Développement d'un logiciel d'acquisition et de traitement pour l'imagerie spirale

L'imagerie spirale par sa faible sensibilité aux artefacts de flux et de mouvement est la technique de choix pour l'imagerie de flux et pour l'imagerie fonctionnelle. Un logiciel a été développé, qui gère la modélisation de la forme des gradients, l'acquisition (intégrée au logiciel d'exploitation du système), la reconstruction des images ainsi que les corrections des trajectoires d'échantillonnage et des inhomogénéités du champ magnétique. Sa facilité d'utilisation en fait un outil adapté aux applications médicales

Implementation of Quantum Computing Algorithms on a Nuclear Magnetic Resonance Quantum Computer Based on Polarized Solid 129Xe.

We briefly summarize here the history, conceptual base, as well as challenges and implications of quantum computing. Then, we present the theoretical requirements for viable quantum computation, as well as thestate-of-the-art experimental approach and a project of solid 129Xe NMR-based quantum computer

Sondes radicalaires pour l'imagerie RPE et PDN stables dans les fluides biologiques

Electron paramagnetic resonance and dynamic nuclear polarisation are two techniques that allow the detection of free radicals. They can also be used for in vivo studies for oximetry in blood or tissues. One of the main problems for the development of these techniques is the need of free radicals that are stable in biological media. We present in this communication a study by EPR and DNP of two free radicals that can be suitable for in vivo applications

Registration of MR/MR and MR/SPECT brain images by fast stochastic optimization of robust voxel similarity measures

This paper describes a robust, fully automated algorithm to register intrasubject 3D single and multimodal images of the human brain. The proposed technique accounts for the major limitations of the existing voxel similarity-based methods: sensitivity of the registration to local minima of the similarity function and inability to cope with gross dissimilarities in the two images to be registered. Local minima are avoided by the implementation of a stochastic iterative optimization technique (fast simulated annealing). In addition, robust estimation is applied to reject outliers in case the images show significant differences (due to lesion evolution, incomplete acquisition, non-Gaussian noise, etc.). In order to evaluate the performance of this technique, 2D and 3D MR and SPECT human brain images were artificially rotated, translated, and corrupted by noise. A test object was acquired under different angles and positions for evaluating the accuracy of the registration. The approach has also been validated on real multiple sclerosis MR images of the same patient taken at different times. Furthermore, robust MR/SPECT image registration has permitted the representation of functional features for patients with partially complex seizures. The fast simulated annealing algorithm combined with robust estimation yields registration errors that are less than 1 degrees in rotation and less than 1 voxel in translation (image dimensions of 128(3)). It compares favorably with other standard voxel similarity-based approaches. (C) 1998 Academic Press.Neuroimag