EFFECT OF INTRAARTICULAR OSMIC ACID ON SYNOVIAL-MEMBRANE VOLUME AND INFLAMMATION, DETERMINED BY MAGNETIC-RESONANCE-IMAGING

The changes in MR-determined synovial membrane volume, early synovial enhancement, and cartilage and bone erosions after osmic acid knee syn ovectomy were studied. Gadolinium-DTPA enhanced magnetic resonance ima ging (MRI) of 18 knees with persistent arthritis was performed before and 1 month after treatment. The synovial membrane volume was signific antly reduced (median -52%) in all 9 patients brought into clinical re mission (p<0.01), while no significant change was found in patients wi th clinical relapse. The early synovial enhancement was not significan tly changed. MRI revealed progressive erosive changes in 2 patients. T he lime of relapse was correlated to a MR-erosion score, but not to ea rly synovial enhancement or volumes of synovium or effusion (Spearman tests). MRI-deternined synovial membrane volumes and early synovial en hancement may be objective quantitative markers of inflammation. MR-sc ores of cartilage and bone erosions are sensitive to progressive chang es occurring within a month.