Graduate School of Health Sciences, Kumamoto University, 4-24-1 Kuhonji, Kumamoto, 862-0976, Japan; Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi Ward, Fukuoka, 812-8582, Japan.
Division of Radiology, Department of Medical Technology, Kyushu University Hospital, 3-1-1 Maidashi, Higashi Ward, Fukuoka, 812-8582, Japan; Department of Health Sciences, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi Ward, Fukuoka, 812-8582, Japan.
Radiography (Lond). 2023 May;29(3):557-563. doi: 10.1016/j.radi.2023.03.003. Epub 2023 Mar 23.
Dual-energy computed tomography (DECT) can generate virtual non-contrast (VNC) images. Herein, we sought to improve the accuracy of VNC images by identifying the optimal slope of contrast media (SCM) for VNC-image generation based on the iodine concentration and subject's body size.
We used DECT to scan a multi-energy phantom including four iodine concentration rods (15, 10, 5, and 2 mg/mL), and 240 VNC images (eight SCM ranging from 0.49 to 0.56 × three body sizes × ten scans) that were generated by three-material decomposition. The CT number of each iodine and solid water rod part was measured in each VNC image. The difference in the CT number between the iodine and the solid water rod part was calculated and compared using paired t-test or repeated measures ANOVA.
The SCM that achieved an absolute value of the difference in CT number of <5.0 Hounsfield units (HU) for all body sizes simultaneously was greater at lower iodine concentration (SCM of 0.5, 0.51, and 0.53 at 10, 5, and 2 mg/mL iodine, respectively). At an iodine concentration of 15 mg/mL, no SCM achieved an absolute difference of <5.0 HU in CT number for all body sizes simultaneously. At all iodine concentrations, the SCM achieving the minimal difference in the CT number increased with the increase in body size.
By adjusting the SCM according to the iodine concentration and body size, it is possible to generate VNC images with an accuracy of <5.0 HU.
Improving the accuracy of VNC images minimizing incomplete iodine subtraction would make it possible to replace true non-contrast (TNC) images with VNC images and reduce the radiation dose.
双能 CT（DECT）可生成虚拟非对比（VNC）图像。在此，我们试图通过基于碘浓度和受检者体型来确定对比剂（SCM）的最佳斜率，从而提高 VNC 图像的准确性，以生成 VNC 图像。
我们使用 DECT 扫描一个包含四个碘浓度棒（15、10、5 和 2 mg/mL）的多能量体模，并生成 240 个 VNC 图像（八个 SCM 范围为 0.49 至 0.56×三种体型×十次扫描），这些图像是通过三物质分解生成的。在每个 VNC 图像中测量每个碘和固体水棒部分的 CT 值。使用配对 t 检验或重复测量 ANOVA 比较和计算碘和固体水棒部分之间的 CT 值差值。
对于所有体型，SCM 的绝对值差值<5.0 个亨氏单位（HU）的碘浓度越低（分别为 10、5 和 2 mg/mL 碘的 SCM 为 0.5、0.51 和 0.53）。在 15 mg/mL 碘浓度下，没有 SCM 能同时对所有体型的 CT 值差值<5.0 HU。在所有碘浓度下，实现 CT 值差值最小的 SCM 随体型的增加而增加。
通过根据碘浓度和体型调整 SCM，可以生成<5.0 HU 准确性的 VNC 图像。
提高 VNC 图像的准确性，最大限度地减少不完全碘减影，将有可能用 VNC 图像替代真正的非对比（TNC）图像，从而降低辐射剂量。
