Department of Radiology, Beijing Friendship Hospital Affiliated to Capital Medical University, Beijing,100050, China.
Eur J Radiol. 2012 Aug;81(8):1677-81. doi: 10.1016/j.ejrad.2011.02.063. Epub 2011 Mar 27.
To investigate the effect of energy spectral CT on the image quality of CT portal venography in cirrhosis patients.
30 portal hypertension patients underwent spectral CT examination using a single-tube, fast dual tube voltage switching technique. 101 sets of monochromatic images were generated from 40keV to 140keV. Image noise and contrast-to-noise ratio (CNR) for portal veins from the monochromatic images were measured. An optimal monochromatic image set was selected for obtaining the best CNR for portal veins. The image noise and CNR of the intra-hepatic portal vein and extra-hepatic main stem at the selected monochromatic level were compared with those from the conventional polychromatic images. Image quality was also assessed and compared.
The monochromatic images at 51keV were found to provide the best CNR for both the intra-hepatic and extra-hepatic portal veins. At this energy level, the monochromatic images had about 100% higher CNR than the polychromatic images with a moderate 30% noise increase. The qualitative image quality assessment was also statistically higher with monochromatic images at 51keV.
Monochromatic images at 51keV for CT portal venography could improve CNR for displaying hepatic portal veins and improve the overall image quality.
探讨能谱 CT 对肝硬化患者 CT 门静脉成像图像质量的影响。
30 例门静脉高压患者采用单管、快速双管电压切换技术行能谱 CT 检查。从 40keV 到 140keV 生成 101 套单能量图像。对单能量图像上门静脉的图像噪声和对比噪声比（CNR）进行测量。选择最佳单能量图像组，以获得门静脉的最佳 CNR。比较选择的单能量水平上肝内门静脉和肝外主支的图像噪声和 CNR，以及常规多光谱图像。对图像质量进行评估并比较。
51keV 的单能量图像为肝内和肝外门静脉提供了最佳的 CNR。在这个能量水平上，单能量图像的 CNR 比多光谱图像高约 100%，噪声增加了 30%。51keV 的单能量图像的定性图像质量评估也具有统计学意义。
CT 门静脉成像的 51keV 单能量图像可以提高显示肝门静脉的 CNR，提高整体图像质量。
