PT - JOURNAL ARTICLE AU - Torsten Diekhoff AU - Iris Eshed AU - Felix Radny AU - Katharina Ziegeler AU - Fabian Proft AU - Juliane Greese AU - Dominik Deppe AU - Robert Biesen AU - Kay Geert Hermann AU - Denis Poddubnyy TI - Choose wisely: imaging for diagnosis of axial spondyloarthritis AID - 10.1136/annrheumdis-2021-220136 DP - 2022 Feb 01 TA - Annals of the Rheumatic Diseases PG - 237--242 VI - 81 IP - 2 4099 - http://ard.bmj.com/content/81/2/237.short 4100 - http://ard.bmj.com/content/81/2/237.full SO - Ann Rheum Dis2022 Feb 01; 81 AB - 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.Data are available on reasonable request. All data relevant to the study are included in the article or uploaded as online supplemental information. All source data including but not limited to scoring results and primary imaging are available from the corresponding author on request.