((18)F)Fluoro-deoxy-D-glucose uptake of knee joints in the aspect of age-related osteoarthritis: a case-control study

BACKGROUND: This study investigated (18)F-fluorodeoxyglucose ((18)F-FDG) uptake at knee joints for determination of metabolic alteration in association with the advance of age and joint degeneration such as osteoarthritis (OA). METHODS: A total of 166 knees from 83 healthy persons who presented for routine health examination and positron emission tomography-computed tomography (PET/CT) were enrolled in this study. History of knee OA and joint symptoms and signs were reviewed. The maximum standardized uptake values (SUVmax) of cartilage and mean SUV (SUVmean) between the epiphyseal plates of femur and tibia were evaluated at knee joints. Assessment of radiological bony changes was performed using the Kallgren-Lawrence (K/L) grading system with reconstructed CT images of the knee. The joint symptoms and signs were counted and used for diagnosis of clinical and radiological OA of the knee. RESULTS: The SUVmean of the knee joints showed a remarkable increase with aging in females (r = 0.503, p < 0.01). Remarkable changes of SUVmean were observed with history of OA (p < 0.01). The SUVmean of joint and the intra-articular SUVmax showed higher values in clinical and radiological OA than in normal joints (p < 0.01). Joint-SUVmean showed significant correlation with OA severity graded according to K/L score (p < 0.05). The intra-articular SUVmax showed a significant increase in symptomatic joints, indicating OA in correlation with the joint-SUVmean (p = 0.01). CONCLUSIONS: The increasing (18)F-FDG uptakes of knee joints showed agreement with aging in females and clinical and radiological knee OA, indicating that the metabolic alterations were consistent with diagnosis and demographic aspect of OA as a surrogate marker for degeneration of the knee in association with aging.