In vivo inorganic chemistry of technetium cations

Technetium-99m cations are of interest because of their potential use as myocardial perfusion imaging agents. These species can undergo in vivo reactions which markedly affect their biodistribution patterns. Four such cases of reactions are presented and discussed: (1) simple ligand substitution; (2) metal centered redox processes; (3) reactions of coordinated ligands; (4) outer sphere association reactions. New experimental techniques appropriate for investigating these reactions at the 10(-10) M concentration level of technetium encountered in vivo are also presented and discussed. The latter three classes of reactions are illustrated by examples taken from the recent literature and from unpublished data.