Background/Purpose: Magnetic resonance imaging (MRI) is the most attractive imaging modality for the investigation of patients with juvenile arthritis (JIA). Musculoskeletal ultrasound (MSUS) has intuitive advantages over MRI including noninvasiveness, low cost, ability to scan multiple joints at once, repeatability and high patient acceptability. The aim of the study was to compare these imaging modalities and to evaluate whether MSUS might replace MRI in the management of JIA in a daily setting.

Methods: All consecutive JIA patients who performed a joint MRI at the study unit over the last 2 years were included. The main clinical indications for MRI were: 1) to quantify disease activity, 2) to confirm disease remission, 3) to evaluate structural damage. The joint assessed by MRI was scanned on the same day with MSUS; the sonographer was blind to MRI’s results. MR and MSUS pathological findings were assessed based on the OMERACT RAMRIS and MSUS definitions and scores. Concordance between MR and MSUS was tested using Cohen’s kappa coefficient and Bland and Altman.

Results:

A total of 101 JIA patients (median age 13.5 years, median disease duration 7.2 years) were included. Overall, 33 patients were imaged in the ankle, 26 in the wrist, 20 in the hip, 10 in the temporomandibular joints (TMJs), 10 in the knee and 2 in the shoulder. Fifty patients had clinically active arthritis; both imaging modalities confirmed active disease in 36/50 (72%) patients; 14/50 (28%) patients had no signs of active disease on MSUS, but only 9 of them showed inactivity on MRI. Concordance between MRI and MSUS for evaluating disease activity was substantial (k=0.72) for the joint recesses and almost perfect (k=0.81) for the tendons. The mean differences (95 %-limits of agreement) between MRI and MSUS were 0.56 (-7.1 to 8.21) for the wrist and 4.8 (-5.85 to 15.38) for the ankle, resulting in an acceptable agreement of these imaging techniques in quantifying disease activity. The concordance was moderate (k=0.56) for the hip. In 51 patients, the imaged joint was clinically inactive. MRI and MSUS confirmed remission in 23/51 (45%) patients, whereas both imaging modalities revealed active disease in 16/51 (31%) patients. In the remaining 12 (24%) patients, persistent synovitis was detected only on MRI. Concordance between MRI and MSUS for evaluating remission was moderate (k=0.53). Major discrepancies between MRI and MSUS were found for the TMJ and hip joints. MRI and MSUS agreed on the presence of structural damage in 11 out of 13 patients (85%) for which MRI was requested for evaluating joint damage.

Conclusion: In patients with clinically active disease, MSUS performs as well as MR not only in detecting but also in quantifying disease activity, especially in the wrist. In patients in remission the concordance between MSUS and MR was acceptable, suggesting the use of MSUS as a first-line imaging modality. In patients with long disease duration and established structural damage MSUS is as sensitive as MR in detecting bone damage. References Colebatch-Bourn AN et al. EULAR-PReS points to consider for the use of imaging in the diagnosis and management of juvenile idiopathic arthritis in clinical practice. Ann Rheum Dis. 2015;74:1946-57.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/when-and-where-musculoskeletal-ultrasound-might-replace-magnetic-resonance-in-the-assessment-of-patients-with-juvenile-idiopathic-arthritis/