GLASGOW, UK—A baseline magnetic resonance image (MRI) of clinically unaffected joints in children with oligoarthritis can predict which children will develop widespread disease 1 year later. This approach might help identify subgroups of children who could benefit from early, aggressive therapy, British researchers say. In a pilot study of 10 children with monoarthritis reported early online in the Journal of Rheumatology, Janet M. Gardner-Medwin, FRCP, PhD, reports that all 4 who developed arthritis in other joints had abnormal MRI scans in clinically unaffected joints at the time the first affected joint was seen.¹ Dr. Gardner-Medwin, who is senior lecturer in pediatric rheumatology at the University of Glasgow, Scotland, conducted the study in collaboration with colleagues at Glasgow and at Children's Hospital, Birmingham, including Drs. Orla G. Killeen, Clive A. J. Ryder, Karen Bradshaw, and Karl Johnson.

"The results suggest a widespread inflammatory process may exist in children whose arthritis extends, and this has implications for our understanding of disease and the design and timing of therapeutic interventions," Dr. Gardner-Medwin writes.

Small Joint Effusions, Synovial Hypertrophy in "Unaffected" Knees

The investigators studied 10 children, mean age 9.4 years (age range 5.2–14.2 years) who presented with monoarthritis. They performed MRI scans (with post-gadolinium sequences) of a clinically unaffected knee within 4 months of the child's initial presentation. The children were followed over a median of 37 months.

Dr. Gardner-Medwin reports that four of the 10 children developed arthritis in other joints over that time at a median of 3.9 months after the MRI scan. "Three of these developed clinical features in the previously normal knee 4–11 months after MRI identified small joint effusions, synovial hypertrophy, and lymph node enhancement," she reports. The fourth child developed arthritis in nine other joints but not in the imaged knee.

"Identifying children at highest risk of extension of arthritis at presentation would allow earlier aggressive management for those most at risk, without overtreatment of others," the authors note.

This study is the first to identify MRI features of clinically normal knees that predict the subsequent clinical course of a patient with juvenile inflammatory arthritis. "MRI revealed subtle changes in the joints, including the synovium, in all the cases that subsequently extended, but in none of those that did not," the investigators write.

This raises the possibility of two different disease processes: a "true" monoarthritis that will not extend, and a widespread inflammatory process in children whose monoarthritis will soon extend beyond one joint. Joints that appeared initially normal in the latter subgroup had MRI features that included:

According to Dr. Gardner-Medwin, a larger confirmatory study is in process.

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