Prevalence of brown adipose tissue (BAT) activity on FDG PET-CT examinations in Hungarian patient population

Objectives The aim of our study was to evaluate the prevalence of BAT activity - may sometimes mimicking or masking malignant process - on FDG PET-CT examinations in Hungarian- Caucasian- patient population in relation to gender, age, seasonal appearance, and compare our results with literature data.

Methods We retrospectively analyzed 3341 consecutive 18F-FDG PET-CT scans (1350 male, 1991 female pts.) performed for various diagnostic reasons in 2008. The examinations were performed according to our standard whole body PET-CT protocol. Pharmaceutical premedication was not used to suppress BAT activity. Monthly prevalence of BAT activity was evaluated in relation to the country’s median temperature in 2008, according to data of National Meteorological Service.

Results The prevalence of BAT activity in total examined population was 5.47%. Its appearance in female patients was 5.1 times higher than in male subjects. Beyond the age of 50 the prevalence was significantly lower than in younger population (under 30y: 19%, 30-50y : 12%, beyond 50y: 2%). The BAT activity ratio of female to male was 1.2 under the age of 30, this F:M ratio became significantly larger in advanced ages (between 30-50y: 10.5 and beyond 50y: 11.5). The seasonal difference in BAT appearance was more evident under the age of 30, correlating with outside median temperature, but this fluctuation disappeared in elderly.

Conclusions According to our results the prevalence of BAT activity in Hungarian population does not differ from the previously published literature data. Interesting findings were the much higher frequency of increased BAT activity in the youngest group among male subjects, and more evident seasonal alteration in this population