Imaging techniques for early diagnosis of ankylosing spondylitis

Diagnosis of ankylosing spondylitis (AS) is still delayed for several years in some patients. The correct diagnosis of early disease has always been a challenge, which has become even more important as with the introduction of TNF-alpha inhibitors, very effective new treatments have become available. For diagnosis of AS imaging methods such as conventional radiography and computer tomography are well established. Functional imaging modalities including magnetic resonance imaging and contrast-enhanced colour Doppler ultrasound provide additional information on the presence of active inflammatory changes in the sacroiliac joints and may help to diagnose AS before radiographic changes become visible. Magnetic resonance imaging and sonography also identifiy other non-sacroiliac axial manifestations of AS and peripheral involvement such as enthesitis and synovitis of peripheral joints.