title: An increased flip angle in late phase Gd-EOB-DTPA MRI shows improved performance in bile duct visualization compared to T2w-MRCP.
abstract: OBJECTIVE
  To estimate the additional value of an increased flip angle of 35° in late phase Gd-EOB-DTPA-enhanced magnetic resonance cholangiography, as compared to T2w-MRCP.
  
  
  METHODS
  40 adult patients underwent Gd-EOB-DTPA enhanced MRI of the liver including a T2-weighted 3D TSE MRCP (T2w-MRCP) as well as a late phase T1-weighted THRIVE sequences applying a flip angle of 35° (fa35). Two experienced observers evaluated the images regarding the delineation of the different biliary regions using a three-point grading system. A five-point scale was applied to determine the readers' confidence in identifying anatomical variations of the biliary tree. ROI analysis was performed to compare the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios.
  
  
  RESULTS
  The quality for visualizing the biliary tree differed between T2w-MRCP and fa35 (p=<0.001). Late phase EOB-MRC was rated as good for delineating the entire biliary system, whereas T2w-MRCP received an overall poor rating. Especially the depiction of the intrahepatic bile ducts was estimated as problematic in T2w-MRCP. T2w-MRCP and fa35 revealed a discordant assessment of anatomical variations in 12.5% of the cases, comprising a generally higher confidence level for fa35 (4.0 ± 1.1 vs. 2.2 ± 1.2, p=<0.001). SNR proofed to be significantly higher in fa35 (p=<0.001), whereas T2w-MRCP revealed a significantly higher CNR (<0.001).
  
  
  CONCLUSIONS
  Gd-EOB-DTPA enhanced magnetic resonance cholangiography acquired with a flip angle of 35° revealed a better diagnostic performance compared to T2w-MRCP and might be a valuable adjunct in assessing functional bile duct abnormalities.
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: lars.stelter@charite.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Stelter
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: patrick.freyhardt@charite.de.
authors.forename: Patrick
authors.initials: P
authors.lastname: Freyhardt
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: christian.grieser@charite.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Grieser
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: thula.walter@charite.de.
authors.forename: Thula
authors.initials: T
authors.lastname: Walter
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: dominik.geisel@charite.de.
authors.forename: Dominik
authors.initials: D
authors.lastname: Geisel
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: alexander.baur@charite.de.
authors.forename: Alexander
authors.initials: A
authors.lastname: Baur
authors.affiliation: Klinik für Allgemein-, Viszeral- und Transplantationschirurgie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: daniel.seehofer@charite.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Seehofer
authors.affiliation: Klinik für Radiologie, Charité - Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. Electronic address: timm.denecke@charite.de.
authors.forename: Timm
authors.initials: T
authors.lastname: Denecke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001660:Biliary Tract Diseases / Q000175:diagnosis*; D049448:Cholangiopancreatography, Magnetic Resonance / Q000379:methods*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D059629:Signal-To-Noise Ratio
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Bile ducts; EOB; Flip angle; Gadoxetic acid; MRI; T2w-MRCP