Development of 99mTc labelled Lipiodol: biodistribution following injection into the hepatic artery of the healthy pig.

Background We develop a method for the radiolabelling of Lipiodol with Tc-99m, using a lipophilic complex, [Tc-99m-(S2CPh)(S3Ph)(2)], dissolved in Lipiodol (Tc-99m-SSS Lipiodol). Results The labelling yield is high (96 +/- 0.8%), and the radiochemical purity satisfactory (92 +/- 2.6%). This labelling is reproducible and stable for up to 24 h in vitro. Studies carried out after injection into the hepatic artery of the healthy pig show that the biodistribution of Tc-99m-SSS Lipiodol is comparable with that observed for Re-188 Lipiodol. Materials and methods The Tc-99m-SSS lipiodol was obtained after dissolving a chelating agent, previously labelled with Tc-99m, in cold lipiodol. The radiochemical purity (RCP) of the labelling was checked immediately and at 24 h. The Tc-99m-SSS lipiodol was injected into the hepatic artery of four healthy pigs for an ex-vivo biodistribution study. An autoradiographic study was performed in two cases. Conclusions Apart from the specific interest of a Lipiodol-bearing technetiated agent for carrying out dosimetric studies, the labelling of Lipiodol with Tc-99m is a preliminary step towards the use of radiolabelling with the Re-188 analogue.