Systematic calibration reduces sources of variability for the preliminary OMERACT juvenile idiopathic arthritis MRI- sacroiliac joint score (OMERACT JAMRIS-SIJ).

Objective: To determine whether systematic calibration enhances scoring proficiency of the OMERACT juvenile idiopathic arthritis MRI-Sacroiliac Joint score (JAMRIS-SIJ) and whether contrast-enhancement enhances its performance.

Methods: MRI SIJ scans of 50 cases with juvenile spondyloarthritis were scored by 7 raters after calibration with 3 different knowledge transfer tools.

Results: Calibrated readers achieved greater reliability for scoring certain inflammatory and structural lesions. Sensitivity and reliability for scoring inflammatory lesions was greater on fluid-sensitive compared to contrast-enhanced sequences.

Conclusion: Systematic calibration should be implemented prior to the use of JAMRIS-SIJ for clinical trials. It is unlikely that contrast-enhanced MRI will improve the performance of this method.