Diagnostic and prognostic performance of artificial intelligence-based fully-automated on-site CT-FFR in patients with CAD

Currently, clinically available coronary CT angiography (CCTA) derived fractional flow reserve (CT-FFR) is time-consuming and complex. We propose a novel artificial intelligence-based fully-automated, on-site CT-FFR technology, which combines the automated coronary plaque segmentation and luminal extraction model with reduced order 3 dimentional (3D) computational fluid dynamics. A total of 463 consecutive patients with 600 vessels from the updated China CT-FFR study in Cohort 1 undergoing both CCTA and invasive fractional flow reserve (FFR) within 90 d were collected for diagnostic performance evaluation. For Cohort 2, a total of 901 chronic coronary syndromes patients with index CT-FFR and clinical outcomes at 3-year follow-up were retrospectively analyzed. In Cohort 3, the association between index CT-FFR from triple-rule-out CTA and major adverse cardiac events in patients with acute chest pain from the emergency department was further evaluated. The diagnostic accuracy of this CT-FFR in Cohort 1 was 0.82 with an area under the curve of 0.82 on a per-patient level. Compared with the manually dependent CT-FFR techniques, the operation time of this technique was substantially shortened by 3 times and the number of clicks from about 60 to 1. This CT-FFR technique has a highly successful (> 99%) calculation rate and also provides superior prediction value for major adverse cardiac events than CCTA alone both in patients with chronic coronary syndromes and acute chest pain. Thus, the novel artificial intelligence-based fully automated, on-site CT-FFR technique can function as an objective and convenient tool for coronary stenosis functional evaluation in the real-world clinical setting.

A simple coronary CT angiography-based jeopardy score for the identification of extensive coronary artery disease: Validation against invasive coronary angiography

PURPOSE

The invasive British Cardiovascular Intervention Society Jeopardy Score (iBCIS-JS) is a simple angiographic scoring system, enabling quantification of the extent of jeopardized myocardium related to clinically significant coronary artery disease (CAD). The purpose of this study was to develop and validate the coronary CT angiography-based BCIS-JS (CT-BCIS-JS) against the iBCIS-JS in patients with suspected or stable CAD.

MATERIALS AND METHODS

Patients who underwent coronary CT angiography followed by invasive coronary angiography, within 90 days were retrospectively included. CT-BCIS-JS and iBCIS-JS were calculated, with a score ≥ 6 indicating extensive CAD. Correlation between the CT-BCIS-JS and iBCIS-JS was searched for using Spearman's coefficient, and agreement with weighted Kappa (κ) analyses.

RESULTS

A total of 122 patients were included. There were 102 men and 20 women with a median age of 62 years (Q1, Q3: 54, 68; age range: 19-83 years). No differences in median CT-BCIS-JS (4; Q1, Q3: 0, 8) and median iBCIS-JS (4; Q1, Q3: 0, 8) were found (P = 0.18). Extensive CAD was identified in 53 (43.4%) and 52 (42.6%) patients using CT-BCIS-JS and iBCIS-JS, respectively (P = 0.88). CT-based and iBCIS-JS showed excellent correlation (r = 0.98; P < 0.001) and almost perfect agreement (κ = 0.93; 95% confidence interval: 0.90-0.97). Agreement for identification of an iBCIS-JS ≥ 6 was almost perfect (κ = 0.94; 95 % confidence interval: 0.87-0.99).

CONCLUSION

The CT-BCIS-JS represents a feasible, and accurate method for quantification of CAD, with capabilities not different from those of iBCIS-JS. It enables simple, non-invasive identification of patients with anatomically extensive CAD.

Utilization of coronary computed tomography angiography and computed tomography-derived fractional flow reserve in a critical limb-threatening ischemia cohort

Objective

Patients with peripheral arterial disease (PAD) have a significant risk of myocardial infarction and death secondary to concomitant coronary artery disease (CAD). This is particularly true in patients with critical limb-threatening ischemia (CLTI) who exceed a 20% mortality rate at 6 months despite standard treatment with risk factor modification. Although systematic preoperative coronary testing is not recommended for patients with PAD without cardiac symptoms, the clinical manifestations of CAD are often muted in patients with CLTI due to poor mobility and activity intolerance. Thus, the true incidence and impact of "silent" CAD in a CLTI cohort is unknown. This study aims to determine the prevalence of ischemia-producing coronary artery stenosis in a CLTI cohort using coronary computed tomography angiography (cCTA) and computed tomography (CT)-derived fractional flow reserve (FFRCT), a noninvasive imaging modality that has shown significant correlation to cardiac catheterization in the detection of clinically relevant coronary ischemia.

