Low-dose CT coronaryangiography with prospective electrocardiogram-triggering using dual-source CT scanner

：Objective To evaluatelow-dose CT coronary angiography with prospective electrocardiogram (ECG)-triggering usingdual-source CT scanner.Methods Sixty-eight patients who underwent coronary CT angiographyusing a dual-source CT scanner were divided into 2 groups: group A (38 cases) and group B(30 cases).Prospective ECG-triggering sequence scan mode was employed for groupA.Inclusion criteria included: heart rate <70 bpm, sinus rhythm, and heart ratefluctuation less than 10 bpm.Data acquisition was set at 70% of theRR-interval.Retrospective ECG-gating helical scan was performed for group B.Inclusioncriteria included heart rates < 70 bpm and sinus rhythm.The exclusion criteria includedheart failure and serious arrhythmias.In both groups, patients with a BMI≥24 kg/m2 were examined with atube voltage of 120 kV, whereas patients with a BMI <24 kg/m2 were examined with a tubevoltage of 100 kV.All images were transferred to a workstation for further processing andanalysis.The imaging quality was evaluated.The imaging quality of coronary artery segmentswere compared with rank sum test between the two groups, and the radiation dose werecompared with t test.Results A total of 476 coronary artery segments were evaluated ingroup A and 372 segments were evaluated in group B.The mean score of imaging quality forcoronary artery segments in group A was 3.48±0.59 and that in group B was 3.53±0.58.Therewas no statistical difference in imaging quality between the two groups (Z=-1.432,P=0.187).The effective dose was on average (2.51±0.54) mSv (range 1.3--3.3 mSv) in groupA, whereas on average (14.55±3.54) rosy (range 7.1--20.2 mSv) in group B.There was astatistical difference between the two groups (t=18.484, P=0.000).Conclusions Low-doseprospective ECG-triggering sequence scan in dual-source CT coronary angiography isfeasible in patients with low heart rate and regular cardiac rhythm.This scan mode cansubstantially reduce radiation doses while preserving good diagnostic image quality. Key words: Tomography, X-ray computed;  Coronary vessels;  Radiationmonitoring