Comparison of R2* correction methods for accurate fat quantification in fatty liver

Purpose: To compare the performance of fat fraction quantification using single-R2* and dual-R2* correction methods in patients with fatty liver, using MR spectroscopy (MRS) as the reference standard. Materials and Methods: From a group of 97 patients, 32 patients with hepatic fat fraction greater than 5%, as measured by MRS, were identified. In these patients, chemical shift encoded fat-water imaging was performed, covering the entire liver in a single breathhold. Fat fraction was measured from the imaging data by postprocessing using 6 different models: single- and dual-R2* correction, each performed with complex fitting, magnitude fitting, and mixed magnitude/complex fitting to compare the effects of phase error correction. Fat fraction measurements were compared with co-registered spectroscopy measurements using linear regression. Results: Linear regression demonstrated higher agreement with MRS using single-R2* correction compared with dual-R2* correction. Among single-R2* models, all 3 fittings methods performed similarly well (slope = 1.0 +/- 0.06, r2 = 0.890.91). Conclusion: Single-R2* modeling is more accurate than dual-R2* modeling for hepatic fat quantification in patients, even in those with high hepatic fat concentrations. J. Magn. Reson. Imaging 2013;37:414422. (C) 2012 Wiley Periodicals, Inc.