To investigate the usefulness of susceptibility-weighted MR imaging to differentiate MSA from PD.

Recent histopathological studies have proposed that iron deposition in the putamen is a characteristic finding in MSA. Susceptibility-weighted imaging is an iron-sensitive MR sequence. Several reports have shown the usefulness of susceptibility-weighted imaging for differentiating MSA from PD because of the unique findings of MSA: hypointensity in posterolateral putamen.

We enrolled seven patients with MSA (parkinsonism-predominant type) and 7 patients with PD, who were diagnosed clinically. Susceptibility-weighted angiography (SWAN) and T2 -weighted imaging (T2WI) were performed on a 1.5T MR imaging system. Firstly, to evaluate the degree of decreased signal intensity (SI) in the posterolateral putamen, the SI ratios (putamen to caudate head) in SWAN were calculated in both MSA and PD. The region-of-interest (ROI) method was used to measure each SI in the posterolateral putamen and ipsilateral caudate head in SWAN. Secondly, we constructed the merged images using SWAN and T2WI to compare the distribution of pathological findings shown in previous reports.

Susceptibility-weighted imaging showed different findings between MSA and PD. It may be helpful for the diagnosis of MSA, because it is thought to reflect the iron-associated degenerating process itself.