The current status of meta-iodobenzylguanidine and related agents for the diagnosis of neuro-endocrine tumors.

Metaiodobenzylguanidine (MIBG) has been in clinical use for 15 years and has been shown to have high sensitivity (about 85%) and specificity (> 95%) for the location of all types of pheochromocytomas. Similar results have been achieved with neuroblastomas. A wide range of other neuroendocrine lesions including carcinoids, medullary thyroid cancer and nonsecretory paragangliomas may also be imaged, but the lower sensitivity. The newly developed radiolabeled somatostatin analogs may have greater utility for these lesions. MIBG scintigraphy may also provide a unique in vivo probe for study of the sympathetic autonomic nervous system, particularly in the heart. Various radiolabels for MIBG and its analogs permit planar scintigraphy, SPECT, PET, intraoperative probe localization and radiopharmaceutical therapy.