Invest Radiol. 2018 Jun;53(6):321-327. doi: 10.1097/RLI.0000000000000446.
The aims of this study were to analyze the effect of dual-energy computed tomography (DECT) scanners and fluid characteristics on iodine quantification and to calculate the measurement variability range induced by those variables.
We performed an experimental phantom study with 4 mediastinal iodine phantoms. Each phantom contained 6 tubes of different iodine concentrations (0, 1.0, 2.5, 5.0, 10.0, and 20.0 mg/mL) diluted in a specific solvent, which was water, 10% amino acid solution, 20% lipid emulsion, or 18% calcium solution, respectively. Mediastinal phantoms were inserted into an anthropomorphic chest phantom and were scanned with 3 different DECT scanners from 3 vendors using 2 radiation dosage settings. Iodine density (IoD) and computed tomography (CT) attenuation at virtual monoenergetic 70-keV images and virtual nonenhanced images were measured for the iodine phantoms. The effects of DECT scanners, solvents, and radiation dosage on the absolute measurement error of IoD and on the CT attenuation profiles were investigated using linear mixed-effects models. Measurement variability range of IoD was also determined.
Absolute error of IoD was not significantly affected by the DECT systems, kind of solvents, and radiation dosage settings. However, CT attenuation profiles were significantly different among the DECT vendors and simulated body fluids. Measurement variability range of IoD was from -0.6 to 0.4 mg/mL for the true iodine concentration 0 mg/mL.
Dual-energy CT systems and fluid characteristics did not have a significant effect on the IoD measurement accuracy. A cutoff of IoD for the determination of a truly enhancing lesion on DECT would be 0.4 mg/mL.
本研究旨在分析双能 CT（DECT）扫描仪和流体特性对碘定量的影响，并计算这些变量引起的测量可变性范围。
我们进行了一项使用 4 个纵隔碘模型的实验性体模研究。每个体模包含 6 个管，管中分别含有不同浓度的碘（0、1.0、2.5、5.0、10.0 和 20.0mg/mL），并分别溶解于特定的溶剂（水、10%氨基酸溶液、20%脂质乳剂或 18%钙溶液）。纵隔体模插入到一个人体胸部体模中，并使用 3 种不同供应商的 3 种 DECT 扫描仪，以 2 种辐射剂量设置进行扫描。对碘模型进行虚拟单能 70keV 图像和虚拟未增强图像的碘密度（IoD）和 CT 衰减测量。使用线性混合效应模型研究 DECT 扫描仪、溶剂和辐射剂量对 IoD 绝对测量误差和 CT 衰减曲线的影响。还确定了 IoD 的测量可变性范围。
IoD 的绝对误差不受 DECT 系统、溶剂种类和辐射剂量设置的显著影响。然而，CT 衰减曲线在 DECT 供应商和模拟体液之间存在显著差异。对于真实碘浓度为 0mg/mL 的 IoD，其测量可变性范围为-0.6 至 0.4mg/mL。
DECT 系统和流体特性对 IoD 测量精度没有显著影响。对于 DECT 上真正增强病变的确定，IoD 的截断值为 0.4mg/mL。
