Pheochromocytoma: diagnosis by scintigraphy using iodine 131 metaiodobenzylguanidine.

We summarize our experience using iodine 131 metaiodobenzylguanidine (131I MIBG) imaging in 24 patients with suspected pheochromocytoma and compare 131I MIBG imaging with other imaging modalities such as computerized tomography and magnetic resonance imaging. Our results confirm the high sensitivity and excellent specificity reported from other centers experienced in 131I MIBG imaging. This radiopharmaceutical permits noninvasive, safe, accurate detection of pheochromocytomas of all types. Iodine 131 MIBG scintigraphy is especially efficacious in the detection of extra-adrenal, recurrent, and metastatic tumors. We review precautions in the screening of patients for 131I MIBG examination, imaging techniques, and drugs that interfere with tumor uptake of 131I MIBG. Though 131I MIBG imaging has some limitations, it deserves strong consideration whenever the diagnosis of pheochromocytoma is suspected.