Glucose metabolism and Radiodensity of Abdominal Adipose Tissue: A 5-year longitudinal study in a large PET cohort

Abstract

ABSTRACTObjective18F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) allows the noninvasive assessment of glucose metabolism and radiodensity of visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT).Research design and methodsWe retrospectively analyzed data from 435 healthy males (mean 42.8 years) who underwent health check-up program twice at baseline and 5-year follow-up. The mean standardized uptake value (SUV) was measured from SAT and VAT and was divided with liver SUV. The mean Hounsfield unit (HU) of SAT and VAT was measured from CT scans. The effects of clinical variable clusters on SUVR were investigated using Bayesian hierarchical modelling. Four clusters were established for predicting SUVR; 1) metabolic cluster (BMI, waist-to-hip ratio, fat percentage, muscle percentage*-1, HOMA-IR), 2) blood pressure (systolic, diastolic), 3) glucose (fasting plasma glucose level, HbA1c), and 4) C-reactive protein.ResultsAll the clinical variables except for C-reactive protein changed during the 5-year follow-up. SUVR and HU of VAT were increased during the 5-year follow-up, however, those of SAT were not changed. SUVR and HU were positively correlated in both VAT and SAT. SAT SUVR and VAT SUVR were negatively associated with metabolic cluster.ConclusionAgeing led to increased glucose metabolism and radiodensity in VAT, not in SAT. VAT may reflect the ageing process more directly than SAT. Glucose metabolism was higher and radiodensity was lower in VAT than in SAT, probably due to the difference in gene expression and lipid-density. Both glucose metabolism and radiodensity of VAT and SAT reflect the metabolic status.