In Vivo Lipid Profiling Using Proton Magnetic Resonance Spectroscopy in an Experimental Liver Fibrosis Model

Abstract

Rationale and Objectives: The aim of this study was to characterize early hepatic lipid changes in an experimental model of liver fibrosis using proton ( 1H) magnetic resonance spectroscopy (MRS) at high magnetic field in vivo. Materials and Methods: Liver fibrosis was induced in 12 Sprague-Dawley rats by twice-weekly carbon tetrachloride (CCl 4) administration up to 4 weeks. Eight normal rats were used as controls. Single-voxel 1H MRS experiments were performed at 7 Tesla to measure signal integrals of various lipid peaks including -CH 3, (-CH 2-) n, -CH 2-C=C-CH 2-, =C-CH 2-C= and -CH=CH- at 0.9, 1.3, 2.0, 2.8, and 5.3 ppm, respectively, and peak from choline-containing compounds (CCC) at 3.2 ppm. Total lipid, total saturated fatty acid, total unsaturated fatty acid, total unsaturated bond, polyunsaturated bond, and CCC indices were quantified. Results: Significant increases (P<.01) in total lipid and total saturated fatty acid indices were found in animals with CCl 4-induced fibrosis as compared with normal animals. In addition, total unsaturated bond and polyunsaturated bond indices of animals at 4 weeks after CCl 4 insult were significantly higher than (P<.01 and P<.05, respectively) those of normal animals and animals at 2 weeks following insult; whereas there was only significant increase (P<.01) in total unsaturated fatty acid index in animals with 4-week CCl 4 insult as compared with normal animals. Conclusion: The hepatic lipid changes in CCl 4-induced experimental fibrosis model were documented in vivo and longitudinally using 1H MRS at 7 Tesla. The experimental findings suggested that total saturated fatty acid increase contributed mainly to the total lipid increase in animals with CCl 4 insult. This study also demonstrated the potential value of high field MRS to resolve lipid composition and alterations in liver fibrosis. © 2011 AUR.