Optimization of coronary computed tomograghy angiography protocol with dose reduction in patients with different body mass index

Abstract

Abstract Background: Reducing the radiation dose in coronary computed tomography angiography (CCTA), while maintaining the image quality, has attracted a lot of interest. This study aims to optimize the CCTA protocol using a retrospective electrocardiogram (ECG)-gated axial scan protocol in patients with different body mass indexes (BMIs). Methods: Participants were 66 patients divided into three main groups underwent CCTA at 80 kVp (Group A), 100 kVp (Group B), and 120 kVp (Group C). Each group was then divided in two subgroups of BMI <25 and >25 kg/m2.Images were reconstructed using the knowledge-based iterative model reconstruction (IMR) algorithm. Image noise, mean vascular attenuation at the aorta, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) at five vital regions of coronary arteries were calculated. CCTA images were qualitatively evaluated using a 4-point grading scale Results: There were no significant differences in CNR, SNR, noise level and the effective dose between BMI> 25 and BMI <25 subgroups at any kVp. The effective radiation dose of group A, B and C were 4.16, 8.46, 14.3 mSv, respectively. There were no significant differences in mean CNR and SNR between the three groups. Subjective evaluation scores for image qualities were 3.18, 3.5, and 3.73 in groups A, B, and C, respectively. Conclusion: Patient radiation dose using retrospective ECG-gated CCTA can be reduced by about 70% at 80 kVp, which is almost close to the prospective CCTA dose ranges. Optimization of CCTA at 80 kVp can be applied even in overweight patients (BMI >25 kg/m2) . Keywords: Cardiac imaging, Coronary computed tomography angiography (CCTA), Radiation dose reduction, Coronary artery disease (CAD)