title: Transient hepatic attenuation difference (THAD) in biliary duct disease.
abstract: BACKGROUND
  THADs are associated with a wide spectrum of hepato-biliary pathologies. The aim of this paper is to find out the role of THADs in the imaging assessment of biliary diseases. We performed a retrospective study to establish the frequency of arterial phenomena in patients with specific biliary diseases.
  
  
  METHODS
  Out of 1833 patients who underwent upper abdomen biphasic CT (2003-2007), we selected those with the following diagnoses: biliary duct dilation due to extrahepatic obstruction (20 patients-group A), intrahepatic-hilar cholangiocellular-carcinoma (19 patients-group B), and cholangitis (14 patients-group C). THAD presence/pattern was assessed for each group. Patients without any demonstrable clinical/imaging signs of liver/biliary pathology (1124) were the control group.
  
  
  RESULTS
  THADs were observed in 36/53 (67.9%) and 20/1124 (1.78%) in study and control groups respectively, with significant association between each diagnostic group and THAD patterns (P < 0.0001). Eleven out of 20 (55%) group A patients showed peribiliary-THAD around dilated biliary tracts; 15/19 (79%) group B patients demonstrated portal involvement and sectorial-THAD; 10/14 (71%) group C patients revealed polymorphous-THAD all along inflamed biliary duct.
  
  
  CONCLUSIONS
  However, THADs are complex phenomena, their evaluation can be an additional diagnostic tool in patients with a biliary pathology. Diffuse peribiliary, sectorial, and polymorphous-THADs show a good rate of correlation (P < 0.0001) with biliary duct ectasia, portal infiltration, and cholangitis, respectively.
authors.affiliation: Department of Clinical Physiopathology, University of Florence, Azienda Ospedaliero-Universitaria Careggi, Italy.
authors.forename: Silvia
authors.initials: S
authors.lastname: Pradella
authors.forename: Nicoletta
authors.initials: N
authors.lastname: Centi
authors.forename: Giorgio
authors.initials: G
authors.lastname: La Villa
authors.forename: Ernesto
authors.initials: E
authors.lastname: Mazza
authors.forename: Stefano
authors.initials: S
authors.lastname: Colagrande
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001660:Biliary Tract Diseases / Q000000981:diagnostic imaging* / Q000473:pathology; D016009:Chi-Square Distribution; D003287:Contrast Media; D005260:Female; D006801:Humans; D007472:Iohexol / Q000031:analogs & derivatives; D008099:Liver / Q000098:blood supply / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D008102:Liver Circulation; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media; D007472:Iohexol; C038192:iopromide