Knee in early juvenile rheumatoid arthritis: MR imaging findings

PURPOSE: To determine the magnetic resonance (MR) imaging findings in the k nee in early juvenile rheumatoid arthritis. MATERIALS AND METHODS: MR imaging (1.5 T) was performed in the more symptom atic knee in 30 children with juvenile rheumatoid arthritis with a symptom duration 1 year or less. Conventional, fast spin-echo, three-dimensional gr adient-echo, and gadolinium-enhanced T1-weighted images were assessed. Two radiologists independently read the images, and a third resolved disagreeme nts. These images were compared with knee radiographs in 27 children. RESULTS: Mean maximal synovial thickness was 4.8 mm +/- 2.4 (SD). Mean syno vial volume was 15.4 mL +/- 10.8. Suprapatellar joint effusions were seen i n 26 (87%) of 30 knees, meniscal hypoplasia in 11 (37%) of 30 knees, and ab normal epiphyseal marrow in eight (27%) of 30 knees. Three knees had articu lar cartilage contour irregularity, fissures, and/or thinning. One knee had a bone erosion. Knee radiographs showed suprapatellar fullness in 78% of t he knees, joint space narrowing in one knee, and no bone abnormalities. CONCLUSION: Synovial hypertrophy and joint effusions are the most frequent MR imaging findings of knees in early juvenile rheumatoid arthritis. Early in the disease, radiographically occult cartilage and bone erosions are unc ommonly seen at MR imaging. The potential relationship of synovitis to cart ilage abnormalities deserves further study.