title: Diffusion-weighted MR imaging of the liver: distinguishing hepatic abscess from cystic or necrotic tumor.
abstract: BACKGROUND
  We evaluated the ability of diffusion-weighted (DW) magnetic resonance (MR) imaging to differentiate between hepatic abscess and cystic or necrotic liver tumor.
  
  
  METHODS
  DW MR imaging was performed in 18 patients who had liver masses with large cystic or necrotic cavities detected by computed tomography or ultrasonography. The final diagnoses were pyogenic abscess (five cases), fungal abscess (one), hepatocellular carcinoma (five), cystic metastasis (four), and hepatic cyst (three). Signal intensities on the DW images and apparent diffusion coefficient (ADC) maps were noted. ADCs in all lesions were calculated and compared with Student's t test.
  
  
  RESULTS
  All lesions, except hepatic cysts, showed either heterogeneous or homogeneous rim enhancement on postgadolinium images. All abscess cavities showed hyperintensity on DW images and hypointensity on ADC maps. Conversely, the cystic or necrotic portions of all tumors showed hypointensity on DW images and hyperintensity on ADC maps. The mean ADCs (mm(2)/s) were 0.67 +/- 0.35 x 10(-3) in hepatic abscess, 2.65 +/- 0.49 x 10(-3) in cystic or necrotic tumor, 2.93 +/- 0.52 x 10(-3) in hepatic cyst, and 1.98 +/- 0.37 x 10(-3) in normal liver parenchyma.
  
  
  CONCLUSIONS
  DW MR imaging, with the help of ADCs, may be a useful noninvasive imaging technique in differentiating hepatic abscess from cystic or necrotic tumor.
authors.affiliation: Department of Diagnostic Radiology, Tuen Mun Hospital, Tsing Chung Koon Road, Tuen Mun, NT, Hong Kong.
authors.forename: J H
authors.initials: JH
authors.lastname: Chan
authors.forename: E Y
authors.initials: EY
authors.lastname: Tsui
authors.forename: S H
authors.initials: SH
authors.lastname: Luk
authors.forename: A S
authors.initials: AS
authors.lastname: Fung
authors.forename: M K
authors.initials: MK
authors.lastname: Yuen
authors.forename: M L
authors.initials: ML
authors.lastname: Szeto
authors.forename: Y K
authors.initials: YK
authors.lastname: Cheung
authors.forename: K P
authors.initials: KP
authors.lastname: Wong
mesh_terms: D003560:Cysts / Q000175:diagnosis; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008099:Liver / Q000473:pathology; D008100:Liver Abscess / Q000175:diagnosis*; D008107:Liver Diseases / Q000175:diagnosis; D008113:Liver Neoplasms / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009336:Necrosis