Methods

Patients presenting with newly diagnosed CLTI at our institution from May 2020 to April 2021 were screened for underlying CAD. Included subjects had no known history of CAD, no cardiac symptoms, and no anginal equivalent complaints at presentation. Patients underwent cCTA and FFRCT evaluation and were classified by the anatomic location and severity of CAD. Significant coronary ischemia was defined as FFRCT ≤0.80 distal to a >30% coronary stenosis, and severe coronary ischemia was documented at FFRCT ≤0.75, consistent with established guidelines.

Results

A total of 170 patients with CLTI were screened; 65 patients (38.2%) had no coronary symptoms and met all inclusion/exclusion criteria. Twenty-four patients (31.2%) completed cCTA and FFRCT evaluation. Forty-one patients have yet to complete testing secondary to socioeconomic factors (insurance denial, transportation inaccessibility, testing availability, etc). The mean age of included subjects was 65.4 ± 7.0 years, and 15 (62.5%) were male. Patients presented with ischemic rest pain (n = 7; 29.1%), minor tissue loss (n = 14; 58.3%) or major tissue loss (n = 3; 12.5%). Significant (≥50%) coronary artery stenosis was noted on cCTA in 19 of 24 patients (79%). Significant left main coronary artery stenosis was identified in two patients (10%). When analyzed with FFRCT, 17 patients (71%) had hemodynamically significant coronary ischemia (FFRCT ≤0.8), and 54% (n = 13) had lesion-specific severe coronary ischemia (FFRCT ≤0.75). The mean FFRCT in patients with coronary ischemia was 0.70 ± 0.07. Multi-vessel disease pattern was present in 53% (n = 9) of patients with significant coronary stenosis.

Conclusions

The use of cCTA-derived fractional flow reserve demonstrates a significant percentage of patients with CLTI have silent (asymptomatic) coronary ischemia. More than one-half of these patients have lesion-specific severe ischemia, which may be associated with increased mortality when treated solely with risk factor modification. cCTA and FFRCT diagnosis of significant coronary ischemia has the potential to improve cardiac care, perioperative morbidity, and long-term survival curves of patients with CLTI. Systemic improvements in access to care will be needed to allow for broad application of these imaging assessments should they prove universally valuable. Additional study is required to determine the benefit of selective coronary revascularization in patients with CLTI.

Limited Axial Interpretation of Coronary CT Angiography in the Emergency Department Setting

PURPOSE

Incorporating coronary CT angiographic (CCTA) imaging into emergency department (ED) workflows has been limited by the need for 24/7 real-time postprocessing. The aim of this study was to determine whether interpretation of transaxial CCTA images alone (limited axial interpretation [LI]) is noninferior to interpretation of combined transaxial and multiplanar reformation images (full interpretation [FI]) in assessing patients with acute chest pain in the ED.

METHODS

CCTA examinations from 74 patients were evaluated by two radiologists, one without dedicated CCTA training and one with basic CCTA experience. Each examination was evaluated three times in separate sessions, once by LI and twice by FI, in random order. Nineteen coronary artery segments were rated as having significant stenoses (≥50%) or not. Interreader agreement was assessed using Cohen's κ statistic. The primary analysis was whether the accuracy of LI for detecting significant stenosis was noninferior to that of FI at the patient level (margin = -10%). Secondary analyses included similar analyses of sensitivity and specificity, at both the patient and vessel levels.

RESULTS

Interreader agreement for significant stenosis was good for both LI and FI (κ = 0.72 vs 0.70, P = .74). Average accuracy for significant stenosis at the patient level was 90.5% for LI and 91.9% for FI, with a difference of -1.4%. The accuracy of LI was noninferior to FI, because the confidence interval did not include the noninferiority margin. Noninferiority was also found for patient-level sensitivity and for accuracy, sensitivity, and specificity at the vessel level.

CONCLUSIONS

LI of the coronary arteries using transaxial CCTA images may be sufficient for the detection of significant coronary artery disease in the ED setting.

Comparison of risk profiles of participants in the Women's IschemiA TRial to Reduce events In non-ObstRuctive CAD (WARRIOR) trial, using Coronary Computed Tomography Angiography vs Invasive Coronary Angiography

OBJECTIVE

To compare baseline characteristics of participants in the Women's IschemiA TRial to Reduce Events In Non-ObstRuctive CAD (WARRIOR) trial by qualification by Coronary Computed Tomography Angiography (CCTA) or Invasive Coronary Angiography (ICA).

