Confounder-corrected T mapping in the liver through simultaneous estimation of T , PDFF, , and in a single breath-hold acquisition.

PURPOSE

Quantitative volumetric T mapping in the liver has the potential to aid in the detection, diagnosis, and quantification of liver fibrosis, inflammation, and spatially resolved liver function. However, accurate measurement of hepatic T is confounded by the presence of fat and inhomogeneous excitation. Furthermore, scan time constraints related to respiratory motion require tradeoffs of reduced volumetric coverage and/or increased acquisition time. This work presents a novel 3D acquisition and estimation method for confounder-corrected T measurement over the entire liver within a single breath-hold through simultaneous estimation of T , fat and .

THEORY AND METHODS

The proposed method combines chemical shift encoded MRI and variable flip angle MRI with a mapping technique to enable confounder-corrected T mapping. The method was evaluated theoretically and demonstrated in both phantom and in vivo acquisitions at 1.5 and 3.0T. At 1.5T, the method was evaluated both pre- and post- contrast enhancement in healthy volunteers.

RESULTS

The proposed method demonstrated excellent linear agreement with reference inversion-recovery spin-echo based T in phantom acquisitions at both 1.5 and 3.0T, with minimal bias (5.2 and 45 ms, respectively) over T ranging from 200-1200 ms. In vivo results were in general agreement with reference saturation-recovery based 2D T maps (SMART Map, GE Healthcare).

CONCLUSION

The proposed 3D T mapping method accounts for fat and confounders through simultaneous estimation of T , , PDFF and . It demonstrates strong linear agreement with reference T measurements, with low bias and high precision, and can achieve full liver coverage in a single breath-hold.