原始图像叠加处理技术在脑CT灌注血管成像中的应用

Application of raw image superposition processing technique in angiography of brain CT perfusion

目的:探讨原始图像叠加处理技术用于脑CT灌注(CTP)血管成像的应用效果。方法:选取2019年9月至2021年6月在温州医科大学附属第一医院行CTP检查的253例慢性缺血性脑卒中患者。经CTP检查获得22组连续动态的增强序列图像,任选两组图像分别作为A组和B组,并进行叠加获得一组新的图像作为C组。分别测得叠加处理前后3组图像的颈内动脉CT值、邻近脑组织(颞叶)CT值和Std值,对253例患者图像重复上述操作,通过计算获得3组图像的对比噪声比(CNR)。结果:叠加处理后的C组图像的主观评分均高于叠加处理前的A组和B组,差异有统计学意义(P<0.05)。C组血管显示更加平滑清晰,末端血管分支也能较为清晰显示,能满足临床诊断要求。其中部分患者C组图像主观评分与其脑动脉造影图像的主观评分相近,差异无统计学意义(P>0.05)。C组CNR高于A组和B组,差异有统计学意义(P<0.01)。结论:经加减法运算将图像叠加处理,得到新一组CTA图像,可以提高颅内血管显示的清晰度与CTA的图像质量,得到近似于脑动脉造影检查的图像效果,减少挑选最佳时相观察颅内血管的时间及可能人为因素造成的伪影误诊率。

Objective:To evaluate the application of raw image superposition technique in CT perfusion(CTP)angiography.Methods:A total of 253 patients with chronic ischemic stroke who underwent CTP examination in the First Affiliated Hospital of Wenzhou Medical University from September 2019 to June 2021were selected.Continuous dynamic enhanced sequence images were obtained by CTP examination from 22groups,of which two groups were randomly selected as group A and group B,and two groups were superposed to obtain a new group of images as group C.CT values of internal carotid artery and adjacent temporal lobe,Std values of the three groups of images before and after superposition were measured respectively.The above operations were repeated for images of 253 patients,and the contrast to noise ratio(CNR)of the three groups of images of each patient was obtained by calculation.Results:The subjective scores of group C were higher than those of group A and group B before superposition,with significant difference(P<0.05).Moreover,the vascular display of group C was smoother and clearer,and the terminal vascular branch could also be clearly displayed,meeting the requirements of clinical diagnosis.Among them,the subjective scores of group C images were similar to those of cerebral arteriography images in some patients,with no statistical significance(P>0.05).The CNR of group C was higher than that of group A and group B,showing statistical difference(P<0.01).Conclusion:A new set of CTA images superimposed by Add/Sub can improve the clarity of intracranial vascular display and the image quality of CTA,achieving the image effect similar to that of cerebral arteriography,which can shorten the selecting time to observe the intracranial vessels and the possible misdiagnosis rate caused by human factors.