Respiratory‐triggered spin‐echo echo‐planar imaging‐based mr elastography for evaluating liver stiffness

Background Magnetic resonance elastography (MRE) has proven to be useful for assessing chronic liver disease. However, MRE images are acquired with breath‐holding (BH) to limit respiratory motion artifacts, which may be difficult in some patients. Purpose To implement a respiratory‐triggered (RT) spin‐echo echo‐planar imaging (SE‐EPI) MRE technique and to validate its performance through comparison to a BH SE‐EPI MRE technique. Study Type Prospective feasibility study. Subjects Twenty‐three adult volunteers (18 without and 5 with liver disease). Field Strength/Sequences 1.5 T Philips Ingenia MR scanner; RT and BH SE‐EPI MRE sequences. Assessment Four axial images were obtained through the middle of the liver with each technique. Liver stiffness measurements (in kPa) were made from elastograms, with 95% confidence maps overlaid, for both MRE sequences. Statistical Tests Liver stiffness measurements were compared using the paired t ‐test (two‐sided). Absolute agreement between the two techniques was evaluated using Lin's concordance coefficient (r c ). Bland–Altman analysis was used to assess the mean bias between the techniques and 95% limits of agreement, using BH MRE as the reference standard. Results There was excellent agreement (r c = 0.98; 95% confidence interval: 0.96–0.99) between RT and BH SE‐EPI MRE. Mean (±SD) stiffness values from BH and RT SE‐EPI MRE techniques were 2.40 ± 1.15 kPa and 2.37 ± 1.06 kPa, respectively, with no significant difference ( P = 0.54) and no significant bias (mean bias of +0.03 kPa; 95% limits of agreement: –0.39 to 0.45 kPa). Measurable regions of interest in the liver were slightly smaller with the RT technique (mean difference of 1.91 cm 2 ; P = 0.04). Data Conclusion RT SE‐EPI MRE is feasible and yields comparable results to BH SE‐EPI MRE. Level of Evidence : 1 Technical Efficacy : Stage 2 J. Magn. Reson. Imaging 2019;50:391–396.