Volumetric relief map for the cortical subarachnoid space analysis

Purpose: Medical image visualization is an important step in the medical diagnosis of hydrocephalus. In this paper, we present planar representations called volumetric relief maps that are generated from three-dimensional images of the cerebrospinal fluid within the cortical subarachnoid space. Such maps are visually interpreted at once and allow to automatically characterize fluid distributions. Consequently, they help specialists to provide a diagnosis and to monitor patients instantly. Methods: Volumetric relief maps are generated by enclosing the cortical subarachnoid space with a hemisphere, and using a ray tracing method and a map projection technique from a hemisphere to a plane. Results: Visualization of maps indicates that healthy adults have more balanced fluid distributions with well-filled sulci, unlike hydrocephalus patients who have more or less large fluid depletions in the posterior regions of the brain. We showed that a moment-based approach allows to efficiently characterize such fluid distributions from maps. In particular, the center of mass of a distribution is an efficient discriminant factor to distinguish between healthy adults and hydrocephalus patients, with resulting sensitivity and specificity of 100%. In addition, we have noted that asymmetry of the fluid distribution increases with depletion for hydrocephalus patients; such asymmetry is generally oriented towards the frontal part of the fissura longitudinalis cerebri. Conclusions: This paper describes an innovative visualization tool used to analyze fluid distribution within the cortical subarachnoid space. It allows to efficiently discriminate between healthy adults and pathological cases, and to monitor patients before and after surgery

Volumetric relief map for intracranial cerebrospinal fluid distribution analysis

International audienceCerebrospinal fluid imaging plays a significant role in the clinical diagnosis of brain disorders, such as hydrocephalus and Alzheimer's disease. While three-dimensional images of cerebrospinal fluid are very detailed, the complex structures they contain can be time-consuming and laborious to interpret. This paper presents a simple technique that represents the intracranial cerebrospinal fluid distribution as a two-dimensional image in such a way that the total fluid volume is preserved. We call this a volumetric relief map, and show its effectiveness in a characterization and analysis of fluid distributions and networks in hydrocephalus patients and healthy adults

Animal welfare, a driving force to change pig production systems?

Animal welfare requirements are expected to affect the future development of pig production systems in France. Rules and regulations play a major role in this evolution. This could be in favour of larger farms, better able to sustain their economic burden. The development of alternative production systems should also be in favour of improved animal welfare. However, French consumer demand for this type of production remains very low due to higher prices. On the other hand, simultaneous improvement of animal performance and welfare provides an interesting approach, as the price increase due to the welfare-related cost may be at least partly offset by enhanced animal performance.La prise en compte du bien-être animal devrait jouer un rôle important dans l'évolution des systèmes de production porcine en France. La réglementation y contribue de manière prépondérante. Elle pourrait favoriser le développement de structures de plus grande taille, mieux armées pour faire face à ses conséquences économiques. Les élevages labellisés incluent dans leurs cahiers des charges le respect du bien-être des animaux. De ce fait leur développement contribue à celui du respect du bien-être animal. Cependant, la demande des consommateurs pour ce type de productions reste jusqu'à présent très limitée en raison de leurs prix plus élevés. L'amélioration conjointe du bien-être et des performances constitue une approche intéressante, dans la mesure où l'augmentation des coûts liés au bien-être peut être, tout au moins en partie, compensée par l'accroissement des performances zootechniques

Étude des volumes du liquide cérébrospinal

This work aims to contribute to the lack of computational methods for medical image analysis and diagnosis about the study of cerebrospinal fluid volumes. In the first part, we focus on the volume assessment of the fluid spaces, from whole body images, in a population consisting of healthy adults and hydrocephalus patients. To help segmentation, these images, obtained from a recent "tissue-specific" magnetic resonance imaging sequence, highlight cerebrospinal fluid unlike its neigh borhood structures. We propose automatic segmentation and separation methods of the different spaces, which allow efficient and reproducible quantification. We show that the ratio of the total subarachnoid space volume to the ventricular one is a proportionality constant for healthy adults, to support a stable intracranial pressure. However, this ratio decreases and varies significantly among patients suffering from hydrocephalus. This ratio provides a reliable physiological index to help in the diagnosis of hydrocephalus. The second part of this work is dedicated to the fluid volume distribution analysis within the superior cortical subarachnoid space. Anatomical complexity of this space induces that it remains poorly studied. We propose two complementary methods to visualize the fluid volume distribution, and which both produce two-dimensional images from the original ones. These images, called relief maps, are used to characterize respectively, the fluid volume distribution and the fluid network, to classify healthy adults and patients with hydrocephalus, and to perform patient monitoring before and after surgeryCette thèse contribue au manque d'outils informatiques pour l'analyse d'images médicales et le diagnostic, en particulier en ce qui concerne l'étude des volumes du liquide cérébrospinal. La première partie concerne la mesure du volume des compartiments du liquide à partir d'images corps entier, pour une population composée d'adultes sains et de patients atteints d'hydrocéphalie. Les images sont obtenues à partir d'une séquence IRM développée récemment et mettant en évidence le liquide par rapport aux structures voisines, de manière à faciliter sa segmentation. Nous proposons une méthode automatique de segmentation et de séparation des volumes permettant une quantification efficace et reproductible. Le ratio des volumes des compartiments sous-arachnoïdien et ventriculaire est constant chez l'adulte sain, ce qui permet de conserver une pression intracrânienne stable. En revanche, il diminue et varie fortement chez les patients atteints d'hydrocéphalie. Ce ratio fournit un index physiologique fiable pour l'aide au diagnostic de la maladie. La seconde partie de la thèse est consacrée à l'analyse de la distribution du liquide dans le compartiment sous-arachnoïdien intracrânial supérieur. Il convient de souligner que ce compartiment, particulièrement complexe d'un point de vue anatomique, demeure peu étudié. Nous proposons deux techniques de visualisation de la distribution du volume liquidien contenu dans ce compartiment, qui produisent des images bidimensionnelles à partir des images d'origine. Ces images permettent de caractériser la distribution du volume liquidien et de son réseau, tout en distinguant les adultes sains des patients souffrant d'hydrocéphali

