Yttrium-90 citrate colloid for radioisotope synovectomy

The preparation of an yttrium-90 citrate colloid is described. This formulation localizes in the synovial membrane and thereby eliminates any irradiation received by extra-articular tissues. Yttrium-90 is eluted from Sr-90 bound to a sulphonic acid ion exchange resin. The colloid is prepared using a 3:1 ratio of carrier yttrium and citrate. Contamination with ionic 90Y and ionic 90Sr was less than 1 percent and 0.001 percent, respectively. In the 28 patients studied, all of the injected dose of 90Y remained in the region of the joint. Brief clinical results are presented.