Etude morphologique et métrologique des sinus de Valsalva par traitement d'images tomographiques

L'objectif de cette thèse est l'élaboration et l'application de traitements d'images pour permettre une étude objective et fiable des sinus de Valsalva, importantes cavités de la base de l'aorte. Les méthodes proposées s'appliquent aux séquences ciné-IRM et aux examens de scanner sans qu'il n'y ait à modifier le paramétrage entre deux examens. Pour cela, nous avons d'abord étudié la morphologie de cette zone anatomique puis détaillé les différentes propriétés communes à toutes les images de sinus. Ceux-ci font en l'occurrence partie des principaux organes clairs et peu mobiles. Nous avons donc développé un algorithme qui détecte ces éléments et caractérise chacun d'entre eux par une trajectoire unique. Divers outils de morphologie mathématique ont été utilisés à cette occasion, tout comme pour l'extraction du contour des sinus dans chaque image. L'étape de segmentation repose elle sur la reconstruction géodésique, qui s'avère plus efficace et surtout plus robuste que l'usage de contours actifs usuels. L'intérieur des sinus forme un domaine simplement connexe et étoilé. Grâce à ce postulat, nous avons conçu une nouvelle reconstruction, nommée transformée en aurore, qui limite la propagation des intensités aux supports radiaux et présente les résultats dans un repère polaire pour une meilleure lecture des contours.Les points caractéristiques des sinus ont également été détectés, par étude de rayons et détermination de points dominants. Ces points fournissent les éléments nécessaires à une mesure automatique des sinus, mesure cohérente avec les mesures actuellement réalisées manuellement et les variations intra et inter-observateurs de celles-ci. D'autres outils sont enfin esquissés pour modéliser le contour par coniques, classer les images d'examens cinétiques en fonction du moment du cycle et suivre le mouvement des valves dans ces mêmes examens.L'ensemble de ces travaux ont amené à la réalisation d'un logiciel d'aide au diagnostic qui intègre nos méthodes et dont l'interface est également présentée dans le présent mémoire.This Phd thesis deals with the design and the use of image processing tools in order to allow a reliable and objective study of the sinuses of Valsalva which are important cavities of the aortic root. The proposed methods can be applied on cine-MR sequences and CT examinations without any change in the settings between two examinations.Firstly, we studied the morphology of this anatomical area and its constant properties in all images of the dataset. Sinuses are one of the main bright organs with limited movements. Hence a new algorithm has been designed. It detects and characterizes each bright organ by a single trajectory. Various tools of mathematical morphology are used for this step, as for the extraction of the contour of the sinuses in each image.The segmentation step is based on the geodesic reconstruction, which is more effective and more robust than the usual active contours. The shape depicting the sinuses is simply connected and a star domain. With this assumption, a new reconstruction is proposed, called the Aurora transform. This transform limits the spread of intensities only on the radial lines and shows its results in a polar space for a better reading of edges.The relevant points of the sinuses are also detected by a study of radii and the determination of dominant points along edges. An automatic measurement of the sinuses is deduced from these points. The values are very close to the manual measures currently done according to the intra-and inter-observer variations.Some other tools are finally outlined. They includes the modeling of edges by conics, the image classification depending on the time of the cycle in sequences and the tracking of the aortic valves in these examinations.This work led to the devlopement of a diagnostic aid software based on our methods. Its interface is also presented herein.DIJON-BU Doc.électronique (212319901) / SudocSudocFranceF

Quelques aspects de la nucléation des bulles de Champagne dans une flûte et de leur ascension à petits nombres de Reynolds

Ce travail de trois ans s'est focalisé sur la genèse et les premiers instants des bulles de Champagne en conditions de consommation, c'est-à-dire dans une flûte. Cette thèse suit chronologiquement la naissance de la bulle. Après un court chapitre (chapitre 2) consacré au matériel et aux méthodes utilisés, la naissance des bulles est présentée en détail (chapitre 3). Ce chapitre amène sous les projecteurs de petits objets solides, les fibres, dans lesquels la formation de la bulle a lieu. L'étude de cette formation dans certains cas simples fait l'objet du chapitre 4 et montre l'importance de la connaissance de la forme des fibres, qui est donc étudiée au chapitre 5. Lorsque la bulle est mûre pour sortir de sa fibre, elle éclot et se libère soudainement. Cette éjection de la bulle est décrite en détail au chapitre 6. Enfin, après sa libération, la bulle commence son ascension vers la surface du verre. Il apparaît que les tout débuts de cette ascension sont marqués par la proximité d'un environnement perturbant jusqu'ici ignoré. Le chapitre 7 est donc dédié aux deux premiers millimètres de la vie de la bulle sevrée. Le dernier chapitre (chapitre 8) dresse un bilan du travail effectué et des perspectives ouvertes.This three years work was focused on the genesis and the first moments of Champagne bubbles in conditions of consumption, i.e. in a flute. This thesis follows the birth of the bubble chronologically. After a short chapter (chapter 2) devoted to the material and the methods used, the birth of the bubbles is presented in detail (chapter 3). This chapter brings under light small solid objects, the fibers, in which the formation of the bubble takes place. The study of this formation in some simple cases is covered in chapter 4 and shows the importance of the knowledge of the shape of the fibers, which is thus studied in chapter 5. When the bubble is ready to leave its fiber, it is released suddenly. This ejection of the bubble is described in detail in chapter 6. Lastly, after its release, the bubble begins its rise towards the surface of glass. It appears that the early stages of this rise are marked by the proximity of a disturbing environment up to now ignored. Chapter 7 is hence dedicated to the first two millimetres of the life of the separated bubble. The final chapter (chapter 8) draws up an assessment of carried out work and open prospects.REIMS-BU Sciences (514542101) / SudocSudocFranceF

