Abstract
OBJECTIVES: To investigate the accuracy of using multi-material decomposition (MMD) algorithm in dual-energy spectral computed tomography (CT) for quantifying fat fraction (FF) in the presence of iron. MATERIALS: Nine tubes with various proportions of fat and iron were prepared. FF were divided into three levels (10%, 20%, and 30%), recorded as references (FF(ref) ). Iron concentrations (in mg/100 g) were divided into three ranges (25.25-25.97, 50.38-51.55 and 75.57-77.72). The nine-tube phantom underwent dual-energy CT and MR. CT attenuation was measured and FF were determined using MMD in CT (FF(CT) ) and Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation (IDEAL-IQ) in MR (FF(MR) ) for each tube. Statistical analyses used were: Spearman rank correlation for correlations between FF(ref) and CT attenuation, FF(CT) , and FF(MR) ; one-way ANOVA, and one-sample t-test for the differences between FF(CT) and FF(ref) and between FF(MR) and FF(ref) . A multivariate linear regression model was established to analyze the differences between the corresponding values with different iron concentrations under the same FF(ref) . RESULTS: Fat fraction on CT (FFCT) and FF(MR) were positively correlated with FF(ref) (all p < 0.001), while the CT attenuation was negatively correlated with FF(ref) in the three iron concentration ranges. For a given FF(ref) , FF(CT) decreased and FF(MR) increased as the iron concentration increased. The mean difference between FF(CT) and FF(ref) over the nine tube measurements was 0.25 ± 2.45%, 5.7% lower the 5.98 ± 3.33% value between FF(MR) and FF(ref) (F = 310.017, p < 0.01). CONCLUSION: The phantom results indicate that MMD in dual-energy CT can directly quantify volumetric FF and is less affected by iron concentration than MR IDEAL-IQ method.