title: Effect of intravenous gadoxetate disodium and flip angle on hepatic proton density fat fraction estimation with six-echo, gradient-recalled-echo, magnitude-based MR imaging at 3T.
abstract: The aim of the study was to determine in patients undergoing gadoxetate disodium (Gx)-enhanced MR exams whether proton density fat fraction (PDFF) estimation accuracy of magnitude-based multi-gradient-echo MRI (MRI-M) could be improved by using high flip angle (FA) on post-contrast images.
  
  
  
  Thirty-one adults with known or suspected hepatic steatosis undergoing 3T clinical Gx-enhanced liver MRI were enrolled prospectively. MR spectroscopy (MRS), the reference standard, was performed before Gx to measure MRS-PDFF. Low (10°)- and high (50°)-flip angle (FA) MRI-M sequences were acquired before and during the hepatobiliary phase after Gx administration; MRI-PDFF was estimated in the MRS-PDFF voxel location. Linear regression parameters (slope, intercept, average bias, R2) were calculated for MRS-PDFF as a function of MRI-PDFF for each MRI-M sequence (pre-Gx low-FA, pre-Gx high-FA, post-Gx low-FA, post-Gx high-FA) for all patients and for patients with MRS-PDFF <10%. Regression parameters were compared (Bonferroni-adjusted bootstrap-based tests).
  
  
  
  Three of the four MRI-M sequences (pre-Gx low-FA, post-Gx low-FA, post-Gx high-FA) provided relatively unbiased PDFF estimates overall and in the low-PDFF range, with regression slopes close to 1 and intercepts and biases close to zero. Pre-Gx high-FA MRI overestimated PDFF in proportion to MRS-PDFF, with slopes of 0.72 (overall) and 0.63 (low-PDFF range). Based on regression bias closest to 0, the post-Gx high-FA sequence was the most accurate overall and in the low-PDFF range. This sequence provided statistically significant improvements in at least two regression parameters compared to every other sequence.
  
  
  
  In patients undergoing Gx-enhanced MR exams, PDFF estimation accuracy of MRI-M can be improved by using high-FA on post-contrast images.
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Charlie C
authors.initials: CC
authors.lastname: Park
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Gavin
authors.initials: G
authors.lastname: Hamilton
authors.affiliation: Department of Diagnostic and Interventional Radiology, Rochester General Hospital, Rochester, NY, USA.
authors.forename: Ajinkya
authors.initials: A
authors.lastname: Desai
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Zand
authors.affiliation: Computational and Applied Statistics Laboratory (CASL), San Diego Supercomputer Center (SDSC), University of California, San Diego, La Jolla, CA, USA.
authors.forename: Tanya
authors.initials: T
authors.lastname: Wolfson
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Hooker
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Costa
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Elhamy
authors.initials: E
authors.lastname: Heba
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Clark
authors.affiliation: Computational and Applied Statistics Laboratory (CASL), San Diego Supercomputer Center (SDSC), University of California, San Diego, La Jolla, CA, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Gamst
authors.affiliation: Division of Gastroenterology, Department of Medicine, University of California, San Diego, La Jolla, CA, USA.|Division of Epidemiology, Department of Family Medicine and Preventive Medicine, University of California, San Diego, La Jolla, CA, USA.
authors.forename: Rohit
authors.initials: R
authors.lastname: Loomba
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA.
authors.forename: Michael S
authors.initials: MS
authors.lastname: Middleton
authors.affiliation: MR3T Bydder Laboratory, Liver Imaging Group, Department of Radiology, University of California, San Diego, 408 Dickinson Street, MC 8226, San Diego, CA, 92103-8226, USA. csirlin@ucsd.edu.
authors.forename: Claude B
authors.identifier: 0000-0002-6639-9072
authors.initials: CB
authors.lastname: Sirlin
mesh_terms: D000328:Adult; D000368:Aged; D003287:Contrast Media / Q000008:administration & dosage*; D005234:Fatty Liver / Q000000981:diagnostic imaging*; D005260:Female; D019786:Gadolinium DTPA / Q000008:administration & dosage*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011522:Protons
chemical_list: D003287:Contrast Media; D011522:Protons; C073590:gadolinium ethoxybenzyl DTPA; D019786:Gadolinium DTPA
keywords: Eovist; Flip angle; Gadoxetate disodium; Hepatic steatosis; MRI; PDFF