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AIM/OBJECTIVE: To assess the pattern of coronary artery disease in Pakistani population according to year, gender, artery and dominance. BACKGROUND: Coronary artery calcium scoring is being used frequently nowadays as a reliable tool in categorisation and prognosis of cardiovascular risk. Calcium scoring is an authentic predictor for diagnosing coronary artery disease having 99% negative predictor value, 91% sensitive and 64% specific. MATERIALS AND METHODS: Total of 3146 patients of last 6 years were selected from the radiology database retrospectively from 2017 to 2023. Coronary angiography vessel based were analysed on Vitrea by consultants, using Toshiba 640 and Siemens 128 slice. Agatston CAC scoring was used in calculating the calcium. Patient s demographics and data were obtained from our hospital record system. RESULT: Out of 3146 patients, 828 females and 1927 males with most common age group from 40-60 years,1494 were diseased and artery most commonly involved was found to be LAD in about 687 patients, 509 males and 178 females followed by RCA and then LCX. Most of the patients were right dominant (1622 males & 706 females) followed by left dominance (217 males & 86 females) and least were codominant (88 males & 36 females). CONCLUSION: Calcium scoring should be assessed in all of the patients whether symptomatic or asymptomatic to evaluate cardiovascular risk irrespective of age, year and gender. [ABSTRACT FROM AUTHOR]

Background: The reference protocol for the quantification of coronary artery calcium (CAC) should be updated to meet the standards of modern imaging techniques. Purpose: To assess the influence of filtered-back projection (FBP), hybrid iterative reconstruction (IR), and three levels of deep learning reconstruction (DLR) on CAC quantification on both in vitro and in vivo studies. Material and Methods: In vitro study was performed with a multipurpose anthropomorphic chest phantom and small pieces of bones. The real volume of each piece was measured using the water displacement method. In the in vivo study, 100 patients (84 men; mean age = 71.2 ± 8.7 years) underwent CAC scoring with a tube voltage of 120 kVp and image thickness of 3 mm. The image reconstruction was done with FBP, hybrid IR, and three levels of DLR including mild (DLRmild), standard (DLRstd), and strong (DLRstr). Results: In the in vitro study, the calcium volume was equivalent (P = 0.949) among FBP, hybrid IR, DLRmild, DLRstd, and DLRstr. In the in vivo study, the image noise was significantly lower in images that used DLRstr-based reconstruction, when compared images other reconstructions (P < 0.001). There were no significant differences in the calcium volume (P = 0.987) and Agatston score (P = 0.991) among FBP, hybrid IR, DLRmild, DLRstd, and DLRstr. The highest overall agreement of Agatston scores was found in the DLR groups (98%) and hybrid IR (95%) when compared to standard FBP reconstruction. Conclusion: The DLRstr presented the lowest bias of agreement in the Agatston scores and is recommended for the accurate quantification of CAC. [ABSTRACT FROM AUTHOR]

Purpose of Review: In this review, we aim to summarize state-of-the-art artificial intelligence (AI) approaches applied to cardiovascular CT and their future implications. Recent Findings: Recent studies have shown that deep learning networks can be applied for rapid automated segmentation of coronary plaque from coronary CT angiography, with AI-enabled measurement of total plaque volume predicting future heart attack. AI has also been applied to automate assessment of coronary artery calcium on cardiac and ungated chest CT and to automate the measurement of epicardial fat. Additionally, AI-based prediction models integrating clinical and imaging parameters have been shown to improve prediction of cardiac events compared to traditional risk scores. Summary: Artificial intelligence applications have been applied in all aspects of cardiovascular CT — in image acquisition, reconstruction and denoising, segmentation and quantitative analysis, diagnosis and decision assistance and to integrate prognostic risk from clinical data and images. Further incorporation of artificial intelligence in cardiovascular imaging holds important promise to enhance cardiovascular CT as a precision medicine tool. [ABSTRACT FROM AUTHOR]

Background and objective: Coronary artery calcium is a specific indicator of and an independent risk factor for atherosclerosis. However, calcium scoring may miss non calcified plaques, which were indicated to be of clinical importance. This study aimed to identify the presence of non calcified plaques in patients with zero coronary artery calcium score who have been examined with computed tomography coronary angiography and find out any association between the presence of non-calcified plaques and risk factors and presenting symptoms in those patients. Methods: In this retrospective study, we analyzed the computed tomography images of 9826 consecutive patients attending the cardiac center in Erbil, Iraq, between January 2016 and September 2020. Of these patients, we included 2805 patients with a zero coronary artery calcium score in the study. Coronary calcium-scoring scans were followed by computed tomography coronary angiography (256 MSCT Philips ICT). The coronary artery calcium scores were calculated, and the presence of non calcified plaques and significant stenosis (>50% of vessel diameter) were evaluated. Results: Of the 2805 patients with a zero coronary artery calcium score, 896 (31.9%) had atherosclerotic plaques; 143 patients (5.1%) had significant coronary stenosis. Among coronary risk factors, diabetes mellitus (OR = 2.1; 95% CI 1.4-3.3), hypertension (OR = 1.3; 95% CI 1.07-1.58)), male sex (OR = 1.9; 95% CI 1.5-2.3) and old age (OR was 3.2 for the age group 35-44 years reaching 27.7 in the age group ≥ 75 years) were significantly correlated with the presence of atherosclerosis and obstructive coronary artery disease. Conclusion: Although coronary artery calcium scoring is a safe and reliable test to exclude obstructive coronary artery disease, the absence of coronary artery calcium does not absolutely exclude the presence of atherosclerosis. Computed tomography coronary angiography is mandatory for determining the atheroma burden from zero coronary artery calcium score plaques.

Stress electrocardiography (sECG) or treadmill stress testing is a well validated noninvasive diagnostic modality available to clinicians at low cost yet providing valuable functional data for coronary artery disease (CAD) diagnostic and prognostic evaluation. With the advances in cardiac imaging in both functional and anatomic fronts and the existing limitations of sECG testing, this modality appears less favored worldwide as reflected in some recent guideline updates. We review the past present and future of sECG to provide a viewpoint on where it stands in CAD evaluation and if it will remain relevant as a diagnostic modality or be retired going forward. We also provide our perspectives on how sECG can co-exist with other modalities such as calcium scoring and discuss the role of such testing in the Indian population.

To evaluate the accuracy of coronary artery calcium (CAC) scoring at various tube voltages and different monoenergetic image reconstructions on a first-generation dual-source photon-counting detector CT (PCD-CT). A commercially available anthropomorphic chest phantom with calcium inserts was scanned at different tube voltages (90 kV, Sn100kV, 120 kV, and Sn140kV) on a first-generation dual-source PCD-CT system with quantum technology using automatic exposure control with an image quality (IQ) level of 20. The same phantom was also scanned on a conventional energy-integrating detector CT (120 kV; weighted filtered back projection) for reference. Extension rings were used to emulate different patient sizes. Virtual monoenergetic images at 65 keV and 70 keV applying different levels of quantum iterative reconstruction (QIR) were reconstructed from the PCD-CT data sets. CAC scores were determined and compared to the reference. Radiation doses were noted. At an IQ level of 20, radiation doses ranged between 1.18 mGy and 4.64 mGy, depending on the tube voltage and phantom size. Imaging at 90 kV or Sn100kV was associated with a size-dependent radiation dose reduction between 23% and 48% compared to 120 kV. Tube voltage adapted image reconstructions with 65 keV and QIR 3 at 90 kV and with 70 keV and QIR 1 at Sn100kV allowed to calculate CAC scores comparable to conventional EID-CT scans with a percentage deviation of ≤ 5% for all phantom sizes. Our phantom study indicates that CAC scoring with dual-source PCD-CT is accurate at various tube voltages, offering the possibility of substantial radiation dose reduction. [ABSTRACT FROM AUTHOR]

Coronary artery calcification affects the arteries that supply the heart with blood, and percutaneous coronary intervention (PCI) is a direct and effective surgery to alleviate this symptom. In this paper, we propose a framework to judge if a patient requires surgery, based on cardiac computerized tomography scans. We adopt generative adversarial network to segment the calcified areas from slices. This architecture provides an environment for the generator to perform joint learning from ground truth images and the high-resolution discriminator. We use images reconstructed using two types of filters to test our method. An F1 score of 96.1% and 85.0% was achieved for the soft and sharp filters. In addition, we explored different recurrent neural networks for making the final decision. Including long short-term memory, which was ultimately used to deal with the calcium score normalized by the age and score threshold. Using the soft reconstruction image as the input, the whole framework achieved an accuracy of 76.6%. These results certify that our method can precisely locate lesion in artery, and make a reasonable risk assessment for PCI.

In this review, the authors summarize the role of coronary computed tomography angiography and coronary artery calcium scoring in different clinical presentations of chest pain and preventative care and discuss future directions and new technologies such as pericoronary fat inflammation and the growing footprint of artificial intelligence in cardiovascular medicine., Competing Interests: Disclosure M.C. Williams has given talks for Canon Medical Systems, Siemens Healthineers, and Novartis. The work of M.C. Williams is supported by the British Heart Foundation, United Kingdom (FS/ICRF/20/26002)., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Aims Our aim was to evaluate the performance of machine learning (ML), integrating clinical parameters with coronary artery calcium (CAC), and automated epicardial adipose tissue (EAT) quantification, for the prediction of long-term risk of myocardial infarction (MI) and cardiac death in asymptomatic subjects. Methods and results Our study included 1912 asymptomatic subjects [1117 (58.4%) male, age: 55.8  ±  9.1 years] from the prospective EISNER trial with long-term follow-up after CAC scoring. EAT volume and density were quantified using a fully automated deep learning method. ML extreme gradient boosting was trained using clinical co-variates, plasma lipid panel measurements, risk factors, CAC, aortic calcium, and automated EAT measures, and validated using repeated 10-fold cross validation. During mean follow-up of 14.5  ±  2 years, 76 events of MI and/or cardiac death occurred. ML obtained a significantly higher AUC than atherosclerotic cardiovascular disease (ASCVD) risk and CAC score for predicting events (ML: 0.82; ASCVD: 0.77; CAC: 0.77, P  < 0.05 for all). Subjects with a higher ML score (by Youden's index) had high hazard of suffering events (HR: 10.38, P  < 0.001); the relationships persisted in multivariable analysis including ASCVD-risk and CAC measures (HR: 2.94, P  = 0.005). Age, ASCVD-risk, and CAC were prognostically important for both genders. Systolic blood pressure was more important than cholesterol in women, and the opposite in men. Conclusions In this prospective study, machine learning used to integrate clinical and quantitative imaging-based variables significantly improves prediction of MI and cardiac death compared with standard clinical risk assessment. Following further validation, such a personalized paradigm could potentially be used to improve cardiovascular risk assessment. [ABSTRACT FROM AUTHOR]

To investigate the accuracy of Agatston scoring and potential for radiation dose reduction of a coronary artery calcium scoring (CACS) CT protocol at 100 kV with tin filtration (Sn100kV) and kV-independent iterative reconstruction, compared to standard 120 kV acquisitions. With IRB approval and in HIPAA compliance, 114 patients (61.8 ± 9.6 years; 66 men) underwent CACS using a standard 120 kV protocol and an additional Sn100kV CACS scan. The two datasets were reconstructed using a medium sharp convolution algorithm and in addition the Sn100kV scans were reconstructed iteratively based on a kV-independent algorithm. Agatston scores and radiation dose values were compared between the Sn100kV and the standard 120 kV protocol. Median Agatston scores derived from the Sn100kV protocol with the kV-independent algorithm and the standard 120 kV were 21.4 (IQR, 0–173.8) and 24.7 (IQR, 0–171.1) respectively, with no significant differences (p= 0.18). Agatston scores derived from the two different protocols had an excellent correlation (r = 0.99). The dose-length-product was 11.5 ± 4.1 mGy × cm using Sn100kV and 50.4 ± 24.9 mGy × cm using the standard 120 kV protocol (p < 0.01), resulting in a significantly lower (77%) effective dose at Sn100kV (0.16 ± 0.06 mSv vs. 0.71 ± 0.35 mSv, p < 0.01). Additionally, 99% of the patients were classified into the same risk category (0, 1–10, 11–100, 101–400, or >400) using the Sn100kV protocol. CACS at Sn100kV using the kV-independent iterative algorithm is feasible and provides high accuracy when compared to standard 120 kV scanning. Furthermore, radiation dose can be significantly reduced for this screening application in a priori healthy individuals. [ABSTRACT FROM AUTHOR]

