title: Magnetic Resonance Elastography of the Liver: Qualitative and Quantitative Comparison of Gradient Echo and Spin Echo Echoplanar Imaging Sequences.
abstract: The aim of this study was to compare 2-dimensional (2D) gradient recalled echo (GRE) and 2D spin echo echoplanar imaging (SE-EPI) magnetic resonance elastography (MRE) sequences of the liver in terms of image quality and quantitative liver stiffness (LS) measurement.
  
  
  
  This prospective study involved 50 consecutive subjects (male/female, 33/17; mean age, 58 years) who underwent liver magnetic resonance imaging at 3.0 T including 2 MRE sequences, 2D GRE, and 2D SE-EPI (acquisition time 56 vs 16 seconds, respectively). Image quality scores were assessed by 2 independent observers based on wave propagation and organ coverage on the confidence map (range, 0-15). A third observer measured LS on stiffness maps (in kilopascal). Mean LS values, regions of interest size (based on confidence map), and image quality scores between SE-EPI and GRE-MRE were compared using paired nonparametric Wilcoxon test. Reproducibility of LS values between the 2 sequences was assessed using intraclass coefficient correlation, coefficient of variation, and Bland-Altman limits of agreement. T2* effect on image quality was assessed using partial Spearman correlation.
  
  
  
  There were 4 cases of failure with GRE-MRE and none with SE-EPI-MRE. Image quality scores and region of interest size were significantly higher using SE-EPI-MRE versus GRE-MRE (P < 0.0001 for both measurements and observers). Liver stiffness measurements were not significantly different between the 2 sequences (3.75 ± 1.87 kPa vs 3.55 ± 1.51 kPa, P = 0.062), were significantly correlated (intraclass coefficient correlation, 0.909), and had excellent reproducibility (coefficient of variation, 10.2%; bias, 0.023; Bland-Altman limits of agreement, -1.19; 1.66 kPa). Image quality scores using GRE-MRE were significantly correlated with T2* while there was no correlation for SE-EPI-MRE.
  
  
  
  Our data suggest that SE-EPI-MRE may be a better alternative to GRE-MRE. The diagnostic performance of SE-EPI-MRE for detection of liver fibrosis needs to be assessed in a future study.
authors.affiliation: From the *Translational and Molecular Imaging Institute, and †Department of Radiology, Icahn School of Medicine at Mount Sinai, New York, NY; ‡Department of Radiology, Mayo Clinic, Rochester, MN; and §GE Healthcare, MR Applications & Workflow, New York, NY.
authors.forename: Mathilde
authors.initials: M
authors.lastname: Wagner
authors.forename: Cecilia
authors.initials: C
authors.lastname: Besa
authors.forename: Jad
authors.initials: J
authors.lastname: Bou Ayache
authors.forename: Temel Kaya
authors.initials: TK
authors.lastname: Yasar
authors.forename: Octavia
authors.initials: O
authors.lastname: Bane
authors.forename: Maggie
authors.initials: M
authors.lastname: Fung
authors.forename: Richard L
authors.initials: RL
authors.lastname: Ehman
authors.forename: Bachir
authors.initials: B
authors.lastname: Taouli
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D017352:Echo-Planar Imaging / Q000379:methods; D054459:Elasticity Imaging Techniques / Q000379:methods*; D005069:Evaluation Studies as Topic; D005260:Female; D006801:Humans; D008099:Liver / Q000000981:diagnostic imaging / Q000473:pathology; D008107:Liver Diseases / Q000000981:diagnostic imaging* / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D015203:Reproducibility of Results; D055815:Young Adult