title: Utility of diffusion-weighted MRI in distinguishing benign and malignant hepatic lesions.
abstract: OBJECTIVE
  To evaluate apparent diffusion coefficient (ADC) values for characterization of a variety of focal liver lesions and specifically for differentiation of solid benign lesions (focal nodular hyperplasia [FNH] and adenomas) from solid malignant neoplasms (metastases and hepatocellular carcinoma [HCC]) in a large case series.
  
  
  METHODS
  A total of 542 lesions in 382 patients were evaluated. ADC values were measured in 166 hemangiomas, 112 hepatomas, 107 metastases, 95 cysts, 10 abscesses, 43 FNH, and nine adenomas. ADCs of 1.5 and 1.6 (x10(-3) mm(2)/second) were selected as threshold values to separate benign and malignant lesions. Sensitivity, specificity, positive, and negative predictive values (PPV, NPV) were calculated. Comparisons were carried out with studentized range test.
  
  
  RESULTS
  There was high interobserver agreement in ADC measurements for all lesion types. The mean ADCs for cysts was 3.40 (x10 (-3) mm(2)/second), hemangiomas 2.26, FNH 1.79, adenomas 1.49, abscesses 1.97, HCC 1.53, and metastases 1.50. The mean ADC for benign lesions was 2.50 and for malignant lesions was 1.52. Cysts were easily distinguished from other lesions. There was, however, overlap between solid benign and malignant lesions.
  
  
  CONCLUSIONS
  Benign lesions have higher mean ADC values than malignant lesions. However, ADC values of solid benign lesions (FNH and adenomas) are similar to malignant lesions (metastases, HCC) limiting the value of diffusion weighted imaging (DWI) for differentiating solid liver masses.
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA. fmiller@northwestern.edu
authors.forename: Frank H
authors.initials: FH
authors.lastname: Miller
authors.forename: Nancy
authors.initials: N
authors.lastname: Hammond
authors.forename: Aheed J
authors.initials: AJ
authors.lastname: Siddiqi
authors.forename: Sagar
authors.initials: S
authors.lastname: Shroff
authors.forename: Gaurav
authors.initials: G
authors.lastname: Khatri
authors.forename: Yi
authors.initials: Y
authors.lastname: Wang
authors.forename: Laura B
authors.initials: LB
authors.lastname: Merrick
authors.forename: Paul
authors.initials: P
authors.lastname: Nikolaidis
mesh_terms: D000236:Adenoma / Q000175:diagnosis*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006528:Carcinoma, Hepatocellular / Q000175:diagnosis*; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D017352:Echo-Planar Imaging / Q000379:methods; D005260:Female; D020518:Focal Nodular Hyperplasia / Q000175:diagnosis*; D006801:Humans; D008099:Liver / Q000473:pathology; D008113:Liver Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000556:secondary; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D019047:Phantoms, Imaging; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D055815:Young Adult