Lundin Margareta, Lidén Mats, Magnuson Anders, Mohammed Ahmed Abdulilah, Geijer Håkan, Andersson Torbjörn, Persson Anders
Department of Radiology, Örebro University Hospital, Örebro University, Örebro, Sweden.
Acta Radiol. 2012 Jul;53(6):689-94. doi: 10.1258/ar.2012.110661.
Dual-energy computed tomography (DECT) has been shown to be useful for subtracting bone or calcium in CT angiography and gives an opportunity to produce a virtual non-contrast-enhanced (VNC) image from a series where contrast agents have been given intravenously. High noise levels and low resolution have previously limited the diagnostic value of the VNC images created with the first generation of DECT. With the recent introduction of a second generation of DECT, there is a possibility of obtaining VNC images with better image quality at hopefully lower radiation dose compared to the previous generation.
To compare the image quality of the single-energy series to a VNC series obtained with a two generations of DECT scanners. CT of the urinary tract was used as a model.
Thirty patients referred for evaluation of hematuria were examined with an older system (Somatom Definition) and another 30 patients with a new generation (Somatom Definition Flash). One single-energy series was obtained before and one dual-energy series after administration of intravenous contrast media. We created a VNC series from the contrast-enhanced images. Images were assessed concerning image quality with a visual grading scale evaluation of the VNC series with the single-energy series as gold standard.
The image quality of the VNC images was rated inferior to the single-energy variant for both scanners, OR 11.5-67.3 for the Definition and OR 2.1-2.8 for the Definition Flash. Visual noise and overall quality were regarded as better with Flash than Definition.
Image quality of VNC images obtained with the new generation of DECT is still slightly inferior compared to native images. However, the difference is smaller with the new compared to the older system.
双能计算机断层扫描（DECT）已被证明在CT血管造影中用于去除骨骼或钙成分很有用，并且有机会从静脉注射造影剂的系列图像中生成虚拟非增强（VNC）图像。高噪声水平和低分辨率先前限制了第一代DECT生成的VNC图像的诊断价值。随着第二代DECT的近期推出，有可能获得图像质量更好且有望比上一代更低辐射剂量的VNC图像。
比较单能量系列图像与使用两代DECT扫描仪获得的VNC系列图像的图像质量。以泌尿系统CT作为模型。
对30例因血尿接受评估的患者使用较旧系统（Somatom Definition）进行检查，另外30例患者使用新一代系统（Somatom Definition Flash）进行检查。在静脉注射造影剂之前获得一个单能量系列图像，之后获得一个双能量系列图像。我们从增强图像中创建了一个VNC系列图像。以单能量系列图像作为金标准，通过视觉分级量表评估对VNC系列图像的图像质量进行评估。
对于两台扫描仪，VNC图像的图像质量均被评定低于单能量图像，Definition扫描仪的比值比为11.5 - 67.3，Definition Flash扫描仪的比值比为2.1 - 2.8。Flash扫描仪的视觉噪声和整体质量被认为优于Definition扫描仪。
与原始图像相比，新一代DECT获得的VNC图像的图像质量仍然略逊一筹。然而，与旧系统相比，新系统的差异较小。
