title: A comparison of non-contrast and contrast-enhanced MRI in the initial stage of Legg-Calvé-Perthes disease.
abstract: BACKGROUND
  A prognostic indicator of outcome for Legg-Calvé-Perthes disease (LCP) is needed to guide treatment decisions during the initial stage of the disease (stage 1), before deformity occurs. Radiographic prognosticators are applicable only after fragmentation (stage II).
  
  
  OBJECTIVE
  We investigated pre- and postcontrast MRI in depicting stage I femoral head involvement.
  
  
  METHODS
  Thirty children with stage I LCP underwent non-contrast coronal T1 fast spin-echo (FSE) and corresponding postcontrast fat-suppressed T1-weighted fast spin-echo (FSE) sequences to quantify the extent of femoral head involvement. Three pediatric radiologists and one pediatric orthopedic surgeon independently measured central head involvement.
  
  
  RESULTS
  Interobserver reliability of percent head involvement using non-contrasted MR images had intraclass correlation coefficient (ICC) of 0.72. Postcontrast MRI improved interobserver reliability (ICC 0.82). Qualitatively, the area of involvement was more clearly visible on contrast-enhanced MRI. A comparison of results obtained by each observer using the two MRI techniques showed no correlation. ICC ranged from -0.08 to 0.03 for each observer. Generally, greater head involvement was depicted by contrast compared with non-contrast MRI (Pearson r = -0.37, P = 0.04).
  
  
  CONCLUSIONS
  Pre- and postcontrast MRI assess two different components of stage I LCP. However, contrast-enhanced MRI more clearly depicts the area of involvement.
authors.affiliation: Center of Excellence in Hip Disorders, Texas Scottish Rite Hospital for Children, Dallas, TX 75219, USA. harry.kim@tsrh.org
authors.forename: Harry K W
authors.initials: HK
authors.lastname: Kim
authors.forename: Sue
authors.initials: S
authors.lastname: Kaste
authors.forename: Molly
authors.initials: M
authors.lastname: Dempsey
authors.forename: David
authors.initials: D
authors.lastname: Wilkes
mesh_terms: D000293:Adolescent; D002648:Child; D003287:Contrast Media; D005260:Female; D005270:Femur Head / Q000473:pathology*; D005682:Gadolinium; D006571:Heterocyclic Compounds; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007873:Legg-Calve-Perthes Disease / Q000473:pathology*; D008297:Male; D015588:Observer Variation; D009942:Organometallic Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C062402:gadoteridol; D005682:Gadolinium