An Empirical Approach to Derive Water T₁ from Multiparametric MR Images Using an Automated Pipeline and Comparison With Liver Stiffness

Water T₁ of the liver has been shown to be promising in discriminating the progressive forms of fatty liver diseases, inflammation, and fibrosis, yet proper correction for iron and lipid is required.

To examine the feasibility of an empirical approach for iron and lipid correction when measuring imaging-based T₁ and to validate this approach by spectroscopy on in vivo data.

Retrospective.

Next to mixed lipid-iron phantoms, individuals with different hepatic lipid content were investigated, including people with type 1 diabetes (N = 15, %female = 15.6, age = 43.5 ± 14.0), or type 2 diabetes mellitus (N = 21, %female = 28.9, age = 59.8 ± 9.7) and healthy volunteers (N = 9, %female = 11.1, age = 58.0 ± 8.1).

3 T, balanced steady-state free precession MOdified Look-Locker Inversion recovery (MOLLI), multi- and dual-echo gradient echo Dixon, gradient echo magnetic resonance elastography (MRE).

T₁ values were measured in phantoms to determine the respective correction factors. The correction was tested in vivo and validated by proton magnetic resonance spectroscopy (¹ H-MRS). The quantification of liver T₁ based on automatic segmentation was compared to the T₁ values based on manual segmentation. The association of T₁ with MRE-derived liver stiffness was evaluated.

Bland-Altman plots and intraclass correlation coefficients (ICCs) were used for MOLLI vs. ¹ H-MRS agreement and to compare liver T₁ values from automatic vs. manual segmentation. Pearson's r correlation coefficients for T₁ with hepatic lipids and liver stiffness were determined. A P-value of 0.05 was considered statistically significant.

MOLLI T₁ values after correction were found in better agreement with the ¹ H-MRS-derived water T₁ (ICC = 0.60 [0.37; 0.76]) in comparison with the uncorrected T₁ values (ICC = 0.18 [-0.09; 0.44]). Automatic quantification yielded similar liver T₁ values (ICC = 0.9995 [0.9991; 0.9997]) as with manual segmentation. A significant correlation of T₁ with liver stiffness (r = 0.43 [0.11; 0.67]) was found. A marked and significant reduction in the correlation strength of T₁ with liver stiffness (r = 0.05 [-0.28; 0.38], P = 0.77) was found after correction for hepatic lipid content.

Imaging-based correction factors enable accurate estimation of water T₁ in vivo.

1 TECHNICAL EFFICACY: Stage 1.