Treatment of rheumatoid arthritis using radiopharmaceuticals.

One hundred and twenty one knees in 97 patients with seropositive rheumatoid arthritis and persistent knee synovitis were treated with the intra-articular injection of 270 mCi (30 GBq) of dysprosium-165 (165Dy) bound to ferric hydroxide macroaggregates. Of 81 knees evaluated at one year, 61% had good results, 23% had fair results and 16% had poor results. Of 44 knees evaluated at two years, 64% had good results, 16% had fair results and 20% had poor results. Knees with Stage I radiographic changes showed 72 and 81% good results at one and two years, respectively. Knees and Stage II radiographic changes showed 53 and 48% good results at one and two years, respectively. Leakage of radioactivity from the injected joint was minimal. Mean leakage to the venous blood was 0.15% of the injected dose. Mean leakage to the liver 24 h after injection was 0.64% of the injected dose. Mean leakage to the draining inguinal lymph nodes was 0.17% of the injected dose. These results indicate that 165Dy-ferric hydroxide macroaggregate is an effective agent for radiation synovectomy, particularly in knees with Stage I radiographic changes. The minimal leakage rates observed offer a definite advantage over previously used agents.