Compared with conventional VMI, VNCa images on spectral PCCT markedly reduced overestimation of calcified coronary stenoses and aligned much more closely with 3D-QCA.
Virtual calcium removal was feasible in most lesions, but about 12% of stenoses had to be excluded because of erroneous plaque subtraction.
When feasible, VNCa substantially improved CAD-RADS stenosis classification accuracy and reduced stenosis overcalling in calcified plaques.
Figure 2. Flowchart detailing the scan protocol.
Figure 4. Sixty three-year-old male patient with chronic coronary syndrome. Curved planar reformations of conventional (A) and virtual non-calcium (VNCa) images (B) show calcified and subtracted calcified plaques, respectively, in the proximal left anterior descending artery (LAD). Corresponding axial images show the calcified plaque (C) and the vessel lumen after subtraction (arrow) (D) invasive coronary angiography (E) confirmed the presence of a moderate stenosis in the proximal LAD.
Source: Mergen et al., Frontiers in Cardiovascular Medicine, 2024, CC BY
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | VA50 |
Scan area | Heart |
Scan protocol | ECG-gated non-contrast cardiac scan followed by ECG-gated CCTA |
Scan mode | QuantumPlus high-pitch or retrospective helical depending on heart rate |
Tube voltage [kV] | 140 high-pitch if HR <70 bpm 120 retrospective helical if HR ≥70 bpm |
Effective mAs [mAs] | n.a. |
IQ level | 110 high-pitch | 60 retrospective helical |
Dose modulation | CARE Dose4D, ECG pulsing 65%–75% RR in helical mode |
CTDIvol [mGy] | 4.6 ± 0.8 high-pitch | 16.8 ± 6.7 retrospective helical |
DLP [mGy*cm] | 101 ± 20 high-pitch | 357 ± 114 retrospective helical |
Rotation time [s] | 0.25 |
Pitch | 3.2 high-pitch |
Matrix | 512 × 512 |
Field of view [mm] | 180 × 180 |
Slice collimation [mm] | 144 × 0.4 |
Reconstruction type | VMI and VNCa |
VMI reconstruction | 70 keV, 0.4 mm slice thickness, 0.2 mm increment, Bv44, QIR 4 |
VNCa reconstruction | PURELumen, 0.6 mm slice thickness, 0.4 mm increment, Qr44, QIR 3 |
Contrast agent | Iomeron 350 mg I/mL |
Contrast volume | 60–80 mL, weight-based |
Saline chaser | 50 mL NaCl 0.9% |
Patient preparation | IV beta-blockers if initial HR >70 bpm; sublingual nitroglycerin 2.5 mg |
Heart rate during acquisition | 60 ± 7 bpm |
Reference standard | 3D-QCA |
Mergen V, Rusek S, Civaia F, et al. Virtual calcium removal in calcified coronary arteries with photon-counting detector CT: first in-vivo experience. Front Cardiovasc Med. 2024;11:1367463.
