VNC-based coronary calcium scoring on PCCT showed strong correlation with TNC scoring, but systematically underestimated Agatston scores by about 11% overall.
Agreement in CAC severity category was 80%, but around 11% of patients were misclassified, which could potentially affect treatment decisions.
Accuracy was best in patients with BMI ≤28 kg/m² and heart rate ≤69 bpm, while underestimation increased in obese and tachycardic patients.
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Fig. 1. Demonstration of coronary artery calcium scoring (CACS) for two examples. Images show maximum intensity projections of axial slices for true non-contrast (TNC) and virtual non-contrast (VNC) reconstructions. Voxels with CT-values exceeding 130 HU are considered to represent calcifications (marked purple) and can be allocated semi-manually to single coronary arteries: green = left main artery (LM), yellow = left anterior descending artery (LAD), blue = circumflex artery (CX), red = right coronary artery (RCA).
Source: Becker et al., International Journal of Cardiovascular Imaging, 2025, CC BY 4.0
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Scan area | Heart |
Scan protocol | True non-contrast scan + coronary CTA |
Scan mode | TNC high-pitch spiral | CTA low-pitch ECG-triggered spiral |
Acquisition mode | Quantum Plus |
Tube voltage [kV] | 120 |
Effective mAs [mAs] | n.a. |
IQ level | 19 TNC | 50 CTA |
Dose modulation | n.a. |
CTDIvol [mGy] | 1.4 (unenhanced) | 28.3 (CTA) |
DLP [mGy*cm] | 27.9 | 437.5 |
Rotation time [s] | n.a. |
Pitch | High-pitch TNC | low-pitch CTA |
Matrix | 512 |
Slice collimation [mm] | 144 × 0.4 |
Slice width [mm] | 3.0 |
Reconstruction increment [mm] | 1.5 |
Reconstruction kernel | Qr36 |
keV level [keV] | 70 |
Iterative reconstruction | QIR 3 |
Reconstruction type | TNC from unenhanced scan; calcium-preserving VNC from CTA |
Energy thresholds [keV] | 20, 35, 65, 70 |
Contrast agent | Ultravist, iopromide 300 mgI/mL |
Contrast protocol | Triphasic bolus tracking protocol |
Contrast volume | 60 mL contrast + 30 mL contrast/30 mL saline mixture + 20 mL saline |
Flow rate | 5 mL/s in all phases |
Patient preparation | No beta-blockers administered |
Scoring threshold | 130 HU |
Software for scoring | Syngo.via VB60A |
Becker J, Decker JA, Bette S, et al. Impact of BMI, heart rhythm, and heart rate on photon-counting detector virtual coronary calcium scoring. Int J Cardiovasc Imaging. 2025;41:1331–1339.
