Visceral fat metabolic activity evaluated by 18F-FDG PET/CT is associated with osteoporosis in healthy postmenopausal Korean women

Abstract

BackgroundTraditionally, obesity has been regarded as protective against osteoporosis. However, recent accumulating evidences suggest that visceral obesity can increase the risk of osteoporosis and obesity-driven dysfunctional metabolic activity in visceral adipose tissue (VAT) is considered as a key underlying mechanism. Visceral obesity is known to increase during menopausal transition.18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) is an established method to assess the degree of VAT metabolic activity. We aimed to investigate the association between VAT metabolic activity evaluated by 18F-FDG PET/CT and osteoporosis in healthy postmenopausal Korean women. MethodsA total of 115 postmenopausal women who underwent routine health check-up were enrolled in this study, retrospectively. They all underwent dual-energy X-ray absorptiometry and 18F-FDG PET/CT. Osteoporosis was defined as bone mineral density (BMD) T-score ≤ −2.5 at either lumbar spine or femoral neck. VAT metabolic activity was defined as the maximum standardized uptake value (SUVmax) of VAT divided by the SUVmax of subcutaneous adipose tissue (V/S ratio). ResultsThe participants with osteoporosis showed significantly higher V/S ratio, age, body mass index, waist circumference, and postmenopausal period than the participants without osteoporosis. V/S ratio of 1.33 was proposed as an optimal cut-off value for identifying osteoporosis. Furthermore, V/S ratio was the most significant predictive factor for osteoporosis in postmenopausal woman by uni-and multivariate analyses. Interestingly, V/S ratio showed significant positive correlation with high sensitivity C-reactive protein, a surrogate marker for systemic inflammation. ConclusionVAT metabolic activity assessed by 18F-FDG PET/CT is associated with osteoporosis in healthy postmenopausal Korean women.