About the Juvenile Idiopathic Arthritis Magnetic Resonance Imaging (JAMRI) Working Group Juvenile Idiopathic arthritis (JIA) is a chronic inflammatory disease that affect joint function, resulting in significant effect on quality of life by limited physical and psychosocial integration. JIA has an estimated worldwide prevalence of 0.07 to 4.01 cases and an incidence rate of 0.008 to 0.226 cases per 1000 children per year, respectively, highlighting the global disease burden and the need for new clinical trials for JIA management.

Magnetic resonance imaging (MRI) is the reference imaging modality for joints in JIA, because it has reported to be sensitive in detecting early inflammatory changes in sacroiliac joints (SIJ) in JIA long before radiography, thus allowing for intervention before the onset of irreversible joint damage. Furthermore, MRI is best suited to evaluate joints which are limited by location and have complex anatomy, making clinical assessment challenging.

As more evidence support the use of imaging as an outcome measure in JIA clinical trials and the inclusion of joint damage and imaging signs of inflammation as part of the JIA core outcome set (COS) in the middle circle of the OMERACT initiative, the JAMRI working group (WG) has been in the forefront of developing and validating pediatric specific joints MRI measurement instruments for use as outcome measure in JIA clinical trials.

The JAMRI working group has three special interest group (SIG); Temporomandibular joint (TMJ), sacroiliac joint (SIJ) and whole-body MRI (WBMRI) Special Interest Groups (SIGs). Through continuous work during over a decade within the respective SIGs, the JAMRI working group has developed the OMERACT Juvenile Idiopathic Arthritis Temporomandibular Joint Score (JAMRIS-TMJ), the Juvenile Idiopathic Arthritis Sacroiliac Joint Score (JAMRIS-SIJ) and the Juvenile Idiopathic Arthritis Whole Body MRI score (JAMRIS-WBMRI). The validation process for MRI measurement instruments for these joints is in different stages of progress.

In the OMERACT meeting to be hold in the spring of 2023 in Colorado Spring, U.S.A., our working group will focus on discussions on the validation process of the SIJ, most specifically on the reliability aspect of the process for the JAMRIS-SIJ. The methodology and results from the validation studies and other imitative in the group will be presented at the OMERACT meeting.