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We evaluated the accuracy of coronary artery calcium (CAC) scoring on a dual-source photon-counting detector CT (PCD-CT). An anthropomorphic chest phantom underwent ECG-gated sequential scanning on a PCD-CT at 120 kV with four radiation dose levels (CTDIvol, 2.0–8.6 mGy). Polychromatic images at 120 kV (T3D) and virtual monoenergetic images (VMI), from 60 to 75 keV without quantum iterative reconstruction (no QIR) and QIR strength levels 1–4, were reconstructed. For reference, the same phantom was scanned on a conventional energy-integrating detector CT (120 kV; filtered back projection) at identical radiation doses. CAC scoring in 20 patients with PCD-CT (120 kV; no QIR and QIR 1–4) were included. In the phantom, there were no differences between CAC scores of different radiation doses (all, p > 0.05). Images with 70 keV, no QIR (CAC score, 649); 65 keV, QIR 3 (656); 65 keV; QIR4 (648) and T3D, QIR4 (656) showed a p < 0.001) and for each 5 keV-increase (all, p < 0.001). Patient data (median CAC score: 86 [inter-quartile range: 38–978] at 70 keV) confirmed relationships and differences between reconstructions from the phantom. First phantom and in-vivo experience with a clinical dual-source PCD-CT system shows accurate CAC scoring with VMI reconstructions at different radiation dose levels.

Abstract Computed tomographic (CT) coronary calcium scoring has been established by large prospective, population-based studies as the single best noninvasive predictor of atherosclerotic cardiovascular risk available today. The calcium score correlates highly with the total burden of coronary atherosclerosis demonstrated at autopsy. It adds significantly to traditional risk calculators such as the Framingham Risk Calculator or the Pooled Cohort Equations. The 2018 U.S. Cholesterol Guidelines endorse the use of CT coronary calcium scoring to refine risk estimates in the intermediate range of 7.5%–20% over 10 years. Most, but not all, adults with calcium scores of zero can reasonably elect to avoid or defer statin therapy, but repeating the calcium score should be considered in 5 to 10 years. Discussants at this roundtable urge that coronary calcium scoring be offered to many more adults than currently receiving this test, including those with borderline 10-year risk in the range of 5%–7.5%. CT coronary angiography is a procedure based on intravenous contrast injection, mostly used in low-risk patients with chest pain. In British guidelines, CT angiography is preferred over stress testing for initial assessment of suspected coronary symptoms. Carotid ultrasound evaluating both the carotid intima-media thickness and presence of plague is less predictive than coronary calcium scoring for overall atherosclerotic risk but more predictive for stroke risk. [ABSTRACT FROM AUTHOR]

Noise is inherent to low-dose CT acquisition. We propose to train a convolutional neural network (CNN) jointly with an adversarial CNN to estimate routine-dose CT images from low-dose CT images and hence reduce noise. A generator CNN was trained to transform low-dose CT images into routine-dose CT images using voxelwise loss minimization. An adversarial discriminator CNN was simultaneously trained to distinguish the output of the generator from routine-dose CT images. The performance of this discriminator was used as an adversarial loss for the generator. Experiments were performed using CT images of an anthropomorphic phantom containing calcium inserts, as well as patient non-contrast-enhanced cardiac CT images. The phantom and patients were scanned at 20% and 100% routine clinical dose. Three training strategies were compared: the first used only voxelwise loss, the second combined voxelwise loss and adversarial loss, and the third used only adversarial loss. The results showed that training with only voxelwise loss resulted in the highest peak signal-to-noise ratio with respect to reference routine-dose images. However, CNNs trained with adversarial loss captured image statistics of routine-dose images better. Noise reduction improved quantification of low-density calcified inserts in phantom CT images and allowed coronary calcium scoring in low-dose patient CT images with high noise levels. Testing took less than 10 s per CT volume. CNN-based low-dose CT noise reduction in the image domain is feasible. Training with an adversarial network improves the CNNs ability to generate images with an appearance similar to that of reference routine-dose CT images. [ABSTRACT FROM PUBLISHER]

Rationale and Objectives: Different computed tomography imaging protocols and patient characteristics can impact the accuracy and precision of the calcium score and may lead to inconsistent patient treatment recommendations. The aim of this work was to determine the impact of reconstruction algorithm and gender characteristics on coronary artery calcium scoring based on a phantom study using computed tomography.Materials and Methods: Four synthetic heart vessels with vessel diameters corresponding to female and male left main and left circumflex arteries containing calcification-mimicking materials (200-1000 HU) were inserted into a thorax phantom and were scanned with and without female breast plates (male and female phantoms, respectively). Ten scans were acquired and were reconstructed at 3-mm slices using filtered-back projection (FBP) and iterative reconstruction with medium and strong denoising (IR3 and IR5) algorithms. Agatston and calcium volume scores were estimated for each vessel. Calcium scores for each vessel and the total calcium score (summation of all four vessels) were compared between the two phantoms to quantify the impact of the breast plates and reconstruction parameters. Calcium scores were also compared among vessels of different diameters to investigate the impact of the vessel size.Results: The calcium scores were significantly larger for FBP reconstruction (FBP > IR3>IR5). Agatston scores (calcium volume score) for vessels in the male phantom scans were on average 4.8% (2.9%), 8.2% (7.1%), and 10.5% (9.4%) higher compared to those in the female phantom with FBP, IR3, and IR5, respectively, when exposure was conserved across phantoms. The total calcium scores from the male phantom were significantly larger than those from the female phantom (P <0.05). In general, calcium volume scores were underestimated (up to about 50%) for smaller vessels, especially when scanned in the female phantom.Conclusions: Calcium scores significantly decreased with iterative reconstruction and tended to be underestimated for female anatomy (smaller vessels and presence of breast plates). [ABSTRACT FROM AUTHOR]

