title: High-b-value diffusion-weighted MR imaging of benign hepatocellular lesions: quantitative and qualitative analysis.
abstract: OBJECTIVE
  To analyze the signal intensity (SI) of benign hepatocellular lesions in high-b-value diffusion-weighted (DW) magnetic resonance (MR) images and to compare the apparent diffusion coefficient (ADC) values of focal nodular hyperplasias (FNHs) with those of hepatocellular adenomas (HCAs).
  
  
  METHODS
  This retrospective study was approved by institutional review board, with waiver of informed consent. Inclusion criteria were consecutive patients with diagnosed FNH or HCA who underwent MR imaging with a DW sequence of the liver at three b values, 0, 150, and 600 sec/mm2. The final study population included 67 patients (seven men, 60 women) with 90 hepatocellular lesions (54 FNHs, 36 HCAs). The mean ADC was compared between the lesions and the liver. Receiver operating characteristic analysis was performed to evaluate the diagnostic value of ADC for differentiating HCAs and FNHs.
  
  
  RESULTS
  The mean ADC value of all FNHs and HCAs was significantly lower than that of the liver (P=.004). An ADC ratio below 15% was observed in 50 of 54 (93%) FNHs and in 29 of 36 (81%) HCAs. The mean ADC value of FNHs was significantly higher than that of HCAs (P<.001). The area under the receiver operating characteristic curve was 0.760. With a cutoff value of 1.37×10(-3) mm2/sec, the sensitivity and specificity for differentiating HCA from FNH were 70% and 76%, respectively. There was no significant difference in ADC values between HCA subtypes. The SI of most FNHs and HCAs (78 of 90, 87%) increased with increasing b values, whereas none showed a decrease in SI with increasing b values. When the DW MR criteria for benign and malignant liver tumors were applied, 44 of 90 (49%) lesions would have been considered malignant lesions, whereas the other lesions (46 of 90, 51%) would have been considered indeterminate.
  
  
  CONCLUSIONS
  On DW MR images, benign hepatocellular lesions often show findings that suggest restricted diffusion.
authors.affiliation: Department of Radiology, Assistance-Publique Hôpitaux de Paris, APHP, Hôpital Beaujon, 100 bd du Général Leclerc, 92110 Clichy, France.
authors.forename: Francesco
authors.initials: F
authors.lastname: Agnello
authors.forename: Maxime
authors.initials: M
authors.lastname: Ronot
authors.forename: Dominique C
authors.initials: DC
authors.lastname: Valla
authors.forename: Ralph
authors.initials: R
authors.lastname: Sinkus
authors.forename: Bernard E
authors.initials: BE
authors.lastname: Van Beers
authors.forename: Valérie
authors.initials: V
authors.lastname: Vilgrain
mesh_terms: D018248:Adenoma, Liver Cell / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000465:Algorithms; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008113:Liver Neoplasms / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult