title: Segmental liver hyperintensity in malignant biliary obstruction on diffusion weighted MRI: associated MRI findings and relationship with serum alanine aminotransferase levels.
abstract: OBJECTIVE
  Segmental liver hyperintensity can be observed in malignant biliary obstruction on diffusion weighted MRI (DW-MRI). We describe MRI findings associated with this sign and evaluate whether DW-MRI segmental hyperintensity has any relationship with serum alanine aminotransferase (ALT) levels.
  
  
  METHODS
  The DW-MRI T(1) weighted, T(2) weighted and gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced T(1) weighted images obtained in 21 patients with hepatic malignancy, who demonstrated biliary obstruction and segmental hyperintensity on DW-MRI (b=0-750 s mm(-2)), were retrospectively reviewed by 2 readers blinded to clinical results. DW-MRI hyperintense liver segments were recorded as hypointense, isointense or hyperintense relative to normal liver on T(1)/T(2) weighted imaging. It was also noted whether contrast enhancement was similar to that observed in normal liver or diminished in the hepatocellular phase. The mean apparent diffusion coefficient (ADC) value (×10(-3) s mm(-2)) of DW-MRI hyperintense segments, normal liver and tumour were compared using Student's t-test. The frequency of MRI findings was corroborated with serum ALT levels, which reflect hepatocyte injury.
  
  
  RESULTS
  DW-MRI hyperintense segments frequently showed T(1) hyperintensity (10/21), T(2) hyperintensity (19/21) and/or diminished contrast enhancement (15/21). Tumours showed significantly lower mean ADC values than liver (1.23 ± 0.08 vs 1.43 ± 0.05; p=0.013). Segments showing concomitant T(1) hyperintensity had lower mean ADC values than liver (1.30 ± 0.05 vs 1.43 ± 0.05; p=0.023). The patients (8/10) with concomitant T(1) and DW-MRI segmental hyperintensity showed elevated ALT levels (p=0.030, Fisher's exact test).
  
  
  CONCLUSIONS
  Concomitantly high T(1) weighted and DW-MRI signal in liver segments was associated with lower ADC values and abnormal liver function tests, which could reflect underlying cellular swelling and damage.
authors.affiliation: Department of Radiology, The Royal Marsden, Sutton, UK. henrytam01@gmail.com
authors.forename: H H
authors.initials: HH
authors.lastname: Tam
authors.forename: D J
authors.initials: DJ
authors.lastname: Collins
authors.forename: T
authors.initials: T
authors.lastname: Wallace
authors.forename: G
authors.initials: G
authors.lastname: Brown
authors.forename: A
authors.initials: A
authors.lastname: Riddell
authors.forename: D-M
authors.initials: DM
authors.lastname: Koh
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000410:Alanine Transaminase / Q000097:blood*; D002780:Cholestasis, Intrahepatic / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D008113:Liver Neoplasms / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies
chemical_list: D000410:Alanine Transaminase