Purpose: Calcium scoring is widely used to assess the risk of coronary heart disease (CHD). Accurate coronary artery calcification detection in noncontrast CT image is a prerequisite step for coronary calcium scoring. Currently, calcified lesions in the coronary arteries are manually identified by radiologists in clinical practice. Thus, in this paper, a fully automatic calcium scoring method was developed to alleviate the work load of the radiologists or cardiologists. Methods: The challenge of automatic coronary calcification detection is to discriminate the calcification in the coronary arteries from the calcification in the other tissues. Since the anatomy of coronary arteries is difficult to be observed in the noncontrast CT images, the contrast CT image of the same patient is used to extract the regions of the aorta, heart, and coronary arteries. Then, a patient-specific region-of-interest (ROI) is generated in the noncontrast CT image according to the segmentation results in the contrast CT image. This patient-specific ROI focuses on the regions in the neighborhood of coronary arteries for calcification detection, which can eliminate the calcifications in the surrounding tissues. A support vector machine classifier is applied finally to refine the results by removing possible image noise. Furthermore, the calcified lesions in the noncontrast images belonging to the different main coronary arteries are identified automatically using the labeling results of the extracted coronary arteries. Results: Forty datasets from four different CT machine vendors were used to evaluate their algorithm, which were provided by the MICCAI 2014 Coronary Calcium Scoring (orCaScore) Challenge. The sensitivity and positive predictive value for the volume of detected calcifications are 0.989 and 0.948. Only one patient out of 40 patients had been assigned to the wrong risk category defined according to Agatston scores (0, 1-100, 101-300, >300) by comparing with the ground truth. Conclusions: The calcified lesions in the noncontrast CT images can be detected automatically by using the segmentation results of the aorta, heart, and coronary arteries obtained in the contrast CT images with a very high accuracy. [ABSTRACT FROM AUTHOR]

Background Impaired myocardial flow reserve (MFR) is a marker of coronary vascular dysfunction with prognostic significance. Objectives We aimed to investigate the relationship between epicardial fat volume (EFV) measured from noncontrast CT and impaired MFR derived from rest-stress Rb-82 positron emission tomography (PET). Methods We retrospectively studied 85 consecutive patients without known coronary artery disease who underwent rest-stress Rb-82 myocardial PET/CT and were subsequently referred for invasive coronary angiography. EFV was computed from noncontrast CT by validated software and indexed to body surface area (EFVi, cm 3 /m 2 ). Global stress and rest MFR were automatically derived from PET. Patient age, sex, cardiovascular risk factors, coronary calcium score (CCS), and EFVi were combined by boosted ensemble machine learning algorithm into a novel composite risk score, using 10-fold cross-validation, to predict impaired global MFR (MFR ≤2.0) by PET. Results Patients with impaired MFR (44 of 85; 52%) were older (71 vs 65 years; P = .03) and had higher frequency of CCS (≥400; P = .02) with significantly higher EFVi (63.1 ± 20.4 vs 51.3 ± 14.1 cm 3 /m 2 ; P = .003). On multivariate logistic regression (with age, sex, number of risk factors, CCS, and EFVi), EFVi was the only independent predictor of impaired MFR (odds ratio, 7.39; P = .02). The machine learning composite risk score significantly improved risk reclassification of impaired MFR compared to CCS or EFVi alone (integrated discrimination improvement = 0.19; P = .007 and IDI = 0.22; P = .002, respectively). Conclusions Increased EFVi and composite risk score combining EFVi and CCS significantly improve identification of impaired global MFR by PET. [ABSTRACT FROM AUTHOR]

Objective: To determine effectiveness of coronary artery calcium score (CACS) alone and combined with Systematic Coronary Risk Evaluation (SCORE) in adult patients for significant coronary artery stenosis by using computed tomography coronary angiography (CTCA) as reference standard. Methods: Two thousand twenty-one patients with suspected coronary artery disease (CAD) underwent CACS test and CTCA. Patients were examined with dual-source CT and were grouped according to their age, gender, CACS, and estimated SCORE risk. Coronary plaque existence and degree of stenosis were assessed with CTCA. Sensitivity, specificity, and ROC curves were analyzed. Results: CACS was the single independent variable in estimating relative risk of critical stenosis and had superior outcome when compared with SCORE risk in logistic regression and ROC curve. Area under the ROC curve was greatest in the interval between 50-59 years. When SCORE was combined with CACS in patients with zero CACS, percentage of significant stenosis increased from 1.4% to 7.0% in patients with high or very high SCORE risk, and decreased to 0.9 % in patients with low or moderate SCORE risk. Conclusions: CACS combination with SCORE risk predicts coronary artery stenosis. When CACS is zero, CTCA can be performed in patients with high or very high SCORE risk. Key Points: • CACS is the major predictor of significant stenosis in the sixth and seventh decade. • CACS has superior outcome when compared with SCORE. • Zero CACS is the most important negative predictor for significant CAS. • Zero CACS, with SCORE better predicts significant CAS. [ABSTRACT FROM AUTHOR]

