A drug containing a form of radioactive iodine called I 123 that is used to detect certain types of tumors, including pheochromocytomas and neuroblastomas. Radiation from the I 123 may help show where cancer cells are in the body. Iobenguane I 123 is a type of radioimaging agent and a type of radioconjugate. Also called 123I-MIBG, AdreView, and iodine I 123 metaiodobenzylguanidine.