Purpose: To describe the spatial distribution of liver fat,using MRI-estimated proton density fat fraction (PDFF), in adults with nonalcoholic fatty liver disease (NAFLD).
Materials and methods: This Investigational Review Board-approved, Health Insurance Portability and Accountability Act-compliant study prospectively enrolled 50 adults (30 women, 20 men) with biopsy-proven NAFLD. Hepatic PDFF was measured by low-flip-angle multiecho spoiled gradient-recalled-echo MRI at 3 Tesla. Three nonoverlapping regions of interest were placed within each liver segment. Statistical analyses included Pearson's correlation, multivariable linear regression, and permutation-based paired tests.
Results: The study population's mean whole-liver PDFF was 16.1% (range: 1.6–39.6%). The mean whole-liver PDFF variability was 1.9% (range: 0.7–4.5%). Higher variability was associated with higher PDFF (r=0.34;P=0.0156). The mean PDFF was significantly higher in the right lobe than the left (16.5% versus 15.3%, P=0.0028). The mean PDFF variability was higher in the left lobe than the right (1.86% versus 1.28%; P<0.0001). Segment II had the lowest mean segmental PDFF (14.8%);segment VIII had the highest (16.7%). Segments V(0.71%) and VI (0.70%) had the lowest mean segmental PDFF variability; segment II had the highest (1.32%).
Conclusion: IN adult NAFLD there are small but significant differences in fat content.