Low radiation dose coronary 64-slice spiral CT angiography using prospective electrocardiograph-triggered scan

Objective: To evaluate radiation dose and image quality of prospective electrocardiograph (ECG)-triggered coronary 64-slice CT angiography (CTA) with different kV, and the feasibility of coronary scan with < 1 mSv radiation dose. Methods: Ninety consecutive patients [heart rate: (54±6) bpm, BMI < 21.5 kg/m2] underwent 64-slice CTA using prospective ECG-triggered axial scan protocol. They were divided into two groups: 45 were in group A(100 kV), 45 were in group B(120 kV), and their electric currents were tailored to patient's BMI. The radiation dose was recorded and the image quality (5 for excellent, 1 for bad) was blindly evaluated. Statistical t-test was performed between two groups on dose and image quality. Results: The radiation dose of group A, B was (0.88±0.32), (1.47± 0.41) mSv respectively. There was no significant difference between image quality of group A with 100 kV (4.32±0.28) and that of group B with 120 kV (4.52±0.34) ( t=0.771,P>0.05). And radiation dose of the patient using axial scan protocol at 100 kV was decreased by 40% compared with that of group B at 120 kV (t=12.125, P<0.01). Conclusion: Prospective ECG-triggered axial scan in 64-slice coronary CTA can significantly reduce radiation exposure. For low-BMI (< 21.5 kg/m2) patients, super low dose scan (< 1 mSv) at 100 kV using prospective ECG-triggered axial scan could be selected. And the image quality can meet clinical diagnostic needs. (authors)