Correspondence on 'MRI lesions in the sacroiliac joints of patients with spondyloarthritis: an update of definitions and validation by the ASAS MRI working group'.

The use of MRI in the evaluation of axial spondyloarthritis (axSpA) has become more established particularly over the past decade. The Assessment in SpondyloArthritis International Society (ASAS) has previously developed criteria for axSpA that incorporated clinical and imaging aspects including the use of MRI in the detection of active sacroiliitis.1 2 In addition to active inflammation represented by bone marrow oedema (BMO), MRI can demonstrate several structural changes that reflect chronic inflammation accumulated during the natural history of axSpA. Although the presence of structural sacroiliac joint (SIJ) changes on their own is not sufficient to meet the ASAS definition for a positive MRI, these features can influence the diagnosis when it is unclear whether the BMO lesion(s) meet the ASAS criterion.2 We read with great interest the article by Maksymowych et al , which provided an update on the ASAS …