Segmentation et métrologie des sinus de Valsalva à partir de ciné-IRM

Automatic segmentation of Valsalva sinuses from cine-MR

Extraction et analyse automatiques des sinus de Valsalva à partir de séquences IRM

National audienceMRI appears to be particularly attractive for the study of the Sinuses of Valsalva (SV), however there is no global consensus on their suitable measurements. In this paper, we propose a new method to automatically evaluate the SV from cine-MRI in a cross-sectional orientation. It consists in the extraction of the shape, the detection of relevant points (commissures, cusps and the centre of the SV), the measure of associated distances and in a classification of the SV as bicuspid or tricuspid. Our method was tested on 23 patient examinations and radii calculations were compared with manual processing. The classification of the valve as tricuspid or bicuspid was correct for all the cases. Moreover there are excellent correlation and concordance between manual and automatic measurements for images at diastole and at systole phases on the patient data set.Bien que l'imagerie IRM soit une technique particulièrement prometteuse pour l'étude des sinus de Valsalva (SV), il n'existe pas aujourd'hui de consensus pour leur mesure. Dans cet article, nous proposons une nouvelle méthode d'évaluation automatique des SV à partir de séquences IRM selon une orientation transversale au niveau de la racine aortique. Tout d'abord les formes des sinus sont extraites, les points caractéristiques (commissures, cuspides et centre des SV) sont détectés, puis les distances associées sont mesurées et les SV sont classés selon leur morphologie comme bicuspide ou tricuspide. La méthode a été testée sur 23 examens et les distances obtenues ont été comparées avec des mesures manuelles. La classification de la valve est correcte pour tous les examens. De plus, sur l'ensemble des séquences, il y a d'excellentes corrélation et concordance entre les mesures manuelles et automatiques, aussi bien en diastole qu'en systole

Use of mathematical laws for optimizing the doses of swelled and dry bentonite during the fining of white wines. Part I: clarification and colloidal stability

White wine clarity is of prime importance for the winemaker as a bottle showing haziness is likely to be rejected by the consumer. It is then important to ensure a perfect colloidal stability to the wine. This study concerns a Sauvignon white wine from the Touraine area (vintage 2000). We have determined the relationships existing between the dose of bentonite used, the manner for preparing the bentonite (the dry cristalites can be directly introduced in the wine; the bentonite can also be used after swelling in water), the decrease of wine protein haze and clarifying efficiency. Clarifying kinetics are identical for 10 g/hl swelled bentonite (SB) and 100 g/hl dry bentonite (DB). The difference of efficiency between SB and DB is all the more marked than the dose used increases. At the end of the kinetics, for identical treatments (the doses are between 10 and 100 g/hl), wines fined with DB have turbidity 2-3 times higher than the same wines fined with the same doses of SB. The mathematical law shows that the turbidity decreases by 17 % when the dose of dry bentonite is doubled. For this example, the relationship between these two parameters follows a power law. The decrease reaches 27 % when the wine is fined with SB. According to heat treatment, the wine must be treated with 30 g/hl SB and 60 g/hl DB to present a good colloidal stability. For this Sauvignon wine, fined with SB, haze risk decreases by 82 % each time the dose of bentonite increases by 10 g/hl. In this case, the relationship between these two parameters follows an exponential law. If an addition of oak tannins is made in the wine fined with 30 g/hl SB or 60 g/hl DB, any trouble appears. For heat treatment test and tannin addition test, the ratio is each time 2 DB for 1 SB to have a correctly fined wine. On the basis of these results, the use of dry bentonite seems to be less interesting than the use of swelled bentonite

Glycine inhibitory dysfunction turns touch into pain through astrocyte-derived D-serine

International audienceGlycine inhibitory dysfunction provides a useful experimental model for studying the mechanism of dynamic mechanical allodynia, a widespread and intractable symptom of neuropathic pain. In this model, allodynia expression relies on N-methyl-D-aspartate receptors (NMDARs), and it has been shown that astrocytes can regulate their activation through the release of the NMDAR coagonist D-serine. Recent studies also suggest that astrocytes potentially contribute to neuropathic pain. However, the involvement of astrocytes in dynamic mechanical allodynia remains unknown. Here, we show that after blockade of glycine inhibition, orofacial tactile stimuli activated medullary dorsal horn (MDH) astrocytes, but not microglia. Accordingly, the glia inhibitor fluorocitrate, but not the microglia inhibitor minocycline, prevented allodynia. Fluorocitrate also impeded activation of astrocytes and blocked activation of the superficial MDH neural circuit underlying allodynia, as revealed by study of Fos expression. MDH astrocytes are thus required for allodynia. They may also produce D-serine because astrocytic processes were selectively immunolabeled for serine racemase, the D-serine synthesizing enzyme. Accordingly, selective degradation of D-serine with D-amino acid oxidase applied in vivo prevented allodynia and activation of the underlying neural circuit. Conversely, allodynia blockade by fluorocitrate was reversed by exogenous D-serine. These results suggest the following scenario: removal of glycine inhibition makes tactile stimuli able to activate astrocytes; activated astrocytes may provide D-serine to enable NMDAR activation and thus allodynia. Such a contribution of astrocytes to pathological pain fuels the emerging concept that astrocytes are critical players in pain signaling

A new morphological tool to extract blood vessels in cross sectional MRI

International audienceIn this paper, we propose a new method of mathematical morphology called Aurora transform. This is a geodesic reconstruction that only spreads in radial orientations from a center. Thanks to this method, star domains such as blood vessels in cross sectional planes are extracted even if these regions are often inhomogeneous or some parts of their edges are not drawn very well. This method has been successfully applied to extract the edges of the aortic root, the ascending and the descending aorta in cross sectional cine-MRI. It has been then compared to the use of some active contours. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only