This research study aims to find new ways to diagnose and track **Parkinson's disease (PD)** and other similar disorders using pictures of the brain, called **neuroimaging**. Neuroimaging helps doctors see how diseases affect the brain. The study will last for 2 years and will look at both people who already have Parkinson's and new participants with conditions like **Multiple System Atrophy (MSA)** or **Progressive Supranuclear Palsy (PSP)**. **Key Points:** - **Duration**: Study will last 2 years with ongoing checks. - **Participation**: New and existing patients will undergo brain scans and clinical evaluations. - **Eligibility**: Participants must be willing to take part for the full study period and not planning to move, among other criteria. Doctors will use computer programs called **machine learning** to study these brain pictures and try to find patterns that help predict and understand these diseases better. Participants will have to meet some health criteria to be part of the study, and some people, like those with certain health conditions or women who might be pregnant, won't be able to join.