Noninvasive quantification of hepatic steatosis in rats using 3.0 T 1H-magnetic resonance spectroscopy.

PURPOSE: To assess the accuracy of noninvasive 3.0 T (1)H-magnetic resonance spectroscopy ((1)H-MRS) in an experimental steatosis model for the discrimination of clinically relevant macrovesicular steatosis degrees and to evaluate three different (1)H-MR spectrum-based fat quantification methods. MATERIALS AND METHODS: Steatosis was induced in rats by a methionine/choline-deficient diet for 0-5 weeks. (1)H-MRS measurements of hepatic fat content were compared with histopathological and biochemical steatosis degree. In (1)H-MR spectra, areas under the curve (AUC) of fat (1.3 ppm), water (4.7 ppm), total fat (0.5-5.3 ppm), and total spectrum peaks (0.5-5.3 ppm) were determined and hepatic fat content calculated as follows: [AUC(total fat peaks)/AUC(total peaks)], [AUC(fat)/AUC(fat) + (AUC(water)/0.7)], and [AUC(fat)/AUC(water)]. RESULTS: A significant correlation was found between (1)H-MRS and macrovesicular steatosis (r = 0.932, P < 0.0001) and between (1)H-MRS and total fatty acids (r = 0.935, P < 0.0001). (1)H-MRS accurately distinguished mild from moderate and moderate from severe steatosis. Calculations using [AUC(fat)/AUC(water)] ratio in severe steatotic livers resulted in higher hepatic fat percentages as compared to the other methods due to a decrease in hepatic water content. CONCLUSION: (1)H-MRS quantification of hepatic fat content showed high correlations with histological and biochemical steatosis determination in an experimental steatosis rat model and accurately discriminated between clinically relevant steatosis degrees. These results encourage further application of (1)H-MRS in patients for accurate steatosis assessment.

Hepatic unsaturated fatty acids in patients with non-alcoholic fatty liver disease assessed by 3.0T MR spectroscopy.

RATIONALE AND OBJECTIVE: Non-alcoholic fatty liver disease (NAFLD) is related to the metabolic syndrome and obesity. Proton magnetic resonance spectroscopy ((1)H MRS) is a non-invasive technique to assess hepatic triglyceride content (HTGC) and allows assessment of unsaturated fatty acids (UFA). There is increasing evidence that hepatic UFA are associated with the development of NAFLD. Therefore the objective of this study was to assess hepatic UFA in patients with NAFLD using (1)H MRS. MATERIALS AND METHODS: We included 26 consecutive patients with deranged liver enzymes, with and without type 2 diabetes mellitus (DM2), suspected for NAFLD. Liver function and metabolic parameters were assessed. (1)H MRS measurements were performed at 3.0T. From the (1)H MR spectra two ratios were calculated: ratio 1 (UFA); unsaturated fatty acid peak vs. reference water peak and ratio 2 (HTGC); total fatty acid peak vs. reference water peak. RESULTS: Twenty-six patients were included. In these patients hepatic UFA (ratio 1) correlated with AST/ALT ratio (r=-0.46, p=0.02), glucose levels (r=0.46, p=0.018), HOMA-IR (r=0.59, p=0.004) and HTGC (r=0.81, p<0.001). In diabetic patients (n=12) hepatic UFA correlated with alkaline phosphatase levels (r=0.72, p=0.01), HOMA-IR (r=0.73, p=0.01) and HTGC (r=0.83, p=0.002). Compared to non-diabetic patients with NAFLD, hepatic UFA levels were increased in patients with DM2 and NAFLD (0.032 vs. 0.014, p=0.03). CONCLUSION: Hepatic UFA can be assessed with (1)H MRS. (1)H MRS determined hepatic UFA correlate with clinical and metabolic parameters associated with NAFLD. Hepatic UFA are increased in patients with DM2. This study provides evidence for the use of non-invasive (1)H MRS to assess hepatic UFA in vivo.