Choose wisely: Imaging for diagnosis of axial spondyloarthritis

Torsten Diekhoff*, Iris Eshed, Felix Radny, Katharina Ziegeler, Fabian Proft, Juliane Greese, Dominik Deppe, Robert Biesen, Kay Geert Hermann, Denis Poddubnyy

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Objective To assess the diagnostic accuracy of radiography (X-ray, XR), CT and MRI of the sacroiliac joints for diagnosis of axial spondyloarthritis (axSpA). Methods 163 patients (89 with axSpA; 74 with degenerative conditions) underwent XR, CT and MR. Three blinded experts categorised the imaging findings into axSpA, other diseases or normal in five separate reading rounds (XR, CT, MR, XR +MR, CT +MR). The clinical diagnosis served as reference standard. Sensitivity and specificity for axSpA and inter-rater reliability were compared. Results XR showed lower sensitivity (66.3%) than MR (82.0%) and CT (76.4%) and also an inferior specificity of 67.6% vs 86.5% (MR) and 97.3% (CT). XR +MR was similar to MR alone (sensitivity 77.5 %/specificity 87.8%) while CT+MR was superior (75.3 %/97.3%). CT had the best inter-rater reliability (kappa=0.875), followed by MR (0.665) and XR (0.517). XR +MR was similar (0.662) and CT+MR (0.732) superior to MR alone. Conclusions XR had inferior diagnostic accuracy and inter-rater reliability compared with cross-sectional imaging. MR alone was similar in diagnostic performance to XR+MR. CT had the best accuracy, strengthening the importance of structural lesions for the differential diagnosis in axSpA.

Original languageEnglish
Pages (from-to)237-242
Number of pages6
JournalAnnals of the Rheumatic Diseases
Issue number2
StatePublished - 1 Feb 2022
Externally publishedYes


  • ankylosing
  • low back pain
  • magnetic resonance imaging
  • spondylitis


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