Visualization of proximal coronary arteries on high-pitch electrocardiogram-triggered computed tomography in pediatric congenital heart disease: effects of heart rate and body surface area

Background As CT technology has advanced, techniques for pediatric cardiac CT in congenital heart disease have evolved from retrospective electrocardiography (ECG)-gating with relatively high radiation doses to lower-dose prospective ECG-gating and even single-beat gated scans. Despite these advances, coronary artery imaging in children remains challenging because of their small vessel size and high heart rates, often necessitating retrospective gating. Objective Evaluate coronary artery visualization in pediatric patients (<20 years) who underwent low-dose high-pitch ECG-triggered scans and stratify the probability of coronary artery visualization based upon heart rate and body surface area (BSA). Materials and methods Two hundred eleven high-pitch ECG-triggered studies from April 2014 to November 2017 were reviewed by two pediatric cardiac imagers in this retrospective study. Patient age, gender, BSA, average heart rate, heart rate variability and use of general anesthesia were recorded as well as dose-length product (DLP) and volumetric CT dose index (CTDIvol). We assessed the coronary artery score using a 5-point scale, with score of >= 3 considered of diagnostic quality. We performed multivariate statistical analysis including logistic regression to analyze effects of heart rate and BSA. Results Patient age range was 1 day to 19 years (median age 3 years). Heart rate range was 49-188 beats per minute (bpm; median 122 bpm) and BSA range was 0.15-2.07 m(2)(median 0.53 m(2)). The origin and proximal coronary arteries were confidently seen (score >= 3) in 61% of studies in this cohort. Coronary artery visualization scores further increased with increased BSA (P<0.002) and with decreased heart rate (P<0.001). At heart rates 0.58, adequate coronary artery visualization was present 72% of the time. Conclusion While in many patients the coronary artery origins are visualized using high-pitch ECG-triggered technique, the importance of coronary artery visualization needs to be weighed with the radiation dose penalty in individual patients to achieve optimal imaging.