Quantification of Hepatic Steatosis With MRI: The Effects of Accurate Fat Spectral Modeling

Purpose: To develop a chemical-shift-based imaging method for fat quantification that accounts for the complex spectrum of fat. and to compare this method with MR spectroscopy (MRS). Quantitative noninvasive biomarkers of hepatic steatosis are urgently needed for the diagnosis and management. of nonalcoholic. Fatty liver disease (NAFLD). Materials and Methods: Hepatic steatosis was measured with fat-fraction images in 31 patients using a multiechochemical-shift-based water-fat separation method at 15T. Fat-fraction images were reconstructed using a conventional signal model that considers fat as a single peak at -210 Hz relative to water (single peak reconstruction). Fat-fraction images were also reconstructed from the same source images using two methods that account I, or the complex spectrum of fat: precalibrated and self-calibrated multipeak reconstruction. Single-voxel MRS that. was coregistered with imaging was performed for comparison. Results: Imaging and MRS demonstrated excellent correlation with single peak reconstruction (r(2) = 0.91). precalibrated multipeak reconstruction (r(2)=0.94). and self-calibrated multipeak reconstruction (r(2)=0.91). However, precalibrated multipeak reconstruction demonstrated the best. agreement. with MRS. with a slope statistically equivalent to 1 (0.96 +/- 0.04: P=0.4). compared to self-calibrated multipeak reconstruction (0.83 +/- 0.05, P=0.001) and single-peak reconstruction (0.67 +/- 0.04, P < 0.001). Conclusion: Accurate spectral modeling is necessary for accurate quantification of hepatic steatosis with MRI.