All MRE examinations were performed on either MRE hardware (GE Healthcare, Waukesha, Wisconsin, USA) with a 1.5-T imaging system or 1.5-T whole-body magnetic resonance unit (Gyroscan Intera, Philips Medical Systems, Best, the Netherlands) using a four-element torso coil. The two-dimensional MRE protocols used were similar to those described previously in the literature.16 17 (link) The liver stiffness (LS) values of the hepatic parenchyma were measured using MRE by placing four regions of interest (ROIs) on the elastogram. ROIs were determined by the attending radiologists. All ROIs were drawn in the area indicated to have a high confidence and good signal-to-noise ratio, with stiffness outliers excluded on the confidence map18 (link) and then copied to the corresponding position on stiffness maps that provided stiffness values in kilopascals. After reconfirming whether the ROIs were adequately placed in the right liver lobe, the LS value was calculated as the median value in multiple ROIs.
The cut-off values for liver fibrosis using MRE in the current study were 1.94, 2.90 and 3.6 kPa for fibrosis stage F1 (mild fibrosis), F2 (significant fibrosis) and ≥F3 (advanced fibrosis), respectively.19–21 (link) The cut-offs of abnormal aspartate transaminase (AST) and alanine aminotransferase (ALT) for both men and women were defined as >33 U/L and >38 U/L, respectively.22