Background In patients with end-stage renal disease (ESRD), coronary artery disease is under-diagnosed. To date, there are no well-conducted studies that clearly demonstrate the incremental value of calcium scoring over traditional assessments of risk factors, and the clinical role of Multi detector CT (MDCT) is yet to be established in terms of screening for disease or risk assessment. Objective To evaluate the prevalence and degree of coronary calcification as a risk of coronary artery disease in patients with ESRD on hemodialysis compared to versus those on peritoneal dialysis by MDCT. Methods Thirty five patients with ESRD were subjected to screening for coronary artery calcium scoring by MDCT, and baseline echocardiography with assessment of valvular calcification. Laboratory assessment for blood urea nitrogen BUN, calcium, phosphorus, blood glucose, lipid profile and parathormone hormone were done. Results Duration of dialysis was significantly longer in hemodialysis group (HD) compared to peritoneal dialysis patients (PD) p= 0.08. Coronary artery calcium score by Agatston scoring method was significantly higher in HD patients (1618.27±633 in HD group vs 170.65±45.60 in PD group p= 0.04) 22% oh HD group had calcium score >400 vs none of PD group p= 0.06. The prevalence of CAC in the left main coronary artery was 17% in HD group vs 12% in PD, LAD 61% vs 82% in PD group but was not statistically significant p= 0.41 and 0.30 respectively data. Conclusions Patients with ESRD on hemodialysis had significant early coronary artery calcification by MDCT, such group of patients are more likely to develop CAD. HD needs more aggressive control of risk factors of CAD than patients with PD. [ABSTRACT FROM AUTHOR]

Background: The need of having feasible screening tools like Coronary Calcium Scoring (CCS) and CT Coronary Artery (CTCA) for Coronary Artery Disease (CAD) has become paramount. We aimed to evaluate the accuracy of CCS in determining the degree of stenosis of coronary vessels as compared to that determined by CTCA in a South Asian population. Methods: A retrospective study was conducted at The Aga Khan University Hospital. A total of 539 patient records were reviewed who had undergone CCS and CTCA between 2008 and 2010. Patient records were reviewed by comparing their CCS and CTCA results. Results: About 268 out of 301 (89%) patients with a CCS of 0-9 were found to be free of stenosis on CTCA. On a CCS of 10-99, 110 out of 121 (91%) patients were either free of stenosis or had mild stenosis. About 66 out of 79 (84%) patients had moderate or severe stenosis with a calcium score of 100-400 while none of the patients were free of stenosis. Around 28 out of 38 (74%) patients with a CCS of more than 400 had severe stenosis. However, only 04 patients (11%) were found to have mild stenosis. Spearman's rho revealed a correlation coefficient of 0.791 with a p-value of <0.001. Conclusion: Our study reaffirms that in South Asian population, low CCS (<100) is associated with no or minimal stenosis while high CCS warrants further investigation; hence, making it a reliable tool for screening patients with CAD. [ABSTRACT FROM AUTHOR]

Aim: Purpose of the present study is to evaluate the value of coronary calcium scoring in predicting the presence and extent coronary artery disease (CAD) determined by 64-slice Computed tomography angiography (CTA) and to compare it with the traditional risk factors of CAD. Material-Method: 545 cases 250 (45.9%) male and 295 (54.1%) female) were included in the study. A non-enhanced CT scan was obtained for calcium scoring immediately before CTA in all cases. CT examinations were performed by 64-slice scanner (Toshiba, Aquillon 64, Toshiba Medical Systems, Otowara, Japan). ROC analysis was performed to determine the predictive value of coronary calcium scoring and multivariate logistic regression analysis was performed to compare it with the predictive value of traditional risk factors. Results: The ROC analysis demonstrated that coronary calcium scoring which has an area under the curve ( AUC) of 0.833, has a high performance in predicting stenotic disease determined by 64- slice CTA. Age, male gender, menopause, DM and HT were the variables which had statistically significant effect on differentiating the non-obstructive and obstructive CAD. The role of coronary calcium scoring in predicting obstructive CAD was found to be independent from the traditional risk factors. Of the 301 cases with 0 score 83 (27.6%) had CAD according to coronary CTA. Conclusion: Coronary calcium scoring is a valuable method in predicting the presence and extent of CAD determined by 64-slice CTA. Its predictive value is independent and incremental to the traditional risk factors. However 0 CAC score does not exclude the disease. [ABSTRACT FROM AUTHOR]

Effective medical management and strategies of secondary prevention for coronary artery disease (CAD) have greatly contributed to the dramatic improvement in heart disease mortality rates seen in the United States during the past decade. Myocardial perfusion imaging (MPI) is useful for diagnosing cardiac ischemia and is a powerful tool for risk stratification of patients with CAD. Indeed, patients with a normal MPI have a very good short to intermediate prognosis. Coronary artery calcium scoring (CACS) using multi-slice or electron beam CT assists in the diagnosis of subclinical CAD, potentially allowing risk factor reduction to begin before physiological significant CAD and coronary events develop. Combining CACS during MPI or performing it after MPI to assist in detecting CAD in patients with normal MPI studies is being utilized with increasing frequency. The additional information obtained by CACS allows the detection of many patients with subclinical disease, alters the prognostic advice to them, leads to alteration in prescribed medical treatment and patient lifestyle, and results in improved risk factor profiles. These cardiovascular risk factor modification and lifestyle changes will presumably result in a reduction in mortality and morbidity related to cardiovascular disease. This review discusses the clinical implications in the diagnosis and treatment of CAD when coronary artery calcium scoring is performed in patients who have a normal myocardial perfusion imaging study. [ABSTRACT FROM AUTHOR]

A negative (zero) Agatston coronary calcium score (CCS) by current methods confers a very low risk for hard coronary events during the next years. However, controversy remains on how to use a negative score since some hard events still occur. We report on a new method with improved detection sensitivity for very small calcifications with the potential to more confidently rule out early atherosclerotic disease. Seventy-eight (78) patients with negative Agatston scores by conventional methods with 2.5 mm slices were selected from routine GE 64 MDCT scans. Each scan was reconstructed a second time from the same data to create 0.625 mm isotropic voxels. The 2.5 mm images were manually scored by the usual Agatston method using the GE SmartScore™ software. Both the 2.5 and 0.625 mm image sets were scored with a new automated and calibrated method (N-vivo™, Image Analysis). The software automatically computes dual scoring thresholds that are statistically defined and specific for each patient, scanner, and scan. The images were hybrid calibrated by simultaneous scanned phantoms in combination with in vivo blood/muscle references. The output reported the calibrated mass scores along with the number of plaques using 18 pt, 3-D connectivity criteria. A CCS Test phantom with known CaHA microspheres was used to validate the method. Twenty-three percent (18 of 78) of the patients with negative Agatston scores by the conventional method scored positive for coronary calcifications by the N-vivo method. The number of small plaques scored per patient varied from 1 to 4. One patient with a single small calcification suffered a hard coronary event during the CT scan. All of the detected plaques were located in the proximal heart. The conventional CCS method misclassified 23% of these patients as having negative coronary calcium scores. The N-vivo automated scoring method with small voxel CT images increased the detection sensitivity of small calcifications with no increase in radiation dose. Detection of small coronary calcified plaques occult to conventional scoring methods may increase the negative predictive power of calcium scoring and may improve plaque composition analysis. [ABSTRACT FROM AUTHOR]

