Voxel-based morphometry and voxel-based relaxometry in multiple system atrophy-a comparison between clinical subtypes and correlations with clinical parameters.

Multiple system atrophy (MSA) is a neurodegenerative disease affecting basal ganglia, brainstem, cerebellum, and intermediolateral cell columns of the spinal cord. Clinically, a cerebellar (MSA-C) and a parkinsonian variant of MSA (MSA-P) are distinguished. We used voxel-based morphometry (VBM) and voxel-based relaxometry (VBR) in 48 MSA patients (32 MSA-C, 16 MSA-P) and 46 controls. In MSA-C, VBM revealed gray matter loss in cerebellum, right thalamus, both putamina and several cortical regions including insular cortex. Gray matter loss in the cerebellum and insular cortex was correlated with disease duration and severity. There was white matter loss in the brainstem, which was correlated with disease duration and severity. VBR analysis in MSA-C showed decreased relaxation rate R2 in cerebellum, pontine brainstem and cortical regions including insular cortex. In MSA-P, gray matter was reduced in cerebellum, dorsal midbrain, both putamina, and several cortical regions including insular cortex. A correlation with disease duration and severity was detected only for some small cortical areas. Direct comparison of MSA-C and MSA-P showed differences only in infratentorial brain regions where structural abnormalities were more pronounced in MSA-C than in MSA-P. In MSA-C, there was a stronger reduction of gray matter in the basal parts of the cerebellum, of white matter in the brainstem and of the relaxation rate R2 in the cerebellum and brainstem.