[High-field MR findings of multiple system atrophy]

Magnetic resonance images obtained at 1.5T were reviewed in 23 patients with clinically diagnosed multiple system atrophy (MSA). The patient group consisted of 13 cases with olivoponto-cerebellar atrophy (OPCA), three with striatonigral degeneration (SND), and seven with Shy-Drager syndrome (SDS). In each disorder group, hypointensity of the pars compacta of the substantia nigra was frequently demonstrated as well as the atrophy of the brain stem and cerebellum. Although T2-weighted images depicted hypointensity of the putamen, which was prominent in its posterolateral part, in cases with SND and SDS, it was not encountered in cases with OPCA. Therefore, this finding was considered to facilitate differential diagnosis between OPCA and other two disorders. These hypointensities in the putamen and pars compacta of the substantia nigra may be due to excessive iron deposition and seem to correlate with extrapyramidal tract signs of MSA.