Comparative radiation dose analysis in pediatric high-pitch cardiac CTA using photon-counting versus energy-integrating detector CT.

Abstract

Background: Previous studies have shown improved image quality in pediatric cardiac imaging using photon-counting detector CT (PCDCT). However, these studies did not evaluate image quality and radiation dose when utilizing the full spectral capabilities of PCDCT scanners. The full spectral capability of PCDCT scanners allows the generation of the entire array of mono-energetic reconstructions, virtual non-contrast (VNC) images, and iodine maps, which have potential advantages in evaluating complex congenital heart disease. For example, following complex congenital cardiac repairs, when distinguishing intraluminal or soft tissue calcifications from contrast, or when evaluating intrastent thrombus.

Objective: To compare image quality and radiation dose between high-pitch cardiac CT using full spectral PCDCT and dual-source energy-integrating detector CT (EIDCT).

Materials and methods: This retrospective, IRB-approved study analyzed high-pitch cardiac CTs from January 2021 to October 2023 in pediatric patients (< 18 years). Patients were scanned using either PCDCT with full spectral technique ("QuantumPlus") or EIDCT. Radiation doses were measured by CT dose index (CTDI) and dose-length product (DLP). Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were also calculated, and image quality was assessed using a 5-point Likert scale. Statistical analysis included unpaired T-test, Shapiro-Wilk test, Mann-Whitney test, and kappa coefficients for interrater agreement.

Results: Two hundred patients were evaluated, with 100 scanned on PCDCT and 100 on EIDCT. In the PCDCT scanner, 47/100 (47%) were male and 53/100 were female (53%) (P = 0.01). In the EIDCT scanner, 65/100 were male (65%) and 35/100 (35%) were female (P = 0.01). In the PCDCT scanner, 68/100 (68%) (P = 0.05) were ≤ 12 months, and 32/100 (32%) (P = 0.05) were > 12 months. In the EIDCT, 80/100 (80%) (P = 0.05) were ≤ 12 months, and 20/100 (20%) (P = 0.05) were > 12 months. In patients ≤ 12 months, the CNR were 31.61 in the PCDCT group and 32.14 in the EIDCT group (P = 0.39). For those > 12 months, CNR were 30.07 for PCDCT and 25.27 for EIDCT (P = 0.17). In patients ≤ 12 months, SNR was significantly lower (P < 0.0001) in PCDCT, compared to EIDCT for the teres minor muscles, while in patients > 12 months, SNR was not significantly lower (P = 0.89); SNR was similar between scanners. Radiation doses were significantly higher for PCDCT across both age groups (P < 0.0001).

Conclusion: High-pitch cardiac CT with PCDCT using spectral processing resulted in higher radiation doses and lower SNR in infants compared to EIDCT.