Cardiac ImagingE3090. Accuracy of Coronary Artery With High-Pitch Spiral Scan on Third Generation DSCT: A Phantom Study
Yokoi T1, Kido T1, Nishiyama H2, Itoh T3, Mochizuki T.1 1. Ehime University Graduate School of Medicine, Toon, Japan; 2. Ehime University Hospital, Toon, Japan; 3. Siemens Healthcare K.K., Osaki, Shinagawa-ku, Japan
Address correspondence to T. Yokoi (email@example.com)
Objective: ECG-triggered high-pitch helical scanning has some advantages in terms of relatively lower radiation dose levels and shorter breath-hold time compared with retrospective ECG-gated helical scanning. However, high-pitch helical scanning is thought to be less robust at higher heart rates than retrospective ECG-gated helical scanning and requires lower heart rate while scanning. According to our observation, this constraint is no longer an issue for pediatric cardiac scans. The purpose of this study is to confirm quantitatively whether our observation is favored by evaluating cross-sectional area and circularity of the coronary lumen with ECG-triggered high-pitch helical scanning (turbo FLASH helical) and ECG-gated retrospective helical scanning on third generation dual-source CT.
Materials and Methods: A coronary vessel phantom (length, 50 mm; inside diameter, 5 mm) was filled with an iodine-saline solution at 250 HU and attached to a pulsating cardiac phantom. Dual-source CT was performed with a turbo FLASH helical scan (90 kV, 600 mAs per rotation) and helical scan (90 kV, 550 mAs per rotation) at simulated heart rates of 0, 60, 70, 80, 100, and 120 beats/min. Images were reconstructed at an R-R interval of 40% of cardiac phase. Scanning was repeated 10 times for each heart rate. Luminal area and circularity were measured at 11 different sites of the vessel phantom using an open-source image processing program (Image-J, NIH).
Results: The mean areas by turbo FLASH helical scanning at each heart rate were 24.1 ± 0.76, 24.1 ± 0.86, 24.4 ± 0.63, 24.2 ± 0.64, 24.0 ± 0.78, and 24.3 ± 0.71 mm2, respectively. The mean area by helical scan at each heart rate was 23.8 ± 0.72, 23.9 ± 0.76, 23.8 ± 0.73, 23.9 ± 0.89, 23.8 ± 0.83, and 23.8 ± 0.77 mm2, respectively. The mean circularity by turbo FLASH helical scan at each heart rate was 0.97 ± 0.03, 0.97 ± 0.02, 0.97 ± 0.03, 0.96 ± 0.03, 0.96 ± 0.03, and 0.95 ± 0.03 mm2, respectively. The mean circularity by helical scanning at each heart rate was 0.98 ± 0.03, 0.97 ± 0.02, 0.96 ± 0.03, 0.96 ± 0.03, 0.96 ± 0.02, and 0.97 ± 0.03 mm2, respectively. The area and the circularity at each heart rate were statistically equivalent to those at heart rate of 0 beats/min between turbo FLASH helical scanning and helical scanning.
Conclusion: ECG-triggered high-pitch helical scanning achieved equivalent measurement accuracy of the coronary lumen in cross-section to ECG-gated retrospective helical scanning with heart rate independence.