MIBG scintigraphy, or metaiodobenzylguanidine scintigraphy, is a nuclear medicine imaging technique used to diagnose certain types of tumors, particularly those in the adrenal glands such as pheochromocytomas and neuroblastomas. It involves the use of a radioactive substance, usually I-123 or I-131 labeled MIBG, which is injected into the bloodstream and taken up by adrenergic tissue, allowing for imaging and diagnosis.