Biomedical subjects

Vicente Grau

Publications and source records attributed to Vicente Grau.

4 recordsLinked to original sources

PubMed2006

Segmentation of trabeculated structures using an anisotropic Markov random field: application to the study of the optic nerve head in glaucoma.

The study of the architecture of the optic nerve head (ONH) may provide valuable information about the development and progression of glaucoma. To this end, we have generated three-dimensional datasets from monkey eyes under controlled intraocular pressure (IOP). Segmentation of the connective tissues in this area is crucial to obtain an accurate measurement of geometrical parameters and to build mechanical models. However, this segmentation is made difficult by the complicated geometry and the artifacts introduced in the dataset building process. We present a novel segmentation algorithm, based on expectation-maximization, which incorporates an anisotropic Markov random field (MRF) to introduce prior knowledge about the geometry of the structure. The structure tensor is used to characterize the predominant structure direction and the spatial coherence at each point. The algorithm, which has been validated on an artificial validation dataset that mimics our ONH datasets, shows significant improvement over an isotropic MRF. Results on the real datasets demonstrate the ability of the new algorithm to obtain accurate, spatially consistent segmentations of this structure.

Algorithms↗

PubMed2006

Three-dimensional models of individual cardiac histoanatomy: tools and challenges.

There is a need for, and utility in, the acquisition of data sets of cardiac histoanatomy, with the vision of reconstructing individual hearts on the basis of noninvasive imaging, such as MRI, enriched by reference to detailed atlases of serial histology obtained from representative samples. These data sets would be useful not only as a repository of knowledge regarding the specifics of cardiac histoanatomy, but could form the basis for generation of individualized high-resolution cardiac structure-function models. The current article presents a step in this general direction: it illustrates how whole-heart noninvasive imaging can be combined with whole-heart histology in an approach to achieve automated construction of histoanatomically detailed models of cardiac 3D structure and function at hitherto unprecedented resolution and accuracy (based on 26.4 x 26.4 x 24.4 microm MRI voxel size, and enriched by histological detail). It provides an overview of the tools used in this quest and outlines challenges posed by the approach in the light of applications that may benefit from the availability of such data and tools.

Animals↗

PubMed2005

Adaptive multiscale ultrasound compounding using phase information.

The recent availability of real-time three-dimensional echocardiography offers a convenient, low-cost alternative for detection and diagnosis of heart pathologies. However, a complete description of the heart can be obtained only by combining the information provided by different acoustic windows. We present a new method for compounding 3D ultrasound scans acquired from different views. The method uses multiscale information about ocal structure definition and orientation to weight the contributions of the images. We propose to use image phase to obtain these image characteristics while keeping invariance to image contrast. The monogenic signal provides a convenient, integrated approach for this purpose. We have evaluated our algorithm on synthetic images and heart scans from volunteers, showing it provides a significant improvement in image quality when compared to traditional compounding methods.

Algorithms↗

PubMed2002

Virtual food in virtual environments for the treatment of eating disorders.

Eating disorders (Eds) are one of the problems with higher social repercussion in the last years. Sometimes, these clinical syndromes, which are characterized by an altered eating behavior, can have dramatic consequences. In eating disorders, one of the more critical situations, in addition to other of equal or more importance, is the patient's confrontation with food: the visual confrontation, the eating process and the repercussion on his weight. Virtual Reality (VR) technology has been used in psychology, as a therapeutic help tool for the treatment of different psychological problems, for several years now. Their helpfulness is increasingly being recognized. Some developed virtual environments (VE) and their corresponding published studies endorse the efficiency of this tool. Nevertheless, in order to increase the possibilities of success, it is very important to obtain a complete patient immersion in the VE: visual, auditory and interactive. Sometimes there are processes or actions of reality, which are difficult to simulate virtually, and simulating them coarsely would result in the patient lack of immersion in the VE, thus seriously decreasing the possibilities of success. The eating process is an example, since it consists of several steps, some of which (biting, chewing, etc.) don't have an evident virtual solution. This article shows how food and eating process have been simulated virtually in the development of a virtual environment for the treatment of eating disorders.

Adaptation, Psychological↗