Background: Reducing tube voltage from 120 kV to 100 kV during noncontrast CT for the detection of coronary artery calcium reduces patient radiation exposure. Objective: We investigated whether coronary calcium scoring by multidetector row CT can be performed at reduced tube current, resulting in lower radiation dose to the patient. Methods: Sixty-six outpatients were scanned on the same visit by dual-source CT (DSCT) with a standard protocol (120 kVp, 150 mAs), followed by a scan with reduced tube current: 85 mAs for patients with body mass index (BMI) ≤ 30 kg/m2 and weight ≤ 85 kg, and 120 mAs for patients with BMI > 30 kg/m2 or weight > 85 kg. Low-dose scans were scored by an experienced reader blinded to the standard scan. Results: Agatston scores (ASs) and calcium volume for standard versus low-dose scans were 236 ± 581 versus 234 ± 586 (P = 0.65, NS), and 189 ± 460 mm3 versus 184 ± 455 mm3 with excellent correlation (r = 1.0, P < 0.0001), and no significant difference (P = 0.14, NS). Effective radiation dose for the low-dose protocol (1.0 ± 0.2 mSv) was significantly lower than for the standard protocol (1.7 ± 0.2 mSv; P < 0.0001). Image noise was higher for the low-dose scan (18.8 ± 5.5 HU vs 15.2 ± 4.8 HU; P < 0.0001), but both were within target limits. Conclusion: Noncontrast CT for measurement of coronary artery calcium with lower tube current optimized for patient body size is equivalent to standard methods at 40% lower radiation dose, indicating that radiation dose can be lowered for coronary calcium scanning. [ABSTRACT FROM AUTHOR]

To evaluate the clinical value of a body mass index (BMI) based tube current (mA) selection method for obtaining consistent image quality with dose optimization in MDCT prospective ECG gated coronary calcium scoring. A formula for selecting mA to achieve desired image quality based on patient BMI was established using a control group (A) of 200 MDCT cardiac patients with a standard scan protocol. One hundred patients in Group B were scanned with this BMI-dependent mA for achieving a desired noise level of 18 HU at 2.5 mm slice thickness. The CTDIvol and image noise on the ascending aorta for the two groups were recorded. Two experienced radiologists quantitatively evaluated the image quality using scores of 1-4 with 4 being the highest. The image quality scores had no statistical difference ( P = 0.71) at 3.89 ± 0.32, 3.87 ± 0.34, respectively, for groups A and B of similar BMI. The image noise in Group A had linear relationship with BMI. The image noise in Group B using BMI-dependent mA was independent of BMI with average value of 17.9 HU and smaller deviations for the noise values than in Group A (2.0 vs. 2.9 HU). There was a 35% dose reduction with BMI-dependent mA selection method on average with the lowest effective dose being only 0.35 mSv for patient with BMI of 18.3. A quantitative BMI-based mA selection method in MDCT prospective ECG gated coronary calcium scoring has been proposed to obtain a desired and consistent image quality and provide dose optimization across patient population. [ABSTRACT FROM AUTHOR]

Abstract: Objective: We set out to determine whether a coronary artery calcium (CAC) score of zero on computed tomography (CT) would predict a normal myocardial perfusion positron emission tomography (PET) in a population mostly at intermediate pretest likelihood of coronary artery disease (CAD). Methods: We enrolled 206 outpatients (36% men, mean age 60±13years) referred for Rb-82 myocardial perfusion PET/CT for suspected CAD. CAC scoring was performed by the Agatston method. The PET images were scored on a 5-point scale using a 17-segment left ventricular model. A summed stress score ≥2 was considered abnormal. Multivariable logistic regression analysis was used to test the independent predictive value of a CAC score of zero to exclude inducible myocardial ischemia. Results: Ninety-nine of 206 patients (48%) had a CAC score of zero and of these only 1 had inducible ischemia on PET. This yielded a negative predictive value of 99% (95% CI 95%–100%). CAC score of zero was the strongest independent predictor of a normal myocardial perfusion PET (OR=0.05; 95% CI=0.006–0.38; p =0.004). Conclusion: In a population of predominately intermediate likelihood of CAD, a CAC score of zero excludes inducible ischemia on myocardial perfusion PET. [Copyright &y& Elsevier]

Background: Test phantoms with simulated micro-calcifications of true calcium hydroxyapatite (CaHA) density were not available to validate advanced calcium scoring methods or plaque density measurements. Objectives: We evaluated a coronary calcium scoring (CCS) test phantom containing very small CaHA microspheres and validated a new scoring method for measurements of plaque densities. Methods: The semianthropomorphic CCS phantom was constructed with CaHA microspheres (volumes, 0.05–3.1 mm3) with the approximate density of biologic calcifications. QRM and CCS phantoms were scored with a new calibrated and automated calcium scoring method (N-vivo; Image Analysis). The densities of the microspheres and 609 individual patient plaques were measured. Results: The range of measured densities of the CaHA microspheres was approximately equivalent to that measured in the patient coronary calcifications. The smallest microspheres scored with the calibrated/automated and the Agatston methods had volumes of 0.075 mm3 and 0.27 mm3, respectively. The standard deviations of the mass scores of the microspheres ranged from 0.02 to 0.17 mg with regression slope of 0.962 and R 2 = 0.997. The relationship of measured density to measured mass of the patient plaques was similar to that of the microspheres, suggesting that vascular calcifications are CaHA density. Conclusions: The CaHA microspheres of the CCS test phantom were found to be representative in density and size of coronary calcifications. The measurements show that CT calcium scoring underestimates plaque density and greatly overestimates volume. The heterogeneity of calcium concentration densities measured in the patient plaques was due largely to CT scanner measurement errors. [ABSTRACT FROM AUTHOR]

