Influence of radiation synovectomy on articular cartilage, synovial thickness and enhancement as evidenced by MRI in patients with chronic synovitis

Radiation synovectomy is a safe and effective treatment for chronic synovit is that is refractory to the repetitive, intra-articular application of glu cocorticosteroids in patients with rheumatoid or seronegative arthritis. Sh ort-term and long-term effects of radiation synovectomy on articular cartil age, synovial enhancement and thickness were assessed in a prospective, cli nical trial by MRI. Methods: Thirteen patients (mean age 39 +/- 13 y) were treated with a median activity of 8.4 GBq Dy-165 ferric hydroxide, a radion uclide with favorable physical properties and a well-documented clinical sa fety and efficacy profile. MRI was performed on a 1.5-T MR unit using a cir cular polarized knee coil. Results: After a mean observation period of 13 m o, a marked reduction in synovial enhancement was observed in 10 patients. The mean reduction in baseline synovial thickness (mean 7.6 +/- 3.0 mm) was 24% (P = 0.03) at 1 wk and 42% (P = 0.01) about 1 y after treatment, respe ctively, Clinically, 9 of 13 patients (69%) exhibited persistent response t o radiation synovectomy. The local clinical score, as defined by the reduct ion in pain, pannus, joint effusion and by the increase in the range of mot ion, improved significantly (P = 0.01), from a median of 7 (range 4-10) to a median of 2 (range 0-9). One year after treatment, changes in the local c linical score were related to the decrease in synovial enhancement in MRI ( r = 0.7, P = 0.008, n = 12). There were no persistent adverse effects, nor was there evidence for any severe radiation-induced damage to the articular cartilage. On later follow-up images, the structure of the articular carti lage remained unaltered in all but 3 patients, who had new, superficial ero sions most likely attributed to an active disease with persistence of infla mmation. Conclusion: This study suggests that radiation synovectomy with Dy -165-ferric hydroxide is effective in terms of reducing chronic synovitis w ithout causing detectable harm to the articular cartilage, as shown by MRI.