METHODS

The WARRIOR trial (NCT03417388) is an ongoing multicenter, prospective, randomized, blinded outcome evaluation of intensive medical therapy vs. usual care in women with suspected Ischemia and No Obstructive Coronary Artery Disease (INOCA) identified by either CCTA or ICA on the outcome of major adverse cardiovascular events (MACE). No obstructive coronary artery disease is defined as <50% luminal stenosis and normal coronary arteries is defined as no evidence of atherosclerosis including calcified and non-calcified plaque. Data presented was extracted on May 27, 2020. No clinical outcomes were assessed.

RESULTS

An initial sample cohort of 797 women was included. The majority were younger than 65 years, White participants (73.3%), 159 had diabetes (19.9%), and 676 had angina (84.8%) with the remainder having symptoms of suspected ischemic heart disease. Over 50% of randomized participants had normal coronaries without luminal irregularities by ICA or CCTA. Participants randomized to ICA were more likely to have worse baseline clinical risk profiles with older age, higher burden of cardiac risk factors and poor quality of life with disabling angina.

CONCLUSIONS

Among this initial sample of women with suspected INOCA randomized in the WARRIOR trial, there is a differential baseline cardiac risk of participants enrolled after CCTA or ICA. However, the majority had no evidence of atherosclerotic plaque or obstructive stenosis, after evaluation by ICA or CCTA. These results suggest that non-invasive evaluation with CCTA is likely to be associated with lower risk of MACE.

Qualitative and quantitative image quality of coronary CT angiography using photon-counting computed tomography: Standard and Ultra-high resolution protocols

PURPOSE

We aimed to identify the optimal reconstruction settings based on qualitative and quantitative image quality parameters on standard and ultra-high resolution (UHR) images using photon-counting CT (PCCT).

METHOD

We analysed 45 patients, 29 with standard and 16 with UHR acquisition, applying both smoother and sharper kernel settings. Coronary CT angiography images were performed on a dual-source PCCT system using standard (0.4/0.6 mm slice thickness, Bv40/Bv44 kernels, QIR levels 0-4) or UHR acquisition (0.2/0.4 mm slice thickness, Bv44/Bv56 kernels, QIR levels 0-4). Qualitative image quality was assessed using a 4-point Likert scale. Image noise (SD), signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated in both the proximal and distal segments.

RESULTS

On standard resolution, larger slice thickness resulted in an average increase of 12.5 % in CNR, whereas sharper kernel led to an average 8.7 % decrease in CNR. Highest CNR was measured on 0.6 mm, Bv40, QIR4 images and lowest on 0.4 mm, Bv44, QIR0 images: 25.8 ± 4.1vs.8.3 ± 1.6 (p < 0.001). On UHR images, highest CNR was observed on 0.4 mm, Bv40, QIR4 and lowest on 0.2 mm, Bv56 and QIR0 images: 21.5 ± 3.9vs.3.6 ± 0.8 (p < 0.001). Highest qualitative image quality was found on images with Bv44 kernel and QIR level 3/4 with both slice thicknesses on standard reconstruction. Additionally, Bv56 with QIR4 on 0.2 mm slice thickness images showed highest subjective image quality. Preserved distal vessel visualization was detected using QIR 2-4, Bv56 and 0.2 mm slice thickness.

CONCLUSIONS

Photon-counting CT demonstrated high qualitative and quantitative image quality for the assessment of coronaries and stents.

Recent advances in cardiovascular risk assessment: The added value of non-invasive anatomic imaging

In 2022, multiple original research studies were conducted highlighting the utility of coronary artery calcium (CAC) imaging in young individuals and provided further evidence for the role of CAC to improve atherosclerotic cardiovascular disease (ASCVD) risk assessment. Mean calcium density was shown to be a more reliable predictor than peak density in risk assessment. Additionally, in light of the ACC/AHA/Multispecialty Chest Pain Guideline's recent elevation of coronary computed tomography angiography (CCTA) to a Class I (level of evidence A) recommendation as an index diagnostic test for acute or stable chest pain, several studies support the utility of CCTA and guided future directions. This review summarizes recent studies that highlight the role of non-invasive imaging in enhancing ASCVD risk assessment across different populations.

