中文摘要：

目的通过模拟冠状动脉CT血管成像（CTA）中应用双扇区重建时心率变化可能导致的时相错位,评价双扇区重建中时相一致性对冠状动脉显示的影响。资料与方法30例患者采用回顾性心电门控扫描行冠状动脉CTA检查,对右冠状动脉垂直走行段行图像重建,包括：①75%单扇区重建;②75%双扇区重建;③前一个心动周期以R-R间期75%为中心,后一个心动周期分别以69%、72%、78%、81%为中心进行双扇区重建。选择各次重建均包含的3个轴面,从血管中心密度、面积、形态（横、纵径比值）、边缘锐利度评价冠状动脉显示情况。结果①75%双扇区重建与75%单扇区重建比较,各参数差异均无统计学意义（P〉0.05）;②其余各次双扇区重建分别与75%单扇区重建比较,各参数差异均有统计学意义（P〈0.05）,且差异随时相间隔增大而增大。结论双扇区重建中时相一致性是保证重建图像准确性的关键因素,心率变化导致的时相差可以改变所显示冠状动脉的形态和特征,并进而可能造成对冠状动脉狭窄评价的偏差。

英文摘要：

Purpose To evaluate the influence of data consistency on image quality of coronary CT angiography（CTA） with bi-sector reconstruction,by simulating phase mismatch that may occur in patients with arrhythmia.Materials and Methods 30 cases with normal findings on coronary CTA using ECG gated spiral scan were included.Targeted retrospective reconstructions of the vertical portion of right coronary artery were performed including half-reconstruction at 75% R-R interval,bi-sector reconstruction at 75%,bi-sector reconstructions with data centered 75% of the first cardiac cycle and those centered at 69%,72%,78% and 81% of the second cardiac cycle respectively.Three slices reconstructed with bi-sector reconstruction algorithm in all bi-sector reconstructions were used for analysis in each case.Central density of vessel enhancement,cross-sectional area,shape of vessel（depicted by ratio of long axis/short axis） and sharpness of vessel margin were analyzed to evaluate image quality.Results ① There was no significant difference between the parameters with half reconstruction and bi-sector reconstruction at 75% R-R interval（P0.05）.② The parameters with all other bi-sector reconstructions were significantly different from those with half reconstruction（P0.05）,while the difference increased as the phase mismatch increasesd.Conclusion Phase matching is critical to the accuracy of CTA in bi-sector reconstruction.Mismatch caused by heart rate variation may lead to alteration of the characteristics of coronary artery,with possible subsequent bias on stenosis evaluation.