Application Study of Double Low Dose in Coronary Computed Tomography Angiography with Different Body Mass Indices

Objective: This study aimed to explore the applicative value of low tube voltage and low-dose contrast agents in coronary computed tomography angiography (CCTA) of 64 rows CT with different body mass indices (BMI). Methods: The participants were 160 patients with clinically suspected coronary heart disease who underwent CCTA examination and divided into groups A (18.5< BMI<24) and B (24≤BMI<28), with 80 cases in each group. Each group was randomly divided into the control (A1/B1) and experimental groups (A2/B2) with 40 patients in each group. The control group was scanned with 120 kV tube voltage, whereas groups A1 and B1 were injected with 60 mL contrast agent+40 mL physiological saline and 80 mL contrast agent+20 mL physiological saline, respectively. All experimental groups adopted a double low-dose method, with group A2 receiving 80 kV tube voltage, 40 mL contrast agent+60 mL physiological saline, and group B2 receiving 100 kV tube voltage, 60 mL contrast agent+40 mL physiological saline. All other scanning parameters were the same. After scanning, the images were reconstructed, data were collected, and differences in image quality, radiation dose, and iodine intake were compared between the control and experimental groups. Results: Image qualification rate, excellent rate, SNR, and CNR between groups A1 and A2 had no statistically significant difference. However, group A2 had higher aortic CT values and image noise than group A1. The image qualification rate, excellent rate, aortic CT value, SNR, and CNR in group B2 were higher than in group B1, and there was no difference in image noise between group B1. The CTDIvol, DLP, and ED of groups A2 and B2 were lower than those of groups A1 and B1. Compared with group A1, group A2 showed a 68.3% decrease in ED, whereas group B2 showed a 41.6% decrease compared to group B1. The iodine intake of groups A2 and B2 decreased by 33.3% and 25%, respectively. Conclusion: Using low tube voltage and low dose contrast agent in CCTA with different BMI not only ensure image quality, but also significantly reduce radiation dose and iodine intake.