title: Diffusion-weighted imaging of the liver: optimizing b value for the detection and characterization of benign and malignant hepatic lesions.
abstract: OBJECTIVE
  To determine the optimal b values required for diffusion-weighted (DW) imaging of the liver in the detection and characterization of benign and malignant hepatic lesions.
  
  
  METHODS
  MR images obtained in 76 patients including 28 malignant hepatic lesions (21 hepatocellular carcinomas and 7 metastases) and 27 benign lesions (12 hemangiomas and 15 cysts) were reviewed. DW-echo planner images (EPIs; b values with 100, 200, 400, and 800 s/mm2) were reviewed solely first, and then with T2-weighted EPIs (b=0 s/mm2).
  
  
  RESULTS
  Sensitivity for malignant lesions (74%) was highest on DW-EPIs with b value of 100 s/mm2 and T2-weighted EPIs combined (P<0.05), and sensitivity for benign lesions (87%) was highest on DW-EPIs with b value of 800 s/mm2 and T2-weighted EPIs (P<0.05). Specificities were comparably high for all sequences. The Az values for malignant lesions were 0.94, 0.90, 0.87, and 0.89, and those for benign lesions were 0.91, 0.89, 0.87, and 0.94 on DW-EPIs with b values of 100, 200, 400, and 800 and T2-weighted EPIs combined, respectively. Hepatic cysts were clearly distinguished with the cutoff ADC value of 2.5x10(-3) mm2/s using a b value of 400 s/mm2 or greater.
  
  
  CONCLUSIONS
  DW-EPIs with middle b values were not required in the detection and characterization of benign and malignant hepatic lesions.
authors.affiliation: Department of Radiology, Gifu University School of Medicine, Gifu University Hospital, Gifu, Japan. gossy@par.odn.ne.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Goshima
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kanematsu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kondo
authors.forename: Ryujiro
authors.initials: R
authors.lastname: Yokoyama
authors.forename: Kimihiro
authors.initials: K
authors.lastname: Kajita
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Tsuge
authors.forename: Haruo
authors.initials: H
authors.lastname: Watanabe
authors.forename: Yoshimune
authors.initials: Y
authors.lastname: Shiratori
authors.forename: Minoru
authors.initials: M
authors.lastname: Onozuka
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Moriyama
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D003937:Diagnosis, Differential; 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; D012680:Sensitivity and Specificity