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Biomedical subjects

S Grand

Publications and source records attributed to S Grand.

At least 19 recordsLinked to original sources
PubMed2006

[Perfusion-diffusion 1H spectroscopy: role in the diagnosis and follow-up of supratentorial brain tumours in adults].

INTRODUCTION: In a few years, magnetic resonance imaging (MRI) has evolved from a morphology-based examination to one that encompasses metabolism and function. STATE OF ART: MRI is a well-established tool for the initial evaluation of brain tumors, but conventional MR sequences have some limitations. Conventional MRI is unable to distinguish high-grade glioma from metastasis and abscess, to define precisely the histopathological grade of gliomas, to determine exactly the limits of tumor extension, to characterize meningeal tumors. Differentiation of tumor recurrence from treatment-related changes may be difficult with standard MR imaging because the interpretation is essentially based on volume analysis. PERSPECTIVES: 1H Spectroscopy, diffusion and perfusion imaging become possible with the development of MR imagers and can be routinely performed in clinical settings. They give complementary information about tumor metabolism and vascularity and allow a better analysis of post-treatment modifications. Functional and metabolic explorations should be used to characterize brain tumors.

Adult↗
PubMed2006

[Functional magnetic resonance imaging in clinical practice].

In the last decade, functional MRI (fMRI) has become one of the most widely used functional imaging technique in neurosciences. However, its clinical applications remain limited. Despite methodological and practical issues, fMRI data has been validated by different techniques (magnetoencephalography, Wada test, electrical and magnetic stimulations, and surgical resections). In neurosurgical practice, fMRI can identify eloquent areas involved in motor and language functions, and may evaluate characteristics of postoperative neurological deficit including its occurrence, clinical presentation and duration. This may help to inform patients and to prepare postoperative care. fMRI may also identify epileptic foci. In neurological practice, fMRI may help to determine prognosis of recovery after stroke, appropriate medication, and rehabilitation. fMRI may help to identify patients at risk of developing Alzheimer disease. Finally, cerebrovascular reactivity imaging is an interesting approach that might provide new radiological insights of vascular function.

Brain↗
PubMed2006

[Perfusion MR imaging in brain tumors].

Perfusion MR Imaging is useful for initial diagnosis and follow up of brain tumors. Dynamic susceptibility contrast MR imaging is described. The limitations and advantages of this technique are discussed with respect to quantification and interpretation of results.

Brain Neoplasms↗
PubMed2005

[MRI for oligodendrogliomas].

MRI has dramatically improved the management of cerebral tumors and consequently oligodendrogliomas. T1 and T2-weighted images and gadolinium enhancement are very useful for tumor detection and characterization. Tumor enhancement is of a great prognostic value because it is highly predictive of high-grade oligodendroglioma. Three-dimensional MR images provide, with high precision, the anatomical location and the relationships with functional structures (motor and language areas). The recent technical progress in MRI and the use of diffusion images in the screening of tumors lead to a better definition of the lesion. Comparative analysis of MRI images is helpful to detect eventual relapse and adverse effects of treatment.

Brain Neoplasms↗
PubMed2005

[Perfusion MR imaging for initial diagnosis and follow-up of brain tumors].

OBJECT: To discuss the pertinency of perfusion MR imaging for initial diagnosis and follow up of brain tumors. METHODOLOGY: Dynamic susceptibility contrast MR imaging was applied. Images were thus obtained with intensities proportional to the cerebral blood volume (CBV). Relative cerebral blood volume (rCBV) maps were then generated by normalizing the signal intensities with respect to measurements made in healthy tissue. RESULTS: The method provided interesting data for establishing the differential diagnosis between different kinds of lesions, in particular between lymphoma and pilocytic astrocytoma, and for grading gliomas. DISCUSSION AND CONCLUSION: Limits of the approach are discussed, in particular with respect to quantification aspects and interpretation of the results. The approach could be particularly useful for grading oligodendrogliomas, for which histological diagnosis on biopsy is sometimes difficult.

