(2026) Hyska | PCCT improves triple rule-out imaging with lower dose and higher confidence

Daniel Stromer

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)