Inflammation in joints and entheses is a common feature in juvenile idiopathic arthritis (JIA). It can be difficult to detect clinically at early stages, especially in deep-rooted axial joints and pelvic entheses. These changes often develop without clinical signs and may lead to irreversible osteochondral joint damage and functional impairments if left untreated.

Whole-body magnetic resonance imaging (WBMRI) is a valuable tool for enabling early disease detection, assessing the inflammatory disease burden and monitoring patients’ global disease activity in JIA, as it can detect the presence of bone marrow and soft tissue changes in the entire body in a single imaging session [1]. However, standardizing the whole-body assessment of arthritis and enthesitis in children faces numerous challenges, including the lack of normative information on a wide variety of anatomical regions and their disease patterns, the confounding of growth related and early inflammatory changes, as well as the limitations in imaging concerning resolution and acquisition time. While there are numerous studies on a composite WBMRI scoring method for assessing rheumatoid arthritis in adults [2,3], and several single joint-specific scoring systems in JIA [4], [5], [6], [7], [8], a scoring system for assessing WBMRI in JIA has not been tested previously.

A comprehensive standardized scoring system for assessing inflammation in WBMRI in JIA was recently devised based on an iterative consensus process by a multi-institutional expert panel of radiologists and rheumatologists within the Outcome Measures in Rheumatology (OMERACT) MRI in juvenile idiopathic arthritis (JAMRI) working group. In 2021, the group published the JIA MRI scoring system for WBMRI (called JAMRIS-WBMRI) for inflammation in peripheral and axial joints and entheses [9]. As the next step in the development of the JAMRIS-WBMRI, we aimed to test the item-wise agreement of inflammatory lesions of JIA using the WBMRI scoring system through an interactive data entry platform.