T1 mapping for liver function evaluation in gadoxetic acid-enhanced MR imaging: comparison of look-locker inversion recovery and B inhomogeneity-corrected variable flip angle method.

OBJECTIVES

To compare look-locker inversion recovery (LLIR) and B inhomogeneity-corrected variable flip angle T1 mapping methods for estimation of liver function and prediction of hepatic insufficiency and decompensation on gadoxetic acid-enhanced MR imaging.

METHODS

In this retrospective study, 248 patients with normal liver function, chronic liver disease, or cirrhosis underwent gadoxetic acid-enhanced liver MR imaging, including T1 mapping at 10-min and 20-min hepatobiliary phase (HBP) by using both methods. T1 relaxation times of the liver (T1, T1) and the spleen (T1) were correlated between two methods. ΔT1 ([T1 - T1]/T1), adjusted T1 ([T1 - T1]/T1), and functional liver volume-to-weight ratio (liver volume on volumetric T1 map/[T1 × patient's weight]) were calculated. The diagnostic performance of T1 parameters and the predictive performance of models (serum marker, serum marker plus T1 parameter) were compared.

RESULTS

T1 showed a strong correlation (r = 0.93, p < 0.001) between two methods but was significantly different. For depicting cirrhosis, LLIR-adjusted T1 at 10-min HBP showed the highest performance (p < 0.025). For predicting hepatic insufficiency and decompensation, LLIR-adjusted T1 (Akaike information criterion (AIC), 58.37; C-index, 0.867) and LLIR-T1 (AIC, 48.82; C-index, 0.885) at 10-min HBP showed the best performance, respectively, when added to serum albumin level.

CONCLUSIONS

T1 showed a strong correlation between two methods but with significant differences. T1 mapping using LLIR at 10-min HBP with obtainment of adjusted T1 and T1 may be the best approach for estimation of liver function and prediction of hepatic insufficiency and decompensation.

KEY POINTS

• T1 showed a strong correlation between LLIR and B inhomogeneity-corrected VFA methods, both at 10-min and 20-min HBP but with significant differences. • T1 at 10-min and 20-min HBP using LLIR and B inhomogeneity-corrected VFA methods could not be used interchangeably during the follow-up in patients with chronic liver disease (CLD) or cirrhosis. • T1 mapping using LLIR at 10-min HBP with obtainment of adjusted T1 and T1 may be the most suitable method and parameter for estimation of global liver function and prediction of clinical outcomes in patients with CLD or cirrhosis.