Clinical study of high-pitch spiral coronary CT angiography under double low technique / 实用放射学杂志

ABSTRACT

Objective To evaluate the feasibility of high-pitch spiral coronary CT angiography (CCTA) under low tube voltage and low contrast agent concentration for the patients with normal body mass index (BMI).Methods Ninety patients suspected with coronary artery diseases and with BMI of 18.6-25 kg/m2 underwent high-pitch CCTA and were randomly divided into three groups (each=30).Group A used iohexol (350 mg I/mL) 60 mL;Group B used iopromide (300 mg I/mL) 60 mL;Group C used iopromide (300 mg I/mL) 45 mL.All of them were scanned under Flash spiral pattern with 80 kV tube voltage,and the original data was calculated with sinogram affirmed iterative reconstruction algorithm(SAFIR).CT values and noises of the aorta root,right coronary artery (RCA),left anterior descending artery (LAD),and left circumflex (LCX) were measured,then signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.All of images were subjectively assessed by using 3-score method.The effective radiation dose (ED) and total iodine were recorded.Results ED of the three groups were all about 0.4 mSv,and there was no statistically significant.Compared with group A,the total iodine in group C decreased by 35.6 ％ and there was significant difference.There were no significant differences in image noise,SNR and CNR between group A and group B.Between group B and group C,there were significant differences in CT values of coronary,LCX-SNR and LCX-CNR,but there were no significant differences in image noise,SNR and CNR of RCA and LAD.There was no significant difference in the number of coronary artery segments for diagnosis among the three groups.Conclusion For the patients with normal BMI,application of high-pitch spiral CCTA with iopromide (300 mg I/mL)45 mL under 80 kV tube voltage could meet the requirement for clinical diagnosis,and the radiation dose and total iodine were significantly decreased.