FDG PET/MR Imaging of Peripheral Pain Generators

Inclusion Criteria: Persistent Post-Surgical Pain Patients * 18-85 years old * Presents with persistent pain with pain score of ≥4 on Numerical Rating Scale \[0:10\] for at least 6 months following joint arthroplasty or arthroscopy. * Able and willing to provide informed consent * Willing and able to undergo PET/MRI (arthroplasty and arthroscopy participants) and PET/CT (arthroplasty participants only) Inclusion Criteria: Asymptomatic controls * 18-85 years old * Asymptomatic (pain score of ≤2 on the NRS) for at least 6 months following joint arthroplasty or arthroscopy. * Able and willing to provide informed consent * Willing and able to undergo PET/MRI Exclusion Criteria: * Inability to understand and communicate with the investigators to complete the study-related questionnaires. * Any co-morbidity which results in severe systemic disease limiting function as defined by the American Society of Anesthesiology (ASA) physical status classification \> 3, such as the presence of current or past (6 months) pulmonary, hepatic, renal disease, arthritis, hematopoietic, and neurological diseases not related to chronic pain. * Pregnant or breastfeeding. (Individuals with childbearing potential will be asked to verbally confirm they are not pregnant. If they cannot confirm, they will have a urine pregnancy test either at the imaging study visit or within 7 days prior to the imaging study visit.) * Subject with contraindication(s) to or inability to undergo PET/MRI * Current diagnosis of malignancy of any kind. Participants in remission for at least two years and not undergoing any treatment may be considered per investigator discretion * Current enrollment in a scientific interventional or treatment study. * Subject unable or unwilling to provide informed consent