Water-T1, PDFF, and T2* mapping of the liver using chemical shift-encoded MOLLI

Hepatic MRI T1 relaxation time is a putative measure of fibrosis and inflammation but may be confounded by hepatic fat. This study evaluated a chemical shift-encoded Modified Look-Locker Inversion Recovery (CSE-MOLLI) technique for simultaneous water-specific T1 (water-T1), proton density fat fraction (PDFF), and T2* mapping within a single breath-hold.

Numerical simulations, reference standard phantoms, and in vivo imaging were used to assess CSE-MOLLI performance. Twenty participants, including healthy/asymptomatic controls, individuals with steatotic liver disease, and individuals with non-steatotic chronic liver disease, underwent CSE-MOLLI and comparator quantitative MRI sequences. All quantitative maps were generated in real-time on the scanner. Water-T1, PDFF, and T2* were measured from regions of interest (ROIs) by two readers and compared with reference standard methods using simple and intraclass correlation and Bland-Altman analysis. Scan-rescan repeatability was assessed for CSE-MOLLI.

Phantom experiments demonstrated strong agreement between CSE-MOLLI and reference measurements for water-T1 (r = 0.98), PDFF (r = 1.00), and T2* (r = 0.99) estimates. In vivo, inter-reader agreement was excellent for water-T1, PDFF, and T2* (ICC > 0.97). CSE-MOLLI showed very strong correlation and excellent agreement with comparator PDFF (r = 1.00; ICC = 0.98) and water-T1 (r = 0.95; ICC = 0.89), while T2* demonstrated strong correlation and moderate agreement with comparator values (r = 0.67; ICC = 0.65). Water-T1 remained relatively consistent across PDFF values from 1% to 43%, suggesting reduced sensitivity of CSE-MOLLI to fat-related deviation. Water-T1 exhibited good scan-rescan repeatability (bias = 2.0 ms, ICC = 0.95).

CSE-MOLLI enables simultaneous water-T1, PDFF, and T2* mapping of the liver within a single breath-hold. Phantom validation, repeatability assessment, and preliminary in vivo results in healthy, steatotic, and non-steatotic liver disease participants suggest that hepatic water-T1 measurements are less sensitive to fat-related deviations than conventional MOLLI-based T1 estimates. Further studies are needed to determine clinical utility in diffuse liver disease.