title: Differentiating hepatic abscess from malignant mimickers: value of diffusion-weighted imaging with an emphasis on the periphery of the lesion.
abstract: OBJECTIVE
  To evaluate the efficacy of diffusion-weighted imaging (DWI) in differentiating hepatic abscess from malignant mimickers with an emphasis on periphery of the lesions.
  
  
  METHODS
  Thirty-nine patients with hepatic abscess and 74 patients with malignant hepatic tumors were included, who underwent gadoxetic acid-enhanced MRI. For qualitative and quantitative analysis, signal intensities and apparent diffusion coefficient (ADC) values of the periphery were assessed. Two observers reviewed DWI and ADC maps rated using a 5-point scale. Diagnostic performance was evaluated using the receiver operating characteristics (ROC) curve analysis.
  
  
  RESULTS
  The periphery of hepatic abscesses was T1-hypointense, arterial hyperintense, and hypointense on hepatobiliary phase less frequently than that of malignant tumors (P < 0.05). No hepatic abscesses showed peripheral washout on 3-min late phase compared with malignant tumors (59.5%) (P < 0.001). Both groups showed hyperintense rims on DWI, but, 37(94.9%) abscesses revealed rims with high ADC values compared with one (1.4%) malignant tumor (P < 0.001). Mean ADC values of abscesses (1.47 × 10(-3) mm(2) /s ± 0.36 [standard deviation]) were significantly higher than those of malignancies (0.68 × 10(-3) mm(2) /s ± 0.20). Diagnostic performance (area under the ROC curve [Az]) of DWI in identifying hepatic abscess was 0.986 and 0.982 for each observer.
  
  
  CONCLUSIONS
  In addition to conventional MRI, DWI is helpful in differentiating hepatic abscess from malignant mimickers.
authors.affiliation: Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Gangnam-gu, Seoul, Korea.
authors.forename: Hyun Jeong
authors.initials: HJ
authors.lastname: Park
authors.forename: Seong Hyun
authors.initials: SH
authors.lastname: Kim
authors.forename: Kyung Mi
authors.initials: KM
authors.lastname: Jang
authors.forename: Soon Jin
authors.initials: SJ
authors.lastname: Lee
authors.forename: Min Jung
authors.initials: MJ
authors.lastname: Park
authors.forename: Dongil
authors.initials: D
authors.lastname: Choi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003287:Contrast Media; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008100:Liver Abscess / Q000473:pathology*; D008113:Liver Neoplasms / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: MRI; diffusion weighted imaging (DWI); hepatic abscess; malignant tumor