An iodine I-123 conjugate of metomidate (MTO) with potential application in adrenal imaging. Metomidate is a potent and selective inhibitor of the cytochrome P-450 enzymes, especially CYP11B1 (11 beta-hydroxylase) and CYP11B2 (aldosterone synthase). Because both CYP11B1 and CYP11B2 are expressed exclusively in the adrenal cortex, I-123 iodometomidate can be used as a radiotracer for adrenal scintigraphy.