title: Value of diffusion-weighted MRI for assessing liver fibrosis and cirrhosis.
abstract: OBJECTIVE
  The objective of our study was to determine the usefulness of the apparent diffusion coefficient (ADC) of liver parenchyma for determining the severity of liver fibrosis.
  
  
  METHODS
  This study investigated 78 patients who underwent diffusion-weighted imaging (DWI) with 1.5-T MRI and pathologic staging of liver fibrosis based on biopsy. DWI was performed with b values of 50 and 400 s/mm(2). ADCs of liver were measured using 2.0- to 3.0-cm(2) regions of interest in the right and left lobes of the liver; the mean ADC value was used for analysis. Pathologic METAVIR scores for liver fibrosis stage were used as a reference standard.
  
  
  RESULTS
  The mean ADC values for fibrosis pathologically staged using the METAVIR classification system as F0 (n = 11), F1 (n = 16), F2 (n = 10), F3 (n = 14), and F4 (n = 27) were 125.9, 105.0, 104.5, 103.2, and 99.1 x 10(-5) s/mm(2), respectively. The correlation between the ADC values and the degree of liver fibrosis was moderate (Spearman's test, rho = -0.36). There was a significant difference in ADC values between patients with nonfibrotic liver (F0) and those with cirrhotic liver (F4) (p = 0.008). The best cutoff ADC value to distinguish between these groups was 118 x 10(-5) s/mm(2). However, ADC values were not useful for differentiating viral hepatitis patients with F2 fibrosis or higher from those with a lower degree of fibrosis (area under the receiver operating characteristic curve [AUC] = 0.66) or for differentiating low-stage fibrosis in all patients from high-stage fibrosis in all patients (AUC = 0.54).
  
  
  CONCLUSIONS
  The ADCs in cirrhotic livers are significantly lower than those in nonfibrotic livers. However, ADC values measured using the current generation of scanners are not reliable enough to replace liver biopsy for staging hepatic fibrosis.
authors.affiliation: Department of Radiology, Indiana University School of Medicine, UH 0279, Indianapolis, IN 46202, USA. ksandras@iupui.edu
authors.forename: Kumaresan
authors.initials: K
authors.lastname: Sandrasegaran
authors.forename: Fatih M
authors.initials: FM
authors.lastname: Akisik
authors.forename: Chen
authors.initials: C
authors.lastname: Lin
authors.forename: Bilal
authors.initials: B
authors.lastname: Tahir
authors.forename: Janaki
authors.initials: J
authors.lastname: Rajan
authors.forename: Romil
authors.initials: R
authors.lastname: Saxena
authors.forename: Alex M
authors.initials: AM
authors.lastname: Aisen
mesh_terms: D000328:Adult; D000368:Aged; D001706:Biopsy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods; D005260:Female; D006801:Humans; D008103:Liver Cirrhosis / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D018709:Statistics, Nonparametric