Pheochromocytoma: detection by unenhanced CT.

During a 2 1/2-year period, 10 patients with suspected pheochromocytoma were evaluated by unenhanced computed tomography (CT). Six adrenal masses, one hyperplastic adrenal gland, and two extraadrenal retroperitoneal masses were detected in seven patients; CT of the adrenals and retroperitoneum was normal in three patients. Scintigraphy with iodine-131 metaiodobenzylguanidine (131I-MIBG) was performed in nine of the 10 patients and corroborated the CT findings in all cases. In the three patients with normal CT and 131I-MIBG scintigraphic findings, follow-up assays of serum catecholamines were normal. In six of the seven patients with abnormal CT scans, surgical and pathologic confirmation was obtained; one patient was lost to follow-up after her CT scan. Unenhanced CT is recommended as the initial localizing procedure in patients with suspected pheochromocytoma, thereby avoiding the small but finite risk of hypertensive crisis associated with intravenous injection of urographic contrast medium.