[en] Full text: Hepatobiliary imaging radionuclide -^99mTc-Mebrofenin is indicated as a hepatobiliary imaging agent for the evaluation of hepatobiliary tract patency to differentiate jaundice resulting from hepatocellular causes from jaundice resulting from partial or complete biliary obstruction; to differentiate extrahepatic biliary atresia from neonatal hepatitis; to detect cystic duct obstruction associated with acute cholecystitis; and to detect bile leaks. Also, ^99mTc-Mebrofenin may be useful to detect intrahepatic cholestasis and to distinguish it from other hepatobiliary diseases, which involve hepatocyte damage. However, the Mebrofenin kit has to be obtained at an exorbitant cost and there was need to develop an indigenous kit that was readily available and could give similar results. For the first time in India, a derivative of DMSA developed by DRDE, Gwalior and modified at INMAS, Delhi to adopt early transition metals, was successfully labelled with ^99mTc (LE>99%). The reaction conditions were optimized after studying the effects of amount of SnCl₂, pH of the reaction and effect of incubation time. The labelled product ^99mTc-O₂ S₄ , was characterized by ITLC-SG using acetone and saline. The complex was found to be fairly stable at room temperature and showed>95% plasma protein binding. The biodistribution studies showed that after intravenous administration, there was immediate accumulation of radioactivity in liver, the activity kept on increasing in gall bladder with time and thereafter the radioactivity moved to common bile duct (CBD) and small intestines. No significant radioactivity was found in kidneys and blood. Clear visualization of the gallbladder and intestines, within 15 to 45 minutes of administration of ^99mTc-O₂S₄ in normal rabbit, demonstrates hepatobiliary tract patency of the newly developed radiotracer. The dynamic and static images showed that the newly developed radiopharmaceutical ^99mTc-O₂S₄ has full potential in studying the various ailments of hepatobiliary route. The extraction time of ^99mTc-O₂S₄ from various organs is being studied and shall be compared with that of ^99mTc-Mebrofenin