The purpose of this study was to compare the correlation and agreement between AS derived from either an energy-integrating detector CT (EID-CT) or a photon-counting detector CT (PCD-CT). Reproducibility was also compared. In total, 26 calcified coronary lesions (from five cadaveric hearts) were identified for inclusion. The hearts were positioned in a chest phantom and scanned in both an EID-CT and a prototype PCD-CT. The EID-CT and PCD-CT acquisition and reconstruction parameters were matched. To evaluate the reproducibility, the phantom was manually repositioned, and an additional scan was performed using both methods. The EID-CT reconstructions were performed using the dedicated calcium score kernel Sa36. The PCD-CT reconstructions were performed with a vendor-recommended kernel (Qr36). Several monoenergetic energy levels (50-150 keV) were evaluated to find the closest match with the EID-CT scans. A semi-automatic evaluation of calcium score was performed on a post-processing multimodality workplace. The best match with Sa36 was PCD-CT Qr36 images, at a monoenergetic level of 72 keV. Statistical analyses showed excellent correlation and agreement. The correlation and agreement with regards to the Agatston score (AS) between the two methods, for each position as well as between the two positions for each method, were assessed with the Spearman s rank correlation. The correlation coefficient, rho, was 0.98 and 0.97 respectively 0.99 and 0.98. The corresponding agreements were investigated by means of Bland-Altman plots. High correlation and agreement was observed between the AS derived from the EID-CT and a PCD-CT. Both methods also demonstrated excellent reproducibility.

Background: As guidelines endorse the use of computed tomography (CT) for examining coronary artery disease (CAD), it is important to compare the advantages and disadvantages of the novel photon counting detector CT (PCD-CT) technology with the established energy integrating detector CT (EID-CT). Purpose: To compare the image quality of coronary computed tomography angiography (CCTA) and the Agatston scores (AS) derived from EID-CT and PCD-CT. Material and Methods: In this prospective observational study, 28 patients underwent clinical calcium score and CCTA scans on an EID-CTand a PCD-CT scanner. CCTA images were qualitatively analyzed by five observers using visual grading characteristics. The correlation and agreement of the AS were assessed using Spearmans rank correlation and Bland-Altman plots. Results: This qualitative analyses demonstrated a high fraction of " good" or "excellent" ratings for the image criteria in both CT systems. The sharpness of the distal lumen and image quality regarding motion artifacts were rated significantly higher for EID-CT (P < 0.05). However, the sharpness of coronary calcification was rated significantly higher for PCD-CT (P < 0.05). Spearmans rank correlation and Bland-Altman plots showed good correlation (P = 0.95) and agreement regarding the AS between EID-CT and PCD-CT. Conclusion: Both CT systems exhibited high CCTA image quality. The sharpness of calcifications was rated significantly higher for PCD-CT. A good correlation was observed between the AS derived from the two systems.

Objectives 

Coronary computed tomography angiography is the primary modality for noninvasive assessment of coronary artery disease. Photon-counting computed tomography (PCCT) offers superior spatial resolution and spectral imaging for detailed characterization of atherosclerotic plaques. This study aimed to evaluate the impact of virtual monoenergetic imaging (VMI) energy levels and reconstruction kernels on segmentation-based measurement of plaque volume in individuals with coronary atherosclerosis using PCCT.

Materials and Methods 

Fifty study participants underwent coronary computed tomography angiography with ultra-high-resolution PCCT. Both polyenergetic, 120 kVp (T3D) images and spectral images at varying VMI energy levels were reconstructed using different kernels. Plaque volumes were measured using semiautomated attenuation-based segmentation, adjusting segmentation thresholds for each VMI energy level. In addition, absolute plaque volume measurements were conducted using a coronary phantom simulating different plaque types.

Results 

Using a sharper kernel (Bv64 vs Bv48) significantly increased noncalcified plaque volume measurements (P < 0.005) in study participants, whereas a 0.2-mm slice thickness reduced calcified plaque volumes compared with 0.4 mm (P < 0.005). VMI energy level had no impact on measured volumes. Phantom measurements confirmed significant variability in measured volumes of calcified and noncalcified plaques depending on reconstruction method, as well as a minor effect of VMI level.

Conclusions 

In PCCT, the reconstruction kernel predominantly affects noncalcified coronary plaque quantification, whereas slice thickness mainly impacts calcified plaque volumes. In study participants, measured plaque volumes were not affected by VMI energy level when energy-specific segmentation thresholds were used, although a minor effect of VMI was observed in the phantom model.

Background: Coronary CT angiography (CCTA) is a key non-invasive tool for evaluating coronary artery disease (CAD). While energy-integrating detector CT (EID-CT) offers high negative predictive value (NPV), its positive predictive value (PPV) is limited in heavily calcified vessels. Photon-counting detector CT (PCD-CT), with higher spatial resolution and reduced blooming, may enhance diagnostic performance. Current PCD-CT systems provide both standard-resolution (SR) and ultra-high-resolution (UHR) modes, but the clinical impact of these modes remains under investigation.

Objectives: To compare the diagnostic accuracy and image quality of SR-PCD-CT versus EID-CT in quantifying coronary stenosis, using quantitative coronary angiography (QCA) as reference. Materials and methods: In this prospective, single-centre study, 21 patients (5 women, mean age 71.5 years) with suspected CAD underwent CCTA with both EID-CT and SR-PCD-CT prior to QCA. A total of 301 coronary segments were assessed for stenosis severity, with ≥50 % stenosis deemed significant. Image quality was graded using a 5-point scale. 

Results: No significant differences in percentage diameter stenosis (%DS) were found between imaging techniques (p = 0.20). Both EID-CT and SR-PCD-CT showed good agreement with QCA (AUC: PCD-CT 0.89, EID-CT 0.86). Specificity and NPV were high for both; sensitivity and PPV were moderate. SR-PCD-CT yielded higher image quality compared to EID-CT (p < 0.001).

Conclusions: In standard resolution mode, PCD-CT offers excellent image quality for quantifying coronary stenosis at comparable diagnostic accuracy compared to EID-CT