Background: Technical advances to minimize radiation exposure because of imaging are in accord with the “as low as reasonably achievable” principle. Objective: We aimed to determine whether coronary calcium scoring (CCS) by multidetector CT at a tube voltage of 100 kVp yields comparable results to the standard 120-kVp protocol while reducing radiation dose. Methods: Sixty consecutive outpatients were scanned with a dual-source CT scanner with both the120- and 100-kVp protocols. The calcium threshold was 130 Hounsfield units (HUs) for 120 kVp and 147 HU for 100 kVp, as determined from phantom data. All 100-kVp scans were scored by an experienced reader blinded to 120-kVp data. Results: Image quality was comparable for 100- and 120- kVp scans. Mean Agatston scores for 100 and 120 kVp were 189 ± 484 and 189 ± 498 (P = 0.92), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -36 to 37; bias, 0.6). Mean coronary calcium volume scores for 100 and 120 kVp were 143 ± 370 mm3 and 149 ± 392 mm3 (P = 0.26), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -35 to 32 mm3; bias, -1.4 mm3). The mean absolute difference for Agatston scores between the protocols was 16.9, with excellent agreement (κ = 0.95; P < 0.0001). Mean effective radiation dose for the 100-kVp protocol was significantly lower (1.17 mSv versus 1.70 mSv; P < 0.0001). Conclusion: A reduced tube current protocol using 100 kVp gives equivalent CCS results at reduced radiation exposure compared with a standard protocol at 120 kVp. [Copyright &y& Elsevier]

Risk stratification and prevention of future cardiac events is an extremely relevant part of the daily medical practice in the large population of asymptomatic or scarcely symptomatic patients. The strategies available to this purpose encompass programs intended either to reduce progression and complications of atherosclerosis, and revascularization procedures aimed to reduce total ischemic burden. The former represents a primary prevention approach and fights the substrate of ischemic heart disease. The latter, instead, is used to reduce the total ischemic burden and thus implies to identify those patients in whom ischemia can be life threatening because of its severity and extension. Today, at least two imaging methods are available for this task: coronary calcium scoring by x-ray CT and ischemia assessment by myocardial perfusion imaging. Although both approaches can accurately estimate cardiovascular risk, from a theoretical point of view, the assessment of ischemia evaluates the functional consequences of coronary obstructions and thus the target of revascularization procedure, while estimating the total atherosclerotic burden represents an indirect index of it. This difference might appear academic in its nature, given the current model of ischemic heart disease pathophysiology that assumes and predicts a very tight correlation between the severity of a coronary stenosis and its capability to cause ischemia. However, the majority of studies focused on the combined risk assessment with both approaches confirm the relevance of this issue. In fact, among 7785 patients reported in the literature, coronary calcium scoring most often resulted in positive findings (78%). However, this sign of atherosclerosis was associated with inducible ischemia in only one-fifth of patients. In the near future, coronary calcium scoring will be easily and immediately completed by the noninvasive definition of coronary stenoses. At that time we will face a still largely unknown risk: the presence of a stenosis in the absence of symptoms and of ischemia. Evaluating the effectiveness of different protocols will thus be needed to improve our capability to help these patients. [ABSTRACT FROM AUTHOR]

The aim of our study was to evaluate attenuation-based tube current adaptation in coronary calcium scoring using ECG-gated multi-detector-row CT (MDCT). A total of 262 patients underwent non-enhanced cardiac MDCT. Group 1 was scanned using a standard protocol with 120 kV and 150 mAs(eff). Groups 2-4 were scanned using an attenuation-based dose-adaptation template (CARE Dose) with different effective reference mAs settings (150, 180, 210 mAs(eff)). Body-mass index (BMI) and CT-dose index values were calculated for each patient. Image noise and subjective image quality were assessed. Regression analysis was performed, and the variation coefficient of image noise was determined. Compared to the standard scan protocol a dose reduction of 31.1% for group 2 and 20.1% for group 3 was observed. Measurement variation of image noise was smaller for the attenuation-based dose adaptation protocols (group 2-4) (16.2-17.1%) compared to the standard scan protocol (32.3%). Regression analysis of groups 2-4 showed better correlation with improved dose usage based on BMI (all P

A fully automated method for coronary calcification detection from non-contrast-enhanced, ECG-gated multi-slice computed tomography (CT) data is presented. Candidates for coronary calcifications are extracted by thresholding and component labeling. These candidates include coronary calcifications, calcifications in the aorta and in the heart, and other high-density structures such as noise and bone. A dedicated set of 64 features is calculated for each candidate object. They characterize the object’s spatial position relative to the heart and the aorta, for which an automatic segmentation scheme was developed, its size and shape, and its appearance, which is described by a set of approximated Gaussian derivatives for which an efficient computational scheme is presented. Three classification strategies were designed. The first one tested direct classification without feature selection. The second approach also utilized direct classification, but with feature selection. Finally, the third scheme employed two-stage classification. In a computationally inexpensive first stage, the most easily recognizable false positives were discarded. The second stage discriminated between more difficult to separate coronary calcium and other candidates. Performance of linear, quadratic, nearest neighbor, and support vector machine classifiers was compared. The method was tested on 76 scans containing 275 calcifications in the coronary arteries and 335 calcifications in the heart and aorta. The best performance was obtained employing a two-stage classification system with a k-nearest neighbor (k-NN) classifier and a feature selection scheme. The method detected 73.8% of coronary calcifications at the expense of on average 0.1 false positives per scan. A calcium score was computed for each scan and subjects were assigned one of four risk categories based on this score. The method assigned the correct risk category to 93.4% of all scans. [ABSTRACT FROM AUTHOR]

