Technetium-99m-tetrofosmin as a new radiopharmaceutical for myocardial perfusion imaging

A new cationic complex, [99mTc(tetrofosmin)2O2]+, where tetrofosmin is the ether functionalized diphosphine ligand 1,2-bis[bis(2-ethoxyethyl)phosphino]ethane, has been synthesized and evaluated for potential use in myocardial perfusion imaging. The structure of the complex has been determined by x-ray crystallography of the 99Tc analog. In comparison with previously reported 99mTc complexes of alkyl-phosphines, the tetrofosmin species shows substantially increased clearance from nontarget tissue, especially blood and liver. A freeze-dried kit formulation has been developed. The kit provides a product of high radiochemical purity up to 8 hr after reconstitution at room temperature.