PT  - JOURNAL ARTICLE
AU  - Robert G W Lambert
AU  - Pauline A C Bakker
AU  - Désirée van der Heijde
AU  - Ulrich Weber
AU  - Martin Rudwaleit
AU  - Kay-Geert A Hermann
AU  - Joachim Sieper
AU  - Xenofon Baraliakos
AU  - Alex Bennett
AU  - Jürgen Braun
AU  - Rubén Burgos-Vargas
AU  - Maxime Dougados
AU  - Susanne Juhl Pedersen
AU  - Anne Grethe Jurik
AU  - Walter P Maksymowych
AU  - Helena Marzo-Ortega
AU  - Mikkel Østergaard
AU  - Denis Poddubnyy
AU  - Monique Reijnierse
AU  - Filip van den Bosch
AU  - Irene van der Horst-Bruinsma
AU  - Robert Landewé
TI  - Defining active sacroiliitis on MRI for classification of axial spondyloarthritis: update by the ASAS MRI working group
AID  - 10.1136/annrheumdis-2015-208642
DP  - 2016 Nov 01
TA  - Annals of the Rheumatic Diseases
PG  - 1958--1963
VI  - 75
IP  - 11
4099  - http://ard.bmj.com/content/75/11/1958.short
4100  - http://ard.bmj.com/content/75/11/1958.full
SO  - Ann Rheum Dis2016 Nov 01; 75
AB  - Objectives To review and update the existing definition of a positive MRI for classification of axial spondyloarthritis (SpA).Methods The Assessment in SpondyloArthritis International Society (ASAS) MRI working group conducted a consensus exercise to review the definition of a positive MRI for inclusion in the ASAS classification criteria of axial SpA. Existing definitions and new data relevant to the MRI diagnosis and classification of sacroiliitis and spondylitis in axial SpA, published since the ASAS definition first appeared in print in 2009, were reviewed and discussed. The precise wording of the existing definition was examined in detail and the data and a draft proposal were presented to and voted on by the ASAS membership.Results The clear presence of bone marrow oedema on MRI in subchondral bone is still considered to be the defining observation that determines the presence of active sacroiliitis. Structural damage lesions seen on MRI may contribute to a decision by the observer that inflammatory lesions are genuinely due to SpA but are not required to meet the definition. The existing definition was clarified adding guidelines and images to assist in the application of the definition.Conclusion The definition of a positive MRI for classification of axial SpA should continue to primarily depend on the imaging features of ‘active sacroiliitis’ until more data are available regarding MRI features of structural damage in the sacroiliac joint and MRI features in the spine and their utility when used for classification purposes.