title: Comparison of MRI with radiography for detecting structural lesions of the sacroiliac joint using CT as standard of reference: results from the SIMACT study.
abstract: Radiographs of sacroiliac (SI) joints are used for the detection of structural damage in patients with axial spondyloarthritis (axSpA), but are often difficult to interpret. Here, we address the question how the T1-weighted MRI (T1w MRI) sequence compares with radiography for SI joints' structural lesions using low-dose CT as the standard of reference.
  
  
  
  Radiographs, T1w MRI and low-dose CT of the SI joints from 110 patients (mean age 36.1 (19-57) years, 52% males and 48% females; 53% with axSpA, 21 non-radiographic axSpA and 32% radiographic axSpA, 47% with non-SpA) referred to the rheumatologist because of unclear chronic back pain, but possible axSpA, were scored for structural lesions (erosions, sclerosis, joint space changes and an overall impression of positivity).
  
  
  
  Using low-dose CT as the standard of reference, T1w MRI showed markedly better sensitivity with significantly more correct imaging findings compared with radiography for erosions (79% vs 42%; p=0.002), joint space changes (75% vs 41%; p=0.002) and overall positivity (85% vs 48%; p=0.001), respectively, while there were no differences between X-rays and MRI-T1 sequence regarding specificity (>80% for all scores). Only for sclerosis, MRI-T1 was inferior to radiography (sensitivity 30% vs 70%, respectively), however, not statistically significant (p=0.663).
  
  
  
  T1w MRI was superior to radiography in the detection of structural lesion of the SI joints in patients with axSpA. Future studies should focus on finding an agreement on the definition of MRI-T1 positivity.
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Torsten
authors.initials: T
authors.lastname: Diekhoff
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Kay-Geert A
authors.initials: KG
authors.lastname: Hermann
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Juliane
authors.initials: J
authors.lastname: Greese
authors.affiliation: SCO:SSiS Statistical Consulting, Berlin, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Schwenke
authors.affiliation: Clinic of Rheumatology, Medical Department I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Humbolt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Denis
authors.initials: D
authors.lastname: Poddubnyy
authors.affiliation: Department of Radiology, Charité-Universitätsmedizin Berlin, Campus Mitte, Humboldt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.affiliation: Clinic of Rheumatology, Medical Department I, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Humbolt-Universität zu Berlin, Freie Universität Berlin, Berlin, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Sieper
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D012446:Sacroiliac Joint / Q000000981:diagnostic imaging*; D058566:Sacroiliitis / Q000000981:diagnostic imaging*; D012680:Sensitivity and Specificity; D025242:Spondylarthropathies / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D055815:Young Adult
keywords: Ankylosing Spondylitis; Inflammation; Magnetic Resonance Imaging; Spondyloarthritis