From the Department of Radiology, University of Washington School of Medicine, Seattle, WA.
J Comput Assist Tomogr. 2021;45(6):877-887. doi: 10.1097/RCT.0000000000001193.
To investigate in an anthropomorphic phantom study the accuracy of dual-energy computed tomography (DECT) techniques for fat quantification in comparison with magnetic resonance (MR) proton density fat fraction (PDFF) and single-energy computed tomography (SECT), using known fat content as reference standard.
Between August 2018 and November 2020, organic material-based cylinders, composed of mixtures of lean and fat tissues mimics, iodine, and iron, were constructed to simulate varying fat content levels (0%, 10%, 15%, 25%, 50%, 75%, and 100%) in a parenchymal organ and were embedded into an anthropomorphic phantom simulating 3 patient sizes (circumference, 91, 126, and 161 cm). The phantom was imaged with multiecho MR, DECT, and SECT. Magnetic resonance PDFF, DECT fat fraction, and computed tomography (CT) numbers (SECT polychromatic and DECT monochromatic data, virtual unenhanced images) were estimated. Performances of MR PDFF and CT techniques to detect differences in fat content were measured using the area under the curve (AUC). Noninferiority of each CT technique relative to MR PDFF was tested using a noninferiority margin of -0.1.
MR PDFF, DECT 140 keV monochromatic data, and fat fraction most closely correlated with known fat content (R2 = 0.98, 0.98, and 0.96, respectively). Unlike SECT and all other DECT techniques, DECT fat fraction was not affected by presence of iodine (mean difference, 0.3%; 95% confidence interval [CI], -0.9% to 1.5%). Dual-energy computed tomography fat fraction showed noninferiority to MR PDFF in detecting differences of 5% in fat content in medium-sized phantoms (ΔAUC, -0.05; 95% CI, -0.08 to -0.01), and 7% in large (ΔAUC, -0.04; 95% CI, -0.0 to 0.00) or extralarge sized phantoms (ΔAUC, -0.02; 95% CI, -0.07 to 0.00).
Dual-energy computed tomography fat fraction shows linear correlation with true fat content in the range up to 50% fat fraction. Dual-energy computed tomography fat fraction has comparable estimation error and shows noninferiority to MR PDFF in detecting small differences in fat content across different body sizes.
在人体模拟体模中进行一项拟人化的研究，以比较磁共振质子密度脂肪分数（PDFF）和单能计算机断层扫描（SECT），评估双能计算机断层扫描（DECT）技术在脂肪定量方面的准确性，将已知的脂肪含量作为参考标准。
在 2018 年 8 月至 2020 年 11 月期间，我们构建了由组织模拟器官中混合的瘦组织和脂肪组织、碘和铁制成的有机材料圆柱体，以模拟不同的脂肪含量水平（0%、10%、15%、25%、50%、75%和 100%），并将其嵌入一个模拟 3 种患者体型（周长 91、126 和 161 厘米）的人体模拟体模中。该体模接受多回波磁共振、DECT 和 SECT 成像。估计磁共振 PDFF、DECT 脂肪分数和计算机断层扫描（CT）数值（SECT 多色和 DECT 单色数据、虚拟未增强图像）。使用曲线下面积（AUC）来测量磁共振 PDFF 和 CT 技术检测脂肪含量差异的性能。使用非劣效性边界 -0.1 来测试每种 CT 技术相对于磁共振 PDFF 的非劣效性。
磁共振 PDFF、DECT 140 keV 单能数据和脂肪分数与已知脂肪含量最密切相关（R2=0.98、0.98 和 0.96）。与 SECT 和所有其他 DECT 技术不同，DECT 脂肪分数不受碘存在的影响（平均差异 0.3%；95%置信区间 [CI]，-0.9%至 1.5%）。DECT 脂肪分数在检测中、大型体模中 5%（ΔAUC，-0.05；95%CI，-0.08 至 -0.01）和大型（ΔAUC，-0.04；95%CI，-0.0 至 0.00）或特大（ΔAUC，-0.02；95%CI，-0.07 至 0.00）体模中脂肪含量差异方面具有非劣效性。
在 0%至 50%脂肪分数范围内，DECT 脂肪分数与真实脂肪含量呈线性相关。DECT 脂肪分数在检测不同体型的脂肪含量差异方面具有与磁共振 PDFF 相当的估计误差，并具有非劣效性。
