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Sacroiliitis seen on MRI common among children with SpA
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The presence of sacroiliitis as evidenced on MRI was common in a study of children with juvenile spondyloarthritis, and HLA-B27-positivity and elevated C-reactive protein were most likely to predict the presence of sacroiliitis, according to recently published research.
Researchers studied 40 children ages 8 years to 18 years with newly diagnosed spondyloarthritis (SpA) at a single tertiary rheumatology clinic. Fourteen healthy children were recruited as control participants. All participants underwent pelvic MRI examinations with a coronal oblique, T1-weighted turbo spin-echo with fat saturation. Contrast-enhanced images were not obtained.
A pediatric rheumatologist completed an unblinded joint and entheses examination, including hip flexion, abduction and external rotation tests. A modified Schober test was used to identify lumbar and sacroiliac flexion with less than 6 cm deemed as an abnormal result. Less than 20 cm of lateral spinal flexion was considered abnormal.
Eight participants (20%) had bone marrow edema (BME) in the sacrum or adjacent ilium. Seven of 36 children (20%) met criteria for entheses-related arthritis (ERA), and one of four of the participants with BME met criteria for psoriatic arthritis. Bilateral BME was bilateral in four participants. Seven patients with BME had sacroiliac joint enthesitis, two patients had capsulitis and six patients had hip enthesitis, while one patient had hip arthritis. Of patients without BME, one patient had hip enthesitis; one patient had unilateral erosion; and no patients had capsulitis or hip arthritis.
Agreement between radiologists reached greater than 91% for all active and chronic sacroiliac lesions indicating sacroiliitis. Positive MRI findings were more likely in children with positive HLA-B27. Moderate agreement was observed for inter-rater reliability. For 6% of the joints, investigators found one rater identified BME and one did not. One rater identified 10% of joints as abnormal, while the other rater identified abnormal joints in 11% of participants.
“In this study we demonstrate that 20% of children with juvenile SpA have sacroiliitis on MRI at disease onset,” the researchers wrote. “Of those subjects with active sacroiliitis, all but one also had evidence of structural damage.” – by Shirley Pulawski
Disclosure: The researchers report support from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (grant R03-AR-062665), the National Center for Research Resources and the National Center for Advancing Translational Sciences (grant UL1-RR-024134).
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