Assessment of Segmental Hepatic Fat Distribution using Magnetic Resonance Proton Density Fat Fraction MR-PDFF in Non-alcoholic Fatty Liver Disease (NAFLD)

Abstract: Background: Non-Alcoholic Fatty Liver Disease (NAFLD) is a significant healthcare challenge. MR proton density fat fraction (MR-PDFF) is a quantitative imaging parameter that allows a precise estimation of hepatic steatosis. Determination of segmental and lobar fat distribution is also important since underestimation or overestimation may lead to hurdles in patient management and may also alter outcomes during liver donor assessment for living donor liver transplant. Objective: To determine the heterogeneity of hepatic fat distribution across different liver segments and both lobes in patients with non-alcoholic fatty liver disease (NAFLD). Materials and Methods: This cross-sectional descriptive study included 35 patients of NAFLD. MR-PDFF sequence was performed, two regions of interest (ROI) were drawn at the periphery of each hepatic segment and their mean was taken. We calculated mean values, ranges, and standard deviations for individual segments, both lobes and the entire liver. Pearson’s correlation was used to assess the relation between MR-PDFF and MR-PDFF variability. Paired sample t-test was utilized to compare the means of the right and the left lobe of the liver. Results: The fat fraction in segment I was the lowest and in segment VII the highest. The right and left lobes showed a significant difference in fat fraction with values of 14% and 11.4% respectively (paired sample t-test, p<0.005). The left lobe showed a greater MR-PDFF variability than the right lobe (1.9 vs 1.6%). Conclusion: In patients with NAFLD, segments VII and VIII show the greatest while segments I and IV show the least fat infiltration. Hepatic fat preferentially gets deposited more in the right lobe of the liver.