Objective: To develop semiaxial magnetic resonance imaging (MRI) scoring methods for assessment of sacroiliac joint (SIJ) bone marrow edema (BME) in patients with axial spondyloarthritis, and to compare the reliability with equivalent semicoronal scoring methods.
Methods: Two semiaxial SIJ MRI scoring methods were developed based on the principles of the semicoronal Berlin and Spondyloarthritis Research Consortium of Canada (SPARCC) methods. A global quadrant-based method was also developed. Baseline and 12-week MRI of the SIJ from 51 patients participating in a randomized double-blind placebo-controlled trial of adalimumab 40 mg every other week versus placebo were scored by the semiaxial and the corresponding semicoronal methods. Results were compared by linear regression analysis. The reproducibility and sensitivity were evaluated by intraclass correlation coefficients (ICC) and smallest detectable change [SDC, absolute values and percentage of the highest observed score (SDC-HOS)].
Results: Interreader and intrareader ICC were moderate to very high for semiaxial scoring methods (baseline 0.83-0.88 and 0.85-0.97; change 0.33-0.78), while high to very high for semicoronal scoring methods (baseline 0.90-0.92 and 0.93-0.97; change 0.77-0.89). Association between semiaxial and semicoronal scores were high for both the Berlin and SPARCC method (baseline: R2 = 0.93 and 0.88; change: R2 = 0.82 and 0.87, respectively), while lower for the global method (baseline: R2 = 0.79; change: R2 = 0.54). The SDC-HOS were 9.8-18.6% and 5.9-10.7% for the semiaxial and semicoronal methods, respectively.
Conclusion: Detection of SIJ BME in the semiaxial scan plane is feasible and reproducible. However, a slightly lower reliability of all 3 semiaxial methods supports the general practice of using the coronal scan-plane in therapeutic studies.
Keywords: BONE MARROW EDEMA; MAGNETIC RESONANCE IMAGING; SACROILIAC JOINT; SEMIAXIAL SCORING; SEMICORONAL SCORING.