To investigate whether initial whole spine magnetic resonance imaging (MRI) predicts radiographic progression and inflammatory activity in patients with axial spondyloarthritis (axSpA).

A retrospective analysis of spine MRI and X-rays from 70 axSpA patients was conducted. The number of affected discovertebral units was determined according to the definition of pathologic lesions on spine MRI set down by the ASAS/OMERACT group. Radiographic progression was defined as an increase in the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS) of≥2 compared with baseline. The association of spine MRI with radiographic progression, cumulative C-reactive protein (CRP), and cumulative erythrocyte sedimentation rate (ESR) was investigated.

The axSpA-relevant lesions on spine MRI at baseline were independent predictors of radiographic progression. Arthritis of the costovertebral and costotransverse joints on MRI showed the highest odds ratio at 3years (OR [95% CI]: 2.54 [1.29–5.02]). Receiver operating characteristic curve analysis revealed that the area under the curve (AUC) for radiographic progression at 2years was 0.89 [95% CI: 0.81–0.96] for structural lesions and 0.83 [95% CI: 0.72–0.94] for inflammatory lesions. Notably, subgroup analysis of 26 patients with mSASSS=0 showed that fatty metaplasia on MRI were highly predictive of radiographic progression at 3years (AUC [95% CI]: 0.87 [0.61–1.00]). Moreover, 3-year cumulative ESR and CRP values increased in proportion to the extent of inflammatory lesions on initial MRI.

Initial MRI assessment of the whole spine may predict radiographic progression and subsequent systemic inflammatory burden in axSpA patients, particularly those without axSpA-relevant abnormalities on spine X-rays.