Technetium-99m-kethoxal-bis(thiosemicarbazone), an uncharged complex with a tetravalent 99mTc state, and its excretion into the bile.

Technetium-99m-kethoxal-bis (thiosemicarbazone) complex (99mTc-KTS), a potentially useful radiopharmaceutical for cholescintigraphy, is prepared by the reaction of KTS with 99mTcO4- in the presence of stannous chloride. Under the described conditions, a complex extractable with organic solvent was detected. Thin-layer chromatography, electrophoresis, and spectrometric analysis indicate the formation of an uncharged 99mTc(IV) complex. Organ distribution and biliary excretion studies are described. The complex showed a marked highly reproducible accumulation in the gallbladder.