A multi-dimensional CFD framework for fast patient-specific fractional flow reserve prediction

Fractional flow reserve (FFR) is considered as the gold standard for diagnosing coronary myocardial ischemia. Existing 3D computational fluid dynamics (CFD) methods attempt to predict FFR noninvasively using coronary computed tomography angiography (CTA). However, the accuracy and efficiency of the 3D CFD methods in coronary arteries are considerably limited. In this work, we introduce a multi-dimensional CFD framework that improves the accuracy of FFR prediction by estimating 0D patient-specific boundary conditions, and increases the efficiency by generating 3D initial conditions. The multi-dimensional CFD models contain the 3D vascular model for coronary simulation, the 1D vascular model for iterative optimization, and the 0D vascular model for boundary conditions expression. To improve the accuracy, we utilize clinical parameters to derive 0D patient-specific boundary conditions with an optimization algorithm. To improve the efficiency, we evaluate the convergence state using the 1D vascular model and obtain the convergence parameters to generate appropriate 3D initial conditions. The 0D patient-specific boundary conditions and the 3D initial conditions are used to predict FFR (FFRC). We conducted a retrospective study involving 40 patients (61 diseased vessels) with invasive FFR and their corresponding CTA images. The results demonstrate that the FFRC and the invasive FFR have a strong linear correlation (r = 0.80, p < 0.001) and high consistency (mean difference: 0.014 ±0.071). After applying the cut-off value of FFR (0.8), the accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of FFRC were 88.5%, 93.3%, 83.9%, 84.8%, and 92.9%, respectively. Compared with the conventional zero initial conditions method, our method improves prediction efficiency by 71.3% per case. Therefore, our multi-dimensional CFD framework is capable of improving the accuracy and efficiency of FFR prediction significantly.

CAD-RADS™ 2.0 - 2022 Coronary Artery Disease - Reporting and Data System.: An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR) and the North America Society of Cardiovascular Imaging (NASCI)

Coronary Artery Disease Reporting and Data System (CAD-RADS) was created to standardize reporting system for patients undergoing coronary CT angiography (CCTA) and to guide possible next steps in patient management. The goal of this updated 2022 CAD-RADS 2.0 is to improve the initial reporting system for CCTA by considering new technical developments in Cardiac CT, including data from recent clinical trials and new clinical guidelines. The updated CAD-RADS classification will follow an established framework of stenosis, plaque burden, and modifiers, which will include assessment of lesion-specific ischemia using CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), when performed. Similar to the method used in the original CAD-RADS version, the determinant for stenosis severity classification will be the most severe coronary artery luminal stenosis on a per-patient basis, ranging from CAD-RADS 0 (zero) for absence of any plaque or stenosis to CAD-RADS 5 indicating the presence of at least one totally occluded coronary artery. Given the increasing data supporting the prognostic relevance of coronary plaque burden, this document will provide various methods to estimate and report total plaque burden. The addition of P1 to P4 descriptors are used to denote increasing categories of plaque burden. The main goal of CAD-RADS, which should always be interpreted together with the impression found in the report, remains to facilitate communication of test results with referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will continue to provide a framework of standardization that may benefit education, research, peer-review, artificial intelligence development, clinical trial design, population health and quality assurance with the ultimate goal of improving patient care.

CAD-RADS™ 2.0 - 2022 Coronary Artery Disease-Reporting and Data System: An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR), and the North America Society of Cardiovascular Imaging (NASCI)

Coronary Artery Disease Reporting and Data System (CAD-RADS) was created to standardize reporting system for patients undergoing coronary CT angiography (CCTA) and to guide possible next steps in patient management. The goal of this updated 2022 CAD-RADS 2.0 is to improve the initial reporting system for CCTA by considering new technical developments in Cardiac CT, including data from recent clinical trials and new clinical guidelines. The updated CAD-RADS classification will follow an established framework of stenosis, plaque burden, and modifiers, which will include assessment of lesion-specific ischemia using CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), when performed. Similar to the method used in the original CAD-RADS version, the determinant for stenosis severity classification will be the most severe coronary artery luminal stenosis on a per-patient basis, ranging from CAD-RADS 0 (zero) for absence of any plaque or stenosis to CAD-RADS 5 indicating the presence of at least one totally occluded coronary artery. Given the increasing data supporting the prognostic relevance of coronary plaque burden, this document will provide various methods to estimate and report total plaque burden. The addition of P1 to P4 descriptors are used to denote increasing categories of plaque burden. The main goal of CAD-RADS, which should always be interpreted together with the impression found in the report, remains to facilitate communication of test results with referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will continue to provide a framework of standardization that may benefit education, research, peer-review, artificial intelligence development, clinical trial design, population health and quality assurance with the ultimate goal of improving patient care.

