颈横动脉64排能谱CT血管造影成像的初步应用研究

Clinical Value of Spectral Imaging in CT Angiography of Transverse Cervical Artery

目的:探讨能谱CT血管造影对于颈横动脉显示的临床应用价值。方法:10例疑颈动脉血管病变的患者(男3例,女7例,61岁～84岁,平均年龄73.8岁),进行64排能谱CT血管造影检查,同时获得混合能量图像及单能量图像;运用GSI软件进行分析处理,寻找最佳单能量图像;测量颈横动脉起始部锁骨下动脉、同层斜方肌的CT值,及同层图像的背景噪声值,计算血管的对比噪声比(CNR)。对颈横动脉血管显示的清晰程度进行分级评价。根据上述参数比较混合能量图像及单能量图像质量。结果:45keV的单能量图像是颈横动显示的最佳单能量图像,其血管强化程度明显高于混合能量图像(P<0.05),其噪声强度及对比噪声比均高于混合能量图像。在血管显示方面单能量图像较混合能量图像略清晰,两者主观评分间具有显著的统计学差异(P<0.05)。结论:能谱CT血管造影能提高颈横动脉等颈部小血管的显示,具有一定的临床应用前景和价值。

Purpose： To investigate the effect of gemstone spectral imaging （GSI） on the image quality of CT angiography in transverse cervical artery. Methods： Ten patients with suspected carotid vascular lesions underwent GSI mode by Discovery CT750 HD using a single source, fast kVp switching technique. One hundred and one sets of monochromatic images and polychromatic images were generated. All cases were analyzed with GSI viewer. An optimal monochromatic image set was selected for obtaining the best contrast-to-noise ratio （CNR） for transverse cervical artery. Image noise and CNR of images were measured. The conspicuity of the transverse cervical artery was assessed with 5 grades （1=poor; 5=excellent）. Image quality was also assessed and compared between the polychromatic and monochromatic images. Resuits： The monochromatic image at 45 keV had the best CNR for transverse cervical artery. The CT value of vascular enhancement on 45keV image was significantly higher than that on the polychromatic image. The CT values of vascular and muscle were 793.75±207.12 and 239.97±48.02 （P〈0.05） respectively. The optimal monochromatic image had about 70% higher CNR than the polychromatic image had while with noise increased. The conspicuity of the transverse cervical artery and the image quality assessment of monochromatic images at 45keV were also higher than that of polychromatic images （P〈0.05）. Conclusion： Monochromatic images for CT angiography could improve CNR for displaying small vascular, such as transverse cervical artery, and improve the image quality. [ Key words ]CT spectral imaging; CT Angiography; Transverse cervical artery