Astrocytoma↗
PubMed2004

Contribution of dynamic contrast MR imaging to the differentiation between dural metastasis and meningioma.

PURPOSE: To determine the perfusion-sensitive characteristics of cerebral dural metastases and compare them with the data on meningiomas. METHODS: Twenty-two patients presenting with dural tumor underwent conventional and dynamic susceptibility-contrast MR imaging: breast carcinoma metastases, two patients; colorectal carcinoma metastasis, one patient; lung carcinoma metastasis, one patient; Merkel carcinoma metastasis, one patient; lymphoma, one patient; meningiomas, 16 patients. The imaging characteristics were analyzed using conventional MR imaging. The cerebral blood volume (CBV) maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral white matter (CBVn). RESULTS: The differentiation between a meningioma and a dural metastasis can be difficult using conventional MR imaging. The rCBVs of lung carcinoma metastasis (1 case: 1.26), lymphoma (1 case: 1.29), breast carcinoma metastasis (2 cases: 1.50,1.56) and rectal carcinoma metastasis (1 case: 3.34) were significantly lower than that of meningiomas (16 cases: mean rCBV = 8.97+/-4.34, range 4-18). Merkel carcinoma metastasis (1 case: 7.56) showed an elevated rCBV, not different from that of meningiomas. CONCLUSION: Dural metastases are sometimes indistinguishable from meningiomas using conventional MR imaging. rCBV mapping can provide additional information by demonstrating a low rCBV which may suggest the diagnosis of metastasis.

Blood Volume↗
PubMed2004

[Diffusion-weighted magnetic resonance imaging in hypoglycemic coma].

Hypoglycemia is a classic cause of coma and can result in irreversible neuronal loss. Until now, the main prognostic factors were depth of hypoglycemia and duration of coma. We report the case of a 55-Year-old woman who suffered severe hypoglycemic coma with abnormal cortico- subcortical diffusion weighted MR images. These MRI abnormalities preceded severe atrophy of these cerebral areas. This findings suggests that diffusion abnormalities in hypoglycemic coma may be related to neuronal loss and may thus have prognostic value.

Alcoholism↗
PubMed2004

[Cerebral abscess: MRI, DWI and MRS features].

Although rare in non immunodeficient patients, the correct diagnosis of brain abscess is essential in order to initiate urgent medical and surgical treatment. We describe the imaging features including spectroscopy and diffusion MRI.

Brain Abscess↗
PubMed2004

Paraneoplastic acute diffuse encephalitis revealing Hodgkin's disease.

Paraneoplastic neurological syndromes are associated with various cancers. Cerebellar and limbic paraneoplastic manifestations are known to be associated with Hodgkin's disease (HD), but reports of diffuse encephalitis associated with HD are very rare. We report a case of acute severe diffuse encephalitis revealing a HD. Clinical presentation, cerebro-spinal fluid modifications and magnetic resonance imagery data are described. The treatment associated specific chemotherapy and plasma exchange. The neurological status improved dramatically within the first days of treatment, with parallel neoplasm regression. This case stresses the fact that encephalopathy can be the first sign of an undiagnosed extra-cerebral neoplasm.

Adolescent↗
PubMed2003

[Magnetic resonance cerebral blood volume maps. Comparison with histologic findings in different types of brain lesions].

Recent developments in magnetic resonance (MR) have made it possible to obtain measurements of the microvasculature within brain lesions. Cerebral blood volume (CBV) maps calculated from dynamic contrast-enhanced MR imaging are particularly sensitive for depicting the microvasculature, and can enable the detection of neovascularization as well as its quantification in relative terms. The purpose of the present work is to compare the results of CBV maps calculated from MR imaging with those from histologic examination of the same region of interest: the biopsy site. Nineteen patients with brain lesions were studied (18 brain tumors and one case of multiple sclerosis). All patients underwent stereotactic biopsy, and calculation of CBV was performed from perfusion MR imaging. Three histopathologic parameters were assessed: the number of vessels (vessel density), the vessel size and the surface area filled by vessels (%). We observed a statistically significant correlation between the vessel density and the CBV, which is consistent with some previous publications. A noninvasive imaging method for characterizing the functional properties, especially hemodynamic activity, of malignant processes seems to be of great benefit to clinical practice.

