Quantitative MRI of Children's Hands with Juvenile Rheumatoid Arthritis

Juvenile rheumatoid arthritis (JRA) is the most common rheumatic disease of childhood, with a prevalence of approximately 1 in 1,000 children. The end result of persistent synovitis is joint destruction with associated pain and loss of function. Newer biologic therapies provide hope of improved outcomes, and sophisticated outcome measures will be needed to compare these therapies. Assessment of disease activity by methods such as number of joints involved is imprecise, and only recently has a standard definition of improvement been developed for clinical trials in JRA.

MSK

The use of conventional radiography as an outcome measure has been advocated and utilized in adult rheumatoid arthritis (RA), but radiographs lack sensitivity compared to magnetic resonance (MR) imaging. MR imaging provides a sensitive assessment of synovitis. Both synovial volume and rate of synovial enhancement (similar to Figure 1) have been utilized in RA to assess disease activity.

We hypothesize that children with JRA, who meet the clinical definition of improvement on methotrexate or a biologic agent (i.e. etanercept), will have a greater percentage reduction in synovial volume and rate of synovial enhancement as determined with MR imaging compared to children who do not meet the clinical definition of improvement. Our long-term goal is to develop quantitative MR imaging methods to evaluate disease activity that can be used to assess efficacy of treatment in larger clinical trials.

MSK

We plan to optimize MR imaging sequences to evaluate synovial disease in the hands of children with JRA. We are developing a dynamic gadolinium-enhanced MR imaging sequence to assess synovial perfusion in the hands of children with JRA. A method for quantification of synovial enhancement rates will be developed to differentiate levels of activity of synovial disease. Dynamic enhancement maps from a knee of a child with osteochondritis dessicans are depicted in Figure 2. Optimal imaging time to obtain enhancement measurements following gadolinium injection will be determined.