Section Editor: Sandy Cheng-Yu Chen, M.D.
Taipei Medical University Hospital, Taipei, Taiwan
Multiple system atrophy-Parkinsonian type (MSA-P), previously known as striatonigral degeneration, is a neurodegenerative disease with unclear etiology. The clinical symptoms are indistinguishable from Parkinson disease in some cases. The typical MRI findings are atrophy of bilateral putamina, along with increased iron deposition, and presence of T2 hyperintense "rim sign" (A, arrows) at the lateral margins of the putamen. SWI typically shows marked hypointensity at the posterolateral to anteromedial aspects of the putamina (B, arrows), which indicates increased iron deposition.