NEW MATERIAL:A compound expressed by formula I (R1 and R2 are H or 1W3C alkyl; X is OH- or halogen anion).

EXAMPLE: Technetium-99m-pentane-2,4-dione-bis(N-methylthiosemicarbazone) complex.

USE: A diagnostic in vivo radioactive medicine, cerebral, myocardial and pancreatic imaging agent.

PREPARATION: For example, a pentane-2,4-dithione-bis(N-alkylthiosemicarbazone) expressed by formula II is dissolved in a phosphoric acid buffer solution (pH8.0) free of dissolved oxygen and a solution of stannous chloride solution in hydrochloric acid and a solution of sodium perthechnetate (99mTc) are added thereto. Nitrogen gas is then bubbled to carry out reaction while heating at 85°C. The reaction mixture is subsequently extracted with hexane, which is thin distilled away to afford the aimed complex expressed by formula I.