An evaluation of 99mTc-labeled hepatobiliary agents.

Scintigraphic imaging of the hepatobiliary system has been significantly improved with the development of 99mTc-labeled compounds. Two of the most promising agents, pyridoxylideneglutamate and HIDA, each formed the basis for the development of a group of structural analogs. Condensation of pyridoxal with leucine and arginine (in place of glutamate) produced pyridoxylideneleucine and pyridoxylidenearginine. Since increasing the molecular weight and the lipid solubility of compounds tends to enhance their biliary excretion, several new IDA derivatives were synthesized by altering the lipophilic substituents on the ring of HIDA. The substitutions included ethyl and ethoxy groups as well as iodine. All compounds were compared with 131I-rose bengal using a baboon model that allowed blood, bile, and urine collection.