Ultralow Dose PET Imaging of 18F-FDOPA

The goal of this clinical trial is to evaluate an investigational ultralow dose PET imaging technique for Parkinsonian syndromes, neuroendocrine tumors, and gliomas detection and monitoring. The main question it aims to answer is: Can the investigators optimize the timing, scan duration, and image reconstruction to reduce the radiation dose 10-100 fold of the current clinical standard? Participants will be injected with a radioactive tracer called 18F-FDOPA and be imaged on a new type of high sensitivity PET scanner for up to 3 hours.

This research study aims to evaluate an investigational ultralow dose PET imaging technique for Parkinsonian syndromes, neuroendocrine tumors, and gliomas detection and monitoring. "Investigational" means that the procedure or drug being studied is not yet approved by the FDA for the specific use being tested in this research. The PET imaging technique used in this study is considered investigational because it is being tested at an ultralow radiation dose that has not yet been approved for clinical use. The radiotracer, 18F-FDOPA, is FDA-approved for detecting prostate cancer at standard doses. 18F-FDOPA is often found to be taken up at higher levels in Parkinsonian syndromes, neuroendocrine tumors, and gliomas. In this study, investigators will use a very small amount of this tracer (less than 1/20th of the standard dose) along with advanced PET imaging technology to see if it is possible to create clear images while using much less radiation. This study aims to develop a safer imaging technique that could potentially be used more frequently for screening and monitoring Parkinsonian syndromes, neuroendocrine tumors, and gliomas. Investigators will enroll individuals with and without Parkinsonian syndromes, neuroendocrine tumors, and gliomas to evaluate how ultralow dose PET imaging detects 18F-FDOPA uptake in different type of tissue. Approximately 200 people will be enrolled in this study at the Nuclear Imaging Institute.

Inclusion Criteria: 1. age ≥18 years. 2. ability to provide informed consent and comply with study procedures. 3. for female participants: * must not be pregnant or breastfeeding. * negative pregnancy test required for women of childbearing potential. Exclusion criteria: 1. participants who have exceeded Nuclear Regulatory Commission regulation for annual radiation exposure from prior research-related scans, including this study (50 mSv total). 2. more than four prior enrollments in this study. 3. participants with severe claustrophobia, chronic pain, or musculoskeletal conditions that prevent completion of the pet scan 4. medication \& prior treatment exclusions • concurrent treatments that may interfere with radiotracer uptake as determined by the Principal Investigator. 5. pregnant or breastfeeding individuals (negative pregnancy test required) 6. inability to provide informed consent 7. any condition that, in the investigator's judgment, may compromise participant safety or study integrity.