Distribution patterns of brown adipose tissue on FDG-PET/CT has age characteristics.

Purpose: Brown adipose tissue (BAT) contributes to thermoregulation and energy expenditure. Although BAT is abundant in early childhood and declines with age, its distribution across age groups remains unclear. This study examined age-related BAT distribution using fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT).

Materials and methods: A total of 8695 FDG-PET/CT scans performed for clinical purposes were retrospectively reviewed. FDG accumulation with a standardized uptake value (SUV) max > 1.5 in known BAT regions was considered positive. BAT distribution patterns were classified into T-type (positive accumulation in the supraclavicular or axillary region), I-type (positive accumulation in the cervical or paravertebral region without supraclavicular or axillary involvement), lipomatous hypertrophy of the interatrial septum (LHIS)-type (positive accumulation localized only to the LHIS), and others (cases not fitting any type).

Results: BAT accumulation was observed in 78 patients (0.9% prevalence): T-type (18), I-type (39), LHIS-type (18), and others (3). The mean ages for T-type, I-type, LHIS-type, and others were 29.8 ± 17.3, 73.6 ± 18.1, 72.9 ± 12.5, and 67.0 ± 11.5 years, respectively. Patients in the T-type group were significantly younger than those in the I-type- and LHIS-type groups (p < 0.01).

Conclusions: This study identified three BAT distribution types, with T-type occurring in mostly younger compared with the I-type and LHIS type. Recognizing these patterns may improve FDG-PET/CT diagnostic accuracy.