Comparison of different MR fat quantification methods at 3.0 T in a phantom study

Abstract

Objective To investigate the value of MR imaging methods for the quantification of fat content in a customized lipid phantom at 3.0 T. Methods Eleven homogeneous fat-water phantoms (50 ml) with fat volume percentages from 0 to 100% were constructed with reference to Bernard's methods. Fat fractions of the lipid phantom were acquired using water selective saturation (WS), fat selective saturation (FS), in- and out-of-phase imaging (IOP), iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) gradient echo imaging and IDEAL Quant imaging methods on a 3.0 T MRI system. For statistical comparisons, paired-sample t test, Pearson correlation test, and Bland-Altman maps were applied. Results Evaluated fat fractions acquired by WS, IDEAL Gradient echo imaging and IDEAL Quant were (49.6±28.8)%, (46.0±28.4)%,(51.0±32.0)%,the result has no significant difference with the true fat contents(t values were -0.186, -2.218, 2.713;P values were 0.856, 0.051, 0.055). Evaluated fat fractions acquired by FS, corrected algorithm and IOP were (64.2±26.7)%, (58.9±31.9)% and (45.3±32.3)%, these three kinds of methods have significant difference with the true fat contents (t values were 5.168, 4.273, -6.441;P<0.01). All the chemical shift imaging methods correlated with the true phantom model fat fractions, r values were 0.977(FS), 0.978 (corrected algorithm), 0.982 (WS), 0.99 8(IOP), 0.993 (IDEAL Gradient echo imaging), 0.999 (IDEAL Quant) (all P<0.01). Each method's 95% confidence interval of the mean difference acquired by Bland-Altman map was WS (-14.7% to 13.8%), FS (-3.6% to 32.0%), corrected algorithm (-4.6% to 22.5%), IOP(-9.4% to 0.0%), IDEAL gradient echo imaging (-15.9% to 7.8%), IDEAL Quant(-2.0% to 4.0%). IDEAL Quant had the best correlation and confidence with the true fat fraction. Conclusions Chemical shift imaging methods (IOP, IDEAL Gradient echo imaging, IDEAL Quant) can acquire more accurate fat quantification results than chemical saturation imaging methods (FS, Corrected algorithm, WS) in a customized lipid phantom at 3.0 T. IDEAL Quant can acquire the best fat quantification result compared with the other imaging methods. Key words: Magnetic resonance imaging; Fat quantification; Phantom model