Sacroiliac-Only MRI Protocol for Detection of Axial Spondyloarthritis: A Quality Improvement Study

Objectives St. Joseph’s Healthcare Hamilton (SJHH) changed its MRI protocol for axial spondyloarthritis (axSpA), shifting from full imaging of the spine and sacroiliac joints (SI) to an SI joint-only protocol. This study aimed to evaluate whether the diagnostic accuracy for axSpA would be reduced with this limited MRI protocol. Methods This was a retrospective chart review. Using electronic medical records from 4 community rheumatologists in Southwestern Ontario, a computerized search was performed to identify all patients newly diagnosed with axSpA between January 2011 to January 2021 who had an MRI-axSpA protocol performed at SJHH. MRI reports were reviewed to determine the presence of isolated spondylitis vs sacroiliitis with or without spondylitis. Patient characteristics including age, sex, HLA-B27 status, CRP and ESR at the time of MRI, personal and family history of psoriasis or psoriatic arthritis, personal and family history of inflammatory bowel disease, and family history of axial spondyloarthritis/ankylosing spondylitis, were also extracted. Data analysis was performed using logistic regression with missing data imputed using the CART method. Results A total of 1,356 patient charts were identified and 135 patients fulfilled inclusion criteria. The mean age was 42 (± 14) and 55% were female. Of these, 126 patients (93%) had sacroiliitis with or without spondylitis and 9 (7%) had spondylitis alone. A sacroiliac-only protocol would have identified 93% of axSpA cases. Patients with isolated spondylitis were more likely to have a personal or family history of psoriatic arthritis (OR 6.77, 95% CI [1.18, 38.76]). We further approximated cost and time savings to be $700 and 30 minutes per scan, or ~$94,500 and 67.5 hours, respectively, over 10 years for this study cohort. Conclusion A sacroiliac-only MRI protocol maintains high diagnostic yield while reducing costs and the time an MRI machine is occupied. However, clinicians should consider spine imaging in select patients specifically those with a personal or family history of psoriasis or psoriatic arthritis. Larger studies are warranted to validate these findings and to better define the role of spinal MRI in patients with suspected axial PsA.