Intrinsic Profile Analysis of Intracranial Cerebrospinal Fluid

International audiencePurpose: We aim at studying intrinsic structures of the intracranial subarachnoid space.Material and methods: Magnetic resonance images were obtained using the SPACE sequence, and the segmentation of the superior intracranial subarachnoid space was performed using geometrical features and a topological assumption of the shapes. Given such segmentation results, we present a method based on a geodesic propagation technique, which allows us to make an intrinsic profile of the space. Intrinsic profiles are then analyzed qualitatively and quantitatively, in particular for classification into healthy and pathological cases based on their intrinsic bilateral asymmetry and histogram moments.Results: The proposed method was applied to a clinical dataset of 15 subjects, of which 7 were healthy volunteers and 8 were hydrocephalus patients. The intracranial cerebrospinal fluid is not (intrinsically) bilaterally asymmetric for healthy volunteers, while hydrocephalus would cause asymmetry. We also observed that the results of a two-class classification (healthy or not) based on histogram moments were suitable; sensitivity, specificity and precision are all 100%.Conclusions: The effectiveness of the proposed method of intrinsic profiling analyses is shown by preliminary experiments on healthy adults and hydrocephalus patients

Cerebrospinal fluid volume analysis for hydrocephalus diagnosis and clinical research

International audienceIn this paper we analyze volumes of the cerebrospinal fluid spaces for the diagnosis of hydrocephalus, which are served as reference values for future studies. We first present an automatic method to estimate those volumes from a new three-dimensional whole body magnetic resonance imaging sequence. This enables us to statistically analyze the fluid volumes, and to show that the ratio of subarachnoid volume to ventricular one is a proportionality constant for healthy adults (=10.73), while in range [0.63, 4.61] for hydrocephalus patients. This indicates that a robust distinction between pathological and healthy cases can be achieved by using this ratio as an index

Relief map of the upper cortical subarachnoid space

International audienceThis paper proposes a method to retrieve a two-dimensional relief map of the cerebrospinal fluid distribution in the upper cortical subarachnoid space from three-dimensional magnetic resonance images. This new representation provides both qualitative and quantitative information on the fluid distribution that surrounds the brain. Relief maps can efficiently be used for the diagnosis and the monitoring of hydrocephalus patients

Volume Assessment of the Cerebrospinal Fluid Spaces for Computer Aided Diagnosis

The present work aims to provide support in the diagnosis of hydrocephalus, which requires an assessment to the volumes of the cerebrospinal fluid (CSF) within its total, ventricular and subarachnoid spaces. In this paper we describe a fully automatic method to estimate the CSF volumes from a new 3D whole body MR imaging sequence. The method was developed using image properties as well as anatomical and geometrical features, completed with a topological assumption on the CSF shape. Experiments on phantoms and clinical data were performed and evaluated by comparing our assessments of volumes with those derived from a segmentation controlled by expert physicians. Then we show that a robust distinction between pathological cases and healthy adult people can be achieved by a linear discriminant analysis on volumes of the ventricular and intracranial subarachnoid spaces. We also find that healthy adults maintain a proportional relationship between these volumes

Quantification of the cerebrospinal fluid from a new whole body MRI sequence

International audienceOur work aims to develop a biomechanical model of hydrocephalus both intended to perform clinical research and to assist the neurosurgeon in diagnosis decisions. Recently, we have defined a new MR imaging sequence based on SPACE (Sampling Perfection with Application optimized Contrast using different flip-angle Evolution). On these images, the cerebrospinal fluid (CSF) appears as a homogeneous hypersignal. Therefore such images are suitable for segmentation and for volume assessment of the CSF. In this paper we present a fully automatic 3D segmentation of such SPACE MRI sequences. We choose a topological approach considering that CSF can be modeled as a simply connected object (i.e. a filled sphere). First an initial object which must be strictly included in the CSF and homotopic to a filled sphere, is determined by using a moment-preserving thresholding. Then a priority function based on an Euclidean distance map is computed in order to control the thickening process that adds "simple points" to the initial thresholded object. A point is called simple if its addition or its suppression does not result in change of topology neither for the object, nor for the background. The method is validated by measuring fluid volume of brain phantoms and by comparing our volume assessments on clinical data to those derived from a segmentation controlled by expert physicians. Then we show that a distinction between pathological cases and healthy adult people can be achieved by a linear discriminant analysis on volumes of the ventricular and intracranial subarachnoid spaces

Gene expression profiling of the hyperplastic growth zones of the late trout embryo myotome using laser capture microdissection and microarray analysis

A unique feature of fish is that new muscle fibres continue to be produced throughout much of the life cycle; a process termed muscle hyperplasia. In trout, this process begins in the late embryo stage and occurs in both a discrete, continuous layer at the surface of the primary myotome (stratified hyperplasia) and between existing muscle fibres throughout the myotome (mosaic hyperplasia). In post-larval stages, muscle hyperplasia is only of the mosaic type and persists until 40% of the maximum body length is reached. To characterise the genetic basis of myotube neoformation in trout, we combined laser capture microdissection and microarray analysis to compare the transcriptome of hyperplastic regions of the late embryo myotome with that of adult myotomal muscle, which displays only limited hyperplasia