title: Liver fibrosis: noninvasive assessment with MR elastography versus aspartate aminotransferase-to-platelet ratio index.
abstract: OBJECTIVE
  To prospectively compare the sensitivity and specificity of magnetic resonance (MR) elastography with those of the routinely available aspartate aminotransferase-to-platelet ratio index (APRI) test for staging hepatic fibrosis in patients who have undergone liver biopsy for suspicion of chronic liver disease, with histopathologic examination as the reference standard.
  
  
  METHODS
  The study was approved by the ethics committee. All patients gave written informed consent. Eighty-eight patients (37 men, 51 women; mean age, 54.0 years +/- 13.1 [standard deviation]) who underwent liver biopsy for suspicion of chronic liver disease underwent MR elastography and APRI testing within 2 days after liver biopsy. At histopathologic examination, the fibrosis stage was assessed according to METAVIR scores (fibrosis scores F0 [no fibrosis] to F4 [cirrhosis]). MR elastography was performed by transmitting mechanical waves within the liver and measuring the small cyclic displacement of the liver spins with a phase-contrast spin-echo sequence. The performances of MR elastography and APRI testing were assessed, and the optimal cutoff values for fibrosis stage were determined with receiver operating characteristic (ROC) curve analysis.
  
  
  RESULTS
  At MR elastography, areas under the ROC curves (A(z)) for elasticity and viscosity, respectively, were 0.999 and 0.863 at fibrosis scores greater than or equal to F2, 0.997 and 0.962 at scores greater than or equal to F3, and 1.000 and 0.986 at score F4. A(z) values for elasticity at MR were significantly larger than those for the APRI (0.854 at scores > or = F2, P < .001; 0.886 at scores > or = F3, P = .003; and 0.851 at score F4, P = .004). Optimal cutoff values of elasticity were 2.5 kPa for fibrosis scores greater than or equal to F2, 3.1 kPa for scores greater than or equal to F3, and 4.3 kPa for score F4.
  
  
  CONCLUSIONS
  Large A(z) values for elasticity (>0.990 for scores > or = F2, > or = F3, and F4) show that MR elastography was accurate in liver fibrosis staging and superior to biochemical testing with APRIs.
authors.affiliation: Diagnostic Radiology Unit, Department of Pathology, and Laboratory of Gastroenterology, Université Catholique de Louvain, St-Luc University Hospital, B-1200, Brussels, Belgium. laurent.huwart@clin.ucl.ac.be
authors.forename: Laurent
authors.initials: L
authors.lastname: Huwart
authors.forename: Christine
authors.initials: C
authors.lastname: Sempoux
authors.forename: Najat
authors.initials: N
authors.lastname: Salameh
authors.forename: Jacques
authors.initials: J
authors.lastname: Jamart
authors.forename: Laurence
authors.initials: L
authors.lastname: Annet
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Frank
authors.initials: F
authors.lastname: Peeters
authors.forename: Leon C
authors.initials: LC
authors.lastname: ter Beek
authors.forename: Yves
authors.initials: Y
authors.lastname: Horsmans
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Van Beers
mesh_terms: D024443:Aspartate Aminotransferase, Cytoplasmic / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008103:Liver Cirrhosis / Q000097:blood* / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D010976:Platelet Count; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D024443:Aspartate Aminotransferase, Cytoplasmic