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Biomedical subjects

J C Froment

Publications and source records attributed to J C Froment.

At least 109 records · Page 6Linked to original sources
PubMedDate not supplied

A pyramidal approach for automatic segmentation of multiple sclerosis lesions in brain MRI.

Quantitative assessment of Magnetic Resonance Imaging (MRI) lesion load of patients with multiple sclerosis (MS) is the most objective approach for a better understanding of the history of the pathology, either natural or modified by therapies. To achieve an accurate and reproducible quantification of MS lesions in conventional brain MRI, an automatic segmentation algorithm based on a multiresolution approach using pyramidal data structures is proposed. The systematic pyramidal decomposition in the frequency domain provides a robust and flexible low level tool for MR image analysis. Context-dependent rules regarding MRI findings in MS are used as high level considerations for automatic lesion detection.

Algorithms↗
PubMedDate not supplied

Demonstration of subclavian steal by MR angiography.

We present three cases of subclavian steal syndrome demonstrated by MR angiography. By using a presaturation pulse located at the bottom or at the top of the acquisition volume we demonstrated the flow direction of vertebral arteries. We used a new investigational two-dimensional time-of-flight sequence.

Adult↗
PubMedDate not supplied

High signal intensity on T2-weighted MRI correlates with hypoperfusion in temporal lobe epilepsy.

Single-photon emission computed tomography (SPECT) and [99mTc]HMPAO were used to assess the functional significance of nonspecific magnetic resonance imaging (MRI) abnormalities observed in patients with temporal lobe epilepsy and no focal lesion on CT scan. We studied 18 patients whose MRI was normal or showed high signal intensity on T2-weighted images (T2WIs) at the site of the EEG focus in 11 and 7 cases, respectively. EEG was monitored during regional cerebral blood flow (rCBF) study. Lateralized hypoperfusion was present in 7 of 17 interictal (41%) and in one postictal cases; it was located in the temporal lobe on the side of the EEG focus in all, and was significantly more frequent in patients with high signal intensity on T2WI (86%) than in patients with a normal MRI (18%). The degree of temporal perfusion asymmetry measured in each individual was higher in patients whose MRI was abnormal.

Adolescent↗
PubMedDate not supplied

Effects of subcortical cerebrovascular lesions on cortical hemodynamic parameters assessed by perfusion magnetic resonance imaging.

A simultaneous decrease of cerebral blood volume (CBV) and cerebral blood flow (CBF) has been described after subcortical stroke with positron emission tomography. However, this imaging modality cannot be applied routinely to stroke patients. Dynamic susceptibility contrast-enhanced MRI techniques (DSC-MRI) might be interesting in the assessment of these effects. Dynamic T2-weighted echo planar imaging was used to produce DSC-MR images during an intravenous bolus injection of gadopentetate dimeglumine in 9 patients who experienced a subcortical stroke involving thalamus or basal ganglia and in 8 control subjects. A series of 50 consecutive images at 1-second intervals was acquired at the anatomic level of the centrum semiovale quite distant from the subcortical lesion, rCBF and rCBV were determined over frontal and parietal regions of interest and through the entire cortical mantle. DSC-MRI enabled the detection of hemodynamic changes induced by subcortical stroke. Analysis of rCBV and rCBF values showed that the hemodynamic parameters were significantly decreased on the affected side. In controls mean rCBF and rCBV values recorded over the whole cortical mantle of each hemisphere showed no significant interhemispheric asymmetry.

Adult↗
PubMedDate not supplied

Hyperacute diffusion-weighted MRI in basilar occlusion treated with intra-arterial t-PA.

Basilar artery thrombosis should be diagnosed immediately, as intra-arterial thrombolysis might improve the outcome. Diffusion-weighted (DWI)-MRI and three-dimensional time-of-flight MR angiography (3D TOF Turbo MRA) may provide additional insight into the extent of ischemia and the level of the occlusion. These methods could be helpful in the early classification of vertebrobasilar stroke, thus reserving the use of conventional angiography and possible intra-arterial thrombolysis for patients who had a severe clinical picture explained by preliminary assessments. We report the case of a 74-year-old woman who experienced a basilar artery occlusion; DWI-MRI and 3D TOF Turbo MRA provided noninvasive information concerning the level of arterial occlusion and its parenchymal ischemic impact, this leading to an intra-arterial thrombolytic therapy. These data suggest the feasibility of a noninvasive urgent diagnostic and prognostic approach with DWI-MRI and 3D TOF Turbo MRA in basilar occlusion.

Aged↗
PubMedDate not supplied

Diffusion-weighted MRI in acute mutism.

Mutism defined as a complete loss of speech may be related to psychiatric or neurologic disorders. The ischemic stroke origins of mutism are often difficult to assess at the acute stage. Accordingly, the search for the underlying mechanism as the localization of the damages may be difficult by conventional radiological techniques. Diffusion-weighted (DWI) MRI may accurately identify patients with acute ischemic stroke and distinguish them from those who mimic acute stroke better than clinical and conventional neuroradiological methods. This report aims to demonstrate the utility of DWI-MRI in the diagnosis of acute mutism.

Acute Disease↗
PubMedDate not supplied

Emergency selective aortography for acute lesions of the thoracic aorta.

Emergency selective aortography is necessary for the definitive diagnosis of acute lesions of the thoracic aorta and defines their therapeutic possibilities. Cineradiography is very helpful and is complementary fo the roentgenograms. In this paper the study of dissecting aneurysms, tears of the aortic wall, ruptured aortic aneurysms and traumatic aortic lacerations is described. A new anatomic classification of dissecting aneurysms combined with that of De Bakey et al. is presented.

Aorta, Thoracic↗
PubMedDate not supplied

[Magnetic resonance imaging in the evaluation of malignant melanoma of the choroid and ciliary body].

We evaluated 16 patients with malignant melanomas of the choroid (11) or the ciliary body (5) by magnetic resonance imaging (MRI), using a 0.5 T magnet and a surface coil. The tumor was seen in all cases, hyperintense in T1-weighted images, and hypointense in T2-weighted sequences (80%). These images reflected the short T1 and T2 relaxation times caused by the presence of melanin in those tumors. This non-invasive method was superior to computed tomography (70%), and sometimes superior to fundoscopy (2 cases), angiofluorography (3 cases) or echography (1 case). MRI also proved valuable for differentiating uveal melanoma from associated subretinal effusion.

Adult↗