Radiologic approach to axial spondyloarthritis: where are we now and where are we heading?

Abstract

Current emphasis on diagnosing axial spondyloarthritis (axSpA) in early stage enforced the search for sensitive and specific diagnostic algorithms with the use of imaging methods. The aim of this review was to summarise current recommendations concerning the use of imaging techniques in diagnostics and monitoring of axSpA as well as to outline possible future directions of the development in this field. MEDLINE database was searched between March and April 2018. In the first phase, such keywords were applied: 'ASAS', 'EULAR', 'ASAS-EULAR', 'ASAS/OMERACT', 'axial spondyloarthritis', while in the second step: 'axial spondyloarthritis', 'ankylosing spondylitis', 'magnetic resonance imaging', 'computed tomography', and 'radiography', 'imaging'. An up-to-date summary of European League Against Rheumatism (EULAR) recommendations enriched with recent updates of Assessment of Spondyloarthritis International Society (ASAS) diagnostic criteria regarding imaging in axSpA course was created. Moreover, we outlined the role of new in this field, promising imaging techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced sequences in magnetic resonance imaging (MRI) or low-dose computed tomography (CT). As precise monitoring of axSpA activity is vital, we reviewed the most precise methods: semiquantitative scores (e.g., Spondyloarthritis Research Consortium of Canada scores or CT Syndesmophyte Score) and quantitative analysis of MRI-based apparent diffusion coefficient or perfusion maps and enhancement curves. According to EULAR and ASAS recommendations, radiography and MRI still remain basic methods of axSpA diagnostics and monitoring. However, the knowledge of state-of-the-art international guidelines combined with the awareness of emerging imaging methods is the key to effective management of axSpA.

Keywords: ASAS recommendations; Ankylosing spondylitis; Axial spondyloarthropathy; EULAR recommendations; Magnetic resonance imaging; Sacroiliac joints.

Fig. 1

Typical axSpA bone-marrow oedema lesion (white arrow) in the lower sacral quadrant of the left sacroiliac joint on STIR sequence (a) and contrast-enhanced T1-weighted sequence (b). STIR, short tau inversion recovery

Fig. 2

Active inflammatory lesion in the course of axSpA (white arrow) located in the iliac part of the left sacroiliac joint on DWI (b = 800) sequence (a) and colour ADC map (b). DWI, diffusion-weighted imaging; ADC, apparent diffusion coefficient

Fig. 3

Active inflammatory lesion in the course of axSpA (white arrow) situated in the iliac part of the left sacroiliac joint visualised with use of DCE sequence (a) and maximal perfusion colour-coded map (b)

Fig. 4

Area under the perfusion curve colour-coded map of the sacral region of the person with axSpA, with marked inflammatory lesion in the upper iliac quadrant of the left sacroiliac joint (Roi 1, blue line) and respective unaffected area in the right sacroiliac joint (Roi 2, orange line) (a). The graph of relative percentage enhancement versus time of acquisition showing the pattern of enhancement in typical axSpA active inflammatory lesion (Roi 1, blue line) in comparison to intact, non-enhancing tissue (Roi 2, orange line) (b)