CAD-RADS™ 2.0 - 2022 Coronary Artery Disease - Reporting and Data System An Expert Consensus Document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Cardiology (ACC), the American College of Radiology (ACR) and the North America Society of Cardiovascular Imaging (NASCI)

Coronary Artery Disease Reporting and Data System (CAD-RADS) was created to standardize reporting system for patients undergoing coronary CT angiography (CCTA) and to guide possible next steps in patient management. The goal of this updated 2022 CAD-RADS 2.0 is to improve the initial reporting system for CCTA by considering new technical developments in Cardiac CT, including data from recent clinical trials and new clinical guidelines. The updated CAD-RADS classification will follow an established framework of stenosis, plaque burden, and modifiers, which will include assessment of lesion-specific ischemia using CT fractional-flow-reserve (CT-FFR) or myocardial CT perfusion (CTP), when performed. Similar to the method used in the original CAD-RADS version, the determinant for stenosis severity classification will be the most severe coronary artery luminal stenosis on a per-patient basis, ranging from CAD-RADS 0 (zero) for absence of any plaque or stenosis to CAD-RADS 5 indicating the presence of at least one totally occluded coronary artery. Given the increasing data supporting the prognostic relevance of coronary plaque burden, this document will provide various methods to estimate and report total plaque burden. The addition of P1 to P4 descriptors are used to denote increasing categories of plaque burden. The main goal of CAD-RADS, which should always be interpreted together with the impression found in the report, remains to facilitate communication of test results with referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will continue to provide a framework of standardization that may benefit education, research, peer-review, artificial intelligence development, clinical trial design, population health and quality assurance with the ultimate goal of improving patient care. Keywords: Coronary Artery Disease, Coronary CTA, CAD-RADS, Reporting and Data System, Stenosis Severity, Report Standardization Terminology, Plaque Burden, Ischemia Supplemental material is available for this article. This article is published synchronously in Radiology: Cardiothoracic Imaging, Journal of Cardiovascular Computed Tomography, JACC: Cardiovascular Imaging, Journal of the American College of Radiology, and International Journal for Cardiovascular Imaging. © 2022 Society of Cardiovascular Computed Tomography. Published by RSNA with permission.

Defining the distance between the His bundle and first septal perforator: implications for left bundle branch pacing

BACKGROUND

Left bundle branch pacing (LBBP) is a developing method of native conduction pacing, but cases of injury to the septal perforator arteries during implantation have been reported. Knowing the distance between the His bundle and the first septal perforator artery can help operators implant LBBP leads more safely.

METHODS

Using previously performed coronary CT angiography (CCTA) studies, the distance between the His bundle and the first septal perforator was measured.

RESULTS

A total of 50 CCTA studies were included. The mean distance from the His bundle to the first septal perforator (His-SP) along the line connecting the His bundle to the RV apex (His-RV apex) was 27.17 ± 7.7 mm with a range of 13.0 to 44.7 mm. The distance was greater than 2.0 cm in 84% of patients. To standardize this distance among patients with varying cardiac structures, the ratio between the His-SP distance and the His-RV Apex distance was also measured. The mean His-SP:His-RV Apex was 0.302 and the median was 0.298. Eighty-six percent of patients had a ratio of greater than 0.20.

CONCLUSION

Using this information, operators can aim to implant LBBP leads within 2.0 cm of the His bundle or 20% of the distance between the His bundle and the RV apex with minimal risk of causing vascular injury.

Atherosclerotic plaque characteristics on quantitative coronary computed tomography angiography associated with ischemia on positron emission tomography in diabetic patients

Patients with diabetes mellitus (DM) may show diffuse coronary artery atherosclerosis on coronary computed tomography angiography (CTA). The present study aimed at quantification of atherosclerotic plaque with CTA and its association with myocardial ischemia on positron emission tomography (PET) in DM patients. Of 922 symptomatic outpatients without previously known coronary artery disease who underwent CTA, 115 with DM (mean age 65 ± 8 years, 58% male) who had coronary atherosclerosis and underwent both quantified CTA (QCTA) and PET were included in the study. QCTA analysis was performed on a per-vessel basis and the most stenotic lesion of each vessel was considered. Myocardial ischemia on PET was based on absolute myocardial blood flow at stress ≤ 2.4 ml/g/min. Of the 345 vessels included in the analysis, 135 (39%) had flow-limiting stenosis and were characterized by having longer lesions, higher plaque volume, more extensive plaque burden and higher percentage of dense calcium (37 ± 22% vs 28 ± 22%, p = 0.001). On univariable analysis, QCTA parameters indicating the degree of stenosis, the plaque extent and composition were associated with presence of ischemia. The addition of the QCTA degree of stenosis parameters (x2 36.45 vs 88.18, p < 0.001) and the QCTA plaque extent parameters (x2 88.18 vs 97.44, p = 0.01) to a baseline model increased the association with ischemia. In DM patients, QCTA variables of vessel stenosis, plaque extent and composition are associated with ischemia on PET and characterize the hemodynamic significant atherosclerotic lesion.

