title: Quantitative chemical shift-encoded MRI is an accurate method to quantify hepatic steatosis.
abstract: OBJECTIVE
  To compare the accuracy of liver fat quantification using a three-echo chemical shift-encoded magnetic resonance imaging (MRI) technique without and with correction for confounders with spectroscopy (MRS) as the reference standard.
  
  
  METHODS
  Fifty patients (23 women, mean age 56.6 ± 13.2 years) with fatty liver disease were enrolled. Patients underwent T2-corrected single-voxel MRS and a three-echo chemical shift-encoded gradient echo (GRE) sequence at 3.0T. MRI fat fraction (FF) was calculated without and with T2* and T1 correction and multispectral modeling of fat and compared with MRS-FF using linear regression.
  
  
  RESULTS
  The spectroscopic range of liver fat was 0.11%-38.7%. Excellent correlation between MRS-FF and MRI-FF was observed when using T2* correction (R(2)  = 0.96). With use of T2* correction alone, the slope was significantly different from 1 (1.16 ± 0.03, P < 0.001) and the intercept was different from 0 (1.14% ± 0.50%, P < 0.023). This slope was significantly different than 1.0 when no T1 correction was used (P = 0.001). When T2*, T1, and spectral complexity of fat were addressed, the results showed equivalence between fat quantification using MRI and MRS (slope: 1.02 ± 0.03, P = 0.528; intercept: 0.26% ± 0.46%, P = 0.572).
  
  
  CONCLUSIONS
  Complex three-echo chemical shift-encoded MRI is equivalent to MRS for quantifying liver fat, but only with correction for T2* decay and T1 recovery and use of spectral modeling of fat. This is necessary because T2* decay, T1 recovery, and multispectral complexity of fat are processes which may otherwise bias the measurements.
authors.affiliation: Department of Radiology and Neuroradiology, Ernst Moritz Arndt University, Greifswald, Germany.
authors.forename: Jens-Peter
authors.initials: JP
authors.lastname: Kühn
authors.forename: Diego
authors.initials: D
authors.lastname: Hernando
authors.forename: Birger
authors.initials: B
authors.lastname: Mensel
authors.forename: Paul C
authors.initials: PC
authors.lastname: Krüger
authors.forename: Till
authors.initials: T
authors.lastname: Ittermann
authors.forename: Julia
authors.initials: J
authors.lastname: Mayerle
authors.forename: Norbert
authors.initials: N
authors.lastname: Hosten
authors.forename: Scott B
authors.initials: SB
authors.lastname: Reeder
mesh_terms: D005234:Fatty Liver / Q000175:diagnosis*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods; D008099:Liver / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results
keywords: chemical shift-encoded imaging; fatty liver; magnetic resonance imaging; magnetic resonance spectroscopy