Radionuclide imaging metabolic activity of brown adipose tissue in a patient with pheochromocytoma.

We describe a patient with extra-adrenal pheochromocytoma and high plasma norepinephrine levels. Radionuclide images of this patient obtained using (18)F-fluorodeoxyglucose and (123)I-metaiodobenzylguanidine revealed bilateral tracer accumulation in the shoulder and lower neck. The regions of radiotracer uptake corresponded to the location of human brown adipose tissue (BAT). Excessive sympathetic stimulation by high circulating catecholamine concentrations augmented the metabolic activity and tracer uptake in the BAT. This study showed that radionuclide imaging can noninvasively visualize human BAT in terms of metabolic and functional activity.