【摘要】 目的:探讨基于双能量CT的新虚拟单能量成像（VMI+）技术应用于头颈部动脉支架成像的图像质量及最佳单能级水平。方法:对21例头颈部动脉支架植入术后复查的患者行双能量CT头颈部血管成像，经后处理获得M＿0.6融合图像（M＿0.6图像）和40～150 keV（10 keV间隔）VMI+图像。计算正常血管管腔及支架内管腔的信噪比（SNR）和对比噪声比（CNR）,并采用5分法对图像质量进行主观评分。测量支架直径，计算支架内、外管腔的CT值差值△CT（内-外）以及支架直径低估率。结果:21例患者共植入23枚支架。80 keV VMI+图像支架血管段的SNR、CNR与M＿0.6图像比较，差异无统计学意义（P>0.05）。80 keV时VMI+图像的支架直径测量值增大趋势开始减缓。与其他单能级图像相比，80 keV和90 keV图像的△CT_{（内-外）}绝对值较小。与M＿0.6图像相比，80 keV图像的主观评分明显提高，差异有统计学意义（分别为4.93±0.23和4.61±0.37,P<0.05）。结论:80 keV VMI+可以提高头颈部动脉支架的图像质量，减少支架产生的射线束硬化伪影，推荐其作为头颈部动脉支架成像的最佳单能级水平。更多还原

【Abstract】 Objective:The purpose of this study was to explore the image quality and determine the optimal single-energy level for noise-optimized virtual monoenergetic imaging(VMI+) technique using dual-energy CT(DECT) in carotid and intracranial artery stent imaging.Methods:Dual-energy carotid and intracranial CT angiography(CTA) was performed on 21 patients who underwent carotid and intracranial artery stenting and were subsequently reviewed.Linearly-blended(M＿0.6) images and VMI+ images at 40～150keV(10keV intervals) were obtained.The signal-to-noise ratio(SNR) and contrast-to-noise ratio(CNR) of native vascular lumen and in-stent lumen were calculated, and the image quality was subjectively scored using a 5-point scale.The in-stent luminal diameters were measured.The difference in CT values between the in-stent and out-stent lumens(ΔCTin-out) and stent diameter underestimation rates were calculated.Results:A total of 23 stents were evaluated in 21 patients.The SNR and CNR of the stented vessel segments of 80keV VMI+ images were statistically insignificant compared to the M＿0.6 images(P>0.05).The trend of the increasing stent diameter measurements of VMI+ images at 80keV began to slow down gradually.The absolute values of ΔCTin-out were lower for 80keV and 90keV images compared with other single-energy level images.The subjective score was significantly higher for 80keV images compared with the M＿0.6 images(4.93±0.23 vs. 4.61±0.37,P<0.05).Conclusion:The 80keV VMI+ is the optimal single-energy level suggested for visualizing carotid and intracranial arterial stents, as it improves image quality and eliminates stent-induced beam hardening artifacts.更多还原