This study is conducted in New Haven, CT, at the Institute for Neurodegenerative Diseases. It looks at how well two different types of cameras, **high resolution** and **standard resolution**, work for taking pictures of the brain in those who might develop Parkinson's disease. **Parkinson's disease** is a condition that affects movement and can cause shaking, stiffness, and difficulty walking. **Positron Emission Tomography (PET)** is a special imaging test that helps doctors see how organs and tissues inside the body work. Participants will have two PET scans: one with the standard PET camera and another with the NeuroEXPLORER (NX) PET camera.

The study will have about 25 participants and last for up to 2 years. Participants will have visits for PET scans at the start, and then again 1 and 2 years later. They might be asked to do more scans depending on study findings. All participants will have additional tests to gather data on their health.

• **Participants need to be part of the PPMI 015 study.**
• **The study involves multiple PET scans over several years.**
• **Participants must be able to provide consent and not have conditions that make participation unsafe.**