131I-metaiodobenzylguanidine--a new agent for scintigraphic imaging and treatment of pheochromocytoma.

In 91 patients with a suspicion of pheochromocytoma 96 scintigraphies with 131I-metaiodobenzylguanidine were performed. The distribution of this radiopharmaceutical agent was studied. In about 71% we found uptake in the liver, in about 20% in the spleen and in about 6% in the gastrointestinal tract. In 13% of our patients a normal tracer uptake in the adrenal medulla was observed. In 23 patients adrenal or extra-adrenal lesion(s) were localized correctly, whereas one false-positive and one false-negative scintigramme was obtained. The 131I-MIBG imaging of adrenal and extra-adrenal, benign and malignant pheochromocytomas and adrenomedullary hyperplasia is highly specific. In the treatment of pheochromocytomas more experience is needed to present final results, but especially in malignant pheochromocytomas 131I-MIBG therapy may be useful.