[Gammagraphy with 123I-meta-iodobenzylguanidine in the diagnosis of pheochromocytoma].

At times pheochromocytoma raises diagnostic problems which cannot be solved by methods already incorporated into diagnostic evaluation, such as catecholamine measurement, echography and computed tomography. These drawbacks are more common with small size tumors, malignant extra-adrenal pheochromocytoma and some cases of relapse after surgery. The present study reports the results of 123I-meta-iodobenzylguanidine (MIBG) scintiscan in 30 patients with suspected pheochromocytoma. The head, the thorax and the abdomen were scanned in all patients after 3, 24 and 48 hours. Areas of normal and abnormal uptake were evaluated in these areas. The scintiscan was positive in seven cases with a diagnosis of pheochromocytoma, which showed markedly increased uptake persisting throughout the study. The results of other studies are analyzed and the functional character of MIBG, its sensitivity and specificity, and the advantages of 123I over 131I are discussed.