Cardiac functional assessment using prospectively electrocardiography-triggered computed tomography in children with congenital heart disease: Comparison of radiation dose and image quality between heart rate-dependent single-extended and heart rate-independent dual-focused scans.

Purpose: To evaluate radiation dose (RD) reduction potential of heart rate-independent dual-focused scan of prospectively electrocardiography (ECG)-triggered computed tomography (CT) for cardiac functional assessment in children with congenital heart disease (CHD), RD and image quality of the scan mode were compared to those of heart rate-dependent single-extended scan.

Methods: This study encompassed 1,252 prospectively ECG-triggered pediatric cardiothoracic CT examinations, including single-focused (a reference in matched comparisons), single-extended (younger patients), and dual-focused (older patients) scans. Propensity score matching was used to reduce the confounding effect of age and sex in two matched groups (MPs) (younger MP: single-focused vs. single-extended; older MP: single-focused vs. dual-focused). CT RD, image noise, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) of the MPs were compared.

Results: The effective dose of single-extended (1.4 ± 0.5 mSv) and dual-focused (1.1 ± 0.4 mSv) scans were approximately 2.0-3.2 times higher than (depending on heart rate) and approximately 1.8 times (irrespective of heart rate) that of the age- and sex-matched single-focused scans (0.6 ± 0.2 mSv), respectively. Image noise and SNR of single-extended and dual-focused scans were similar to those of the age- and sex-matched single-focused scans (p values > 0.05). The CNR was also comparable between single-focused and single-extended scans (younger MP) (p > 0.05), but a slightly lower CNR of the dual-focused scans compared to single-focused scans was observed in the older MP (p < 0.02).

Conclusion: For cardiac functional assessment in children with CHD, heart rate-independent dual-focused prospectively ECG-triggered scan can reduce CT RD, especially at lower heart rates, with comparable image quality, compared to heart rate-dependent single-extended scan.