CHANGES IN SYNOVIAL-MEMBRANE AND JOINT EFFUSION VOLUMES AFTER INTRAARTICULAR METHYLPREDNISOLONE - QUANTITATIVE ASSESSMENT OF INFLAMMATORY AND DESTRUCTIVE CHANGES IN ARTHRITIS BY MRI

Objective. To evaluate synovial membrane volumes, effusion volumes, an d cartilage and bone erosion scores determined by magnetic resonance i maging (MRI) as markers of disease activity and severity in arthritis. Methods. Gadolinium-DTPA enhanced MRI of 18 arthritic knees was perfo rmed before and 1, 7, 30 and 180 days after intraarticular methylpredn isolone injection until clinical relapse, Intraobserver, interobserver , and inter-MRI variations were determined from 2 successive MRI of an other 6 knees. Results. In all knees synovial membrane and effusion vo lumes decreased within the first posttreatment week (median decrease 4 9 and 65%, respectively), and remained low during remission. Synovial volumes, but not effusion volumes, increased to pretreatment levels in case of clinical relapse, indicating that synovial volumes were most important to the clinical appearance. The intraobserver + interobserve r + inter-MR variation was maximally 26%. Total volumes and volumes in a selected sagittal slice were highly statistically correlated. The d uration of clinical remission in patients with rheumatoid arthritis (R A) was significantly inversely correlated to the pretreatment synovial volume (both total and ''one slice'' volumes): but not to the effusio n volume, MRL or radiography scores of erosions or any clinical/labora tory variables. Cartilage and bone erosions, invisible by radiography, were visualized by MRI. No progressive erosive changes were observed. Conclusion. MRI-determined synovial and effusion volumes and MRT scor es of cartilage and bone erosions are reproducible acid may be sensiti ve measures of disease activity and severity in RA, The synovial volum e may rather than the effusion volume determine clinical appearance, B oth are influenced by the present inflammatory activity. The pretreatm ent synovial volume may have predictive value to treatment outcome in RA.