title: Hepatic fat fraction: MR imaging for quantitative measurement and display--early experience.
abstract: The institutional review board approved this HIPAA-compliant study. After all five patients with nonalcoholic fatty liver disease signed a consent, they underwent magnetic resonance (MR) imaging for hepatic fat quantification. The purpose of this study was to develop a fast and accurate method to acquire and display quantitative maps of the percentage of hepatic fat. In-phase and out-of-phase gradient-echo MR imaging was performed with dual flip angles (70 degrees, 20 degrees) to resolve ambiguity of the dominant constituent. T2* corrections were also estimated and applied to generate color-coded maps of the estimated percentage of hepatic fat. MR imaging results were compared with biopsy results in two of five patients, and the technique was validated qualitatively and quantitatively with a water-oil phantom. Results of the phantom study confirmed that the dual-flip angle algorithm can be used to correctly identify the dominant constituent, allowing depiction of 0%-100% of fat content. The estimated liver fat fraction was comparable to quantitative fat measurements at biopsy in both patients (MR imaging, 18.3% +/- 2.8 [standard deviation] and 28.6% +/- 2.4, vs quantitative histopathologic analysis, 11.2% and 28.5%, respectively).
  
  
  BACKGROUND
  radiology.rsnajnls.org/cgi/content/full/2373041639/DC1
authors.affiliation: Department of Radiology/MRI, University of Michigan Health System, 1500 E Medical Center Dr, MRI UHB2A209, Ann Arbor, MI 48109-0030, USA.
authors.forename: Hero K
authors.initials: HK
authors.lastname: Hussain
authors.forename: Thomas L
authors.initials: TL
authors.lastname: Chenevert
authors.forename: Frank J
authors.initials: FJ
authors.lastname: Londy
authors.forename: Vikas
authors.initials: V
authors.lastname: Gulani
authors.forename: Scott D
authors.initials: SD
authors.lastname: Swanson
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: McKenna
authors.forename: Henry D
authors.initials: HD
authors.lastname: Appelman
authors.forename: Saroja
authors.initials: S
authors.lastname: Adusumilli
authors.forename: Joel K
authors.initials: JK
authors.lastname: Greenson
authors.forename: Hari S
authors.initials: HS
authors.lastname: Conjeevaram
mesh_terms: D000328:Adult; D000465:Algorithms; D005234:Fatty Liver / Q000473:pathology*; D005260:Female; D006801:Humans; D008111:Liver Function Tests; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging