title: Diagnostic utility of magnetic resonance imaging and radiography in juvenile spondyloarthritis: evaluation of the sacroiliac joints in controls and affected subjects.
abstract: OBJECTIVE
  To compare the utility of radiography and magnetic resonance imaging (MRI) for the diagnosis of juvenile-onset spondyloarthritis in pediatric patients presenting with low back and/or sacroiliac (SI) pain of potentially inflammatory etiology.
  
  
  METHODS
  Radiographs and MRI studies of the SI joints in 26 patients with juvenile spondyloarthritis (JSpA) and 35 controls were assessed independently by 2 radiologists, with discrepancies arbitrated by a third. Radiographs and MRI were blinded and read in separate batches in random order.
  
  
  RESULTS
  Erosion was common and was the most useful diagnostic feature on radiography [positive likelihood ratio (LR) = 3.5] and was especially diagnostic of SpA on MRI (LR = 6.7). Subchondral sclerosis was common but was the least specific feature for both modalities. Joint space narrowing had some utility on radiography (LR = 2.0) and MRI (LR = 2.7) but was uncommon and had poor reader reliability. Bone marrow edema (LR = 3.1) and subarticular fat infiltration (LR = 4.5), detectable only on MRI, were both useful features. Global diagnostic impression of MRI (LR = 9.4) had very high utility for the diagnosis of JSpA, exceeding radiography (LR = 4.4) because of superior specificity. In addition, global diagnosis of SpA is much more reliably made on MRI (κ = 0.80) compared to radiography (κ = 0.30).
  
  
  CONCLUSIONS
  Specificity and reliability of MRI of the SI joints are superior to radiography for the diagnosis of juvenile-onset SpA and, where available, MRI should replace radiography as the first line of investigation.
authors.affiliation: From the Department of Radiology and Diagnostic Imaging, and the Department of Pediatrics, W.C. Mackenzie Health Sciences Centre, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Jaremko
authors.forename: Lei
authors.initials: L
authors.lastname: Liu
authors.forename: Naomi J
authors.initials: NJ
authors.lastname: Winn
authors.forename: Janet E
authors.initials: JE
authors.lastname: Ellsworth
authors.forename: Robert G W
authors.initials: RG
authors.lastname: Lambert
mesh_terms: D000293:Adolescent; D001175:Arthrography / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D001853:Bone Marrow / Q000000981:diagnostic imaging / Q000473:pathology; D016208:Databases, Factual; D004487:Edema / Q000000981:diagnostic imaging / Q000473:pathology; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards / Q000706:statistics & numerical data; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012189:Retrospective Studies; D058566:Sacroiliitis / Q000000981:diagnostic imaging / Q000473:pathology; D012680:Sensitivity and Specificity; D025242:Spondylarthropathies / Q000000981:diagnostic imaging* / Q000473:pathology*; D013167:Spondylitis, Ankylosing / Q000000981:diagnostic imaging* / Q000473:pathology*
keywords: ANKYLOSING SPONDYLITIS; MAGNETIC RESONANCE IMAGING; PEDIATRICS; RADIOGRAPHY; SPONDYLARTHROPATHIES