Comparison of the Agatston score acquired with photon-counting detector CT and energy-integrating detector CT: ex vivo study of cadaveric hearts

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.

Epicardial fat volume is associated with preexisting atrioventricular conduction abnormalities and increased pacemaker implantation rate in patients undergoing transcatheter aortic valve implantation

Epicardial fat tissue (EFT) is a highly metabolically active fat depot surrounding the heart and coronary arteries that is related to early atherosclerosis and adverse cardiac events. We aimed to investigate the relationship between the amount of EFT and preexisting cardiac conduction abnormalities (CCAs) and the need for new postinterventional pacemaker in patients with severe aortic stenosis planned for transcatheter aortic valve implantation (TAVI). A total of 560 consecutive patients (54% female) scheduled for TAVI were included in this retrospective study. EFT volume was measured via a fully automated artificial intelligence software (QFAT) using computed tomography (CT) performed before TAVI. Baseline CCAs [first-degree atrioventricular (AV) block, right bundle branch block (RBBB), and left bundle branch block (LBBB)] were diagnosed according to 12-lead ECG before TAVI. Aortic valve calcification was determined by the Agatston score assessed in the pre-TAVI CT. The median EFT volume was 129.5 ml [IQR 94–170]. Baseline first-degree AV block was present in 17%, RBBB in 10.4%, and LBBB in 10.2% of the overall cohort. In adjusted logistic regression analysis, higher EFT volume was associated with first-degree AV block (OR 1.006 [95% CI 1.002–1.010]; p = 0.006) and the need for new pacemaker implantation after TAVI (OR 1.005 [95% CI 1.0–1.01]; p = 0.035) but not with the presence of RBBB or LBBB. EFT volume did not correlate with the Agatston score of the aortic valve. Greater EFT volume is associated independently with preexisting first-degree AV block and new pacemaker implantation in patients undergoing TAVI. It may play a causative role in degenerative processes and the susceptibility of the AV conduction system.

Comparability of coronary risk assessment methods with chest ultra-LDCT and CT coronography with ECG synchronization

Purpose. To assess the comparability of coronary calcium values measured on ultralow-dose computed tomography studies without ECG-synchronization versus a) non-contrast computed tomography with ECG synchronization, b) CT coronography with ECG synchronization.Materials and methods. The study comprised 283 studies: 68 patients who underwent contrast-free ultra-LDCT without ECG synchronization and contrast-free CT with ECG synchronization performed in a single visit, and 49 patients with contrast-free ultra-LDCT without ECG synchronization, non-contrast CT with ECG synchronization, and CT coronography with ECG synchronization and intravenous injection of contrast agent, also carried out in one visit, meeting all inclusion and exclusion criteria of the study.Quantitative coronary calcium values were calculated with the Agatston score and the CAC-DRS scale (score of calcification degree from 0 to 3 and the number of affected arteries from 0 to 4 points). The degree of coronary artery stenosis was analyzed with CAD-RADS scale (0-5).The above parameters were compared using visual/quantitative assessment of coronary calcium on ultra-LDCT without ECG synchronization and visual/quantitative assessment for CT with ECG synchronization, as well as the degree of stenosis on CT coronography in the same patients.Results. Based on the results of accuracy indices comparison, the possibility to use quantitative scale (Agatston score, CAC-DRS quantitative scale) to assess coronary calcification in the lung cancer screening in comparison with ECG-synchronized CT was determined during interpretation of ultra-LDCT without ECG synchronization. The correlation matrix to assess correlation between visual, quantitative scales of coronary artery changes and calcification at ultra-LDCT without ECG synchronization and quantitative scale at CT with ECG synchronization vs. CT coronography identifies very strong positive statistically significant correlations.Conclusion. Methods of coronary calcinosis assessment with chest ultra-LDCT and CT with ECG synchronization are comparable, therefore it is possible to assess coronary calcium in lung cancer screening by ultra-LDCT data at a reliable-high level using both quantitative and visual CAC-DRS scales.

