POS1323 SACROILIAC JOINT MRI ABNORMALITIES IN JUVENILE SPONDYLOARTHRITIS: AN UPDATE OF DEFINITIONS AND SCORING OF THE OMERACT JUVENILE IDIOPATHIC ARTHRITIS MRI SCORE

Background: Preliminary definitions for SIJ lesions in the OMERACT Juvenile Idiopathic Arthritis Magnetic Resonance Imaging score has been reported 1 . Investigators identified need to revise JAMRIS-SIJ item definitions. Objectives: To update and scoring method. Methods: The JAMRI working group was convened discuss performance of a reliability exercise using 30 patients. Twenty investigators (12 radiologists, 8 rheumatologists) decided which methods be revised, retained or added. Results: revised JAMRI-SIJ is Table 1. Revised JAMRIS-SIJ. Component Definition Segmentation/slice Score range/slice Bone Marrow Edema (BME) An ill-defined area high bone marrow signal intensity within subchondral ilium sacrum on fluid sensitive images 4 quadrants/SIJ 0-8 BME Intensity Presence hyperintensity presacral veins cerebrospinal as reference score/SIJ 0-2 Depth Continuing increased depth ≥ 5mm/ 1cm from articular surface Osteitis contrast enhanced T1 weighted sequences Capsulitis Increased involving superior portion capsule halves/SIJ Joint space High equivalent CSF joint cartilaginous 0-4 enhancement Inflammation erosion cavity an Enthesitis and/or adjacent soft tissue at sites where ligaments tendons attach excluding retroarticular enthesitis per case 0-1 Damage Domain Sclerosis A substantially wider than normal very low non-fat suppressed sequence, preferably sequence. This feature must also present all other sequences, available Erosion focal loss cortical osteochondral interface matrix Fat metaplasia lesion Homogeneous T1weighted Backfill non-contrast typical location erosion, with greater marrow, clearly demarcated by irregular band reflecting sclerosis border original Ankylosis regional continuously bridging between iliac sacral bones Statement overarching consideration definitions: “[…] comparison physiological changes normally seen MRI examinations age- sex-matched children, visible 2 planes wherever available.” Conclusion: developed. Validation steps are underway. References: [1]Otobo TM, et al. Definitions Sacroiliac Pathologies (OMERACT JAMRIS-SIJ). Journal rheumatology. 2019;46(9):1192-7. Acknowledgements: authors acknowledge Hospital SickKids Research Trainee Competition (RESTRACOMP) Queen Elizabeth II/Edward Dunlop Foundation Scholarship In Science Technology (QEII-GSST) University Toronto funding provided Dr. Tarimobo M. Otobo. Prof. Desiree van der Heijde providing expert commentary. Disclosure Interests: None declared