Project Abstract Overview: This project aims to develop a novel 18F-fluorodeoxyglucose (18F-FDG) PET/MRI method with novel metal artifact correction techniques to provide early identification of painful complications in the prosthetic joint area causing persistent postsurgical pain (PPSP) following total hip arthroplasty (THA). Relevance: THA is one of the most rapidly growing procedures to treat the end-stage hip joint pain and dysfunction and is estimated to reach 572,000 annual cases by 2030. Unfortunately, a substantial number of patients experience PPSP after the procedure, which, without proper treatment, can significantly impair the quality of life. However, the early identification of pain generators for these patients is very difficult because the current diagnostic methods including X-ray, CT, and MRI, have limited sensitivity to pain and suffer from severe artifacts induced by metal in prostheses. Therefore, there is a pressing need for a novel diagnostic approach to accurately identify the abnormal inflammatory changes causing pain without prohibitive metal artifacts to guide the appropriate treatment matched to the exact cause of pain. Approach: We propose the use of 18F-FDG PET/MRI for early identification of sources of PPSP following THA. Our previous 18F-FDG PET/MRI study of chronic pain syndromes demonstrated promising improvements in detecting sites of painful inflammation. However, the severe metal artifacts near metallic prostheses limit the application of 18F-FDG PET/MRI to THA patients. Therefore, our first aim in this project is the development of metal-aware attenuation correction for PET to enable reliable 18F-FDG PET near the metallic prosthesis. Our second aim is the development of high-resolution hip MRI at 3T with metal artifact correction to maximize our ability to identify morphologic causes of PPSP symptoms. Our third aim is to validate the improvements in detection of the painful lesions using serial 18F-FDG PET/MRI sessions. This will be accomplished by correlating the pain score measurements with 18F-FDG PET/MRI abnormalities at 6 months, 12 months, and 18 months following the unilateral THA procedure. Summary: We propose to develop a novel 18F-FDG PET/MRI method with metal artifact correction techniques for early detection of complications causing PPSP following THA. Successful implementation of our method will enable early indication of individualized, effective treatments for THA patients with PPSP.