Synaptic Loss in Multiple System Atrophy

This study is using a specialized brain PET scan to look at synapse (nerve connection) loss in people with multiple system atrophy (MSA) — a rare and progressive neurological disorder that affects movement, balance, and automatic body functions. Understanding where and how quickly synapses are lost may help researchers track disease progression and test future treatments. **You may be eligible if...** - You are 45–80 years old with a diagnosis of probable or possible MSA (based on established clinical criteria) - You are able to complete brain scanning and study procedures - If female, you are post-menopausal, surgically sterile, or using adequate contraception - You have a healthy volunteer available to act as a comparison group participant (healthy volunteers are also enrolled in separate cohorts) **You may NOT be eligible if...** - You have significant other neurological or psychiatric conditions that might interfere - You have active cancer or are receiving chemotherapy or other treatments that could affect brain imaging - You are pregnant or breastfeeding - You are claustrophobic or otherwise unable to undergo PET/MRI scanning - You have significant kidney or liver impairment Talk to your doctor to see if this trial is right for you.