Interobserver Reliability of Magnetic Resonance Imaging of Sacroiliac Joints in Axial Spondyloarthritis

Introduction: Axial spondyloarthritis (axSpA) is characterized by damage to the axial skeleton and entheses, and is often associated with extra-articular manifestations, in the presence of the human leukocyte antigen (HLA) B27. The aim of our study is to assess the performance of rheumatologists in interpreting the inflammatory and structural damage to sacroiliac joints, in comparison to radiologists. Material and Methods: The present study included a total of 34 patients diagnosed with axSpA, according to the Assessment of SpondyloArthritis International Society (ASAS) criteria for axSpA, examined from January 2021 to November 2021 in the Departments of Rheumatology and Radiology and Medical Imaging of the University of Medicine and Pharmacy of Craiova. All patients underwent physical examination, laboratory tests, and magnetic resonance imaging (MRI) of the sacroiliac joints. The images were interpreted by a senior radiologist (SR), a junior radiologist (JR), a senior rheumatologist (SRh), and a junior rheumatologist (JRh), who were blinded to the clinical and paraclinical data. Results: The overall kappa was 0.7 for the JR (substantial agreement), 0.707 for the SRh (substantial agreement), and 0.601 for the JRh (moderate agreement), in comparison with the SR. Regarding the overall inflammatory changes, the SRh and JR were proven to have substantial agreement (kappa = 0.708 and 0.742, respectively) with the SR, while the JRh was proven to have moderate agreement (kappa = 0.607). The structural damage observed by the JR showed substantial agreement (kappa = 0.676) with the SR, while the SRh and JRh had substantial and moderate agreement (kappa = 0.705 and 0.596, respectively) with the SR. Conclusions: Our study showed substantial agreement between the senior radiologist, senior rheumatologist, and junior radiologist, and moderate agreement with the junior rheumatologist.