Establishing 18F-PBR06 PET Imaging as a Viable Pharmacodynamic Endpoint in MSA

The specific aims of the study are: Primary: To determine the presence and regional distribution of microglial activation, as assessed by \[F-18\]PBR06 PET, in subjects with MSA as compared to healthy controls, at baseline and at 9 months follow-up. Secondary: To assess the relationship between microglial activation and clinical progression at baseline and follow-up. Hypothesis: The working hypothesis is that there is microglial activation in Multiple System Atrophy and that the presence and regional distribution of microglial activation is different in MSA versus healthy controls and correlates with disease severity and comorbidities.