(2022) Mergen | First in-human quantitative plaque characterization with UHR cCCTA

Daniel Stromer

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