Imaging in the diagnosis and management of axial spondyloarthritis in children.

Imaging is often used at the time of diagnosis to exclude conditions other than arthritis, to confirm the physical examination if equivocal, and to assess the degree of inflammation and baseline damage. Plain radiography is helpful in the evaluation of damage from chronic inflammation, while ultrasound and magnetic resonance imaging (MRI) are helpful in the assessment of early disease and active inflammation. Multiple studies have shown that tenderness on physical examination of the sacroiliac joint is often discordant with imaging results, so MRI is increasingly relied upon to assess for objective evidence of inflammation. There are no widely accepted, validated tools for the pediatric population using ultrasound or MRI assessment of the peripheral joints. Validated tools exist for objective assessment of pediatric hip disease on radiographs and axial disease on MRI, but not on other imaging modalities. The utility of these scoring systems in clinical care and clinical trials remains untested.