Dixon-Based Water T1 Mapping for Fat-Corrected Assessment of Hepatic Fibrosis in Chronic Liver Disease.

Objectives: The diagnostic value of conventional T1 mapping for noninvasive assessment of liver fibrosis is limited in the presence of hepatic steatosis. To evaluate the diagnostic value of water T1 (wT1) with continuous inversion-recovery Look-Locker (CIR-LL) method, integrating spiral readout, Dixon, and dictionary-based processing, for the fat-corrected assessment of hepatic fibrosis in patients with chronic liver disease (CLD).

Materials and methods: In this prospective study, consecutive participants with CLD underwent liver magnetic resonance imaging (MRI), which included assessment of MR-elastography (MRE)-derived liver stiffness, proton density fat fraction (PDFF), T1 relaxation times using modified Look-Locker inversion recovery (T1-MOLLI) and extracellular volume fraction (ECV), and wT1 relaxation times. MRE served as the reference standard to evaluate the diagnostic performance of MRI-based mapping parameters. Significant fibrosis (≥F2) was defined as MRE-derived liver stiffness >3.66 kPa in patients with PDFF≤5%, or >3.14 kPa in patients with PDFF>5%. Statistical analysis included Student t test, receiver operating characteristic (ROC) analysis, and Spearman correlation coefficient.

Results: A total of 81 CLD patients (mean age, 50±14 y; 32 female; 40 patients with PDFF>5%) were included. All measured mapping values were significantly higher in patients with significant fibrosis compared with those without (eg, wT1: 628±82 vs. 546±41 ms, P<0.001). wT1 showed a strong correlation with MRE-derived liver stiffness, outperforming T1-MOLLI and ECV mapping [whole cohort: r=0.67 (wT1) vs. 0.53 (T1-MOLLI) vs. 0.48 (ECV); cohort with PDFF>5%: r=0.69 (wT1) vs. 0.44 (T1) vs. 0.49 (ECV); P<0.05 in each case, respectively]. wT1 had a superior diagnostic performance for the detection of significant fibrosis [whole cohort, area under the curve (AUC): 0.82 (wT1); 0.77 (T1-MOLLI); 0.73 (ECV), P<0.001 in each case; cohort with PDFF>5%, AUC: 0.84, P=0.002 (wT1), 0.70, P=0.04 (T1-MOLLI), 0.70, P=0.04 (ECV)].

Conclusion: Compared with T1-MOLLI and ECV mapping, the proposed fat-corrected CIR-LL wT1 method proved to be a more robust marker of hepatic fibrosis in CLD, also in the presence of hepatic steatosis.