Objective To assess the image quality of coronary CT angiography(CCTA) by using high-pitch spiral CT under 80 kV in patients with a normal body mass index(BMI), and to investigate the feasibility of low radiation dose.Methods 60 patients,who suspicious coronary artery diseases and BMI between 18.6-25.0 kg/m2 underwent CCTA in our hospital.All patients were randomly divided into group A and group B(each with 30).Patients in group A were given 100 kV CCTA and filter back-projection algorithm (FBP), and patients in group B were given 80 kV CCTA and iterative reconstruction(IR).CT values of aortic root, right coronary artery (RCA), left anterior descending artery (LAD), left circumflex (LCX) and standard deviation (SD) were measured.Then signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated.All images were given quality subjective scoring by using 3-score method.The CT dose index was recorded and effective radiation dose (ED) was calculated.Results ED of group A and group B was 0.8 mSv and 0.41 mSv, respectively.Statistically significant difference was found between these two groups.In the study, SD was (28±6) HU in group A and (46±9) HU in group B, and the difference was statistically significant between the two groups.The CT values of aortic root, RCA, LAD and LCX under 80 kV were significantly increased, and the difference was statistically significant between the two groups.There was no statistically significant difference between two groups in RCA-SNR, LAD-SNR and RCA-CNR.But in LCX-SNR, LAD-CNR, LCX-CNR, there was statistically significant difference between two groups.There was no significant difference between the two groups in coronary artery segments which could be used for diagnosis.Conclusion For patients with a normal BMI, CCTA using Flash spiral CT under 80 kV could diagnose coronary artery disease and significantly reduce the radiation dose.

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.