Magnetic resonance imaging and spectroscopy for monitoring liver steatosis

Purpose: To compare noninvasive MRI and magnetic resonance spectroscopy (MRS) methods with liver biopsy to quantify liver fat content. Materials and Methods: Quantification of liver fat was compared by liver biopsy, proton MRS, and MRI using in-phase/out-of-phase (IP/OP) and plus/minus fat saturation (+/- FS) techniques. The reproducibility of each MR measure was also determined. An additional group of overweight patients with steatosis underwent hepatic MRI and MRS before and after a six-month weight-loss program. Results: A close correlation was demonstrated between histological assessment of steatosis and measurement of intrahepatocellular lipid (IHCL) by MRS (r(s) = 0.928, P < 0.0001) and MRI (IP/OP r(s) = 0.942, P < 0.0001; FS r(s) = 0.935, P < 0.0001). Following weight reduction, four of five patients with >5% weight loss had a decrease in IHCL of >= 50%. Conclusion: These findings suggest that standard MRI protocols provide a rapid, safe, and quantitative assessment of hepatic steatosis. This is important because MRS is not available on all clinical MRI systems. This will enable noninvasive monitoring of the effects of interventions such as weight loss or pharmacotherapy in patients with fatty liver diseases.