Hepatic fat during fasting and refeeding by MRI fat quantification

Abstract

Purpose: To explore the sensitivity of high-field small animal magnetic resonance imaging to dynamic changes in fat content in the liver and to characterize the effect of prandial state on imaging studies of hepatic fat. Materials and Methods: A total of three timepoints were acquired using asymmetric spin-echo acquisitions for 12 mice with 24-hour spacing. After the first scan, half of the cohort was placed on a water-only diet. The second half of the cohort continued to have access to their high-fat chow. The scans were repeated after 24 hours. All animals were then returned to the high-fat diet, and the scans were again repeated after 24 hours. Fat fraction maps were computed using previously described methods. Regions of interests were manually drawn in the livers and the patterns of the two groups over time were compared. Results: Five out of six of the animals in the starved group showed an increase in hepatic fat fraction during the fasting period (average increase 0.54 ± 0.48), which decreased on refeeding. Analysis of variance indicated that the results significantly depended on both the group and the timepoint (P = 0.003). Conclusion: Fat-water imaging methods are able to measure hepatic fat changes caused by short-term dietary perturbations.