Characterization of Re-188–Sn microparticles used for synovitis treatment

Rhenium-188 labeled tin (Sn) microparticles were developed for pain palliation therapy in the patients suffering from synovitis with acute pain. The rhenium tin microparticles were prepared using stannous chloride and freshly eluted 188ReO4− from 188W/188Re generator. The aggregated colloidal particles, packed in a spherical form after boiling for 90–120 min were analyzed using electron microscope. The size, surface morphology and stability of microparticles were analyzed by changing temperature and volume conditions. The small colloidal particles clustered and formed spherical microparticles. The 90% of microparticles were in 5–10 μm range, after 90 min and 120 min of boiling. The radiolabeling efficiency was improved to 98% after centrifugation for 10 min at 3500 rpm. The formulations were stable but the increase in volume had inverse effect on labeling efficiency. No leak was observed from knee area up to 24 h with 15–20 mCi injection of 188Re–Sn microparticles. The relief in treated patients, from the pain and inflammation, was observed clinically and by 99mTc-MDP perfusion scan.