A New Personalized Cooling Protocol to Activate Brown Adipose Tissue in Young Adults

Abstract

Brown adipose tissue (BAT) activity is induced when humans are exposed to cold. Therefore, cold exposure prior to the 18F-FDG-PET/CT scan is used as a tool to quantify BAT. Several cooling protocols, including fixed and personalised ones are currently in use. The aim of the present study was to determine the effect of a new personalised cooling protocol where the shivering threshold was measured on a separate day, on BAT volume and activity in young adults. A total of 47 adults (n=28 women) aged 22±2 years participated in the study. We determined participants’ shivering threshold (visually and self-reported) using a water perfused cooling vest in an air-conditioned cold room. 48-72 hours later, participants wore the cooling vest set at ~4ºC above the shivering threshold for 60 minutes prior to injection of 18F-FDG and ~5ºC above the shivering threshold for ~60 minutes after injection, until PET/CT scan. We quantified BAT following BARCIST 1.0 recommendations. We identified 40 participants (85%, n=25 women) as PET+ and 7 (n=3 women) as PET-. The PET+ group presented significantly higher BAT volume and activity than PET- group (all P<0.05). PET+ women had higher BAT mean activity than PET+ men (SUVmean: 5.0±1.6 vs. 3.6±0.9 g/ml respectively, P=0.003), and there were no significant sex differences in BAT volume (P=0.161). A total of 9 out of 47 participants did not shiver during the shivering threshold test. Our findings are similar to previous cold-stimulated human BAT studies; therefore, we conclude that our personalised cooling protocol is able to activate BAT in young adults.