Coronary vein tracking from MSCT using a minimum cost path approach

International audienceIn this paper, we deal with the problem of tracking the coronary venous tree from Multi-Slice Computed Tomography (MSCT) angiography. Contrast inhomogeneities are a major issue. The proposed tracking procedure is based on minimum-cost path computation and makes use of `Fast-Marching' technique. The algorithm aims at propagating a front inside a vascular structure and extracting a centered path. To achieve this goal, a specific cost function which combines the vessel local orientation to a vesselness measure is designed. Experiments on synthetic data and real data have been performed. Coronary veins with contrast difficulties are extracted with a low computing time

Computer Vision Techniques for Transcatheter Intervention

Minimally invasive transcatheter technologies have demonstrated substantial promise for the diagnosis and treatment of cardiovascular diseases. For example, TAVI is an alternative to AVR for the treatment of severe aortic stenosis and TAFA is widely used for the treatment and cure of atrial fibrillation. In addition, catheter-based IVUS and OCT imaging of coronary arteries provides important information about the coronary lumen, wall and plaque characteristics. Qualitative and quantitative analysis of these cross-sectional image data will be beneficial for the evaluation and treatment of coronary artery diseases such as atherosclerosis. In all the phases (preoperative, intraoperative, and postoperative) during the transcatheter intervention procedure, computer vision techniques (e.g., image segmentation, motion tracking) have been largely applied in the field to accomplish tasks like annulus measurement, valve selection, catheter placement control, and vessel centerline extraction. This provides beneficial guidance for the clinicians in surgical planning, disease diagnosis, and treatment assessment. In this paper, we present a systematical review on these state-of-the-art methods.We aim to give a comprehensive overview for researchers in the area of computer vision on the subject of transcatheter intervention. Research in medical computing is multi-disciplinary due to its nature, and hence it is important to understand the application domain, clinical background, and imaging modality so that methods and quantitative measurements derived from analyzing the imaging data are appropriate and meaningful. We thus provide an overview on background information of transcatheter intervention procedures, as well as a review of the computer vision techniques and methodologies applied in this area

Coronary Artery Segmentation and Motion Modelling

Conventional coronary artery bypass surgery requires invasive sternotomy and the use of a cardiopulmonary bypass, which leads to long recovery period and has high infectious potential. Totally endoscopic coronary artery bypass (TECAB) surgery based on image guided robotic surgical approaches have been developed to allow the clinicians to conduct the bypass surgery off-pump with only three pin holes incisions in the chest cavity, through which two robotic arms and one stereo endoscopic camera are inserted. However, the restricted field of view of the stereo endoscopic images leads to possible vessel misidentification and coronary artery mis-localization. This results in 20-30% conversion rates from TECAB surgery to the conventional approach. We have constructed patient-specific 3D + time coronary artery and left ventricle motion models from preoperative 4D Computed Tomography Angiography (CTA) scans. Through temporally and spatially aligning this model with the intraoperative endoscopic views of the patient's beating heart, this work assists the surgeon to identify and locate the correct coronaries during the TECAB precedures. Thus this work has the prospect of reducing the conversion rate from TECAB to conventional coronary bypass procedures. This thesis mainly focus on designing segmentation and motion tracking methods of the coronary arteries in order to build pre-operative patient-specific motion models. Various vessel centreline extraction and lumen segmentation algorithms are presented, including intensity based approaches, geometric model matching method and morphology-based method. A probabilistic atlas of the coronary arteries is formed from a group of subjects to facilitate the vascular segmentation and registration procedures. Non-rigid registration framework based on a free-form deformation model and multi-level multi-channel large deformation diffeomorphic metric mapping are proposed to track the coronary motion. The methods are applied to 4D CTA images acquired from various groups of patients and quantitatively evaluated

Traitement et exploration d'images TDM pour l'évaluation des bioprothèses valvulaires aortiques

