Photon-counting CT reduced radiation dose by 32% compared with energy-integrating detector CT while significantly improving contrast-to-noise ratio across the coronary, pulmonary, and aortic vascular territories.
PCCT achieved pulmonary artery contrast-to-noise ratios with 75 mL contrast equivalent to EID-CT using 98.5 mL, demonstrating improved contrast efficiency without sacrificing image quality.
Despite markedly improved image quality and diagnostic confidence, coronary stenosis detection remained equally accurate between PCCT and EID-CT, confirming that the principal advantage of PCCT lies in improved image quality and dose efficiency rather than diagnostic accuracy.
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Figure 4. Representative triple rule-out CT examinations comparing EID-CT and PCCT. Photon-counting CT demonstrates substantially higher vascular attenuation across the thoracic aorta and pulmonary arteries, with comparable enhancement using 75 mL contrast on PCCT versus 98.5 mL on EID-CT.
Source: Hyska S, Vecsey-Nagy M, Emrich T, et al. Added value of photon-counting CT for triple rule-out imaging: A propensity-matched comparison with energy-integrating CT. Journal of Cardiovascular Computed Tomography. 2026.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Scan area | Triple rule-out CTA (thoracic aorta, coronary arteries, pulmonary arteries) |
Scan mode | QuantumPlus Retrospectively ECG-gated low-pitch spiral |
Scan direction | Cranio-caudal |
Tube voltage [kV] | CARE keV |
Effective mAs [mAs] | Automatic exposure control |
IQ level | 64 |
CTDIvol [mGy] | 29.3 (23.5–41.4) median |
DLP [mGy·cm] | 928 median (PCCT groups: 850–1006 depending on contrast protocol) |
Rotation time [s] | 0.25 |
Pitch | 0.2 |
Field of view [mm] | 205 × 205 (coronary reconstruction) |
Slice collimation [mm] | 144 × 0.4 |
Slice width [mm] | 1.0 mm (thorax), 0.6 mm (coronary) |
Reconstruction increment [mm] | 0.8 mm (thorax), 0.4 mm (coronary) |
Reconstruction kernel | Br36 (thorax), Bv36 (coronary) |
Iterative reconstruction | Quantum Iterative Reconstruction (QIR) level 3 |
Reconstruction | Polychromatic images |
Contrast agent | Ultravist 370 (iopromide) |
Contrast volume | 75 mL or 98.5 mL triphasic protocol |
Flow rate | 5 mL/s |
Bolus triggering | 110 HU ascending aorta + 7 s delay |
ECG gating | Retrospective ECG-gated spiral |
Reconstruction comparison | Dual-source PCCT vs dual-source EID-CT |
Key Results
Outcome | PCCT | EID-CT |
|---|
CTDIvol | 29.3 mGy | 43.3 mGy |
Radiation reduction | −32.3% | — |
Coronary CNR | 24.5 | 11.3 |
Thoracic aorta CNR | 32.2 | 17.9 |
Pulmonary artery CNR | 36.8 | 24.2 |
Pulmonary CNR (75 mL PCCT vs 98.5 mL EID) | Comparable (22.4 vs 24.2) | p = 0.437 |
Pulmonary diagnostic confidence | Excellent | Fair |
Coronary stenosis AUC | 0.936 | 0.961 (NS) |
