\[18F\] FDG PET/MRIFDG PET/MRI Imaging of Patellofemoral Joint Osteoarthritis

This project aims to develop an \[18F\] fluorodeoxyglucose (FDG) positron emission tomography (PET) / magnetic resonance imaging (MRI) method to locate the painful inflammation in PFJ OA associated with joint loading. \[18F\] FDG PET/MRI is an emerging pain imaging approach with enhanced sensitivity to painful hypermetabolic inflammation through evaluation of intracellular glucose utilization rate via (\[18F\]FDG PET) and fine anatomy details (MRI). The investigative group has shown its promise in revealing previously unidentified or unspecified pain generators in various musculoskeletal pain conditions. The investigators have also demonstrated the feasibility of visualizing the structural changes between unloaded and loaded knee joints with MRI, which can be easily adopted in the current PET/MRI setting. The main challenge in the proposed \[18F\]FDG PET/MRI approach is to differentiate the normal uptake of FDG for metabolic changes by weight-bearing from abnormal changes indicating eventual pain aggravation by weight-bearing and knee-flexion. The investigators have garnered the following two aims to validate the proposed method by comparing unloaded and loaded knee imaging results between PFJ OA pain patients and asymptomatic, matched controls.