Background Different systems to quantify inflammatory changes in sacroiliac MRI have been developed.[1, 2] These systems include the Spondyloarthritis Research Consortium of Canada (SPARCC), the Berlin, the Aarhus-Puhakka, and Aarhus-Madsen, the Leeds, the MR Imaging of Seronegative SpA (MISS), Leeds, Sieper/Rudwaleit and Hermann/Bollow scoring systems. In addition, the use of these quantification methods is restricted to clinical trials, since their use in clinical practice is limited due to their complexity, need for trained personal, and prolonged procedural time. The development of computers and data processing software has led to significant advances in methods for image analysis. With the objective to improve interobserver quantification of sacroiliitis while maintaining a practical perspective, our group has developed a semi-automated method to measure bone marrow edema (BME) in MRI images from sacroiliac (SI) joints.
Objectives The aim of this study is to analyze the validity and reliability of the method.
Methods The development of the method to quantify inflammation in SI joints involved software selection from a list of potential programs, process-mapping based on discussion, and tuning. Once developed, feasibility (time spent) interobserver reliability (intraclass correlation coefficient), and construct validity (convergent validity) were analysed. Two rheumatologists and a radiologist independently quantified sacroiliitis from SI images from 12 patients with a diagnosis of axial SpA by the new method, and by non-automated methods to rate sacroiliitis (SPARCC* and Berlin). Convergent validity, reliability and feasibility were calculated. (* In the present study, for simplicity reasons and in order to make it closer to the developed technique, the authors modified the SPARCC method by using a single coronal section instead of the standard six consecutive ones).
Results The interobserver reliability was high, with intraclass correlation coefficients for global score of 0.81 (95% CI: 0.59–0.94). Convergent validity was good, with high correlation with the Berlin (rho between 0.797 and 0.913) and the SPARCC methods (rho between 0.566 and 0.897). Mean time employed in the reading procedure was 30 seconds.
Conclusions The developed semi-automatic technique permits a fast and valid calculation of overall BME lesion at the SI joint on MRI images.
van der Heijde DM, Landewe RB, Hermann KG, et al. Application of the OMERACT filter to scoring methods for magnetic resonance imaging of the sacroiliac joints and the spine. Recommendations for a research agenda at OMERACT 7. J Rheumatol 2005; 32(10):2042–2047.
Ostergaard M, Poggenborg RP, Axelsen MB, et al. Magnetic resonance imaging in spondyloarthritis–how to quantify findings and measure response. Best Pract Res Clin Rheumatol 2010; 24(5):637–657.
Disclosure of Interest None declared