Dose Reduction in Coronary Artery Calcium Scoring Using Mono-Energetic Images from Reduced Tube Voltage Dual-Source Photon-Counting CT Data: A Dynamic Phantom Study

In order to assess coronary artery calcium (CAC) quantification reproducibility for photon-counting computed tomography (PCCT) at reduced tube potential, an anthropomorphic thorax phantom with low-, medium-, and high-density CAC inserts was scanned with PCCT (NAEOTOM Alpha, Siemens Healthineers) at two heart rates: 0 and 60–75 beats per minute (bpm). Five imaging protocols were used: 120 kVp standard dose (IQ level 16, reference), 90 kVp at standard (IQ level 16), 75% and 45% dose and tin-filtered 100 kVp at standard dose (IQ level 16). Each scan was repeated five times. Images were reconstructed using monoE reconstruction at 70 keV. For each heart rate, CAC values, quantified as Agatston scores, were compared with the reference, whereby deviations >10% were deemed clinically relevant. Reference protocol radiation dose (as volumetric CT dose index) was 4.06 mGy. Radiation dose was reduced by 27%, 44%, 67%, and 46% for the 90 kVp standard dose, 90 kVp 75% dose, 90 kVp 45% dose, and Sn100 standard dose protocol, respectively. For the low-density CAC, all reduced tube current protocols resulted in clinically relevant differences with the reference. For the medium- and high-density CAC, the implemented 90 kVp protocols and heart rates revealed no clinically relevant differences in Agatston score based on 95% confidence intervals. In conclusion, PCCT allows for reproducible Agatston scores at a reduced tube voltage of 90 kVp with radiation dose reductions up to 67% for medium- and high-density CAC.

Comparison of the Agatston score acquired with photon-counting detector CT and energy-integrating detector CT: Ex vivo study of cadaveric hearts

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. Method 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. Results 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. Conclusion High correlation and agreement was observed between the AS derived from the EID-CT and a PCD-CT. Both methods also demonstrated excellent reproducibility.

Improving the predictive capability of Framingham Risk Score for risk of myocardial infarction based on coronary artery calcium score in healthy Singaporeans

Introduction: Cardiovascular disease emerged as the top cause of deaths and disability in Singapore in 2018, contributing extensively to the local healthcare burden. Primary prevention identifies at-risk individuals for the swift implementation of prevention or corrective measures. This has been traditionally done using the Singapore-adapted Framingham Risk Score (SG FRS). However, its most recent recalibration was done more than a decade ago. Recent changes in patient demographics and risk factors have undermined the accuracy of SG FRS, and the rising popularity of wearable health metrics have given rise to new data types with the potential to improve risk prediction. Methods: In healthy Singaporeans enrolled in the SingHEART study (in the absence of any clinical outcomes), we investigated potential improvements in the SG FRS to predict myocardial infarction risk based on high/low classifications of the Agatston score (surrogate outcome). Logistic regression, receiver operating characteristic and net reclassification index (NRI) analyses were conducted. Results: We demonstrated a significant improvement in the area under curve (AUC) of the SG FRS (AUC=0.641) after recalibration and incorporation of additional variables (fasting glucose and wearable-derived activity levels) (AUC=0.774) (p<0.001). SG FRS++ significantly increases accuracy in risk prediction (NRI=0.219, p=0.00254). Conclusion: We suggest that existing Singapore CVD risk prediction guidelines be updated to improve risk prediction accuracy. Recalibrating existing risk functions and utilising wearable metrics which provide a large pool of objective health data can help improve existing risk prediction tools. Lastly, activity levels and pre-diabetic state are important factors to consider for CHD risk stratification methods, especially in low-risk individuals.

Aortic Valve Calcium Score as Measured by Native Vs. Contrast Enhanced Computer Tomography and the Implications for the Diagnosis of Severe Aortic Stenosis in TAVR Patients With Low Gradient Aortic Stenosis.

Purposewe compared between patients with low gradient (LG) and high gradient (HG) severe aortic stenosis (AS) as regard the burden of aortic valve calcium (AVC) using different methodologies. Moreover, we evaluated the accuracy of published thresholds for the diagnosis of severe AS in both groups. Methodswe measured the calcium volume and score using Agatston methodology in non-contrast (n-c) CT and with modified and fixed 850 Hounsfield unit (HU) thresholds in contrast enhanced (ce) CT. ResultsThe medians (IQR) of Agatston score, score with 850 HU and modified thresholds were 1288 AU (750-1815), 101 (65-256), 701 (239-1632), respectively. The calcium volume in ceCT using fixed 850 HU thresholds is significantly lower than the assessed volume in ncCT or in ceCT using modifiable threshold. LG patients were more obese; BMI 31.2 (29.1-35.1) vs 27.6 (26-31) and presented more with coronary artery disease (71.4% vs 40%). AF was documented in 42% in LG-patients vs 30% in HG patients. LVEF was severely depressed (less than 30%) in 28.6% in LG-patients. LG patients were more symptomatic (NYHA ≥ III in 71.4% patients vs 42%).The LG patients had smaller anatomy: annulus diameter 23.5mm (21.5-27) vs 25mm (23-25.5), LVOT diameter 23mm (20-20) vs 25mm (23-26.7mm). The annulus geometry was more eccentric; eccentric index 0.23 (0.19-0.27) vs 0.11 (0.1-0.2). Agatston score and calcium volume were lower in patients with LG; 1641AU (1292-1990) vs 928AU (572-1284) and 1537mm³ (644-1860) vs 286mm³ (160-700), respectively. Only 20% of patients with LG had Agatston score less than the previously supposed AVC score threshold for the diagnosis of severe AS (>2000AU in men and >1200 in women). The elimination of ncCT from the protocol reduced significantly the radiation dose by 400.3 ± 140 mGy*cm and 2.4 ± 2.8mSv.ConclusionThe diagnosis of severe LGAS should not depend on a single parameter as calcium score. The measurement of calcium score in contrast CT underestimate the calcium load significantly.

