Sacroiliac and spine imaging in spondyloarthritis: Does phenotype or sex matter?

Abstract

Spondyloarthritis (SpA) encompasses a spectrum of immune-mediated inflammatory conditions primarily affecting the axial skeleton, including sacroiliitis and spondylitis, each with distinct features. This study aimed to investigate imaging disparities, focusing on sacroiliac magnetic resonance and spine radiography, across phenotypes and between males and females in axial SpA. A cross-sectional study was conducted to assess clinical data, laboratory findings, magnetic resonance imaging (MRI) scores of sacroiliac joints using the Spondyloarthritis Research Consortium of Canada (SPARCC) and Sacroiliac Joint Structural Score (SSS), and cervical and lumbar spine radiographs utilizing the Modified Stoke Ankylosing Spondylitis Spine Score (mSASSS). The study aimed to compare these parameters between two groups: axial spondyloarthritis (axSpA, radiographic and non-radiographic) and axial psoriatic arthritis (axPsA), as well as between males and females. Ninety-four patients were included, with 62 patients in the axSpA group and 32 patients in the axPsA group. There were no differences in disease activity, mobility, radiographic damage in the spine (Modified Stoke Ankylosing Spondylitis Spine Score– mSASSS), or sacroiliac magnetic resonance imaging (MRI) scores (Spondyloarthritis Research Consortium of Canada Magnetic Resonance Imaging Index - SPARCC and Sacroiliac Joint Structural Score - SSS) between the two phenotypes. Regarding sex, in imaging exams, men had higher mSASSS (p = 0.008), SSS (p = 0.001), and fat metaplasia (MG) score based on SSS (p = 0.001), while women had significantly higher SPARCC scores (p = 0.039). In the male group, the presence of HLA-B27 allele had an impact on more structural lesions on MRI (SSS), p = 0.013. In this study, imaging of sacroiliac joints and spine in patients with axial SpA did not show differences in phenotypes but did reveal differences based on sex, which may have an impact on future diagnostic recommendations. Further studies are needed to confirm these findings.