Half-cycle reconstruction improve image quality in high heart rate patients with unanticipated free-breathing 320-row coronary CT angiography

Objective: To assess the image quality of half-cycle reconstruction of free-breathing 320-detector row coronary CT angiography (CTA) in patients with heart rates above 65 beats per minute. Methods: From March 1 to August 31, 2011, 31 patients with unanticipated free-breathing during coronary CTA were included in the study. CTA was performed using the standard breath-holding method. All images were reconstructed using half-cycle reconstruction (HCR) and multi-cycle reconstruction (MCR) methods. The image quality for 15 segments of all coronary arteries was scored as 1 (excellent), 2 (good), and 3 (poor). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared. Results: With HCR, 97.4% of the coronary artery segments were evaluable with image quality scores of 1 and 2 compared to 65.6% with MCR group (P < 0.001). The image quality score of lung vessels was also significantly higher with HCR than that with MCR (P < 0.001). The SNR was significantly (P < 0.001) lower with HCR (14.0 ± 3.4) than that with MCR(17.6 ± 4.2). The CNRs were not significantly different in the left main coronary artery (P = 0.052), proximal right coronary artery (P = 0.058), middle right coronary artery (P = 0.081) and distal right coronary artery (P = 0.112) between the two reconstructive methods. Conclusions: Half-cycle reconstruction can improve image quality of unanticipated free-breathing on 320-detector row coronary CTA in patients with heart rates above 65 beats per minute. (authors)