Quantitative chemical shift-encoded MRI is an accurate method to quantify hepatic steatosis

Abstract

Purpose To compare the accuracy of liver fat quantification using a three-echo chemical shift-encoded magnetic resonance imaging (MRI) technique without and with correction for confounders with spectroscopy (MRS) as the reference standard. Materials and Methods Fifty patients (23 women, mean age 56.6 ± 13.2 years) with fatty liver disease were enrolled. Patients underwent T2-corrected single-voxel MRS and a three-echo chemical shift-encoded gradient echo (GRE) sequence at 3.0T. MRI fat fraction (FF) was calculated without and with T2 and T1 correction and multispectral modeling of fat and compared with MRS-FF using linear regression. Results The spectroscopic range of liver fat was 0.11%-38.7%. Excellent correlation between MRS-FF and MRI-FF was observed when using T2 correction (R2=0.96). With use of T2 correction alone, the slope was significantly different from 1 (1.16 ± 0.03, P < 0.001) and the intercept was different from 0 (1.14% ± 0.50%, P < 0.023). This slope was significantly different than 1.0 when no T1 correction was used (P=0.001). When T2 , T1, and spectral complexity of fat were addressed, the results showed equivalence between fat quantification using MRI and MRS (slope: 1.02 ± 0.03, P=0.528; intercept: 0.26% ± 0.46%, P=0.572). Conclusion Complex three-echo chemical shift-encoded MRI is equivalent to MRS for quantifying liver fat, but only with correction for T2 decay and T1 recovery and use of spectral modeling of fat. This is necessary because T2 decay, T1 recovery, and multispectral complexity of fat are processes which may otherwise bias the measurements. Copyright © 2013 Wiley Periodicals, Inc.