Should ¹²³I-MIBG scintigraphy be part of the workup for pheochromocytomas?

Abstract

This Practice Point commentary discusses the findings and limitations of a retrospective study by Bhatia et al. that compared the performance of ¹²³I-labeled metaiodobenzylguanide (¹²³I-MIBG) scintigraphy with that of cross-sectional CT and MRI for the detection of pheochromocytomas. The sensitivity of ¹²³I-MIBG scintigraphy for detection of adrenal pheochromocytomas was higher than that for extra-adrenal pheochromocytomas (85% versus 58%). Adrenal pheochromocytomas ≥5 cm in diameter were more likely to be detected by ¹²³I-MIBG scintigraphy than those <5 cm (92% versus 79%, respectively). The rate of detection by ¹²³IMIBG scintigraphy for extra-adrenal pheochromocytomas was not influenced by tumor size. I discuss how the characteristics of affected patients (e.g. hereditary syndromes, history of previous pheochromocytoma, and the presence of multifocal, bilateral, extra-adrenal disease, etc.) influence imaging decisions and interpretation. The findings of Bhatia et al. suggest that abdominal MRI or CT should be the initial imaging modality in a patient with a (biochemically) suspected pheochromocytoma.