Magnetic resonance imaging (MRI) in patients with multiple sclerosis (MS) has provided major insights into the disease's natural history, and many studies have focussed on possible correlations between MRI findings and the clinical manifestations of MS. In contrast, there are few reports on possible relationships between functional imaging data and cognitive function. The present study assessed the relationship between clinical presentation and combined anatomical and functional imaging data in MS. Twenty patients with definite MS underwent MRI and positron emission tomography (PET) to evaluate cerebral blood flow (rCBF) and oxygen metabolism (rCMRO2). The relationships between these neuroimaging findings and clinical data, including the Expanded Disability Status Scale (EDSS), Mini-mental status scale, Hasegawa Dementia Scale and relapse time, were evaluated with Spearman's rank correlation coefficients. A general reduction in rCBF and rCMRO2 in the gray and white matter were found in the MS patients. EDSS was correlated with the number and size of the lesions on MRI and was negatively correlated with rCMRO2. A correlation between the decrease in rCMRO2 and the level of cognitive impairment was also found. The severity of cerebral hypometabolism was also related to the number of relapses. Morphological and functional findings obtained by MRI and PET are closely related to the clinical status in MS. Our results suggest that measurement of cerebral metabolism in MS has the potential to be an objective marker for monitoring disease activity and to provide prognostic information.

We studied cerebral perfusion and oxygen metabolism in three patients with chorea-acanthocytosis using positron-emission tomography and oxygen-15 labeled O2 and CO2. High-field magnetic resonance imaging also was performed. Regional cerebral blood flow (rCBF) and oxygen metabolism (rCMRO2) were significantly reduced in the caudate and putamen when compared with seven control subjects. Mild but significant reductions of rCBF (lower than the normal control values -2 SD) were found in the bilateral frontal, left temporal and parietal, and bilateral thalamic areas; rCMRO2 was reduced in the bilateral frontal and left temporal areas. Magnetic resonance imaging showed increased signal intensity accompanied by scattered bright spots in the caudate head and putamen on T2-weighted images; decreased signal intensity was shown at these sites on T1-weighted images. These findings were not observed in 10 neurologically normal volunteers and are rare in the common hyperkinetic form of Huntington's disease. Reduced cerebral perfusion and oxygen metabolism seem to be related to the intellectual and personality changes that occur in chorea-acanthocytosis. Combined positron-emission tomography and magnetic resonance imaging studies may improve diagnostic accuracy in patients with chorea-acanthocytosis and related disorders.

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