Segment-resolved assessment of hydration effects on liver water-specific T1 in comparison with T1-MOLLI and transient elastography

Background: Quantitative liver T1 mapping is a promising noninvasive biomarker for diffuse liver disease, but it is influenced by physiological variability. Hydration alters tissue water content and perfusion, yet its effect on liver water-specific T1 (wT1) remains poorly characterized, particularly across liver segments. Prior studies relied on single-slice acquisitions, limiting assessment of spatial heterogeneity. The objective is to assess hydration-related changes in liver wT1 across all Couinaud segments using an accelerated multi-slice technique and to compare results with single-slice T1-modified Look-Locker inversion recovery (T1-MOLLI) and vibration-controlled transient elastography (VCTE).

Methods: Twenty-nine healthy adults underwent blood sampling, VCTE, and liver magnetic resonance imaging (MRI) after an ≥8-hour fast without fluid intake and again after ingestion of 1 L of water followed by a 1-hour equilibration period. Multi-slice wT1 mapping was performed using a Dixon-based continuous inversion-recovery Look-Locker (CIR-LL) sequence covering the entire liver in a single breath-hold. Single-slice T1-MOLLI and whole-liver proton density fat fraction (PDFF) and T2* mapping were acquired for comparison. Regions of interest (ROIs) were placed on PDFF, T2*, and wT1 maps in all liver segments. Statistical analysis included intraclass correlation coefficient (ICC; [2, 1]), linear regression, Pearson correlation coefficients Bland-Altman plots and paired two-sided t-tests.

Results: Hydration resulted in a higher global increase in mean liver wT1 (before: 773.4±63.2 ms, after: 800.3±66 ms) than T1-MOLLI (before: 853±68.8 ms, after: 861.6±55.9 ms). PDFF, T2*, and liver stiffness varied modestly within the physiological range. For liver stiffness, T1-MOLLI, and wT1, measurements obtained before and after hydration showed good agreement, with wT1 (y=0.9x+80.5, r=0.89, P