Supraclavicular brown adipose tissue 18F-FDG uptake and cardiovascular disease

Abstract

Preclinical data suggest a negative correlation between brown adipose tissue (BAT) and the degree of coronary atherosclerosis. We sought to evaluate the relationship between 18F-FDG uptake in supraclavicular BAT in relation to arterial inflammation and subsequent cardiovascular disease (CVD) events in humans. Methods: Individuals who underwent 18F-FDG PET/CT for clinical indications but who did not have either cancer or known atherosclerotic disease at the time of imaging were included. A radiologist masked to clinical data measured 18F-FDG uptake within BAT (in the supraclavicular region) as well as in subcutaneous adipose tissues. Tissue density was evaluated using CT (Hounsfield units). Arterial inflammation was assessed by measuring arterial 18F-FDG uptake and calculating target-to-background ratio. CVD events were independently adjudicated by masked cardiologists. Thereafter, the relationship between BAT activity and CVD events was evaluated. Results: A total of 443 patients (age, 55 y [44-66 y]; 44% men; body mass index [BMI], 26 [range, 23-31]) were included, and 30 patients experienced a cardiovascular event during a median follow-up of 4 y. BAT activity negatively correlated with arterial inflammation (r =-0.178, P < 0.01), a relationship that persisted after correcting for age and BMI (r =-0.147, P < 0.01). When either high sensitivity or high accuracy thresholds (from receiver-operating curve analyses) were used to define elevated BAT, high BAT was associated with a reduced risk of CVD events (P = 0.048), even after correcting for age (P = 0.037). Conclusion: Our results suggest that increased supraclavicular BAT activity is inversely associated with arterial inflammation, independently of age and BMI. Additionally, increased BAT may be associated with fewer cardiovascular events.