MRI Contributes to Accurate and Early Diagnosis of Non-Radiographic HLA-B27 Negative Axial Spondyloarthritis

Background: Structural changes to sacroiliac joints cannot be adopted to confirm active sacroiliitis on magnetic resonance imaging in the absence of bone marrow edema (BME). However, less than half of Asian patients with axial spondyloarthritis were characterized by BME. We aim to define the best methodology for accurate diagnosis, especially in the area with less common bone marrow edema and serum human leukocyte antigen-B27 (HLA-B27). Methods
We included 103 patients with inflammatory back pain and morning stiffness in this prospective study. No radiograph met the definition of positive modified New York criteria. Inflammation and structural damage on magnetic resonance imaging were evaluated. Serum c-reactive protein and HLA-B27 levels were collected. Correlations between the various collected variables were analyzed.
Results
We demonstrated a positive association between inflammatory lesions and structural damage in the 58 ASAS-defined nr-axSpA subjects. BME on magnetic resonance imaging is moderately correlated with sclerosis and focal joint space widening (fJSW) (phi score of 0.372 and 0.319, p = 0.005 and 0.015, respectively). A moderately positive correlation between either the severity of BME and fJSW ( p = 0.004) in 36 patients who had BME and met Assessment of Spondyloarthritis international Society criteria. There is a positive correlation between BME and fJSW across the whole cohort (phi score of 0.389; p < 0.001). We also identified a positive correlation between fJSW and BME in patients with non-radiographic axial spondyloarthritis and normal serum c-reactive protein levels (phi score of 0.362 and p = 0.001).
Conclusion
Severe erosions like fJSW on MRI-SIJs is positively correlated with development of BME on MRI and helps contribute to accurate diagnosis of non-radiographic axial spondyloarthritis either in the absence of HLA-B27 or normal serum inflammatory biomarkers, which might be used alternatively for early diagnosis of non-radiographic axial spondyloarthritis in Asian people who are characterized by less prevalence of BME and HLA-B27.