IN-VIVO METABOLISM OF THE TECHNETIUM ISONITRILE COMPLEX [TC(2-ETHOXY-2-METHYL-1-ISOCYANOPROPANE)(6)](+)

netium(2-ethoxy-2-methyl-1-isocyanopropane)(6)(+), [Tc-EIBI] is a comp lex of technetium(I) structurally similar but slightly more lipophilic than the commercial myocardial perfusion agent Cardiolite(R) [Tc-MIBI ]. Tc-EIBI exhibits rapid extraction from the blood into heart, liver, kidney and striated muscle and rapid hepatobiliary clearance. In the guinea pig, unlike Tc-MIBI, this compound is almost completely enzymat ically metabolized to numerous cationic complexes containing a mixture of ethyl ether and hydroxy isonitrile ligands. Substitution of the et hyl ether group for a methyl ether produces an agent that shows select ive in vivo metabolism and more rapid clearance from the liver.