Brown adipose tissue (BAT) has lower fat content than white adipose tissue (WAT), which has been exploited using Dixon-based MRI to identify BAT. We sought to identify the optimal threshold to differentiate between BAT and WAT in rats on the basis of fat fraction.
Fat fraction within BAT was significantly lower than WAT in rodents. Receiver operating characteristic analysis showed that differentiating BAT and WAT on the basis of fat fraction had excellent accuracy in both ex vivo and in situ. The optimal cut-off to separate BAT and WAT was significantly lower in rats exposed to cold, likely secondary to lipolysis.