title: Flip angle modulations in late phase Gd-EOB-DTPA MRI improve the identification of the biliary system.
abstract: OBJECTIVE
  To assess the improvement of bile duct visualization in Gd-EOB-DTPA enhanced MR-cholangiography (EOB-MRC) by using an increased flip angle.
  
  
  METHODS
  35 patients underwent Gd-EOB-DTPA enhanced MRI of the liver including T2-weighted MRCP and hepatobiliary phase EOB-MRC using a flip angle of 10° (FA10) and of 35° (FA35), respectively. Images were evaluated regarding the delineation of biliary ducts, the order of branching and anatomic visualization of the biliary tree. ROI analysis was performed to estimate the signal-to-noise (SNR) and contrast-to-noise (CNR) ratios.
  
  
  RESULTS
  Applying the FA35 resulted in a significantly better SNR and CNR as compared to FA10. The overall image quality was rated as good for both, FA10 and FA35. The overall rating for regional delineation of the biliary system was rated significantly better for FA35 than for FA10 (p=0.02). Classification of bile duct anatomy variations, however, was equivalent in both techniques.
  
  
  CONCLUSIONS
  Increasing the flip angle of a T1-weighted 3D-sequence from 10° to 35° during the hepatobiliary phase of Gd-EOB enhanced MRI visually and quantitatively improved the visualization of the biliary ducts.
authors.affiliation: Klinik für Radiologie, Charité-Universitätsmedizin Berlin, Campus Virchow-Klinikum, Augustenburger Platz 1, 13353 Berlin, Germany. lars.stelter@charite.de
authors.forename: Lars
authors.initials: L
authors.lastname: Stelter
authors.forename: Christian
authors.initials: C
authors.lastname: Grieser
authors.forename: Carmen Maria Pérez
authors.initials: CM
authors.lastname: Fernándes
authors.forename: Jan Holger
authors.initials: JH
authors.lastname: Rothe
authors.forename: Florian
authors.initials: F
authors.lastname: Streitparth
authors.forename: Daniel
authors.initials: D
authors.lastname: Seehofer
authors.forename: Bernd
authors.initials: B
authors.lastname: Hamm
authors.forename: Timm
authors.initials: T
authors.lastname: Denecke
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D001650:Bile Duct Neoplasms / Q000473:pathology*; D001652:Bile Ducts / Q000473:pathology*; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
chemical_list: D003287:Contrast Media; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA