The contribution of imaging in the diagnosis and treatment of axial spondyloarthritis.

Abstract

The concept of axial Spondyloarthritis (axSpA) includes patients with non-radiographic axSpA and ankylosing spondylitis (AS). Inflammatory and chronic/structural changes of the sacroiliac joints and the spine are pathognomonic in patients who are diagnosed with axSpA. In the last years, the evaluation of the natural course of axSpA has been in the focus of research, especially with respect to the relationship between inflammation or postinflammatory changes [detected by magnetic resonance imaging (MRI)] and bone formation (detected by conventional radiographs). Based on the analysis of spinal MRI data, development of new syndesmophytes is directly associated with the parallel occurrence of inflammatory and postinflammatory (fatty) changes in the edges of the vertebral bodies. In contrast, vertebral edges that show only inflammation but no transformation into fatty lesions show a decreased relative risk for development of new bone formation over time. An inhibitory effect on radiographic progression had not been demonstrated during the first 2years of continuous anti-TNFa treatment, however, very recently first studies reported a decreased rate of radiographic progression when patients were continuously treated with TNFa-blockers for a time period of ≥4years. These data are crucial in the understanding of the long-term clinical course of patients with axSpAin daily practice. According to these results, it becomes obvious that anti-inflammatory treatment, especially by using tumor-necrosis-factor alpha (TNFa)-blockers, has the best effect on the radiographic outcomes when it is started in anearly disease stage, where only inflammation is driving the disease activity and where structural, postinflammatory changes have not yet occurred.