The rheumatoid knee before and after arthrocentesis and prednisolone injection: evaluation by Gd-enhanced MRI.

In patients with rheumatoid arthritis, intraarticular injection of corticosteroids is an accepted means of treating a symptomatic joint. It has previously been impossible to precisely quantitate the effects of these injections on synovial effusion and pannus. Magnetic resonance imaging (MRI) is a safe, effective means of evaluating joint anatomy, and the use of intravenous gadolinium (Gd)-containing contrast allows clear differentiation of fluid from abnormal synovial tissue. The current study utilized MRI and Gd-labeled diethylene-triamene pentacetic acid (Gd-DTPA) contrast to evaluate serial changes in 6 knees of 6 patients with rheumatoid arthritis, following arthrocentesis and intraarticular injection of prednisolone. One week after the corticosteroid was injected, 2 patients had reduction of pannus width to 20% and 68% of baseline measurements. In these same individuals, follow-up sagittal views showed decreases of total effusion and fluid-plus-pannus width. The other 4 patients, who were followed for 4 weeks, had minimal changes in fluid and synovium. Gd-DTPA-enhanced MRI permits precise assessment of effects of intraarticular injections on synovial fluid and pannus in the rheumatoid knee.