Reduction of radiation exposure and preserved image quality using photon-counting detector cardiac computed tomography without electrocardiographic gating in children with congenital heart disease.

OBJECTIVES

To evaluate the radiation exposure, quantitative, and qualitative image quality in pediatric cardiac CT by using photon-counting detector computed tomography (PCD CT) versus energy-integrating detector CT (EID CT) in matched children.

MATERIALS AND

METHODS

Thirty-seven contrast-enhanced, clinically indicated cardiac CTs performed on PCD CT were matched with 37 examinations acquired by EID CT. The patients were matched according to water-equivalent diameters. Quantitative evaluation of image quality comprised a region of interest (ROI)-based analysis, calculating image noise, signal-to-noise (SNR) and contrast-to-noise (CNR) ratio. Differences of the attenuation variation of the paraspinal and the pectoral muscles were calculated to measure beam hardening artifacts. Volume CT dose index (CTDIvol) and dose length product (DLP) were documented, and the effective radiation dose was calculated for each patient. Statistical analysis comprised t-tests and Wilcoxon signed rank tests.

RESULTS

The mean age of the children on PCD CT was 794 ± 1016 days, similar to the mean age of 815 ± 957 days of the children on EID CT (p = 0.76). Moreover, age, height, weight, and body mass index (BMI) were also not significantly different between the two groups (p ≥ 0.32). Radiation exposure was significantly lower on PCD CT (CTDIvol 0.20 ± 0.12 mGy and DLP 4.06 ± 3.22 mGy*cm) versus EID CT (CTDIvol 0.37 ± 0.17 mGy, p < 0.001 and DLP 7.21 ± 4.67 mGy*cm, p < 0.001). No significant differences in SNR, CNR, or beam hardening artifacts could be observed. Qualitative image quality was also comparable for PCD CT versus EID CT.

CONCLUSIONS

With a reduction in radiation exposure exceeding 40% by using PCD CT, image quality remained stable compared to EID CT. Reducing radiation with PCD CT while preserving image quality might substantially advance cardiac imaging in children.

KEY POINTS: Question Children are particularly sensitive to radiation exposure, highlighting the need for dose reduction. Findings Radiation dosage can be significantly reduced while preserving image quality when using photon-counting detector (PCD) CT in pediatric patients with congenital heart disease. Clinical relevance Since radiation exposure can be significantly reduced by PCD CT compared to energy-integrating detector (EID) CT, while image quality was comparable, PCD CT is advisable for children with congenital heart disease.