Quantitative coronary stenosis and plaque volumes have demonstrated intra-individual
differences between ultrahigh-resolution (UHR) photon-counting detector (PCD)-CT and
energy-integrating detector (EID)-CT. This study aimed to assess the impact of UHR
PCD-CT on semiquantitative scores of coronary artery disease (CAD) burden compared
with EID-CT.Patients undergoing coronary CT angiography (CCTA) on an EID-CT system
for stable chest pain or pre-transcatheter aortic valve replacement evaluation were
prospectively enrolled for UHR PCD-CT scan within 30 days. Both datasets were visually
evaluated using five established semiquantitative scores: Segment Involvement Score
(SIS), Segment Stenosis Score (SSS), Multivessel Aggregate Stenosis Score (MVAS),
CCTA-adapted Leaman score (CT-LeSc), and Coronary Artery Disease Reporting and Data
System (CAD-RADS). Additionally, the total number of detected plaques and high-risk
features were reported (positive remodeling, spotty calcification, low-attenuation,
and napkin-ring sign).The cohort comprised 46 patients (37 men, 68.4 ± 6.9 years).
When assessing stenosis severity, PCD-CT showed lower SSS (3.5 [1.3-5.0] vs 6.5 [3.0-9.8],
p < 0.001), MVAS (5.5 [4.0-7.0] vs 7.0 [5.0-9.0], p < 0.001), and CT-LeSc (10.4
[8.5-13.9] vs 11.2 [8.8-15.4], p = 0.032). Furthermore, 52 % (24/46) of patients
were reclassified to a lower CAD-RADS category compared to EID-CT. In terms of CAD
extent, PCD-CT demonstrated higher SIS (8.0 [6.0-9.0] vs 7.0 [6.0-8.8], p = 0.018)
and plaque count (9.0 [7.0-13.8] vs 7.0 [7.0-9.8] p < 0.001). Positive remodeling
was less frequent in PCD-CT datasets (2.0 [1.0-4.3] vs 1.0 [0.0-3.0], p = 0.012),
with no significant differences in other high-risk features.The use of UHR PCD-CT
detects less severe, but more extensive CAD compared to EID-CT. The effect of such
CCTA-based differences on individual risk stratification needs further investigation.
