Comparison of diagnostic accuracies of two- and three-dimensional MR elastography of the liver

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-MRE_3D versus conventional GRE-MRE_2D for liver fibrosis staging. Materials and Methods: Three MRE methods (EPI-MRE_3D, EPI-MRE_2D, and GRE-MRE_2D) 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-MRE_3D and GRE-MRE_2D. Results: Stiffness values of the soft and mildly stiff phantoms were 2.4 kPa and 4.0 kPa by EPI-MRE_3D; 2.6 kPa and 4.2 kPa by EPI-MRE_2D; and 2.7 kPa and 4.2 kPa by GRE-MRE_2D. In patients, EPI-MRE_3D provided significantly lower stiffness values than other methods (P < 0.001). However, there was no significant difference between GRE-MRE_2D and EPI-MRE_2D (P = 0.12). The AUCs and accuracies of EPI-MRE_3D and GRE-MRE_2D were statistically equivalent in the diagnoses of significant fibrosis (F3–4) and cirrhosis (F4) (all P < 0.005). Conclusion: EPI-MRE_3D showed modestly lower liver stiffness values than conventional GRE-MRE_2D. The diagnostic performances of EPI-MRE_3D and GRE-MRE_2D were equivalent for liver fibrosis staging. Level of Evidence: 3. J. Magn. Reson. Imaging 2017;45:1163–1170.