Adult↗
PubMed2002

Dynamic contrast-enhanced MRI: differentiating melanoma and renal carcinoma metastases from high-grade astrocytomas and other metastases.

We performed conventional and dynamic susceptibility-contrast MRI imaging in 38 patients with brain tumours: 20 with metastases (breast carcinoma: two; renal carcinoma: five; colorectal carcinoma: one; lung carcinoma: seven; melanoma: five), and 18 with high-grade astrocytomas. We obtained cerebral blood volume (CBV) maps and calculated the relative CBV (rCBV) in different areas using the ratio between the CBV in the pathological area (CBVp) and in the contralateral white matter (CBVn). We calculated the maximum rCBV (rCBVmax) for each tumour and compared the mean rCBVmax in each group of tumours. The mean rCBV of melanoma metastases (5.35+/-2.32, range 3.14-9.23) and of renal carcinoma metastases (8.17+/-2.39, range 5.41-11.64) were significantly greater than those of high-grade astrocytomas (2.61+/-1.17, range 1.3-5.0) ( P=0.002 and <0.001, respectively) and of lung carcinoma metastases (2.94+/-0.86, range 1.43-4.04) ( P=0.003 and 0.002). There was no statistically significant difference between the mean rCBV of lung metastases and of high-grade astrocytomas ( P=0.59). Large, solitary, necrotic metastases can be indistinguishable from high-grade astrocytomas using conventional MRI. Demonstration of an elevated rCBV which may suggest a hypervascular lesion such as renal carcinoma or melanoma.

Astrocytoma↗
PubMed2002

Chordoid glioma of the third ventricle: CT and MRI, including perfusion data.

Chordoid glioma is a homogeneous tumour involving the third ventricular region of middle-aged women, containing a small central cyst or necrosis. Histologically the tumour has a chordoid appearance. We report a new case with a haemodynamic imaging approach which indicates tumour angiogenesis at the capillary level.

Adult↗
PubMed2002

Cerebral blood volume mapping by MR imaging in the initial evaluation of brain tumors.

PURPOSE: To assess the contribution of magnetic resonance (MR) cerebral blood volume (CBV) mapping in the initial evaluation of brain tumors. METHODS: 63 patients presenting a brain tumor underwent dynamic susceptibility-contrast MR imaging before surgery or biopsy: 28 high grade gliomas, 8 low grade gliomas, 2 pilocytic astrocytomas, 4 lymphomas, 12 metastases, 9 meningiomas. The CBV maps were obtained for each patient and the relative CBV (rCBV) in different areas was calculated using the ratio between the CBV in the pathological area (CBVp) and in the contralateral normal tissue(CBVn). The maximum rCBV (rCBVmax) for each tumor was determined and the mean values of rCBVmax in each group of tumors were compared using an unpaired Student t test (p=0.05). RESULTS: The rCBVmax for high grade gliomas (mean +/- SD: 2.6 +/- 1,2) was statistically different from low grade gliomas (0.9 +/- 0.4) (p<0.001), lymphomas (0.7 +/- 0.2) (p=0.002), meningiomas (9.1 +/- 4.4) (p<0.001) and kidney metastases (8.9 +/- 2.1) (p<0.001). The two pilocytic astrocytomas had a much lower rCBVmax than high grade gliomas. No statistically significant difference was found between high grade gliomas and lung metastases (2.4 +/- 0.9) (p=0.72). CONCLUSION: CBV mapping provides additional information on the vascularity of the lesions, which is not available with conventional MR imaging. It might be useful for differentiating certain lesions showing contrast enhancement, mainly high grade gliomas from kidney metastases, meningiomas, lymphomas or pilocytic astrocytomas.

Blood Volume↗