Assessment of relevant hepatic steatosis in obese adolescents by rapid fat-selective GRE imaging with spatial-spectral excitation: a quantitative comparison with spectroscopic findings.

OBJECTIVE: To test the feasibility of fat-selective GRE imaging using a spectral-spatial excitation technique for determination of intrahepatic lipid content (IHL) in obese adolescents.
METHODS: Fat-selective MR imaging (1.5 T) was applied to record a single axial slice through a representative liver region within a single breath-hold. The sequence uses six equidistant slice-selective excitation pulses with binomial amplitude ratios to achieve high selectivity for lipid signals after appropriate shimming. IHL(MRI) content was quantified using signal intensity of adjacent subcutaneous adipose tissue. As the gold standard for IHL quantification, single-voxel stimulated echo magnetic resonance spectroscopy (MRS) was applied. IHL(MRS) was quantified using the water peak as a reference.
RESULTS: Forty-five MR examinations could be performed, and IHL(MRS) content ranged from 0.7% to 19.1%. Results from MRS and fat-selective imaging correlated well with Spearman coefficients between r = 0.78 and r = 0.86. There were no relevant regional differences in IHL within the liver parenchyma (p > 0.6359). Fat-selective imaging was able to reliably identify patients with IHL content above 5% with positive/negative likelihood ratio of 11.8 and 0.05, respectively.
CONCLUSION: Fat-selective MR imaging provides both a reliable and a convenient method of rapidly quantifying IHL content in obese adolescents.