Diagnostic efficacy of m-[131I] iodobenzylguanidine (I-131 MIBG) scintigraphy in locating pheochromocytoma

Scintigraphic images using I-131 MIBG were reviewed in the 28 patients with suspected pheochromocytoma. The diagnostic efficacy of the I-131 MIBG scintigraphy for location of mass was discussed comparing with computed tomography (CT) and ultrasonography (US). The smallest size of the pheochromocytoma revealed by both I-131 MIBG scintigraphy and US was 2.0 x 2.5 x 2.0 cm. On the other hand, CT detected smaller mass, 1.0 x 1.5 x 0.4 cm in size. The sensitivity was 88.9 % in I-131 MIBG scintigraphy, 100 % in CT, and 88.9 % in US. The specificity was 100 % in I-131 MIBG, 66.7 % in CT, and 80.0 % in US. And the accuracy was 95.8 % in I-131 MIBG, 79.2 % in CT, and 83.3 % in US. Thus I-131 MIBG scintigraphy was proved to be more sensitive than both CT and US for the location of pheochromocytoma, and is an available method for the first choice. (author)