Mapping tissue water T (1) in the liver using the MOLLI T (1) method in the presence of fat, iron and B (0) inhomogeneity

Modified Look‐Locker inversion recovery (MOLLI) T (1) mapping sequences can be useful in cardiac and liver tissue characterization, but determining underlying water T (1) is confounded by iron, fat and frequency offsets. This article proposes an algorithm that provides an independent water MOLLI T (1) (referred to as on‐resonance water T (1)) that would have been measured if a subject had no fat and normal iron, and imaging had been done on resonance. Fifteen NiCl(2)‐doped agar phantoms with different peanut oil concentrations and 30 adults with various liver diseases, nineteen (63.3%) with liver steatosis, were scanned at 3 T using the shortened MOLLI (shMOLLI) T (1) mapping, multiple‐echo spoiled gradient‐recalled echo and (1)H MR spectroscopy sequences. An algorithm based on Bloch equations was built in MATLAB, and water shMOLLI T (1) values of both phantoms and human participants were determined. The quality of the algorithm's result was assessed by Pearson's correlation coefficient between shMOLLI T (1) values and spectroscopically determined T (1) values of the water, and by linear regression analysis. Correlation between shMOLLI and spectroscopy‐based T (1) values increased, from r = 0.910 (P < 0.001) to r = 0.998 (P < 0.001) in phantoms and from r = 0.493 (for iron‐only correction; P = 0.005) to r = 0.771 (for iron, fat and off‐resonance correction; P < 0.001) in patients. Linear regression analysis revealed that the determined water shMOLLI T (1) values in patients were independent of fat and iron. It can be concluded that determination of on‐resonance water (sh)MOLLI T (1) independent of fat, iron and macroscopic field inhomogeneities was possible in phantoms and human subjects.