Brown fat FDG Uptake - A Common Finding in FDG PET CT Scan and the Relation to Demographic, Environmental, and Clinical Factors.

Introduction: Brown adipose tissue (BAT) is crucial for thermogenesis and energy expenditure. This study examines the demographic, environmental, and clinical factors influencing brown fat fluorodeoxyglucose (FDG) uptake, particularly in relation to its anatomical distribution, body mass index (BMI), gender, and temperature. Methods: Data from 139 participants were analyzed, documenting demographics, BMI, weight, and environmental temperatures. FDG uptake by BAT at various anatomical sites was assessed using positron emission tomography/computed tomography scans. Statistical analyses, including Chi-square tests, Fisher's exact tests, and Mann-Whitney U-tests, were conducted to explore the associations between BAT uptake and the variables of interest. Results: Lower external temperatures were associated with increased BAT uptake at perivascular, periviscus, and solid organ sites. Meanwhile, higher ambient room temperatures were linked with increased uptake at these same sites, possibly due to contrast with the cold external environment during winter. Conclusion: Our findings highlight the significant influence of gender and environmental temperatures on BAT uptake. The thermogenic role of BAT in colder conditions underscores its metabolic significance. Further research is needed to explore the underlying mechanisms of these associations and their potential implications for metabolic health interventions.