Vessel filtering and segmentation of coronary CT angiographic images

PURPOSE

Coronary artery segmentation in coronary computed tomography angiography (CTA) images plays a crucial role in diagnosing cardiovascular diseases. However, due to the complexity of coronary CTA images and coronary structure, it is difficult to automatically segment coronary arteries accurately and efficiently from numerous coronary CTA images.

METHOD

In this study, an automatic method based on symmetrical radiation filter (SRF) and D-means is presented. The SRF, which is applied to the three orthogonal planes, is designed to filter the suspicious vessel tissue according to the features of gradient changes on vascular boundaries to segment coronary arteries accurately and reduce computational cost. Additionally, the D-means local clustering is proposed to be embedded into vessel segmentation to eliminate noise impact in coronary CTA images.

RESULTS

The results of the proposed method were compared against the manual delineations in 210 coronary CTA data sets. The average values of true positive, false positive, Jaccard measure, and Dice coefficient were [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text], respectively. Moreover, comparing the delineated data sets and public data sets showed that the proposed method is better than the related methods.

CONCLUSION

The experimental results indicate that the proposed method can perform complete, robust, and accurate segmentation of coronary arteries with low computational cost. Therefore, the proposed method is proven effective in vessel segmentation of coronary CTA images without extensive training data and can meet clinical applications.

Comparison of fluid dynamics changes due to physical activity in 3D printed patient specific coronary phantoms with the Windkessel equivalent model of coronary flow

Background

3D printing (3DP) used to replicate the geometry of normal and abnormal vascular pathologies has been demonstrated in many publications; however, reproduction of hemodynamic changes due to physical activities, such as rest versus moderate exercise, need to be investigated. We developed a new design for patient specific coronary phantoms, which allow adjustable physiological variables such as coronary distal resistance and coronary compliance in patients with coronary artery disease. The new design was tested in precise benchtop experiments and compared with a theoretical Windkessel electrical circuit equivalent, that models coronary flow and pressure using arterial resistance and compliance.

Methods

Five phantoms from patients who underwent clinically indicated elective invasive coronary angiography were built from CCTA scans using multi-material 3D printing. Each phantom was used in a controlled flow system where patient specific flow conditions were simulated by a programmable cardiac pump. To simulate the arteriole and capillary beds flow resistance and the compliance for various physical activities, we designed a three-chamber outlet system which controls the outflow dynamics of each coronary tree. Benchtop pressure measurements were recorded using sensors embedded in each of the main coronary arteries. Using the Windkessel model, patient specific flow equivalent electrical circuit models were designed for each coronary tree branch, and flow in each artery was determined for known inflow conditions. Local flow resistances were calculated through Poiseuille’s Law derived from the radii and lengths of the coronary arteries using CT angiography based multi-planar reconstructions. The coronary stenosis flow rates from the benchtop and the electrical models were compared to the localized flow rates calculated from invasive pressure measurements recorded in the angio-suites.

Results

The average Pearson correlations of the localized flow rates at the location of the stenosis between each of the models (Benchtop/Electrical, Benchtop/Angio, Electrical/Angio) are 0.970, 0.981, and 0.958 respectively.

Conclusions

3D printed coronary phantoms can be used to replicate the human arterial anatomy as well as blood flow conditions. It displays high levels of correlation when compared to hemodynamics calculated in electrically-equivalent coronary Windkessel models as well as invasive angio-suite pressure measurements.

Implementation of Process Improvements to Facilitate Cardiac CT Re-Credentialing in a Rural Healthcare System

Background: Because rural providers may experience barriers in achieving the necessary components to successfully re-credential in cardiac computed tomography (Cardiac CT), we evaluated the current system for re-credentialing at our organization and implemented processes to facilitate Cardiac CT re-credentialing for our providers.Methods: Institutional opportunities for Cardiac CT quality assurance (QA) conference attendance, Cardiac CT imaging evaluation, and Cardiac CT continuing medical education (CME) acquisition were assessed in 2009 and 2013. Process improvement strategies were implemented in 2014 including adding electronic media hosting sites, a "hands-on" image interpretation course, and more options for CME acquisition. Pre- and post-educational improvements were evaluated over a 10-year period. The number and type of events hosted, attendees, image review opportunities, and CME credits awarded were assessed and compared at the provider level.Results: Attendance at Cardiac CT QA conferences increased substantially following implemented changes despite fewer certified Cardiac CT providers. Electronic attendance accounted for 26% of this increased attendance, while the "hands on" course provided 43 images for review per year. The number of Cardiac CT CME credits awarded increased substantially, paralleling increased QA and "hands-on" attendance.Conclusion: In rural healthcare systems, institutional strategies can increase provider access to components necessary for Cardiac CT level II re-credentialing. In the COVID-19 era, rural and urban health organizations may find considerable provider benefit and engagement by using similar process improvement methods to help providers meet local and national requirements for certification.

