Self‐Gated Radial Free‐Breathing Liver MR Elastography: Assessment of Technical Performance in Children at 3 T

Abstract

BackgroundConventional liver magnetic resonance elastography (MRE) requires breath‐holding (BH) to avoid motion artifacts, which is challenging for children. While radial free‐breathing (FB)‐MRE is an alternative for quantifying liver stiffness (LS), previous methods had limitations of long scan times, acquiring two slices in 5 minutes, and not resolving motion during reconstruction.PurposeTo reduce FB‐MRE scan time to 4 minutes for four slices and to investigate the impact of self‐gated (SG) motion compensation on FB‐MRE LS quantification in terms of agreement, intrasession repeatability, and technical quality compared to conventional BH‐MRE.Study TypeProspective.PopulationTwenty‐six children without fibrosis (median age: 12.9 years, 15 females).Field Strength/Sequence3 T; Cartesian gradient‐echo (GRE) BH‐MRE, research application radial GRE FB‐MRE.AssessmentParticipants were scanned twice to measure repeatability, without moving the table or changing the participants' position. LS was measured in areas of the liver with numerical confidence ≥90%. Technical quality was examined using measurable liver area (%).Statistical TestsAgreement of LS between BH‐MRE and FB‐MRE was evaluated using Bland–Altman analysis for SG acceptance rates of 40%, 60%, 80%, and 100%. LS repeatability was assessed using within‐subject coefficient of variation (wCV). The differences in LS and measurable liver area were examined using Kruskal–Wallis and Wilcoxon signed‐rank tests. P < 0.05 was considered significant.ResultsFB‐MRE with 60% SG achieved the closest agreement with BH‐MRE (mean difference 0.00 kPa). The LS ranged from 1.70 to 1.83 kPa with no significant differences between BH‐MRE and FB‐MRE with varying SG rates (P = 0.52). All tested methods produced repeatable LS with wCV from 4.4% to 6.5%. The median measurable liver area was smaller for FB‐MRE (32%–45%) than that for BH‐MRE (91%–93%) (P < 0.05).Data ConclusionFB‐MRE with 60% SG can quantify LS with close agreement and comparable repeatability with respect to BH‐MRE in children.Level of Evidence2Technical EfficacyStage 1