Selection of optimal cardiac phases for ECG-triggered coronary CT angiography in pediatrics.

PURPOSE:The use of coronary computed tomography angiography (CCTA) in children remains limited by patient's irradiation, and motion artefacts impairing image quality. Triggering the acquisition at the appropriate moment, and acquiring only necessary components of the cardiac cycle could overcome these limitations. Yet, optimal cardiac intervals to perform CCTA as a function of heart rate (HR) have not yet been addressed in pediatrics. METHODS:Fifty children with coronary artery anomalies underwent a CCTA on a wide-coverage single-beat CT scanner. Multiple phases from 25% to 85% of the R-R interval were acquired and reconstructed with 10% increments. Two radiologists independently assessed motion artifacts on each cardiac phase using a 4-point semi-quantitative scale. RESULTS:At patient level, the best phase for acquisition was found in diastole for patients with HR ≤ 75 bpm and in systole for patients with HR > 85 bpm. At coronary segments and structures level, median optimal phases were reported at 70%, 80%, 47%, 50%, and 54% of the R-R interval for patients with HR ≤ 60, 61-75, 86-100, 101-130, and >130 bpm respectively. For patients with HR between 76 and 85 bpm, no clear trend could be observed. Optimal acquisition durations represented 10% (2 phases), 20% (3 phases), 50% (multiphase), 20% (3 phases), and 10% (2 phases) of the R-R interval for patients with HR ≤ 60, 61-75, 76-100, 101-130, and >130 bpm, respectively. CONCLUSIONS:Optimal positioning and duration of CCTA acquisition intervals were investigated as a function of children's HR, to reduce motion artifacts and patient's irradiation.