Comparison of radiation dose and its correlates between coronary computed tomography angiography and invasive coronary angiography in Northeastern Thailand

Background

The number of coronary computed tomography angiography (CCTA) exams is steadily growing. A novel computed tomography (CT) system has been developed to increase image quality while lowering patient radiation. The radiation dose attributed to CCTA has received considerable attention, whereas the dose associated with invasive catheter angiography (ICA) has received less. This study aims to investigate the radiation exposure of CCTA in patients and compare it to ICA.

Results

The mean effective dose of CCTA was 2.88 ± 0.85 mSv which was significantly lower than the mean effective dose of ICA (5.61 ± 0.55 mSv), p < 0.0001. The effective dose of CCTA correlated with the weight, height, and BMI, while the effective dose of ICA was associated with patient weight and BMI. The radiation exposure from CCTA has been considerably reduced over the last ten years by almost 2.5 folds. The mean radiation dose from the newer generation CT used in 2019 was significantly lower than that of the single-source CT in 2010 (2.88 ± 0.85 mSv vs. 7.15 ± 3.4 mSv, p < 0.001).

Conclusions

CCTA allows evaluation of CAD with a significantly less effective radiation dose to patients than diagnostic ICA. There was a significant decrease in radiation dose from CCTA over time. Regular measurement of patient doses is an essential step to optimize exposure. It makes operators aware of their performance and allows comparisons with generally accepted practices.

A specific plasma lipid signature associated with high triglycerides and low HDL cholesterol identifies residual CAD risk in patients with chronic coronary syndrome

BACKGROUND AND AIMS

Elevated triglycerides (TG) and low high-density lipoprotein cholesterol (HDL-C) define a specific lipid profile associated with residual coronary artery disease (CAD) risk independently of total cholesterol and low-density lipoprotein cholesterol (LDL-C) levels. Aim of the present study was to assess whether TG/HDL-C ratio, coronary atherosclerosis and their change over time are characterized by a specific lipidomic profiling in stable patients with chronic coronary syndrome (CCS).

METHODS

TG/HDL-C ratio was calculated in 193 patients (57.8 ± 7.6 years, 115 males) with CCS characterized by clinical, bio-humoral profiles and cardiac imaging. Patient-specific plasma targeted lipidomics was defined through a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) strategy. Patients underwent coronary computed tomography angiography (CTA) and an individual CTA risk score, combining extent, severity, composition, and location of plaques, was calculated. All patients entered a follow-up (6.39 ± 1.17 years), including clinical, lipidomics and coronary CTA assessments.

RESULTS

Patients were divided in groups according to baseline TG/HDL-C quartiles: IQ (<1.391), IIQ (1.392-2.000), IIIQ (2.001-3.286), and IVQ (≥3.287). A specific pattern of altered lipids, characterized by reduced plasma levels of cholesterol esters, phosphatidylcholines and sphingomyelins, was associated with higher TG/HDL-C both at baseline and follow-up (IVQ vs IQ). The CTA risk score increased over time and this lipid signature was also associated with higher CTA score at follow-up.

CONCLUSIONS

In stable CCS, a specific lipidomic signature identifies those patients with higher TG/HDL- C ratio and higher CTA score over time, suggesting possible molecular pathways of residual CAD risk not tackled by current optimal medical treatments.

Diagnosis and prognostic significance of anomalous origin of coronary artery from the opposite sinus of Valsalva assess by dual-source coronary computed tomography angiography

Background

Clinically recognized coronary anomalies in adults are infrequent and characteristically establish on autopsy. The clinical importance coronary arteries consist of those with anomalous origin of the coronary artery from the opposite sinus of Valsalva (ACAOS) with an inter-arterial course (IAC). We have endeavored to attribute variable risk based on morphological appearances of the ACAOS by dual-source coronary computed tomography angiography (DSCTA).

Material and methods

ACAOS patients who undergoing DSCTA over a 5-year period were identified and assess morphologic characteristics. Medical records were reviewed for major adverse cardiovascular events (MACEs).

