Magnetic resonance imaging evaluation of the effects of juvenile rheumatoid arthritis on distal femoral weight-bearing cartilage

Objective. To examine magnetic resonance imaging-derived T2 relaxation times in the weight-bearing cartilage of the distal femur in healthy children and in children with juvenile rheumatoid arthritis (JRA). Methods. T2 relaxation time maps were created for 39 girls (ages 4.9-10.9 years), 21 of whom were considered healthy and 18 of whom had JRA. The spatial distribution of T2 relaxation times for the distal femoral weight-bearing cartilage (including epiphyseal and articular cartilage) was mapped for each group as a whole. Average data sets for each group were then compared using paired t-tests to detect differences between the 2 populations. Results. The spatial distribution of T2 relaxation time values was nearly identical in the 2 groups, with a concave curve that was highest near the subchondral bone and articular surfaces. The average T2 relaxation times were significantly higher in the girls with JRA than in the group of healthy girls (P < 0.05). sConclusion. The finding of an increased average T2 relaxation time in the children with JRA suggests that T2 relaxation time maps may reflect cartilage microstructure differences that occur in JRA. T2 relaxation time mapping may allow for early detection of cartilage changes and provide an objective, quantitative method of monitoring disease progression, with the long-term potential to guide therapy.