Imaging in axial spondyloarthritis: Changing concepts and thresholds.

Imaging is key to recognition of axial spondyloarthritis (SpA) because clinical and laboratory examinations have limited diagnostic utility. Only MRI can capture both inflammation and bone remodeling by simultaneous depiction of active and structural lesions and their anatomic location. Bone marrow edema of limited extent on the sacroiliac joint (SIJ) MRI is often nonspecific and should be interpreted along with the clinical context. Contextual interpretation of the SIJ lesion signature viewed simultaneously on fluid- and fat-sensitive MRI sequences enhances confidence in the recognition of disease. A critical re-appraisal of using pelvic radiographs in clinically suspected early spondyloarthritis is warranted because of substantial limitations. In health care settings with low threshold access to advanced imaging, MRI is the preferred modality in early SpA. CT has recently advanced spinal outcome research, but substantial radiation exposure in young patients with spondyloarthritis and limited evidence on its relevance in practice do not advocate its use in daily routine.