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Modèles déformables surfaciques, implicites et volumiques, pour l'imagerie médicale

Eric Bittar 1
1 TIMC-GMCAO - Gestes Medico-chirurgicaux Assistés par Ordinateur
TIMC - Techniques de l'Ingénierie Médicale et de la Complexité - Informatique, Mathématiques et Applications, Grenoble - UMR 5525
Abstract : The improvement of the medical images quality allows the obtention of volumetric images, which contain a great deal of information. An efficient approach to treat these images consists in using the a priori knowledge of the shape of the objects to be analysed, and to employ intrinsically 3D methods. Deformable models meet both criterions. We propose to formalise the deformable models and their evolution in a data image by distinguishing five components : binding characteristics, geometrical representation, deformation, deformability, and control. We describe three deformable models. We employ the delta-snakes surface model to reconstruct objets from unstructured points of their surface. We approximate this surface with an octree-spline distance map. We developed interactive tools to complete missing data or directly deform the surface. Then we propose for the same kind of application an implicit model based on primitives generating a local potential field. The primitives are interactively placed, or automatically selected in the discrete medial axis of the data. The optimisation of the parameters of the primitives leads to a compact representation of the objects. With these two models, we reconstruct objects digitized by range finders or segmented in volumetric images. Our last model is volumetric. Its hierarchical deformation via an octree-spline minimizes a generalized distance between its characteristics and the ones of the data. It is realized under the control of the Levenberg-Marquardt algorithm, within the limits placed by a regularisation function. We developed an iterated generalised distance calculation algorithm in a kd-tree. We apply this model to volumetric images segmentation. Other kind of application have also been conducted.
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Submitted on : Thursday, February 19, 2004 - 10:50:11 AM
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Eric Bittar. Modèles déformables surfaciques, implicites et volumiques, pour l'imagerie médicale. Autre [cs.OH]. Université Joseph-Fourier - Grenoble I, 1998. Français. ⟨tel-00004869⟩

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