Ultra-high-resolution (UHR) photon-counting coronary CT angiography demonstrated significantly higher precision than standard-resolution (SR) PCCT for quantifying coronary stenosis, particularly in heavily calcified vessels. Compared with invasive 3D quantitative coronary angiography (QCA), UHR-PCCT reduced median stenosis measurement error from 6% to 3% and achieved near-perfect agreement for CAD-RADS classification.
The study also demonstrated that the primary benefit of UHR-PCCT stems from its 0.2 mm acquisition mode, which markedly reduces calcium blooming artifacts and improves lumen visualization. While diagnostic accuracy improved substantially, these gains came at the expense of a 2.7-fold increase in radiation dose compared with standard-resolution PCCT.
Importantly, spectral calcium subtraction (Quantum PURE Lumen) did not outperform native UHR imaging, indicating that improved spatial resolution is currently more valuable than post-processing for accurate coronary lumen assessment.
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Figure 1. Representative examples comparing standard-resolution PCCT, ultra-high-resolution PCCT, and invasive coronary angiography. UHR-PCCT provides markedly improved visualization of calcified coronary plaques and more accurate luminal stenosis assessment, closely matching invasive 3D quantitative coronary angiography.
Protocol
Detail | Value |
|---|
Scanner | NAEOTOM Alpha |
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Software | VA50 SP1 |
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Scan area | Coronary CTA |
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Scan mode | Quantum HD Cardiac retrospective ECG-gated Flex/Spiral |
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Acquisition mode | Photon-counting detector CT |
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Tube voltage [kV] | 120 (UHR) |
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Effective mAs [mAs] | CARE Dose4D automatic |
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IQ level | CARE keV IQ 69 (UHR) |
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Temporal resolution [ms] | 66 ms |
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Rotation time [s] | 0.25 |
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Detector slice collimation | 96 x 0.2 mm |
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Acquisition slice thickness | 0.2 mm |
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Reconstruction kernel | Bv60 Q4 |
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Reconstruction | Blended-energy UHR |
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ECG gating | Retrospective |
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Contrast agent | Omnipaque 350 |
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Contrast volume | 80 mL |
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Saline flush | 50 mL |
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Injection rate | 4.5 mL/s |
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Heart-rate target | <60 bpm |
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Nitroglycerin | 800 μg SL |
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Beta-blocker | IV metoprolol (≤40 mg) |
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Key Results
Outcome | Standard Resolution | Ultra-High Resolution |
|---|
Slice thickness | 0.4 mm | 0.2 mm |
Median stenosis error vs 3D QCA | 6% | 3% |
CAD-RADS agreement (κ) | 0.63 | 0.90 |
CAD-RADS agreement (calcified vessels) | 0.67 | 0.90 |
Diagnostic AUC | 0.94 | 0.99 |
Sensitivity | 87% | 96% |
Specificity | 88% | 100% |
Effective radiation dose | 2.8 mSv | 7.5 mSv |
Source: Kotronias RA, de Maria GL, Xie C, et al. Benchmarking Photon-Counting Computed Tomography Angiography Against Invasive Assessment of Coronary Stenosis: Implications for Severely Calcified Coronaries. JACC: Cardiovascular Imaging. 2025.
