Vitrea工作站三种头颈CTA减影技术效果对比及临床应用价值

Comparison of effects and Clinical Applications of Three Head and Neck CTA Subtraction Techniques on Vitrea Workstation

目的:比较佳能CT Vitrea工作站上三种不同减影后处理技术(Ortho减影、Carotid减影、Cow减影)对头颈CT血管成像(CTA)的减影效果并探讨各技术的临床应用价值。方法:将42例于我院行头颈CTA检查患者的扫描数据导入Vitrea工作站,分别采用Ortho减影、Carotid减影及Cow减影技术对图像进行减影处理,然后分别进行客观和主观图像质量评价:对减影后的三组图像的颈内动脉C2段、大脑中动脉M2段、大脑前动脉膝部、颅顶右侧顶骨的CT值和SD值以及血管的信噪比(SNR)、对比噪声比(CNR)分别进行比较;对减影后三组图像行容积再现重组后,分部位评价去骨效果和血管显示情况。结果:颈内动脉C2段:Carotid减影的CT值、SNR最低,SD值最高(P<0.05),CNR值由高到低依次为Carotid减影、Ortho减影、Cow减影(P<0.05);大脑中动脉M2段和大脑前动脉膝部:Cow减影的CT值最高(P<0.05),Carotid减影的CNR最高(P<0.05);右侧顶骨:Ortho减影CT值和SD值均低于Carotid减影(P<0.05),Cow减影的CT值恒定为-1 024HU且不存在噪声。头部去骨效果:Cow减影最佳(Ⅰ级图像率为92.86%);颈胸部去骨效果:Ortho减影最佳(Ⅰ级图像率为47.62%)。三种减影技术在颈总动脉的减影效果无明显差异(P>0.05),在颈内动脉、大脑前、中、后动脉、基底动脉及椎动脉差异有统计学意义(P<0.05);Cow和Ortho减影对大脑中动脉的显示优于Carotid减影(P<0.05);Ortho减影和Carotid减影对颈内动脉和椎动脉的显示优于Cow减影(P<0.05)。结论:Cow减影对头动不敏感,头部去骨效果最优,小血管显示效果好,但容易出现减影过度所致假性狭窄。Ortho减影和Carotid减影对运动敏感,头部去骨情况较差,但对位范围较大,颈胸部去骨效果较好且血管显示光滑。

Purpose: To compare the effects of three subtraction post-processing techniques(Ortho subtraction,Carotid subtraction, and Cow subtraction) on head and neck CT angiography(CTA) on Canon CT Vitrea workstation,and to discuss better clinical applications of each technique. Methods: Scanned data of 42 patients who underwent head and neck CTA examinations in our hospital from September to October 2020 were imported into the Vitrea workstation, after which the image quality was objectively and subjectively evaluated after subtraction by the three subtraction techniques. CT and SD values of regions of interest in the internal carotid artery(ICA), middle cerebral artery(MCA), the knee of the anterior cerebral artery(ACA) and the parietal bone were then compared. SNR and CNR of blood vessels from the three groups of images after subtraction were also compared. Subsequently, after volume rendering of these three groups of images, effects of bone removal and vascular visualization quality were evaluated differently. Results: For ICA, the CT value and SNR obtained using Carotid subtraction were the lowest,however the SD value was highest(P<0.05). The order of CNR from high to low was Carotid subtraction, Ortho subtraction and Cow subtraction(P<0.05). For MCA and the knee of ACA, Cow subtraction had the highest CT value(P<0.05), whereas Carotid subtraction had the highest CNR(P<0.05). For parietal bone, the CT and SD values of Ortho subtraction were lower than those of Carotid subtraction(P<0.05). Besides the CT value of Cow subtraction was constant at-1 024 HU without signal noises. It was observed that Cow subtraction had the best bone removal effect on the head(92.86% grade I image rate), whereas Ortho subtraction had the best on the neck and chest(47.62% grade Ⅰ image rate). Although no significant difference in the subtraction effect of the three techniques on CCA was observed(P>0.05), significant differences in ICA, ACA, MCA, PCA, BA and VA were discovered(P<0.05). The visualization of MCA using Cow and Ortho subtraction methods was better than that by Carotid subtraction(P<0.05). Conversely, the visualization of ICA and VA by Ortho subtraction was better than that by Cow subtraction(P<0.05).Conclusion: Therefore, although Cow subtraction is insensitive to head movement and had the best effect of head bone removal and small vessel visualization, it majorly cause vascular pseudostenosis. Ortho and Carotid subtraction methods are easier to have motion artifacts and poor head bone removal effects. However, they have lager registration ranges and vessels appear smooth. So, they do better at neck and chest bone removal.