Role for imaging in spondyloarthritis

INTRODUCTION: Despite major progress in the imaging diagnosis of spondyloarthritis (SpA), the relative advantages of various available imaging techniques remain unclear. The aim of this study is to assess the current use of imaging in the diagnosis of SpA and to provide suitable recommendations for the use of imaging as an outcome measure as defined in the Assessment in SpondyloArthritis international Society (ASAS) criteria. EVIDENCE ACQUISITION: A systematic literature search regarding imaging in SpA was performed. Articles were assessed by two reviewers to identify and summarized key information pertaining to imaging in SpA. EVIDENCE SYNTHESIS: The search identified 180 relevant articles. Conventional radiography (CR) (17 articles), ultrasound (US) (26 articles), conventional computed tomography (CT) (13 articles), spectral computed tomography (spectral CT) (2 articles), bone scintigraphy (24 articles), and magnetic resonance imaging (MRI) were assessed (98 articles). Sacroiliitis and enthesitis were the major imaging findings in SpA. Multiple studies assessed the feasibility, validity, or differences among imaging modalities for the diagnosis of SpA; however, comprehensive assessments were not available due to a paucity of prospective imaging studies. CR is a widely available, inexpensive initial approach to evaluate patients with suspected SpA. CT enables assessment of structural changes from chronic sacroiliitis including bony erosions, subchondral sclerosis, joint space narrowing, and ankyloses; however, both CR and CT modalities are insensitive for demonstrating early enthesitis and sacroiliitis in SpA. US mainly identifies appendicular enthesitis but is more limited with respect to the sacroiliac joints. Bone scintigraphy can identify sacroiliac joint lesions and semi-quantitatively assess active sacroiliitis. MRI optimally evaluates not only early enthesitis and sacroiliitis of SpA but also chronic structural changes to the sacroiliac joints. CONCLUSIONS: More than one modality may be required for diagnostic and assessment of SpA depending upon disease characteristics and evolution. CR is a suitable initial examination while MRI is able to detect both early and late changes of SpA. A combination of CR and MRI is recommended for the diagnosis and assessment of SpA.