HDCT能谱技术提高肝脏门静脉血管成像质量的可行性研究

Nvestigation of Improving the Image Quality of Portal Venography Using Spectral CT

目的探讨能谱技术在提高CT门静脉成像质量方面的价值。资料与方法 21例可疑肝脏病变的患者,采用能谱扫描模式行动脉期、门静脉期扫描后,运用能谱分析软件获得最佳对比信噪比单能图像和70 keV单能图像。测量传统(混合能量,QC)图像和70 keV单能图像、最佳对比信噪比单能图像中门静脉的信号噪声比(SNR)和对比噪声比(CNR),并对三组图像行容积再现(VR)、最大密度投影法(MIP)重组,采用双盲法对重组质量进行评估。对三组图像的数据行单因素方差分析。结果混合能量图像、70 keV单能图像、最佳CNR的单能图像同层对比,发现最佳CNR的单能图像的SNR、CNR大于混合能量图像和70 keV单能图像,差异有显著统计学意义(P<0.01)。最佳CNR的单能图像的VR、MIP重组图像对门静脉分支的显示级别优于混合能量图像和70 keV单能图像,差异有显著统计学意义(P<0.01)。结论最佳CNR的单能图像可以提高CT门静脉成像(CTPV)门静脉分支的显示级别和图像质量。

Objective To investigate the value of spectral CT in improving the image quality of CT portal venography.Materials and Methods 21 patients with suspected liver disease received spectral CT with GSI mode during the arterial and portal phase.The spectrum analysis was used to select the monochromatic images for obtaining the best contrast to noise ratio（CNR） for main portal veins.The SNR and CNR of main liver portal veins at 70 keV and the best monochromatic level were measured and analyzed,as well as the conventional polychromatic images.Image quality of MIP and VR reconstruction of portal venography was evaluated in a double blind manner by two radiologists.Results SNR and CNR of the monochromatic images at 70 keV and best monochromatic level were significantly different with polychromatic images（P0.01）.At the best energy level,CNR and SNR of monochromatic images were higher than that of polychromatic images.The image quality of VR and MIP on portal vein was also statistically higher with monochromatic images at optimal CNR than that of polychromatic and 70 kev images（P0.01）.Conclusion Monochromatic images at best keV for CT Portal Venography can improve CNR and SNR for displaying main portal veins and also improve the overall image quality of CTPV..