Purpose of review: The study of the early involvement of the axial skeleton has dominated the research map in spondyloarthritides (SpA) in recent months. MRI remains the imaging method of choice to visualize the sacroiliac joint and spine as recognized by the new classification criteria for axial SpA. This review synthesises the most recently published data and offers a critical appraisal of findings.
Recent findings: MRI studies of inflammatory back pain of short duration have identified disease starting simultaneously in the lumbar spine and sacroiliac joints in a proportion of patients and confirm MRI as a reliable measure to assess efficacy of biologic agents in early axial SpA. The new Assessment of SpondyloArthritis International Society classification criteria can be applied in the presence and absence of radiographic abnormalities of the sacroiliac joints. Imaging studies of the spine have confirmed the diagnostic utility of spinal MRI in SpA and have described highly specific lesions such as inflammatory vertebral and posterior element lesions or the postinflammatory fatty Romanus lesions.
Summary: MRI in axial SpA is the most rapidly expanding area of translational research in SpA. The publication of the new Assessment of SpondyloArthritis International Society classification criteria for axial SpA heralds a new era for the identification of early disease and mirrors the existing use of MRI in clinical practice for the evaluation of inflammatory back pain.