Brown adipose tissue (BAT) oxidative metabolism can be measured by 11C-acetate PET with a 3-tissue pharmacokinetic model. However, this model can have trouble distinguishing between increased oxidation and increased blood volume, both of which occur in active BAT. A sequential DCE-MRI and 11C-acetate PET protocol was performed in male Wistar rats with and without BAT activation. DCE-MRI perfusion measures were comparable to those obtained previously with 68Ga-DOTA PET. Incorporating the DCE-MRI blood volume information into the 11C-acetate model revealed higher oxidation in activated BAT than indicated by the unconstrained model.