In 37 children with congenital heart disease matched to 37 EID-CT controls by water-equivalent diameter, non-ECG-gated high-pitch PCCT substantially reduced radiation exposure: CTDIvol 0.20 ± 0.12 vs 0.37 ± 0.17 mGy and DLP 4.06 ± 3.22 vs 7.21 ± 4.67 mGy·cm (p < 0.001 for both), corresponding to roughly 46% and 44% reductions, respectively.
Despite the lower dose, SNR, CNR, beam-hardening artifacts, overall subjective image quality, and proximal coronary-artery visualization were not significantly different between PCCT and EID-CT. This was achieved with an extremely fast 70-kV, pitch-3.2, non-ECG-gated PCCT acquisition.
The practical implication is particularly relevant for infants and young children requiring repeated cardiovascular imaging: sub-second, free-breathing cardiac PCCT can preserve diagnostic anatomy without ECG gating at very low radiation dose. However, patients with visible metallic devices were excluded, and the retrospective cohort was relatively small.
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Figure 4. A, B Cardiac examination on photon-counting detector CT of a 7-month-old female patient, born with tetralogy of Fallot. Volume CT dose index (CTDIvol) of this examination was 0.11 mGy, dose length product (DLP) was 1.9 mGycm, water-equivalent diameter was 118 mm. C, D Cardiac examination on energy-integrating detector CT of a 5-month-old female patient, born with atrioventricular septal defect. CTDIvol of this examination was 0.35 mGy, DLP was 5.8 mGycm, water-equivalent diameter was 118 mm. The cardiac anatomy can be very well depicted in both studies, including the coronary arteries (arrows in the axial orientations A and C). B and D show the aortic arch in parasagittal orientation.
Protocol
Detail | PCCT |
|---|
Scanner | NAEOTOM Alpha |
Scan area | Whole thorax and heart |
Patient position | Supine, arms elevated |
Scan direction | Craniocaudal |
Scan mode | Quantum Fast high-pitch helical |
ECG gating | None |
Breathing | Free-breathing |
Tube voltage [kV] | 70 |
IQ level | 45 |
Dose modulation | Automated exposure control |
CTDIvol [mGy] | 0.20 ± 0.12 |
DLP [mGy·cm] | 4.06 ± 3.22 |
Rotation time [s] | 0.25 |
Pitch | 3.2 |
Detector slice collimation [mm] | 144 × 0.4 |
Matrix | 768 × 768 |
Reconstruction slice thickness [mm] | 1.0 |
Reconstruction increment [mm] | 0.7 |
Kernel | Br40 |
Iterative reconstruction | QIR 2 |
Contrast | Iomeprol 400 |
Contrast volume | 7 mL at 3–6 kg; 1 mL/kg at ≥7 kg |
Saline | Saline flush |
Bolus triggering | Bolus tracking; scan initiated when all four cardiac chambers were optimally opacified |
Acquisition time | <1 s on average |
The study used a CARE keV Image Quality level of 45 as the PCCT reference-mAs control parameter. Acquisition was performed without ECG triggering, using free-breathing high-pitch scanning.
Key Results
Parameter | PCCT vs EID-CT |
|---|
Study population | 37 vs 37 size-matched children |
CTDIvol | 0.20 ± 0.12 vs 0.37 ± 0.17 mGy, p < 0.001 |
DLP | 4.06 ± 3.22 vs 7.21 ± 4.67 mGy·cm, p < 0.001 |
Dose reduction | Approximately 46% lower CTDIvol and 44% lower DLP |
Quantitative image quality | No significant difference in SNR, CNR, or beam-hardening artifacts |
Qualitative image quality | No significant difference in overall image quality or proximal coronary visualization |
Source:
Hellms S, Werncke T, Böttcher J, Happel CM, Eckstein J, Krueger MB, Panknin C, Pfeil A, Kaireit TF, Beerbaum P, Vogel-Claussen J, Wacker F, Renz DM. Reduction of radiation exposure and preserved image quality using photon-counting detector cardiac computed tomography without electrocardiographic gating in children with congenital heart disease. European Radiology. 2026;36:324–333. doi:10.1007/s00330-025-11719-6.
