enhancement within fluid-filled ABC cavities following the IV injection of Gd-chelates, which has never been previously reported, and discuss the mechanisms which could account for such a phenomenon.