Objective To compare the feasibility of two scanning delay techniques in high-pitch coronary CT angiography(CCTA).

Methods A total of 58 patients suspected with coronary heart disease detected by CCTA(heart rate ≤60 beats/min) were prospectively collected, and randomly divided into the Bolus-tracking group(31 cases) and Test-bolus group(27 cases).The CT values and noise in the interest areas of aortic root, left main trunk, left anterior descending branch, left circumflex branch, right coronary artery, pulmonary artery, left atrium and left ventricle were measured.The CT values and noise were measured, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), left atrioventricular ratio, left ventricular pulmonary artery ratio and principal pulmonary artery ratio were calculated, the image quality in two groups were evaluated, and the differences between objective and subjective evaluation indexes were compared between two groups.

Results The differences of the enhanced CT values, SNR and CNR of target vessels were not statistically significant (P>0.05), and the CT value of pulmonary artery, left atrioventricular ratio, left ventricular pulmonary artery ratio and principal pulmonary artery ratio in Bolus-tracking group were significantly lower than those in Test-bolus group (P < 0.01).There was no statistical significance in the subjective image quality scores between two groups (P>0.05).The CT dose index, dose length product, effective radiation dose, injection flow rate and contrast dose in the Bolus-tracking group were significantly lower than those in Test-bolus group (P<0.05 to P<0.01).

Conclusions The high-pitch CCTA with Bolus-tracking method can increase the value of vascular enhanced CT and reduce the dose of radiation and contrast agent.