Is preoperative iodine 123 meta-iodobenzylguanidine scintigraphy routinely necessary before initial adrenalectomy for pheochromocytoma?

Background. Iodine 123 meta-iodobenzylguanidine (MIBG) scintigraphy has been used in patients with clinical suspicion of pheochromocytoma to confirm the nature of an adrenal or extraadrenal mass or to identify occult disease. Additionally, it may be used to identify unsuspected bilaterality or metastases in the selling of a known unilateral adrenal mass before operation. We sought to determine the role of I-123 MIBG scintigraphy in this apparently routine preoperative setting. Our hypothesis was that I-123 MIBG would provide additional preoperative information that could modify operative intervention. Methods. All patients undergoing I-123 MIBG scintigraphy at our institution between 1992 and 2002 were identified. MIBG results, operative procedures and findings, and pathologic findings were retrospectively reviewed and compared. Results. The I-123 MIBG scintigraphy was performed in a total of 315 patients. Of these, 48 were patients with an initial biochemical diagnosis of pheochromocytoma and a unilateral adrenal mass. 4 7 of the 48 (98%) primary scans were positive for a single focus of activity concordant with anatomic imaging data from computed tomography or magnetic resonance imaging and operative findings. The I-123 MIBG did not reveal unsuspected metastatic or bilateral disease in any patient. Conclusion. In this large series of Patients undergoing I-123 MIBG scintigraphy, the test served only to confirm diagnostic impressions and corroborate anatomic imaging. The I-123 MIBG did not alter the operative management of any patient with a solitary adrenal lesion in the clinical context of biochemically-proven catecholamine excess.