Rhenium-188 sulphur colloid as a radiation synovectomy agent

Radiation synovectomy has been shown to be an effective treatment for the rheumatoid arthritic knee. In this study, we evaluated the suitability of rhenium-188 as a radiation synovectomy agent. In addition, we were successful in labelling sulphur colloid with¹⁸⁸Re. In vitro stability tests revealed that more than 95% of the¹⁸⁸Re remained in colloid form over a 3-day period. Intra-articular injection of¹⁸⁸Re sulphur colloid into arthritic rabbit joints was followed by gamma camera imaging to quantify the leakage. The mean retention percentages of¹⁸⁸Re colloid in arthritic knees were 93.7% (±1.4%), 90.8% (±1.7%) and 87.2% (±0.6%) at 1 h, 1 day and 2 days, respectively. A biodistribution study of the arthritic rabbits revealed that the highest activity outside the knees was in the liver and the kidneys. Our preliminary results indicate that 188Re sulphur colloid may be an effective radiopharmaceutical for radiation synovectomy.