Abstract: Electron beam computed tomography (EBCT) revolutionized cardiac imaging by combining a constant high temporal resolution with prospective ECG triggering. For years, EBCT was the primary technique for some non-invasive diagnostic cardiac procedures such as calcium scoring and non-invasive angiography of the coronary arteries. Multislice spiral computed tomography (MSCT) on the other hand significantly advanced cardiac imaging through high volume coverage, improved spatial resolution and retrospective ECG gating. This pictorial review will illustrate the basic differences between both modalities with special emphasis to their image quality. Several experimental and clinical examples demonstrate the strengths and limitations of both imaging modalities in an intraindividual comparison for a broad range of diagnostic applications such as coronary artery calcium scoring, coronary angiography including stent visualization as well as functional assessment of the cardiac ventricles and valves. In general, our examples indicate that EBCT suffers from a number of shortcomings such as limited spatial resolution and a low contrast-to-noise ratio. Thus, EBCT should now only be used in selected cases where a constant high temporal resolution is a crucial issue, such as dynamic (cine) imaging. Due to isotropic submillimeter spatial resolution and retrospective data selection MSCT seems to be the non-invasive method of choice for cardiac imaging in general, and for assessment of the coronary arteries in particular. However, technical developments are still needed to further improve the temporal resolution in MSCT and to reduce the substantial radiation exposure. [Copyright &y& Elsevier]

Current multi-detector CT and electron beam tomography (EBT) technology enables the evaluation of coronary calcification. Multiple software packages are available to quantify calcification using several scoring algorithms implementing user-definable scoring parameters. We investigated the effect of scoring parameters on the calcium score outcome. Three parameters (four-connected or eight-connected, lesion size threshold and interpolation) are evaluated. Their theoretical influence on the scoring outcome is shown using simplified examples. To evaluate the effect in real data, we performed calcium scoring on randomly chosen EBT scans from 50 participants in an epidemiological study. Both the Agatston and volume scores were calculated. Changing from eight-connected to four-connected connectivity decreased both Agatston and volume scores (mean variability Agatston 3.15% and volume score -3.52%). Decreasing the threshold from 4 to 2 pixels increased the calcium scores because smaller lesions were also selected as calcified plaques (mean variability Agatston 16.23% and volume score 18.66%). Finally, the use of interpolation had a large negative effect on the volume score (mean variability -29.67%) and almost no effect on the Agatston score. Parameter settings in software for quantification for coronary calcification affect the calcium score outcome. Therefore, parameter settings for calcium scoring should be standardized. [ABSTRACT FROM AUTHOR]

Stress electrocardiography (sECG) or treadmill stress testing is a well validated noninvasive diagnostic modality available to clinicians at low cost yet providing valuable functional data for coronary artery disease (CAD) diagnostic and prognostic evaluation. With the advances in cardiac imaging in both functional and anatomic fronts and the existing limitations of sECG testing, this modality appears less favored worldwide as reflected in some recent guideline updates. We review the past present and future of sECG to provide a viewpoint on where it stands in CAD evaluation and if it will remain relevant as a diagnostic modality or be retired going forward. We also provide our perspectives on how sECG can co-exist with other modalities such as calcium scoring and discuss the role of such testing in the Indian population., Competing Interests: Declaration of competing interest No conflicts of interest for any authors in this manuscript. There is no funding sources to declare for this manuscript., (Copyright © 2022 Cardiological Society of India. Published by Elsevier, a division of RELX India, Pvt. Ltd. All rights reserved.)

We aimed to develop a novel deep-learning based method for automatic coronary artery calcium (CAC) quantification in low-dose ungated computed tomography attenuation correction maps (CTAC). In this study, we used convolutional long-short -term memory deep neural network (conv-LSTM) to automatically derive coronary artery calcium score (CAC) from both standard CAC scans and low-dose ungated scans (CT-attenuation correction maps). We trained convLSTM to segment CAC using 9543 scans. A U-Net model was trained as a reference method. Both models were validated in the OrCaCs dataset (n=32) and in the held-out cohort (n=507) without prior coronary interventions who had CTAC standard CAC scan acquired contemporarily. Cohen's kappa coefficients and concordance matrices were used to assess agreement in four CAC score categories (very low: <10, low:10-100; moderate:101-400 and high >400). The median time to derive results on a central processing unit (CPU) was significantly shorter for the conv-LSTM model- 6.18s (inter quartile range [IQR]: 5.99, 6.3) than for UNet (10.1s, IQR: 9.82, 15.9s, p<0.0001). The memory consumption during training was much lower for our model (13.11Gb) in comparison with UNet (22.31 Gb). Conv-LSTM performed comparably to UNet in terms of agreement with expert annotations, but with significantly shorter inference times and lower memory consumption.

We evaluated the accuracy of coronary artery calcium (CAC) scoring on a dual-source photon-counting detector CT (PCD-CT). An anthropomorphic chest phantom underwent ECG-gated sequential scanning on a PCD-CT at 120 kV with four radiation dose levels (CTDIvol, 2.0–8.6 mGy). Polychromatic images at 120 kV (T3D) and virtual monoenergetic images (VMI), from 60 to 75 keV without quantum iterative reconstruction (no QIR) and QIR strength levels 1–4, were reconstructed. For reference, the same phantom was scanned on a conventional energy-integrating detector CT (120 kV; filtered back projection) at identical radiation doses. CAC scoring in 20 patients with PCD-CT (120 kV; no QIR and QIR 1–4) were included. In the phantom, there were no differences between CAC scores of different radiation doses (all, p > 0.05). Images with 70 keV, no QIR (CAC score, 649); 65 keV, QIR 3 (656); 65 keV; QIR4 (648) and T3D, QIR4 (656) showed a <1% deviation to the reference (653). CAC scores significantly decreased at increasing QIR levels (all, p < 0.001) and for each 5 keV-increase (all, p < 0.001). Patient data (median CAC score: 86 [inter-quartile range: 38–978] at 70 keV) confirmed relationships and differences between reconstructions from the phantom. First phantom and in-vivo experience with a clinical dual-source PCD-CT system shows accurate CAC scoring with VMI reconstructions at different radiation dose levels. [ABSTRACT FROM AUTHOR]