title: High SNR Acquisitions Improve the Repeatability of Liver Fat Quantification Using Confounder-corrected Chemical Shift-encoded MR Imaging.
abstract: OBJECTIVE
  To determine whether high signal-to-noise ratio (SNR) acquisitions improve the repeatability of liver proton density fat fraction (PDFF) measurements using confounder-corrected chemical shift-encoded magnetic resonance (MR) imaging (CSE-MRI).
  
  
  METHODS
  Eleven fat-water phantoms were scanned with 8 different protocols with varying SNR. After repositioning the phantoms, the same scans were repeated to evaluate the test-retest repeatability. Next, an in vivo study was performed with 20 volunteers and 28 patients scheduled for liver magnetic resonance imaging (MRI). Two CSE-MRI protocols with standard- and high-SNR were repeated to assess test-retest repeatability. MR spectroscopy (MRS)-based PDFF was acquired as a standard of reference. The standard deviation (SD) of the difference (Δ) of PDFF measured in the two repeated scans was defined to ascertain repeatability. The correlation between PDFF of CSE-MRI and MRS was calculated to assess accuracy. The SD of Δ and correlation coefficients of the two protocols (standard- and high-SNR) were compared using F-test and t-test, respectively. Two reconstruction algorithms (complex-based and magnitude-based) were used for both the phantom and in vivo experiments.
  
  
  RESULTS
  The phantom study demonstrated that higher SNR improved the repeatability for both complex- and magnitude-based reconstruction. Similarly, the in vivo study demonstrated that the repeatability of the high-SNR protocol (SD of Δ = 0.53 for complex- and = 0.85 for magnitude-based fit) was significantly higher than using the standard-SNR protocol (0.77 for complex, P < 0.001; and 0.94 for magnitude-based fit, P = 0.003). No significant difference was observed in the accuracy between standard- and high-SNR protocols.
  
  
  CONCLUSIONS
  Higher SNR improves the repeatability of fat quantification using confounder-corrected CSE-MRI.
authors.affiliation: Department of Radiology, University of Wisconsin.|Department of Radiology, University of Yamanashi.
authors.forename: Utaroh
authors.initials: U
authors.lastname: Motosugi
authors.affiliation: Department of Radiology, University of Wisconsin.
authors.forename: Diego
authors.initials: D
authors.lastname: Hernando
authors.affiliation: Department of Radiology, University of Wisconsin.
authors.forename: Curtis
authors.initials: C
authors.lastname: Wiens
authors.affiliation: Department of Radiology, University of Wisconsin.|Department of Radiology, University Hospital Hamburg-Eppendorf.
authors.forename: Peter
authors.initials: P
authors.lastname: Bannas
authors.affiliation: Department of Radiology, University of Wisconsin.|Department of Biomedical Engineering, University of Wisconsin.|Department of Medical Physics, University of Wisconsin.|Department of Medicine, University of Wisconsin.|Department of Emergency Medicine, University of Wisconsin.
authors.forename: Scott B
authors.initials: SB
authors.lastname: Reeder
mesh_terms: D000328:Adult; D005234:Fatty Liver / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D011522:Protons; D015203:Reproducibility of Results; D059629:Signal-To-Noise Ratio
chemical_list: D011522:Protons
keywords: chemical shift-encoded magnetic resonance imaging; fatty liver disease; proton density fat fraction; repeatability; signal to noise ratio