Characterization of glucose uptake metabolism in visceral fat by ¹⁸ F-FDG PET/CT reflects inflammatory status in metabolic syndrome

Objective: The inflammatory activity of visceral adipose tissue (VAT) is elevated in metabolic syndrome (MS), and associated with vulnerability to atherosclerosis. Inflammation can be assessed by glucose uptake in atherosclerotic plaques. We investigated whether the glucose uptake of VAT, assessed by ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸F-FDG PET/CT), is associated with systemic inflammatory status, and related to the number of MS components. Methods: ¹⁸F-FDG PET/CT was performed in a total of 203 participants: 59 without MS component; M (0), 92 with one or two MS components; M(1-2), and 52 with MS. Glucose uptake in VAT was evaluated using the mean standardized uptake value (SUVmean) and the maximum SUV (SUVmax). Glucose uptakes of immune-related organs such as the spleen and bone marrow (BM) were evaluated using the SUVmax. Results: VAT SUVmax correlated with high-sensitivity C-reactive protein (hsCRP) and the SUVmax of spleen and BM, which reflect the status of systemic inflammation. Both hsCRP and the SUVmax of the spleen and BM were higher in the MS group than in the M(1-2) or M(0) groups. In VAT, SUVmax increased with increasing number of MS components, while SUVmean decreased. Conclusions: The SUVmax and SUVmean of VAT assessed by ¹⁸F-FDG PET/CT reflected inflammation-driven unique glucose metabolism in the VAT of MS patients, distinct from that of atherosclerotic plaques.