Deep learning for automatic calcium scoring in population based cardiovascular screening

Background High volumes of standardized coronary artery calcium (CAC) scans are generated in screening that need to be scored accurately and efficiently to risk stratify individuals. Purpose To evaluate the performance of deep learning based software for automatic coronary calcium scoring in a screening setting. Methods Participants from the Robinsca trial that underwent low-dose ECG-triggered cardiac CT for calcium scoring were included. CAC was measured with fully automated deep learning prototype and compared to the original manual assessment of the Robinsca trial. Detection rate, positive Agatston score and risk categorization (0–99, 100–399, ≥400) were compared using McNemar test, ICC, and Cohen's kappa. False negative (FN), false positive (FP) rate and diagnostic accuracy were determined for preventive treatment initiation (cut-off ≥100 AU). Results In total, 997 participants were included between December 2015 and June 2016. Median age was 61.0 y (IQR: 11.0) and 54.4% was male. A high agreement for detection was found between deep learning based and manual scoring, κ=0.87 (95% CI 0.85–0.89). Median Agatston score was 58.4 (IQR: 12.3–200.2) and 61.2 (IQR: 13.9–212.9) for deep learning based and manual assessment respectively, ICC was 0.958 (95% CI 0.951–0.964). Reclassification rate was 2.0%, with a very high agreement with κ=0.960 (95% CI: 0.943–0.997), p&lt;0.001. FN rate was 0.7% and FP rate was 0.1% and diagnostic accuracy was 99.2% for initiation of preventive treatment. Conclusion Deep learning based software for automatic CAC scoring can be used in a cardiovascular CT screening setting with high accuracy for risk categorization and initiation of preventive treatment. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): Robinsca trial was supported by advanced grant of European Research Council

Incremental Diagnostic Value of CT Fractional Flow Reserve Using Subtraction Method in Patients with Severe Calcification: A Pilot Study

Although on-site workstation-based CT fractional flow reserve (CT-FFR) is an emerging method for assessing vessel-specific ischemia in coronary artery disease, severe calcification is a significant factor affecting CT-FFR’s diagnostic performance. The subtraction method significantly improves the diagnostic value with respect to anatomic stenosis for patients with severe calcification in coronary CT angiography (CCTA). We evaluated the diagnostic capability of CT-FFR using the subtraction method (subtraction CT-FFR) in patients with severe calcification. This study included 32 patients with 45 lesions with severe calcification (Agatston score >400) who underwent both CCTA and subtraction CCTA using 320-row area detector CT and also received invasive FFR within 90 days. The diagnostic capabilities of CT-FFR and subtraction CT-FFR were compared. The sensitivities, specificities, positive predictive values (PPVs), and negative predictive values (NPVs) of CT-FFR vs. subtraction CT-FFR for detecting hemodynamically significant stenosis, defined as FFR ≤ 0.8, were 84.6% vs. 92.3%, 59.4% vs. 75.0%, 45.8% vs. 60.0%, and 90.5% vs. 96.0%, respectively. The area under the curve for subtraction CT-FFR was significantly higher than for CT-FFR (0.84 vs. 0.70) (p = 0.04). The inter-observer and intra-observer variabilities of subtraction CT-FFR were 0.76 and 0.75, respectively. In patients with severe calcification, subtraction CT-FFR had an incremental diagnostic value over CT-FFR, increasing the specificity and PPV while maintaining the sensitivity and NPV with high reproducibility.