多排CT冠状动脉CTA成像技术的研究

Study of the Imaging Technology in Coronary Angiography with Multi-slice Computed Tomography

目的研究和探讨16排CT冠状动脉CTA成像的图像采集方式和技术参数,提高冠脉CTA的成像质量。材料和方法无明确器质性病变的患者40名,分为性别、年龄分布相近的A、B两组。扫描采用GE公司的Lightspeed 16排螺旋CT,造影剂采用Omnipaque(300mgI/ml,GE Health)。A、B两组分别采用不同的扫描参数及重建方式,A组:层厚选定为0.625mm,重建算法选择[Burst]或[BurstPlus],门控〔Heart Rate Override〕选择关闭,造影剂采用80ml以2.8ml/s的速率团注,常规重建;B组:层厚选定为1.25mm,重建算法选择〔Segment〕,门控〔Heart Rate Override〕选择开启,对比剂采用100ml以4ml/s的速率团注,采用常规重建和间隔为0.625mm的重叠重建。原始图像通过3D表面重建及血管树重建,由专业医师对CTA的图像质量进行评价,通过t检验来比较A、B两组的不同采集和重建方式对图像质量的影响。结果采用B组扫描参数的CTA图像质量明显优于A组,在有无阶梯状伪影、血管分支的显示限度上两者的差异有明显的统计学意义。结果提示在不影响成像质量的前提下,层厚的提高使扫描速度明显提高,有利于搏动性器官心脏的成像;对比剂大剂量的高速团注,可使冠脉更好地充盈,显示末梢;重叠重建后冠脉的CTA图像更易产生阶梯状伪影,因此不宜采用。结论16排CT心脏冠脉扫描时,空间分辨率和时间分辨率之间的平衡对最终的CTA图像质量有很大影响,因此采用合适的参数和重建方式才能得到高质量的图像。

Objective Through the discussing of the best technical parameters used in coronary computer tomographic angiography （CTA） to improve the 3D image quality of the coronary artery.Materials and Methods 40 patients with no apparent heart disease were included in our study, and were divided into 2 groups （group A and B） according to their age and sex. The scanning parameter and reconstructing mode were different for group A and B. The original data were 3D reconstnicted on the workstation using surface mode, the quality of the coronary CTA data were evaluated by professional radiologists, and t-test was used to compare the difference effect of parameters used in group A and group B on the final 3D image quality. Results The result suggested that the increase of slice thickness would speed up the scan time which could improve the imaging of the heart; the administration of large amount contrast media would better fulfill the coronary artery, and this could increase the visualization rate of the distal branches; the overlap reconstruction would lead to ladder artifact Conclusion It was important for coronary CTA examination to balance the spatial resolution and the temporal resolution. The suitable parameter and proper reconstruction mode will lead to high quality images.