Dose and image quality comparison between prospectively gated axial and retrospectively gated helical coronary CT angiography

OBJECTIVE: Our aim was to compare image quality, coronary segment assessability and radiation dose in prospectively gated axial (PGA) coronary CT angiography (CTA) and conventional retrospectively gated helical (RGH) coronary CTA. METHODS: Institutional review committee approval and informed consent were obtained. RGH CTA was performed in 41 consecutive patients (33 males, 8 females; mean age 52.6 years), then the PGA CTA technique was evaluated in 41 additional patients (24 males, 17 females; mean age 57.3 years) all with a pre-scan heart rate of ≤70 beats per minute (bpm). Two radiologists, blinded to clinical information, independently scored subjective image quality on a five-point ordinal scale. RESULTS: The mean effective dose in the PGA group was 4.7±0.9 mSv, representing a 69% dose reduction compared with the RGH CTA group (15.1±1.9 mSv, p<0.001). The mean segmental image quality score was significantly higher in the PGA group (3.4 vs 3.2) than in the RGH CTA group (p<0.005). The percentage of assessable segments was 98.1% in the PGA group and 97.3% in the RGH group (p = 0.610). CONCLUSION: PGA CTA offers a significant reduction in radiation dose compared with RGH CTA, with comparable image quality for patients with heart rates below 70 bpm.