Study on tumor affinity of sup(99m)Tc-labeled radiopharmaceuticals

Biologic characteristics of various sup(99m)Tc-labeled radiopharmaceuticals have been comprehensively investigated to get a promising indicator for tumor imaging in contrast to biologic behaviour of 67Ga-citrate in Ehrlich's tumor bearing mice. The following eleven preparations were included: sup(99m)Tc-HSA (human serum albumin), sup(99m)TcO4- (pertechnetate), sup(99m)Tc-TSL (trasylol), sup(99m)Tc-EHDP (diphosphonate), sup(99m)Tc-DMSA (dimercaptosuccinate), sup(99m)Tc-DSDP (diethyl stilbestrol diphosphate), sup(99m)Tc-LASP (L-asparaginase), sup(99m)Tc-BLM (bleomycin), sup(99m)Tc-UK (urokinase), sup(99m)Tc-Man (mannitol), and sup(99m)Tc-ConA (concanavaline A). The following biologic characteristics of each has been comprehensively investigated: 1) absolute concentration in tumor tissue (expressed as a percent of the administered dose per g of tissue weight), 2) a concentration ratio of tumor tissue to organ, 3) the clearance from blood and skeletal muscle tissue, and 4) the relative superiority index (RSI) calculated from a comparison with the biologic characteristics of 67Ga-citrate. It could be concluded from this investigation that sup(99m)Tc-labeled radiopharmaceuticals such as sup(99m)Tc-Man and sup(99m)Tc-BLM which disappear faster from the blood and which do not accumulate in specific organs may be preferable and practical for tumor imaging, considering the short physical half life of technetium-99m and the hazardous radiation to patients due to extensive administration. (Evans, J.)