S. Grand

A new approach for analyzing proton magnetic resonance spectroscopic images of brain tumors: nosologic images

A new approach for analyzing proton magnetic resonance spectroscopic images of brain tumors: nosologic images

Clinical characteristics and topography of lesions in movement disorders due to thalamic lesions

Objective: To determine which thalamic subnuclei are involved in symptomatic unilateral movement disorders due to localized thalamic infarction, and the clinical characteristics of these abnormal movements. Methods: The authors studied 22 patients with thalamic infarcts for their clinical presentation and the topography of the lesions, using three-dimensional T1-weighted MRI sequencing and stereotaxic analysis of the lesions. Results: Patients were divided into four groups: 1) absence of abnormal involuntary movements (AIM) (nine patients); 2) isolated dystonic posture (two patients); 3) myoclonic dystonia (five patients); and 4) tremor or myoclonus (six patients). In patients with AIM, thalamic lesions were contralateral to the abnormal movements, involving the thalamogeniculate territory, centered on the ventral intermediate (Vim) and ventral caudal (Vc) nuclei. No significant difference in the volumes or center of mass of the lesions was found between patients with tremor and myoclonus and patients with dystonia, although the central nucleus and the internal part of the Vim nucleus were more consistently damaged in dystonic patients. Conclusion: Movement disorders related to thalamic lesions included: 1) myoclonic dystonia with predominating myoclonus and “thalamic” hand associating dystonic posture and slow, pseudo-athetoid movements, both related to lesions in the Vim and Vc nuclei of the thalamus; and 2) postural and action tremor, also related to lesions in the Vim, similar to tremor associated with midbrain lesions, as a result of abnormal functioning of the cerebello-thalamic pathways.

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

PurposeTo determine the perfusion-sensitive characteristics of cerebral dural metastases and compare them with the data on meningiomas.MethodsTwenty-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).ResultsThe 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.ConclusionDural 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.

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

Abstract. 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.

Intérêt de l’imagerie de perfusion dans l’étude des astrocytomes pilocytiques et des hémangioblastomes : étude préliminaire

PURPOSE Pilocytic astrocytomas (PA) and hemangioblastomas (HB) can present the same morphological characteristics on conventional MRI sequences, most usually in the form of a cerebellar cystic mass with a mural nodule that strongly enhances on post-contrast T1 images. We discuss here the value of perfusion MRI in the differentiation of these two tumors, the diagnoses of which have already been histopathologically established. METHOD Eleven patients with PA and eight with HB underwent first-pass perfusion MRI. The maximum relative cerebral blood volume (rCBV(max)), defined as the ratio between the CBV(max) in tumor tissue and the CBV in healthy, contralateral white matter, is considered to be indicative of the type of tumor. RESULTS The difference between the rCBV(max) of PA (rCBV(max)=1.19+/-0.71, range 0.6-3.27) compared with that of HB (rCBV(max)=9.37+/-2.37, range 5.38-13) was significant (P<0.001). The first-pass curve crossed the baseline, corresponding to vascular permeability problems in both PA and HB. CONCLUSION The first-pass method of perfusion MRI is a quick and useful way to differentiate between PA and HB.

Imagerie de perfusion : principes et applications cliniques

MR and CT imaging techniques provide both morphological data and functional data. MR and recently CT perfusion have substantially modified the treatment of acute stroke. CT perfusion offers new opportunities to improve the management strategy in vasospasm after subarachnoid hemorrhage. Both are also helpful for the diagnosis of brain tumors and the assessment of treatment effects.

Pseudotumoral brain lesion as the presenting feature of sarcoidosis

Sarcoidosis rarely presents as an intracranial mass lesion. We report the case of a patient presenting a disturbance of cognitive functions in whom CT and MRI demonstrated a large right fronto-temporal mass lesion with contrast enhancement and surrounding marked oedema, highly suggestive of a brain tumour. The diagnosis of neurosarcoidosis was made after stereotactic biopsy of the lesion.

Dynamic susceptibility contrast-enhanced MRI evaluation of cerebral intraventricular tumors: preliminary results.

INTRODUCTION The aims of the present study were to determine the perfusion characteristics of several types of intraventricular tumors and to evaluate the usefulness of dynamic contrast-enhanced MRI in making the differential diagnosis. METHODS A total of 28 patients with intraventricular tumors (five meningiomas, five papillomas, three ependymomas, four subependymomas, seven central neurocytomas, two subependymal giant cell astrocytomas and two metastases) underwent conventional and dynamic susceptibility contrast-enhanced MRI. Cerebral blood volume (CBV) maps were obtained and the relative CBV (rCBV) calculated for each tumor. Mean rCBV(max) values were compared across the different types of tumors (ANOVA, P=0.05). RESULTS Intraventricular tumors presented with three different patterns of vascularization: highly vascularized tumors (mean rCBV(max)>3), including papillomas, meningiomas and renal carcinoma metastases; poorly vascularized tumors (mean rCBV(max)<2), including ependymomas and subependymomas; and intermediately vascularized tumors (mean rCBV(max)>2 but<3), including central neurocytomas and lung metastases. There was a significant difference between the highly vascularized (papillomas, meningiomas) and poorly vascularized (subependymomas) tumors. In cases of suspected meningioma, papilloma or neurocytoma, low rCBV values (<3) point to a diagnosis of neurocytoma rather than either of the other tumor types. CONCLUSION Susceptibility contrast-enhanced MRI can provide additional information on the vascularization of intraventricular cerebral tumors and may help in making the differential diagnosis.

IRM de perfusion des tumeurs cérébrales

Resume L’approche de la perfusion par IRM des tumeurs cerebrales permet une caracterisation de l’angiogenese tumorale et devient un element important dans le diagnostic initial et le suivi de l’evolution des tumeurs cerebrales. La technique la plus facile a utiliser est la technique de premier passage: elle requiert l’injection intraveineuse d’un embole de produit de contraste IRM et des acquisitions rapides ponderees en T2 ou T2*. La realisation pratique et l’interpretation des donnees sont analysees. La discussion porte sur les aspects methodologiques et d’interpretation clinique.

Abcès cérébral : aspects caractéristiques en imagerie morphologique et fonctionnelle

Resume Bien que rare chez l’immunocompetent, l’abces cerebral doit etre evoque et diagnostique rapidement pour une prise en charge therapeutique adaptee. A partir d’un cas, nous decrivons les signes semiologiques typiques en imagerie morphologique et fonctionnelle.