This study is about testing a new PET tracer called SST001. A PET tracer is a special substance used in scans to look at the inside of the body. SST001 helps detect a protein called alpha-synuclein which is linked to diseases like Parkinson's Disease (PD) and Multiple System Atrophy (MSA). The study aims to see how safe SST001 is and how it behaves in the body.

Participants can be either healthy adults or adults diagnosed with PD or MSA. They must be over 18, have good organ function, and not have any severe health problems. Pregnant people or those with other severe neurological issues cannot join. The study is non-randomized and open-label, meaning everyone gets the same treatment and knows what it is.

• The study checks various factors like safety and how the body processes the tracer.
• Participants must follow study procedures and agree to the terms.
• The study isn't for those who've had other similar treatments recently.