Contrast-enhanced MRI of brown adipose tissue after pharmacological stimulation

A non-invasive method for studying the modifications induced in lipid depots by hormonal stimulation could extend knowledge of adipose tissues. We studied the effect of adrenergic stimulation on interscapular brown adipose tissue (IBAT) of rats using contrast-enhanced MRI. Controls and rats pre-treated with adrenaline 40 s before the acquisition of pre-contrast images were used. In the control group, IBAT showed an enhancement of 56 +/- 29%, whereas adrenaline pre-treatment resulted in a significantly higher value (83 +/- 49%, P < 0.05). In the control group, the skeletal muscle of the anterior limb showed an enhancement of 24 +/- 12%, while adrenaline pre-treatment led to a higher value (26 +/- 10%), although the difference was not significant. In the control group, the skeletal muscle adjacent to the IBAT showed an enhancement of 30 +/- 13%, while adrenaline pre-treatment resulted in a non-significantly higher value (33 +/- 10%). In both groups, enhancement values in the muscle adjacent to the IBAT were significantly higher than the values in the muscle of the anterior limb (P < 0.05). This study demonstrates the feasibility of detecting the effect of hormonal stimulation on small fat depots. The demonstration of greater blood flow in the muscles surrounding the IBAT than in the muscles of the anterior limb suggests that the muscles of the back operate in synergy with the IBAT.