Purpose: To evaluate the effect of imaging sequence (spin-echo echo-planar imaging [EPI] and gradient-echo [GRE]) and postprocessing method (two-dimensional [2D] and 3D inversion algorithms) on liver MR elastography (MRE) and to validate the diagnostic performance of EPI-MRE3D versus conventional GRE-MRE2D for liver fibrosis staging.
Materials and methods: Three MRE methods (EPI-MRE3D , EPI-MRE2D , and GRE-MRE2D ) were performed on soft and mildly stiff phantoms and 58 patients with chronic liver disease using a 3 Tesla clinical MRI scanner, and stiffness values were compared among the three methods. A validation study comprised 73 patients with histological liver fibrosis (F0-4, METAVIR system). Areas under the receiver operating characteristic curves (AUCs) and accuracies for diagnosing significant fibrosis (F3-4) and cirrhosis (F4) were compared between EPI-MRE3D and GRE-MRE2D .
Results: Stiffness values of the soft and mildly stiff phantoms were 2.4 kPa and 4.0 kPa by EPI-MRE3D ; 2.6 kPa and 4.2 kPa by EPI-MRE2D ; and 2.7 kPa and 4.2 kPa by GRE-MRE2D . In patients, EPI-MRE3D provided significantly lower stiffness values than other methods (P < 0.001). However, there was no significant difference between GRE-MRE2D and EPI-MRE2D (P = 0.12). The AUCs and accuracies of EPI-MRE3D and GRE-MRE2D were statistically equivalent in the diagnoses of significant fibrosis (F3-4) and cirrhosis (F4) (all P < 0.005).
Conclusion: EPI-MRE3D showed modestly lower liver stiffness values than conventional GRE-MRE2D . The diagnostic performances of EPI-MRE3D and GRE-MRE2D were equivalent for liver fibrosis staging.
Level of evidence: 3 J. Magn. Reson. Imaging 2017;45:1163-1170.
Keywords: echo planar imaging (EPI); gradient-echo imaging (GRE); liver fibrosis staging; magnetic resonance elastography (MRE); three-dimensional postprocessing.
© 2016 International Society for Magnetic Resonance in Medicine.