Le but de cette étude est d évaluer la faisabilité de l analyse tomodensitométrique 3D des bioprothèses aortiques pour faciliter leur évaluation morphologique durant le suivi et d aider la sélection de cas et améliorer la planification d une procédure valvein-valve. Le challenge était représenté par le rehaussement des feuillets valvulaires, en raison d images très bruitées. Un angio-scanner synchronisé était réalisé chez des patients porteurs d une bioprotèses aortique dégénérée avant réintervention (images in-vivo). Différentes méthodes pour la réduction du bruit étaient proposées. La reconstruction tridimensionnelle des bioprothèses était réalisée en utilisant des méthodes de segmentation de régions par "sticks". Après réopération ces méthodes étaient appliquées aux images scanner des bioprothèses explantées (images ex-vivo) et utilisées comme référence. La réduction du bruit obtenue par le filtre stick modifié montrait meilleurs résultats en rapport signal/bruit en comparaison aux filtres de diffusion anisotropique. Toutes les méthodes de segmentation ont permis une reconstruction 3D des feuillets. L analyse qualitative a montré une bonne concordance entre les images obtenues in-vivo et les altérations des bioprothèses. Les résultats des différentes méthodes étaient comparés par critères volumétriques et discutés. Les bases d'une première approche de visualisation spatio-temporelle d'images TDM 3D+T de la prothèse valvulaire ont été proposés. Elle implique des techniques de rendu volumique et de compensation de mouvement. Son application à la valve native a aussi été envisagée. Les images scanner des bioprothèses aortiques nécessitent un traitement de débruitage et de réduction des artéfacts de façon à permettre le rehaussement des feuillets prothétiques. Les méthodes basées sticks semblent constituer une approche pertinente pour caractériser morphologiquement la dégénérescence des bioprothèses.The aim of the study was to assess the feasibility of CT based 3D analysis of degenerated aortic bioprostheses to make easier their morphological assessment. This could be helpful during regular follow-up and for case selection, improved planning and mapping of valve-in-valve procedure. The challenge was represented by leaflets enhancement because of highly noised CT images. Contrast-enhanced ECG-gated CT scan was performed in patients with degenerated aortic bioprostheses before reoperation (in-vivo images). Different methods for noise reduction were tested and proposed. 3D reconstruction of bioprostheses components was achieved using stick based region segmentation methods. After reoperation, segmentation methods were applied to CT images of the explanted prostheses (exvivo images). Noise reduction obtained by improved stick filter showed best results in terms of signal to noise ratio comparing to anisotropic diffusion filters. All segmentation methods applied to the best phase of in-vivo images allowed 3D bioprosthetic leaflets reconstruction. Explanted bioprostheses CT images were also processed and used as reference. Qualitative analysis revealed a good concordance between the in-vivo images and the bioprostheses alterations. Results from different methods were compared by means of volumetric criteria and discussed. A first approach for spatiotemporal visualization of 3D+T images of valve bioprosthesis has been proposed. Volume rendering and motion compensation techniques were applied to visualize different phases of CT data. Native valve was also considered. ECG-gated CT images of aortic bioprostheses need a preprocessing to reduce noise and artifacts in order to enhance prosthetic leaflets. Stick based methods seems to provide an interesting approach for the morphological characterization of degenerated bioprostheses.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

Traitement et exploration d'images TDM pour l'évaluation des bioprothèses valvulaires aortiques

Le but de cette étude est d évaluer la faisabilité de l analyse tomodensitométrique 3D des bioprothèses aortiques pour faciliter leur évaluation morphologique durant le suivi et d aider la sélection de cas et améliorer la planification d une procédure valvein-valve. Le challenge était représenté par le rehaussement des feuillets valvulaires, en raison d images très bruitées. Un angio-scanner synchronisé était réalisé chez des patients porteurs d une bioprotèses aortique dégénérée avant réintervention (images in-vivo). Différentes méthodes pour la réduction du bruit étaient proposées. La reconstruction tridimensionnelle des bioprothèses était réalisée en utilisant des méthodes de segmentation de régions par "sticks". Après réopération ces méthodes étaient appliquées aux images scanner des bioprothèses explantées (images ex-vivo) et utilisées comme référence. La réduction du bruit obtenue par le filtre stick modifié montrait meilleurs résultats en rapport signal/bruit en comparaison aux filtres de diffusion anisotropique. Toutes les méthodes de segmentation ont permis une reconstruction 3D des feuillets. L analyse qualitative a montré une bonne concordance entre les images obtenues in-vivo et les altérations des bioprothèses. Les résultats des différentes méthodes étaient comparés par critères volumétriques et discutés. Les bases d'une première approche de visualisation spatio-temporelle d'images TDM 3D+T de la prothèse valvulaire ont été proposés. Elle implique des techniques de rendu volumique et de compensation de mouvement. Son application à la valve native a aussi été envisagée. Les images scanner des bioprothèses aortiques nécessitent un traitement de débruitage et de réduction des artéfacts de façon à permettre le rehaussement des feuillets prothétiques. Les méthodes basées sticks semblent constituer une approche pertinente pour caractériser morphologiquement la dégénérescence des bioprothèses.The aim of the study was to assess the feasibility of CT based 3D analysis of degenerated aortic bioprostheses to make easier their morphological assessment. This could be helpful during regular follow-up and for case selection, improved planning and mapping of valve-in-valve procedure. The challenge was represented by leaflets enhancement because of highly noised CT images. Contrast-enhanced ECG-gated CT scan was performed in patients with degenerated aortic bioprostheses before reoperation (in-vivo images). Different methods for noise reduction were tested and proposed. 3D reconstruction of bioprostheses components was achieved using stick based region segmentation methods. After reoperation, segmentation methods were applied to CT images of the explanted prostheses (exvivo images). Noise reduction obtained by improved stick filter showed best results in terms of signal to noise ratio comparing to anisotropic diffusion filters. All segmentation methods applied to the best phase of in-vivo images allowed 3D bioprosthetic leaflets reconstruction. Explanted bioprostheses CT images were also processed and used as reference. Qualitative analysis revealed a good concordance between the in-vivo images and the bioprostheses alterations. Results from different methods were compared by means of volumetric criteria and discussed. A first approach for spatiotemporal visualization of 3D+T images of valve bioprosthesis has been proposed. Volume rendering and motion compensation techniques were applied to visualize different phases of CT data. Native valve was also considered. ECG-gated CT images of aortic bioprostheses need a preprocessing to reduce noise and artifacts in order to enhance prosthetic leaflets. Stick based methods seems to provide an interesting approach for the morphological characterization of degenerated bioprostheses.RENNES1-Bibl. électronique (352382106) / SudocSudocFranceF

