Ultra-high-resolution PCCT reconstructions reduced apparent calcified plaque burden and increased visualization of non-calcified plaque components compared with standard reference reconstructions.
The combination of 0.2 mm slice thickness and the sharp Bv64 kernel yielded the lowest calcified plaque fraction and the highest lipid-rich plaque fraction, suggesting less blooming from calcium.
These findings indicate that ultra-high-resolution coronary PCCT may improve quantitative plaque characterization and potentially support better identification of high-risk plaque features.
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Figure 2. Segmentation and quantitative results of plaque characteristics in the circumflex artery of a 75-year-old male patient who underwent coronary CT angiography with photon-counting detector CT. Note the shift of CT values in the histogram towards lower values using ultra-high-resolution reconstructions with a slice thickness of 0.2 mm and the Bv64 kernel (B) compared with reconstructions with a slice thickness of 0.6 mm and the Bv40 kernel (A).
Source: Mergen et al., Frontiers in Cardiovascular Medicine, 2022, CC BY
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
Software | VA50 |
Scan area | Heart |
Scan protocol | ECG-gated unenhanced cardiac scan for calcium scoring, followed by ultra-high-resolution CCTA |
Scan mode | Prospective ECG-gated dual-source sequential or retrospective ECG-gated dual-source helical |
Acquisition mode | Quantum HD |
Tube voltage [kV] | 120 |
IQ level | 64 |
Dose modulation | CARE Dose4D |
CTDIvol [mGy] | 36.8 ± 6.3 retrospective 28.1 ± 6.8 prospective |
Pitch | 0.22–0.28 in retrospective helical mode, heart-rate dependent |
Matrix | 512 × 512 |
Field of view [mm] | 200 × 200 |
Slice collimation [mm] | 120 × 0.2 |
Slice width [mm] | 0.6 | 0.4 | 0.2 |
Reconstruction increment [mm] | 0.3 for reference standard; others not explicitly stated |
Reconstruction kernels | Bv40 smooth vascular | Bv64 sharp vascular |
Iterative reconstruction | QIR 4 |
keV level [keV] | Single energy threshold at 20 keV for ultra-high-resolution reconstruction |
Reference reconstruction | 0.6 mm, increment 0.3 mm, Bv40 |
Contrast agent | Ultravist 370 mg iodine/mL |
Contrast volume | 50–70 mL |
Flow rate | 3.3–4.4 mL/s, weight-based |
Saline chaser | 20 mL at same flow rate |
Bolus tracking | ROI in ascending aorta, scan start after >140 HU at 90 kV |
Patient preparation | Sublingual nitroglycerin 2.5 mg isosorbide dinitrate; no beta-blockers |
Average heart rate during scan | 69 ± 15 bpm |
