TY - JOUR T1 - MRI lesions in the sacroiliac joints of patients with spondyloarthritis: an update of definitions and validation by the ASAS MRI working group JF - Annals of the Rheumatic Diseases JO - Ann Rheum Dis SP - 1550 LP - 1558 DO - 10.1136/annrheumdis-2019-215589 VL - 78 IS - 11 AU - Walter P Maksymowych AU - Robert GW Lambert AU - Mikkel Østergaard AU - Susanne Juhl Pedersen AU - Pedro M Machado AU - Ulrich Weber AU - Alexander N Bennett AU - Juergen Braun AU - Ruben Burgos-Vargas AU - Manouk de Hooge AU - Atul A Deodhar AU - Iris Eshed AU - Anne Grethe Jurik AU - Kay-Geert Armin Hermann AU - Robert BM Landewé AU - Helena Marzo-Ortega AU - Victoria Navarro-Compán AU - Denis Poddubnyy AU - Monique Reijnierse AU - Martin Rudwaleit AU - Joachim Sieper AU - Filip E Van den Bosch AU - Désirée van der Heijde AU - Irene E van der Horst-Bruinsma AU - Stephanie Wichuk AU - Xenofon Baraliakos Y1 - 2019/11/01 UR - http://ard.bmj.com/content/78/11/1550.abstract N2 - Objectives The Assessment of SpondyloArthritis international Society (ASAS) MRI working group (WG) was convened to generate a consensus update on standardised definitions for MRI lesions in the sacroiliac joint (SIJ) of patients with spondyloarthritis (SpA), and to conduct preliminary validation.Methods The literature pertaining to these MRI lesion definitions was discussed at three meetings of the group. 25 investigators (20 rheumatologists, 5 radiologists) determined which definitions should be retained or required revision, and which required a new definition. Lesion definitions were assessed in a multi-reader validation exercise using 278 MRI scans from the ASAS classification cohort by global assessment (lesion present/absent) and detailed scoring (inflammation and structural). Reliability of detection of lesions was analysed using kappa statistics and the intraclass correlation coefficient (ICC).Results No revisions were made to the current ASAS definition of a positive SIJ MRI or definitions for subchondral inflammation and sclerosis. The following definitions were revised: capsulitis, enthesitis, fat lesion and erosion. New definitions were developed for joint space enhancement, joint space fluid, fat metaplasia in an erosion cavity, ankylosis and bone bud. The most frequently detected structural lesion, erosion, was detected almost as reliably as subchondral inflammation (κappa/ICC:0.61/0.54 and 0.60/0.83) . Fat metaplasia in an erosion cavity and ankylosis were also reliably detected despite their low frequency (κappa/ICC:0.50/0.37 and 0.58/0.97).Conclusion The ASAS-MRI WG concluded that several definitions required revision and some new definitions were necessary. Multi-reader validation demonstrated substantial reliability for the most frequently detected lesions and comparable reliability between active and structural lesions. ER -