CT Scanning

Since its introduction in 1972, X-ray computed tomography (CT) has evolved into an essential diagnostic imaging tool for a continually increasing variety of clinical applications. The goal of this book was not simply to summarize currently available CT imaging techniques but also to provide clinical perspectives, advances in hybrid technologies, new applications other than medicine and an outlook on future developments. Major experts in this growing field contributed to this book, which is geared to radiologists, orthopedic surgeons, engineers, and clinical and basic researchers. We believe that CT scanning is an effective and essential tools in treatment planning, basic understanding of physiology, and and tackling the ever-increasing challenge of diagnosis in our society

Recalage préservant la topologie des vaisseaux: application à la cardiologie interventionnelle

In percutaneous coronary interventions, integrating into the live fluoroscopic image vessel calcifications and occlusion information that are revealed in the pre-operative Computed Tomography Angiography can greatly improve guidance of the clinician. Fusing pre- and intra-operative information into a single space aims at taking advantage of two complementary modalities and requires a step of registration that must provide good alignment and relevant correspondences between them. Most of the existing 3D/2D vessel registration algorithms do not take into account the particular topology of the vasculature to be matched, resulting into pairings that may be topologically inconsistent along the vasculature.A first contribution consisted in a registration framework dedicated to curve matching, denoted the Iterative Closest Curve (ICC). Its main feature is to preserve the topological consistency along curves by taking advantage of the Frechet distance that not only computes the distance between two curves but also builds ordered pairings along them. A second contribution is a pairing procedure designed for the matching of a vascular tree structure that endorses its particular topology and that can easily take advantage of the ICC-framework. Centerlines of the 3D tree are matched to curves extracted from the 2D vascular graph while preserving the connectivity at 3D bifurcations. The matching criterion used to build the pairings takes into account the geometric distance and the resemblance between curves both based on a global formulation using the Frechet distance.To evaluate our approach we run experiments on a database composed of 63 clinical cases, measuring accuracy on real conditions and robustness with respect to a simulated displacement. Quantitative results have been obtained using two complementary measures that aim at assessing the results both geometrically and topologically, and quantify the resulting alignment error as well as the pairing error. The proposed method exhibits good results both in terms of pairing and alignment and demonstrates to be low sensitive to the rotations to be compensated (up to 30 degrees).Cette thèse s’inscrit dans le cadre de la cardiologie interventionnelle. Intégrer des informations telles que la position des calcifications ainsi que la taille et forme d’une occlusion dans les images fluoroscopiques constituerait un bénéfice pour le praticien. Ces informations, invisibles dans les images rayons-X pendant la procédure, sont présentes au sein du scanner CT préopératoire. La fusion de cette modalité avec la fluoroscopie apporterait une aide précieuse au guidage temps réel des outils interventionnels en bénéficiant des informations fournies par le CT. Cette fusion requiert une étape de recalage qui vise à aligner au mieux les deux modalités et fournir des correspondances pertinentes entre elles. La plupart des algorithmes de recalage 3D/2D de vaisseaux rencontrent des difficultés à construire des appariements anatomiquement pertinents, essentiellement à cause du manque de cohérence topologique le long du réseau vasculaire.Afin de résoudre ce problème, nous proposons dans cette thèse un cadre générique pour le recalage de structures curvilinéaires. L’algorithme qui en découle préserve la structure des courbes appariées. Les artères coronaires pouvant être représentées par un ensemble de courbes arrangées en arbre, nous proposons aussi une procédure d’appariement qui respecte cette structure. Le recalage d’un arbre 3D sur un graphe 2D est ainsi réalisé en assurant la préservation des connectivités aux bifurcations. Le choix de l’appariement est basé sur un critère prenant en compte la distance géométrique ainsi que la ressemblance entre courbes. Ce critère est évalué grâce à une forme modifiée de la distance de Fréchet.Une base de données de 63 cas cliniques a été utilisée à travers différentes expériences afin de prouver la robustesse et la précision de notre approche. Nous avons proposé deux mesures complémentaires visant à quantifier la qualité de l’alignement d’une part et des appariements engendrés d’autre part. La méthode proposée se montre précise pour les alignements de la projection du modèle CT et des artères coronaires observées dans les images angiographiques. De plus, les appariements obtenus sont anatomiquement pertinents et lálgorithme a prouvé sa robustesse face aux perturbations de la position initiale. Nous attribuons cette robustesse à la qualité des appariements construits au fur et à mesure des itérations