[Magnetic resonance imaging in multiple system atrophy]

We studied 18 patients with multiple system atrophy (MSA) by high field strength MRI: 6 striatonigral degeneration (SND), 4 Shy-Drager syndrome (SDS), and 8 olivo-ponto-cerebellar atrophy (OPCA). We also studied 30 Parkinson's disease (PD) and 10 age-matched controls. The diagnoses of SND, SDS, and OPCA were based on criteria after Hirayama et al (1985). Bradykinesia, rigidity, and tremor were assessed with the summed scores of the signs used as the extrapyramidal scores. The mean extrapyramidal scores were not significantly different in patients with SND, SDS, OPCA, and PD. MRI studies were performed on 1.5 tesla MRI unit, using a T2 weighted spin echo pulse sequence (TR2500 ms/TE40 ms). The width of the pars compacta signal in all subjects was measured by the method of Duguid et al (1986). Intensity profiles were made on a straight line perpendicular to the pars compacta through the center of the red nucleus on an image of the midbrain. We measured the width of the valley at half-height between the peaks of intensity representing the red nucleus and the crus cerebri-pars reticulata complex and used this measurement as an index of the width of the pars compacta signal. The mean widths of the pars compacta signal were: 2.8 +/- 0.4 mm (SND), 2.8 +/- 0.7 mm (SDS), 3.6 +/- 0.6 mm (OPCA), 2.7 +/- 0.3 mm (PD), and 4.3 +/- 0.6 mm (control). The mean widths of the pars compacta signal in PD, SND, and SDS were significantly narrower than that in the control group (p < 0.05), while the OPCA group was not significantly narrower.(ABSTRACT TRUNCATED AT 250 WORDS)