Comparing Image Quality of Coronary CT Angiography with and without ECG-gating in Wide-detector CT

Kun Wang Yueqiao Zhang Bin Chen Hong Ren ^*

• Zhejiang University School of Medicine Sir Run Run Shaw Hospital, Hangzhou, China

Objective: To compare the image quality, radiation dose, and examination time between non-electrocardiogram (ECG)-gated coronary CT angiography (ECG-less CCTA) and conventional ECG-gated CCTA using wide-detector CT, and validate its clinical applicability.In this prospective study, 109 patients with suspected coronary artery disease were divided into ECG-less (Group A, n=59) and ECG-gated (Group B, n=50) groups.Objective metrics (CT attenuation, noise, SNR, CNR), subjective image quality (4point scale), and examination time were analyzed. Diagnostic performance (sensitivity, specificity) was evaluated against invasive coronary angiography (ICA). A modified ECG-less protocol (Group A2, n=30) was implemented to optimize radiation dose.Plaque characterization agreement was assessed using Cohen's κ.The ECG-less group demonstrated higher radiation dose (2.83±0.93 vs.1.90±1.41 mSv, P<0.001) but significantly shorter examination time (225.03±33.37 vs. 330.06±56.35 seconds, P<0.001). The modified ECG-less protocol reduced the effective dose by 28% (2.03±0.75 mSv, P<0.001 vs. Group A), achieving statistical comparability to the conventional group (P=0.62). Subjective image scores (4-point scale) and SNR/CNR showed no significant differences between groups (P>0.05).ECG-less CCTA achieved per-segment sensitivity/specificity of 93.3%/97.5% and perpatient 94.4%/50% for detecting ≥50% stenosis. Plaque characterization exhibited high agreement (calcified: κ=0.82; non-calcified: κ=0.78; mixed: κ=0.75).ECG-less CCTA provides comparable image quality and diagnostic accuracy to conventional ECG-gated CCTA while significantly reducing examination time. This technique is applicable in emergency scenarios where ECG lead placement is unfeasible (e.g., severe trauma, unreliable ECG signals).