Spatial distribution of MRI-determined hepatic proton density fat fraction in adults with nonalcoholic fatty liver disease

Author(s): Bonekamp, S; Tang, A; Mashhood, A; Wolfson, T; Changchien, C; Middleton, MS; Clark, L; Gamst, A; Loomba, R; Sirlin, CB | Abstract: 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%; Pl0.0001). 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 and variability between lobes and some of the segments. Copyright © 2013 Wiley Periodicals, Inc.