目的 研究扫描触发阈值技术对 CT冠状动脉造影中图像质量的的影响。方 法 选取2015年2月-2016年1月期间入我院 接受双源CT冠状动脉造影检查的75例冠 心病(CHD)患者，其中男46例，女29例， BMI＜23。将其抽签随机分为3组：A组25 例，扫描触发阈值120HU；B组25例，扫 描触发阈值130HU；C组25例，扫描触发 阈值140HU。根据患者个人体质数(BMI) 注射对比剂后扫描，测量左冠开口、右 冠状开口、左前降支近段和左回旋近段 血管的CT、SD平均值，并据此计算图像 信噪比(SNR)、对比噪声比(CNR)作为图 像质量评估的客观依据，由2名经验医师 采用双盲法对冠状动脉图像质量进行评 估，比较不同触发阈值下的指标及图像 质量差异。结果 B组扫描的强化SD值分 别较A、C2组低，SNR较A、C2组低，均差 异显著(P<0.05)；B组图像质量评分、图 像优良率分别较A、C2组高，差异显著 (P<0.05)。结论 扫描触发阈值技术作为 CT冠状动脉造影中常用的扫描方法，双源 CT将扫描触发阈值设定在130HU时能获得 较好质量的图像，便于临床观察诊断，值 得临床推广。

Objective To study the effect of scan triggering threshold technique on the image quality of CT coronary angiography. Methods 75 cases of patients with coronary heart disease (CHD) who underwent dual-source CT coronary angiography in our hospital between February 2015 and January 2016 were selected, including 46 male cases and 29 female cases, BMI < 23. They were randomized into 3 groups: 25 cases in group A, and the triggering threshold value was 120HU. 25 cases in group B, and the scan triggering threshold was 130HU. 25 cases in group C, and the scan triggering threshold was 140HU. According to the patient's body mass index (BMI), patients were scanned after injection of contrast agents. The mean values of CT and SD in the left coronary opening, right coronary opening, left anterior descending branch and left anterior descending branch were measured. According to the measured results, the image signal to noise ratio (SNR) and contrast to noise ratio (CNR) were calculated as the objective basis for image quality assessment. The coronary artery image quality was evaluated by 2 experienced doctors with double blind method. The differences of indexes and image quality under different triggering thresholds were analyzed. Results The SD value of enhanced scan in group B was lower than that of group A and group C2 group, and SNR was also lower than that of group A and group C2 (P<0.05); The image quality score and the excellent and good rate of image in group B were higher than those in group A and group C2 (P<0.05). Conclusion The scan triggering threshold technique, as commonly used scanning method in CT coronary angiography, to set the scan triggering threshold of dual-source CT at 130HU can obtain images of better quality, facilitate clinical observation and diagnosis,which is worthy of clinical promotion.