title: Respiratory-triggered three-dimensional T2-weighted MR cholangiography after injection of gadoxetate disodium: is it still reliable?
abstract: OBJECTIVE
  To test the null hypothesis that there is no quantitative or qualitative difference between respiratory-triggered three-dimensional (3D) T2-weighted magnetic resonance (MR) cholangiography performed before or after administration of gadoxetate disodium.
  
  
  METHODS
  For this retrospective HIPAA-compliant dual-center study, institutional review board approval was obtained, and a waiver of informed consent was granted. Between July and December 2008, 60 patients (age range, 18-82 years) who were referred for liver MR imaging with gadoxetate disodium underwent respiratory-triggered 3D MR cholangiography before and immediately after completion of portal venous phase contrast material-enhanced T1-weighted MR imaging. Quantitative signal-to-noise ratio (SNR) measurements were obtained in the extrahepatic biliary tract in both MR cholangiographic data sets in each patient. Qualitative assessment was performed by four readers with a four-point scale to assess the depiction of extra- and intrahepatic ducts up to the third order. Statistical analysis consisted of a one-sided Wilcoxon signed rank test, with a P value of less than .05 indicating a significant difference.
  
  
  RESULTS
  There was a significant decrease in mean SNR in the MR cholangiographic data set after injection of gadoxetate disodium. SNR was 96 + or - 50 [standard deviation] and 78 + or - 47 before and after contrast media administration, respectively (P < .0001). For all readers, qualitative differences were most obvious in the depiction of the common bile duct and second- and third-order biliary branches, with the precontrast MR cholangiographic data sets being preferred (P < .0001). Precontrast data sets were also significantly preferred in the assessment of the right and left hepatic ducts by all readers.
  
  
  CONCLUSIONS
  Gadoxetate disodium adversely affects respiratory-triggered 3D MR cholangiography, both qualitatively and quantitatively. We recommend that such a sequence be performed before injection of gadoxetate disodium.
authors.affiliation: Department of Radiology, Hannover Medical School, Carl-Neuberg Strasse 1, 30625 Hannover, Germany. ringe.kristina@mh-hannover.de
authors.forename: Kristina I
authors.initials: KI
authors.lastname: Ringe
authors.forename: Rajan T
authors.initials: RT
authors.lastname: Gupta
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Brady
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Massey
authors.forename: Andreas
authors.initials: A
authors.lastname: Hahn
authors.forename: Michael
authors.initials: M
authors.lastname: Galanski
authors.forename: Elmar M
authors.initials: EM
authors.lastname: Merkle
authors.forename: Joachim
authors.initials: J
authors.lastname: Lotz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D049448:Cholangiopancreatography, Magnetic Resonance / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008107:Liver Diseases / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D055425:Respiratory-Gated Imaging Techniques / Q000379:methods; D012189:Retrospective Studies; D018709:Statistics, Nonparametric
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA