PCCT reduced radiation exposure by 32% while improving image quality across the coronary, aortic, and pulmonary vascular territories compared with energy-integrating detector CT.
PCCT achieved substantially higher contrast-to-noise ratios (CNR) in all vascular beds and maintained pulmonary artery image quality with a lower contrast volume protocol that matched conventional CT using a higher iodine load.
Diagnostic confidence improved most for segmental pulmonary arteries and coronary arteries, addressing two of the major technical limitations that have historically restricted broader adoption of triple rule-out CT.
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Figure 4. Exemplary contrast-enhanced axial triple rule-out CT images depicting the thoracic aorta and pulmonary arteries across detector technologies and contrast protocols in a 63-year-old woman (EID-75), a 76-year-old woman (EID-98.5), a 72-year-old woman (PCD-75) and a 64-year-old man (PCD-98.5) with no evidence of acute vascular pathology. Regions of interest demonstrate higher vascular attenuation with photon-counting detector (PCD)-CT compared with energy-integrating detector (EID)-CT, including comparable attenuation between PCD-75 mL and EID-98.5 mL acquisitions. Note that window width and center were identical across all images. Abbreviations: C, center; CM, contrast media; HU, Hounsfield units; SD, standard deviation (representing image noise); W, width.
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 CT (coronary arteries, thoracic aorta, pulmonary arteries) |
Scan mode | QuantumPlus Retrospectively ECG-gated spiral |
Scan direction | Craniocaudal |
Tube voltage [kV] | Automatic (CARE keV) |
Effective mAs [mAs] | IQ Level 64 |
IQ level | 64 |
Dose modulation | CARE keV / automated exposure control |
CTDIvol [mGy] | 28.1–31.3 median |
DLP [mGy·cm] | 850–1006 median |
Rotation time [s] | 0.25 |
Pitch | 0.2 |
Matrix | n.a. |
Field of view [mm] | 205 × 205 (coronary reconstruction) |
Slice collimation [mm] | 144 × 0.4 |
Slice width [mm] | 0.6 (coronary), 1.0 (thorax) |
Reconstruction increment [mm] | 0.4 (coronary), 0.8 (thorax) |
Reconstruction kernel | Bv36 (coronary), Br36 (thorax) |
Iterative reconstruction | QIR 3 |
ECG gating | Retrospective ECG-gated spiral |
Contrast agent | Ultravist 370 |
Contrast volume | 75 mL or 98.5 mL protocol |
Flow rate | 5 mL/s |
Bolus triggering | 110 HU ascending aorta + 7 s delay |
Saline chaser | 30 mL |
Patient preparation | Standard TRO protocol |
Phase selection | Cardiac phase with least motion artifacts |
