F-18 FDG PET/CT imaging of non-malignant hypermetabolic musculoskeletal processes

Learning Objectives 1. To present the PET/CT imaging of non-malignant hypermetabolic musculoskeletal entities encompassing inflammation, infection, injury, post-operative changes, physiologic variants, and benign tumors, and 2. to discuss different methods to distinguish these benign processes from malignancy.

F-18 FDG PET/CT is a well-established imaging modality for the staging and post-therapeutic surveillance of lymphoma, melanoma, and cancer of the lung, esophagus, colon and breast. The imaging is based on uptake and retention of glucose-analog radiotracer by highly metabolic tumors and related metastases. During this combined anatomic and functional evaluation of malignancy, musculoskeletal uptake may be purportedly or fortuitously demonstrated. In this exhibit, the authors present the spectrum of non-malignant hypermetabolic musculoskeletal processes encountered during PET/CT imaging. Three categories of these entities are presented: 1. benign lesions with easily recognizable features such as brown adipose tissue, muscle exertion, hemangioma, musculoskeletal injury, ischio-gluteal bursitis, arthroplasty-induced granuloma and post-procedural changes, 2. benign lesions requiring further imaging or biopsy for diagnosis such as island of red marrow, aneurysmal bone cyst, pigmented villonodular synovitis, schwannoma, sarcoidosis, and 3. benign lesions responsible for paraneoplastic syndromes: oncogenic osteomalacia