Assessing the Reliability of SE-EPI MRE for Liver Stiffness Estimation Under Free-Breathing Instruction Compared to Breath-Holding

Motivation: Magnetic resonance elastography (MRE) provides non-invasive liver fibrosis assessment, but breath-holding (BH) requirements limit its use in certain patients. Goal(s): To compare liver stiffness (LS) estimates from SE-EPI MRE acquired under BH and free-breathing (FB) instruction. Approach: Forty-three adults underwent both BH and FB SE-EPI MRE. We assessed the Structural Similarity Index Measure (SSIM) among MRE images and measurable region-of-interest (ROI) size. Agreement between LS estimates was evaluated using Bland-Altman and regression analyses. Results: While FB had lower SSIM values and smaller ROIs, mean LS did not significantly differ from BH SE-EPI, with minimal bias (0.00kPa) and an intra-class correlation coefficient of 0.988. Impact: Free-breathing SE-EPI MRE without explicit motion compensation provides reliable mean LS estimates comparable to breath-holding scans, enabling rapid liver stiffness assessment in patients with difficulty performing breath-holding.