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International audience; The hyperthyroid disease treatment consists in swallowing iodine 131. The quantity of these radio isotope results in an evaluation of the thyroid volume from a single scintigraphic image. In medical routine, the volume is calculated from a manual selection of an isocontour defining the boundary of the thyroid. We propose in this paper an automatic method to extract this boundary using Cellular Neural Network (CNN). Results show that our method is comparable to manual choice given by four experts. Studied on 35 patients with hyperthyroid diseases, we conclude that CNN is a comprising approach in segmentation of scintigraphic images.

In humans CT imaging is a validated method for the study of adipose tissue distribution and for quantification of visceral and subcutaneous fat. Equivalent methods adapted to murine models of obesity are still lacking. Indeed most attempts to quantify fat tissues in vivo, using dedicated small animal micro-CT, involve long-term X-ray exposure which limits longitudinal studies. We have overcome this limitation by using a human clinical CT which allows very fast 3D imaging and minimal radiation exposure for the study of adipose tissue distribution in mice in vivo. Moreover, we have developed an automatic image analysis method for the segmentation of Hounsfield units of adipose tissues and for the localization of abdominal regions of interest.

International audience; Image registration is a valuable technique for medical diagnosis and treatment. In this paper, we present an enhanced implementation of the popular iterative closest point (ICP) algorithm developed for the registration of 3D free-form closed surfaces. The main step of the ICP consists of finding the closest points between data sets which are then used to estimate the parameters of the global rigid transformation. We propose a new technique based on the use of a look up matrix for finding the best correspondence pairs. The algorithm, called Comprehensive ICP (CICP) algorithm, is then successfully applied for the registration of 3D data of the left ventricle of the heart, acquired using two different medical imaging modalities.

In the framework of domestic waste disposals, the in-situ compaction of soil is usually used to obtain engineered clay barriers with suitable confining properties. Permeability and pollutant retention are the major properties which should be investigated in this context for barrier evaluation. Considering clay barriers in contact with waste leachates, they may be saturated by solutes of various chemical compositions, including in particular toxic heavy metals. In this context, the expansive Fo-Ca clay, a natural Ca-smectite from the Paris basin of Ypersian (Sparnacian) age, was chosen because of its very low permeability and ability for pollutant retention through cationic exchanges. The smectic is associated with kaolinite (up to 20%), and minor quartz, calcite, goethite and gypsum.

National audience

Actuellement, lors du stockage de déchets ménagers et industriels, une barrière argileuse est mise en place en fond et sur les flancs des alvéoles, pour respecter la réglementation en terme de perméabilité et permettre la rétention des polluants. Dans ce domaine, un des enjeux scientifiques est la prédiction du comportement à long terme des argiles gonflantes utilisées comme barrière de confinement. Dans cette optique, des essais de laboratoire reproduisant les conditions hydrauliques in situ d'un site de stockage ont été effectués à l'aide d'une cellule œdométrique munie d'un système d'injection approprié (Jullien et Lecomte, 2000). Les expériences ont été réalisées avec la Fo-Ca, matériau argileux naturel choisi pour ses propriétés de gonflement, sa faible perméabilité et sa capacité d'échanges cationiques. La Fo-Ca, d'âge Yprésien et issue du bassin de Paris, contient plus de 80% de minéraux argileux (dont 80% d'interstratifiés smectite-kaolinite et 20% de kaolinite) et comme phases mineures, du quartz, de la goethite, de la calcite et du gypse. Des travaux antérieurs (Jullien et al., 2002) ont permis de tester les performances de la Fo-Ca soumises à des sollicitations chimio-hydro-mécaniques lors de l'infiltration sous pression de solutions de nitrate de cuivre. Les lixiviats obtenus sont analysés par spectrométrie d'absorption atomique, caractérisant ainsi l'aptitude de rétention du matériau argileux en fonction du temps (figure 1). Ces échantillons d'argile compactés puis infiltrés peuvent ainsi être considérés comme un système soumis à un paramètre externe x(t) et délivrant une réponse y(t).

International audience; In the transgenic research era, the understanding of the functional consequences of the genes deletions or mutations in order to investigate the origin of human transgenic disease, requires the development of non invasive study methods on murine models. Our aim is to develop new Down syndrome models and a 3D reconstruction software using MEMRI at 9.4T. To improve contrast and spatial resolution at high magnetic field, the Mn2+ contrast agent shows powerful paramagnetic properties leading to a significant increase of MRI signal [1]. Mn2+ is a unique marker for neuroarchitecture, neuronal connections and functions therefore particularly interesting for neuropathological studies in vivo. In order to investigate the morphological and structural consequences on the central nervous system development in new mice models of human chromosome 21 aneuploïdies, we used MEMRI and. we also developed a powerful tool in order to perform an automatic segmentation and 3D reconstruction of three brain structures.

International audience; In this paper, a semi automatic active contour method based on Chan-Vese model is proposed for the segmentation of mouse brain MR images. First, a 2 ½ D strategy is applied on the axial images to segment the 3D volume of interest. The method takes into account the special shape of the object to segment. Moreover, the user defines the limits where to search these contours and also provides an initial contour. This semi automatic method makes that human intervention is limited and the tedious manual handling is greatly reduced. Results have shown that the brain volumes estimated by the method are identical to expert manually estimated volumes. Last but not least, the new method was used in the analysis of the cerebral malformations linked to Trisomy 21: no significant difference of the brain volumes between Tri-somy 21 mice and the control ones were found.

International audience; The segmentation of different cerebral structures of mice is becoming more and more important due to the growing interest in finding small animal models of human diseases. In this work, variational atlases are constructed by manual segmentation of various MRI brain images of reference and trisomy 21 mice. These atlases are then registered to assist the segmentation of fine cerebral structures such as the cerebellum and the hippocampus. A modified Chan-Vese segmentation method is used for the detection of these structures. Global as well as local comparison of the reconstructed surfaces and volumes are hence conducted to better understand the gene involved in the morphological malformations associated to trisomy.