3D reconstruction of blood vessels by data fusion from angiographic and echographic images

Three-dimensional reconstruction of vascular lesions is of great medical interest for diagnosis and prognosis of the atheromateous disease, as well as for a better understanding of restenosis phenomena related to the revascularisation techniques. In order to provide a quantitative description of the geometry of complex atheromateous lesions, we propose an original approach for 3D vessel surface reconstruction, which relies on fusion of data obtained with both digital angiography and intravascular echography. This method is based on a first step consisting of a geometrical modelization of acquisitions and data, which yields a first rough reconstruction by geometrical fusion of the parameters extracted from the vessel contours obtained from both modalities which provides, by interpolation of echographic contours, the 3D surface of the vessel lumen . The next step consists in taking into account the imprecision on the parameters estimated during the first step. For this task, we propose an original method based on a modelization of parameters as fuzzy numbers which allows to introduce, through fuzzy mathematical morphology, the imprecision on the acquisitions and on the 3D data. This provides a 3D reconstruction which takes into account all data about the problem . The first results prove clearly the feasibility of the method and the interest of using information issued from different modalities for improving the 3D reconstruction of blood vessels, without any a priori mathematical model of vessel morphology. The explicite introduction of imprecisions in the fusion process allows to eliminate ambiguities and contradictions we would obtain in a simple reconstruction from only one modality, and leads to a decision about the true morphology of vessels.La reconstruction tridimensionnelle des lésions vasculaires présente un intérêt médical majeur pour le suivi diagnostique et pronostique de la maladie athéromateuse, ainsi que pour une meilleure compréhension des phénomènes de resténose associés aux techniques interventionnelles de revascularisation. Afin de fournir une meilleure description morphologique et quantitative des lésions athéromateuses complexes, nous proposons une approche originale de reconstruction 3D de la surface des vaisseaux, par la fusion de données issues d'angiographies numérisées et d'échographies endovasculaires. Cette méthode repose sur une première étape de modélisation géométrique des acquisitions et des données, qui débouche sur une première reconstruction par fusion géométrique des paramètres extraits des deux modalités et interpolation des contours échographiques. L'étape suivante consiste à prendre en compte l'imprécision sur les paramètres estimés lors de la première étape. Pour cela, nous proposons une méthode originale reposant sur la modélisation des paramètres sous forme de nombres flous et sur la morphologie mathématique floue, fournissant une reconstruction 3D prenant en compte toutes les données du problème. Les premiers résultats obtenus démontrent clairement la faisabilité de la méthode et l'intérêt d'exploiter les informations issues de différentes modalités pour améliorer la reconstruction 3D des vaisseaux sanguins, sans modèle mathématique a priori de la forme des vaisseaux. L'introduction explicite des imprécisions dans le processus de fusion permet d'éliminer les ambiguités et les contradictions qu'on aurait dans une reconstruction simple à partir d'une seule modalité et conduit à une décision sur la morphologie réelle des vaisseau

Methodology for Jointly Assessing Myocardial Infarct Extent and Regional Contraction in 3-D CMRI

Automated extraction of quantitative parameters from Cardiac Magnetic Resonance Images (CMRI) is crucial for the management of patients with myocardial infarct. This work proposes a post-processing procedure to jointly analyze Cine and Delayed-Enhanced (DE) acquisitions in order to provide an automatic quantification of myocardial contraction and enhancement parameters and a study of their relationship. For that purpose, the following processes are performed: 1) DE/Cine temporal synchronization and 3D scan alignment, 2) 3D DE/Cine rigid registration in a region about the heart, 3) segmentation of the myocardium on Cine MRI and superimposition of the epicardial and endocardial contours on the DE images, 4) quantification of the Myocardial Infarct Extent (MIE), 5) study of the regional contractile function using a new index, the Amplitude to Time Ratio (ATR). The whole procedure was applied to 10 patients with clinically proven myocardial infarction. The comparison between the MIE and the visually assessed regional function scores demonstrated that the MIE is highly related to the severity of the wall motion abnormality. In addition, it was shown that the newly developed regional myocardial contraction parameter (ATR) decreases significantly in delayed enhanced regions. This largely automated approach enables a combined study of regional MIE and left ventricular function

Optimizing multicompression approaches to elasticity imaging

Breast lesion visibility in static strain imaging ultimately is noise limited. When correlation and related techniques are applied to estimate local displacements between two echo frames recorded before and after a small deformation, target contrast increases linearly with the amount of deformation applied. However, above some deformation threshold, decorrelation noise increases more than contrast such that lesion visibility is severely reduced. Multicompression methods avoid this problem by accumulating displacements from many small deformations to provide the same net increase in lesion contrast as one large deformation but with minimal decorrelation noise. Unfortunately, multicompression approaches accumulate echo noise (electronic and sampling) with each deformation step as contrast builds so that lesion visibility can be reduced again if the applied deformation increment is too small. This paper uses signal models and analysis techniques to develop multicompression strategies that minimize strain image noise. The analysis predicts that displacement variance is minimal in elastically homogeneous media when the applied strain increment is 0.0035. Predictions are verified experimentally with gelatin phantoms. For in vivo breast imaging, a strain increment as low as 0.0015 is recommended for minimum noise because of the greater elastic heterogeneity of breast tissue

Impact of Recirculation in Dynamic Contrast-Enhanced Ultrasound: A Simulation Study

International audienc

Élastographie par ondes de cisaillement et nodules thyroïdiens à cytologie indéterminée : résultats d’une étude prospective bicentrique

International audienc