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The frontal eye field and parietal eye field are known to be involved during visually guided saccades. As the location of the human parietal eye field is not yet well known, functional MRI was used during such a saccade task to better localise this field. Besides activity in visual areas of the occipital cortex, bilateral activity was seen in the precentral(More)
Functional MRI (f-MRI) is a non-invasive technique developed to permit functional mapping of the brain with a better temporal and spatial resolution than that offered by PET techniques. In our study, f-MRI was performed using blood oxygenation level dependent (BOLD) contrast imaging based on the magnetic properties of hemoglobin. This method relies on(More)
Progressive Multifocal Leukoencephalopathy is a demyelinating disease. MRI shows high signal intensity areas on T2w sequence and low intensity aeras on T1w sequence, without enhancement after intravenous contrast injection. The involvement of arcuate fiber (U fibers) creates a sharp border with the cortex. There is no mass effect. Involvement of(More)
To assess the value of MRI for meningioma of the posterior cerebral fossa, in correlation with surgical and pathological findings, we retrospectively reviewed 31 cases. The patients (24 females and 6 males ranging in age from 25 to 79 years) were preoperatively studies on a 1,5 T MR imager (GEMS Signa) between july 1989 and november 1993. The protocol(More)
OBJECTIVE In 1988, the neurosurgeons and neuroradiologists at the Val-de-Grâce hospital decided to create a stereotaxis site using advanced medical imaging date (CT-scan or MRI). METHODS Two MRI machines and on CT unit were linked to a network (ETHERNET) available for radiologists in 1989. Neurosurgeons adapted stereotaxis sites using Leksell, Fisher and(More)
The authors report their experience of cerebral stereotaxis for biopsy purposes. Since January 1990, they have been using MRI which provides vascular images and makes it possible to simulate surgical procedures beforehand. The authors have developed a specific program on an independent console. MRI sections are acquired with a 1.5 Tesla Sigma (G.E.)(More)
PURPOSE State-of-the-art imaging of the normal and pathologic vestibule. METHODS AND MATERIAL This study is based on the experience of three French imaging centers (Val de Grâce, Bégin, and Saint-Antoine hospitals) working with 1- and 1.5-tesla magnetic resonance units and high-resolution computed tomography, and it includes a review of the literature.(More)
Involvement of the deep grey matter is unusual in Progressive Multifocal Leukoencephalopathy (PML), which is disease of the white matter. Basal ganglia involvement is usually secondary to extension from lesions of adjacent white matter and easy to recognize. We report a biopsy-proven case of PML in which lesions were mainly thalamic.
Several kinds of images, each giving a different information, are now available to radiologists. The MRI images have excellent contrast resolution and enable soft tissues to be differentiated, but they do not distinguish structures with low water content, notably air and bone, whereas these are easily recognized by CT. The aim of this study is to present a(More)
The MRI technology may be the starting-point of geometric distorsion. The mathematical preciseness of a spatial location may be disturbed and alter the guidance of an MRI interventionnal act, especially in stereotactic brain biopsy. A review of the literature shows errors of 1 to 1.5 mm. Our results show an error of 0.16 +/- 0.66 mm. The control of quality:(More)