Radiolabeled angiotensin converting enzyme inhibitors for radiolabeling mammalian organ sites

Radiolabeled angiotensin converting enzyme inhibitors having the general formula: wherein X is a radiolabeling substituent, preferably a radiolabeling halogen substituent such as 123I, 125I, 131I, 75Br or 77Br, Y is hydroxy, alkoxy containing from 1 to 6 carbon atoms, phenoxy, benzyloxy, or amino, R1 is hydrogen or methyl, R2 is hydrogen, an ester moiety hydrolyzable under mammalian in vivo conditions, such as alkyl of 1 or 2 carbon atoms, phenyl or benzyl, or an ionically bonded anion of a physiologically acceptable non-toxic salt, and m is an integer of from 1 to 6, are useful as in vivo radioimaging compounds for mammalian sites.