The role of imaging in the diagnosis and management of axial spondyloarthritis

MRI of the sacroiliac joints is increasingly acknowledged as being indispensable in the early diagnosis of axial spondyloarthritis (axSpA) and as having a prominent role in the prognosis and classification of axSpA. Technological advances include improvements in the resolution of structural lesions and in methodologies for the quantification of lesions. Limited access and expertise in interpretation of MRI have led to a resurgence of interest in CT, especially the development of low radiation protocols for assessing the sacroiliac joints. Trials of TNF inhibitors in patients with non-radiographic axSpA have led to greater understanding of the role of MRI in selecting which patients might respond well to this therapy. The role of MRI features as target end points in treat-to-target strategies remains unclear because the effect of such targeting on structural damage parameters has only recently been explored. The relative importance of active and structural lesions for prognostic risk assessment and selection of appropriate treatment is also an area of current research. Given the increased capacity to visualize a broad array of lesions in both the sacroiliac joints and the spine using MRI and CT, these modalities will probably be increasingly employed for assessment of the disease-modifying activity of new therapies.