Biomedical subjects

A Bouliou

Publications and source records attributed to A Bouliou.

3 recordsLinked to original sources

PubMed1999

Evaluation of a new MEG-EEG spatio-temporal localization approach using a realistic source model.

This paper introduces a new technique for the localization of brain electromagnetic activity: a spatio-temporal fit (SPTF). This algorithm uses some properties of the principal component analysis and makes no assumptions about the number of sources to be located. It was applied to both simulated and real MEG/EEG signals and was compared to the well-known moving dipole fit (MDF) technique. For the simulations, we constructed extended sources, rather than single dipoles, that respected realistic anatomical and temporal properties. From these, we generated, under different noise conditions, MEG and EEG signals from which localization was performed. The real signals were auditory evoked fields. Firstly, it appeared that the SPTF was able to separate simultaneously activated sources even on strongly noisy signals while, most of the time, the MDF failed to give a clear description of the source configuration. Secondly, although we used the same head model to both generate the signals and locate the sources, localization for EEG was inferior to that for MEG. In conclusion, since in all test conditions the SPTF is found to be far superior to MDF, we suggest the use SPTF for the localization of equivalent dipoles.

Algorithms↗

PubMed1996

A ray-traced texture mapping for enhanced virtuality in image-guided neurosurgery.

3D imaging systems and algorithms give virtual representations of the real world. New emergent hardware systems can combine virtual information and the real world. Virtual and real information must be also visually confronted in order to facilitate our comprehension of the data. We propose a solution which entails the superimposition of a real image of the anatomical areas visualised in a surgical operation with 3D digital data sets. Unlike other solutions which display virtual images in the real world, our method involves ray traced texture mapping which displays real images in a computed world.

Algorithms↗

PubMed1988

Computer graphics in medicine: a survey.

Increased interest is presently given to three-dimensional (3-D) medical applications due to simultaneous emergence of high-resolution imaging systems and computer graphics techniques. This paper intends to present a survey of this field together with discussion and prospective views. The general framework is composed of six parts: data acquisition and preprocessing, polygonal object representation, voxel description, system architecture, medical applications, and prospects. Data base acquisition includes characterization of imaging modalities and medical specificity. Preprocessing schemes are directed to improvements (filtering), windowing, and spatial anisotropy (linear or spline interpolation). The two following sections are devoted to descriptions of the main object representations. Particular emphasis is given to optimal contour approximation, surface triangulation, mathematical surfaces on one hand, and cuberille and voxel representations on the other. Display capabilities--hidden surface removal, surface normal shading, structure enhancement--and data base structuration--hierarchical and nonhierarchical (graph and tree encoding)--are, respectively, described. An overview of 3-D systems is further given (Section V), and features of medical applications are reviewed and gathered in basic functionalities, surgery, and radiotherapy specifications (Section VI). The last section provides some prospective views on reconstruction from a few projections, model-guided labeling, multimodality image overlay, and local image network. Some of these issues are illustrated by examples of 3-D images.

Computer Graphics↗