Sacroiliac Joint Magnetic Resonance Imaging in Asymptomatic Patients with Recurrent Acute Anterior Uveitis: A Proof-of-concept Study

Objective. Our aim was to quantify bone marrow edema (BME) and/or structural lesions in the sacroiliac joints (SIJ) of patients with recurrent acute anterior uveitis (rAAU) with or without back pain, to evaluate the frequency of axial (axSpA) and peripheral spondyloarthritis (pSpA) and to establish which criterion for magnetic resonance imaging (MRI) positivity best reflected the global assessment of SIJ MRI. Methods. A total of 50 patients with rAAU without prior rheumatologic diagnosis were included in our cross-sectional study, and these patients were compared to 21 healthy volunteers. SIJ MRI scans were read by 2 rheumatologists according to the Spondyloarthritis Research Consortium of Canada (SPARCC/MORPHO) protocol. Discrepant cases were adjudicated by a radiologist. Results. Patients with rAAU were diagnosed with axSpA (Group 1, n = 20, 40%) and nonspecific back pain (Group 2, n = 6, 12%), or as being asymptomatic (Group 3, n = 24, 48%). Group 3 results showed 9 patients (37.5%) had SIJ MRI and/or were radiography-positive for axSpA (5 MRI and radiograph, 1 MRI, 3 radiograph). SIJ MRI scans that were compatible with SpA in groups 1 (n = 12) and 3 (n = 6) were similar in acute and structural lesions that were analyzed according to SPARCC/MORPHO. The best sensitivity/specificity criterion for defining a positive global MRI assessment was a BME score = 3 (88%/94%). Conclusion. This is the first study evaluating SIJ MRI in patients with rAAU without back symptoms, showing positive findings for sacroiliitis. Moreover, a BME score >= 3 had better performance to define an SIJ MRI as positive for axSpA.