title: MR imaging of children and young adults with classic findings of osteonecrosis on unenhanced MR images: do contrast-enhanced sequences help?
abstract: BACKGROUND
  The added value of routine contrast-enhanced MR imaging in children with classic findings of osteonecrosis on unenhanced MR images has not been determined.
  
  
  OBJECTIVE
  Our purpose was to determine the added value of routine contrast-enhanced MR sequences for identifying complications of osteonecrosis.
  
  
  METHODS
  Sixty-four patients who underwent 139 contrast-enhanced MR examinations were retrospectively identified. Unenhanced images and subsequently both unenhanced and enhanced images were reviewed in consensus. The location of osteonecrosis and the presence of complicating features (epiphyseal collapse, marrow edema, joint effusion, soft tissue edema) were recorded. Cohen's kappa coefficients (κ) were calculated to assess agreement.
  
  
  RESULTS
  A diagnosis of classic osteonecrosis was made in 22.3% of unenhanced examinations and 28.1% of enhanced examinations (κ = 0.734, P < 0.001). Among patients with complicated osteonecrosis, unenhanced images interpreted without and with contrast-enhanced images showed epiphyseal collapse in 51.2% and 42.5% (κ = 0.796, P < 0.001), marrow edema in 50.4% and 46.8% (κ = 0.727, P < 0.001), joint effusion in 44.9% and 51.2% (κ = 0.686, P < 0.001), and soft tissue edema in 12.2% and 10.1% (κ = 0.674, P < 0.001).
  
  
  CONCLUSIONS
  The high observed agreement between the unenhanced MR images interpreted without and with contrast-enhanced images shows little marginal benefit from the use of routine contrast-enhanced imaging in children and young adults with classic findings of osteonecrosis on unenhanced MR images.
authors.affiliation: EB Singleton Department of Pediatric Radiology, Texas Children's Hospital, 6621 Fannin Street, Houston, TX, 77030, USA, lamya.atweh@gmail.com.
authors.forename: Lamya A
authors.initials: LA
authors.lastname: Atweh
authors.forename: Robert C
authors.initials: RC
authors.lastname: Orth
authors.forename: R Paul
authors.initials: RP
authors.lastname: Guillerman
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: J Herman
authors.initials: JH
authors.lastname: Kan
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging / Q000706:statistics & numerical data*; D008297:Male; D015588:Observer Variation; D010020:Osteonecrosis / Q000453:epidemiology* / Q000473:pathology*; D015995:Prevalence; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D017678:Sex Distribution; D013781:Texas / Q000453:epidemiology; D055815:Young Adult
chemical_list: D003287:Contrast Media; D019786:Gadolinium DTPA