Magnetic resonance imaging in ankylosing spondylitis

MRI has been increasingly used as an imaging modality in patients with ankylosing spondylitis (AS) and other spondyloarthritides due to its capacity to identify both active inflammation and chronic structural changes in the spine and sacroiliac joints. Traditionally, the structural changes of AS are assessed using conventional radiographs at those sites. According to the modified New York criteria the diagnosis/classification of AS requires radiographic changes in the sacroiliac joints of at least grade 2 unilaterally [1]. This approach does not allow a diagnosis for cases of 'early' spondyloarthritis or AS in which structural change has not yet occurred. This may, in turn, mean that a window of opportunity to treat patients before they develop irreversible bony changes may be missed. This review looks at the current role of MRI in assessing AS, and its potential in identifying early disease for early intervention.