Preparation of 191Os–phytate, an in-vivo radionuclide generator, for radiosynovectomy application

Abstract

191Os is a parent radionuclide with a 15.4 d half-life. It decays by beta emission to 191mIr, which is a radionuclidewith a 4.96s half-life. It decays by the isomeric transition to stable 191Ir, emitting a 129-keV gamma photon. In thisstudy, 191Os–phytate was developed into an in-vivo radionuclide generator for simultaneous radiosynovectomy and imaging. 191Os-hexachloroosmate was used to prepare 191Os–phytate (100 μCi/50 μl) using reaction condition optimization followed by an intraarticular injection to rat knee joints. Also, its distribution and stability were assessed. The imaging of 191Os cation and 191Os–phytate was performed by SPCET. The 191Os–phytate complex was obtained at pH=5.5 with normal saline at room temperature. Radio-TLC showed an overall radiochemical yield of 95-98%. The complex was injected into the rats’ knees, and the whole injected dose remained at the injection site even three days after injection. Due to the stability and retention of the complex in joints approved by biodistribution and imaging studies, the complex is a potential in vivo generator for cavital radiosynovectomy of minor joints.

Keywords

• radiosynovectomy
• phytate
• osmium-191
• biodistribution
• imaging