The primary objective of this study is to measure the concentration and the regional brain distribution of activated brain microglia/macrophages using the PET radiopharmaceutical [F-18]DPA-714 in individuals with chronic pain and fatigue suspected to be associated with neuroinflammation. The PET tracer [F-18]DPA-714 binds to the 18 kDa translocator protein (TSPO, also known as the peripheral benzodiazepine receptor) in the mitochondria of activated microglia/macrophages and provides a non-invasive measure of neuroinflammation. The primary objective of this study is to determine if pain and fatigue patients have higher levels of neuroinflammation than HC individuals as measured with [F-18]DPA-714-PET/MRI.

Inclusion Criteria:

1. 18 to 65 years of age
2. Healthy volunteer OR Clinical diagnosis of Multiple Sclerosis (MS) OR Meets 2016 American College of Rheumatology (ACR) case definition criteria for fibromyalgia OR Meets 1994 Fukuda case definition criteria for Chronic Fatigue Syndrome

Exclusion Criteria:

1. Contraindication to MRI
2. Pregnancy
3. Lactation
4. Individuals who are unable to participate in the imaging portion due to severity of their medical condition
5. Chronic infectious disease (e.g. HIV, HCV)
6. Viral or bacterial illness requiring medical attention and/or antibiotics within 1 month of study participation
7. Diagnosis of cancer, including leukemia
8. Blood or blood clotting disorder
9. Except for individuals with MS, a diagnosis of autoimmune disease is exclusionary
10. Positive urine β-hCG test day of procedure or a serum -hCG test within 48 hours prior to the administration of [18F]DPA-714
11. Currently enrolled in a clinical trial utilizing experimental therapies