Abstract: Objective　To investigate the image quality and radiation dose of Force CT coronary angiography using prospectively ECG-triggered high-pitch spiral Turbo Flash mode in different acquisition phases（diastolic and systolic） in patients with 65-75 bpm heart rates.Methods　We collected 60 patients who underwent Force CT coronary angiography in the Zhejiang Hospital from September to December 2016.According to the acquisition phase，the patients were divided into group A（30 cases，Turbo Flash high-pitch diastolic phase acquisition） and group B（30 cases，Turbo Flash high-pitch systolic phase acquisition）．The subjective and objective image quality of CTA in the two groups was evaluated，and the radiation doses in the two groups were recorded and compared.Results　A total of 779 coronary segments were evaluated in the two groups.In group A，392 coronary segments were evaluated，of which the second obtuse marginal branches（OM2） had the best quality，and the image quality of the middle part of the right coronary artery（RCA） was poorest.In group B，387 coronary segments were evaluated，of which OM2 had the best quality，and the distal part of the left circumflex artery（LCX） was poorest.The image quality of the first diagonal branch（D1） and the proximal and middle parts of the LCX and OM1 in group A were better than those in group B （P<0.05）．There were no significant differences in the CT values of the proximal part of the RCA，proximal part of the left main coronary artery（LM），proximal part of the left anterior descending （LAD），proximal part of the LCX，signal-to-noise ratio （SNR），contrast-to-noise ratio （CNR），aorta CT value，SNR，CNR and image noise between the two groups（P>0.05）．There were no significant differences in volume CT dose index（CTDIvol），dose length product（DLP） and effective dose（ED） between the two groups（P>0.05）．Conclusion　Force CT high-pitch Turbo Flash CTA combined with low-voltage（100 kV） and the ADMIRE iterative reconstruction algorithm can obtain images of coronary branches that meet the requirements for clinical diagnosis，with an effective radiation dose less than 1 mSv.For patients with a 65–75 bpm heat rate，it is recommended to apply diastolic acquisition mode，and the image quality of LCX is better than systolic acquisition.

Key words: Diagnostic techniques, cardiovascular；Coronary angiography；Image quality；High-pitch mode

摘要： 目的　研究65~75 次/min心率下患者使用Force CT前瞻性心电触发大螺距Turbo Flash扫描模式采集舒张期与收缩期不同时相的图像质量和辐射剂量。方法　选取2016年9—12月于浙江医院行Force CT冠状动脉CT血管造影（CTA）检查的 60例患者为研究对象，依据检查时预设触发采集时相的不同分为A组（30例，使用大螺距Turbo Flash舒张期时相采集模式）和B组（30例，使用大螺距Turbo Flash收缩期时相采集模式）。对两组患者冠状动脉CTA图像进行主观及客观图像质量评价，记录并比较两组的辐射剂量。结果　两组患者共779个冠状动脉节段，其中A组冠状动脉节段392个，图像质量最好的节段是第二钝缘支（OM2），图像质量最差的是右冠状动脉（RCA）中段；B组冠状动脉节段387个，图像质量最好的节段是OM2，图像质量最差的是回旋支（LCX）远段。A组第一对角支（D1）、LCX近段及中段、OM1图像质量优于B组（P<0.05）。两组RCA近端、左冠状动脉（LM）近端、前降支（LAD）近端、LCX近端的CT值、信噪比（SNR）、对比噪声比（CNR）和主动脉的CT值、SNR、CNR、图像噪声比较，差异无统计学意义（P>0.05）。两组容积CT剂量指数（CTDIvol）、剂量长度乘积（DLP）、有效剂量（ED）比较，差异无统计学意义（P>0.05）。结论　Force CT前瞻性触发大螺距Turbo Flash扫描配合低管电压（100 kV）技术和ADMIRE迭代重建算法，所得冠状动脉各分支图像能够达到临床影像诊断的需要，且有效辐射剂量<1 mSv。当患者心率在65~75 次/min时建议使用大螺距Turbo Flash舒张期采集模式，其LCX的图像质量优于收缩期采集模式。

关键词: 诊断技术, 心血管；冠状血管造影术；图像质量；大螺距模式