High-pitch non-gated scans on the second and third generation dual-source CT scanners: comparison of coronary image quality

Objective: To examine differences in image quality of the coronary arteries when performing high-pitch non-electrocardiography (ECG)-gated scans on the second-generation (2G) and third-generation (3G) dual-source CT scanners. Methods: We retrospectively examined patients with high-pitch non-ECG-gated CT angiography (CTA) of the chest or chest/abdomen/pelvis. Outpatient scans from 59 patients in the 3G high-pitch group and 53 patients in the 2G high-pitch group were included. Two blinded cardiac imagers independently scored the coronary image quality using a 4-point Likert scale (from completely diagnostic to completely non-diagnostic) and evaluated the presence of coronary artery disease. Results: Diagnostic image quality of the coronaries in high-pitch CTA exams using 3G scanner was improved compared to 2G scanner, both on a per-vessel basis (45-94% versus 23-86%) and on a per-study basis (34% versus 14%). The 3G group showed a statistically significant improvement in image quality when evaluating the left main coronary, right coronary, and overall coronary arteries. Coronary artery disease was detected in 65% of high-pitch scans. Radiation doses in terms of CTDIvol and DLP were lower for 3G high-pitch scans (7.5 mGy and 491 mGy*cm) compared to 2G high-pitch scans (14.8 mGy and 911 mGy*cm). Conclusions: We found a higher proportion of diagnostic image quality of the coronary arteries in high-pitch non-ECG-gated CTA exams using a 3G dual-source CT scanner, compared to 2G. In scans with diagnostic image quality, underlying coronary artery disease may be confidently diagnosed and should prompt considerations for further management in the appropriate clinical setting.