Optimization of Retrospective Gated-ECG Coronary Computed Tomography Angiography by Dose Reduction in Patients with Different Body Mass Indexes.

BACKGROUND

The reduction of patient radiation dose in coronary Computed Tomography Angiography (CCTA) with acceptable image quality is considered an important factor in the research.

OBJECTIVE

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).

MATERIAL AND METHODS

In this cross-sectional study, 66 patients into three main groups: 80 kVp (Group A), 100 kVp (Group B), and 120 kVp (Group C), underwent CCTA. Each group was then divided into two subgroups of BMI<25 and >25 kg/m. Image noise, mean vascular attenuation at the aorta, signal-to-noise ratio (SNR), and Contrast-to-Noise Ratio (CNR) at five regions of coronary arteries, in which Coronary artery anomalies are common were qualitatively evaluated by subjective image quality analysis.

RESULTS

At each kVp, there were no significant differences in CNR, SNR, noise level, and the effective dose between BMI>25 kg/m and BMI<25 kg/m. The effective radiation dose of groups A, B, and C were 4.16, 8.46, and 14.3 mSv, respectively. Subjective image quality assessment scores were 3.18, 3.5, and 3.73 out of 4 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. The retrospective CCTA at 80 kVp can be optimized even in overweight patients (BMI>25 kg/m).