Anatomy G.I.T b4d24c74 The substance used in OCG is A Iopanoic acid B Sodium diatrozite C Meglumine iodothalamate D Biligraffin High-Yield Explanation Iopanoic acid is used in oral cholecystography Biligraffin is used in IV cholangiography Ref: Sabiston 20th edition Pgno :1487