Results

A total of 1126 patients who undergoing DSCTA were evaluated. Twenty-four patients with ACAOS with IAC were recognized with a prevalence of 2.1% of study population. Twenty patients had anomalous origin of right coronary artery from left sinus of Valsalva (RCA-LSV) and 4 patients had anomalous origin of left coronary from right sinus of Valsalva (LCA-RSV). A significant increased prevalence of MACEs in were observed in intramural, slit-like and high inter-arterial course morphology group. Median follow-up time was 13 months (IQR 3-18  months). During follow-up 2 died, 4 had PCI, 13 had myocardial infarction and 7 had surgical treatment.

Conclusions

Intramural, slit-like and high type inter-arterial course morphology of ACAOS with IAC are high risk features for MACEs which can be identified by DSCTA.

Progression of whole-heart Atherosclerosis by coronary CT and major adverse cardiovascular events

BACKGROUND

The current study aimed to examine the independent prognostic value of whole-heart atherosclerosis progression by serial coronary computed tomography angiography (CCTA) for major adverse cardiovascular events (MACE).

METHODS

The multi-center PARADIGM study includes patients undergoing serial CCTA for symptomatic reasons, ≥2 years apart. Whole-heart atherosclerosis was characterized on a segmental level, with co-registration of baseline and follow-up CCTA, and summed to per-patient level. The independent prognostic significance of atherosclerosis progression for MACE (non-fatal myocardial infarction [MI], death, unplanned coronary revascularization) was examined. Patients experiencing interval MACE were not omitted.

RESULTS

The study population comprised 1166 patients (age 60.5 ​± ​9.5 years, 54.7% male) who experienced 139 MACE events during 8.2 (IQR 6.2, 9.5) years of follow up (15 death, 5 non-fatal MI, 119 unplanned revascularizations). Whole-heart percent atheroma volume (PAV) increased from 2.32% at baseline to 4.04% at follow-up. Adjusted for baseline PAV, the annualized increase in PAV was independently associated with MACE: OR 1.23 (95% CI 1.08, 1.39) per 1 standard deviation increase, which was consistent in multiple subpopulations. When categorized by composition, only non-calcified plaque progression associated independently with MACE, while calcified plaque did not. Restricting to patients without events before follow-up CCTA, those with future MACE showed an annualized increase in PAV of 0.93% (IQR 0.34, 1.96) vs 0.32% (IQR 0.02, 0.90), P ​< ​0.001.

CONCLUSIONS

Whole-heart atherosclerosis progression examined by serial CCTA is independently associated with MACE, with a prognostic threshold of 1.0% increase in PAV per year.

Coronary plaque burden, plaque characterization and their prognostic implications in familial hypercholesterolemia: A computed tomographic angiography study

BACKGROUND AND AIMS

Heterozygous familial hypercholesterolemia (FH) is associated with premature atherosclerotic cardiovascular disease. Semi-automated plaque characterization (SAPC) by coronary computed tomographic angiography (CTA) provides information regarding coronary plaque burden and plaque characterization. Our aim was to quantify and characterize the coronary plaque burden of patients with FH using SAPC analysis and to identify which factors are related to plaque burden and plaque characteristics. A second aim was to analyse the prognostic implications of these parameters.

METHODS

Two hundred and fifty-nine asymptomatic individuals with molecularly determined FH were enrolled in this follow-up cohort study and underwent a coronary CTA analysed with SAPC.

RESULTS

Mean follow-up time after coronary CTA was 3.9 ± 2 years. Mean age was 46.9 (10.7) years (130 women, 50.2%). Median plaque burden was 25.0% (19.0-29.0), non-calcified plaque burden 22.83% (17.94-26.88), calcified plaque-burden 1.12% (0.31-2.86) and CCS 8.9 (0-93). Five-year risk was independently related to plaque burden, non-calcified plaque burden, calcified plaque burden and coronary calcium score (B:3.75, 95%CI:2.92-4.58; p < 0.001, B:2.9, 95%CI:2.15-3.66; p < 0.001, B:0.75, 95%CI 0.4-1.1; p < 0.001 and B:82.2, 95%CI:49.28-115.16; p < 0.001 respectively). During follow-up, there were 15 (5.81%) nonfatal events and 1 (0.4%) fatal event. Plaque burden was significantly related to event-free survival during follow-up (HR:1.11; 95%CI:1.05-1.18; p < 0.001).

CONCLUSIONS

Coronary atherosclerosis and its qualitative components may be quantified by means of SAPC in patients with FH. Plaque burden, calcified plaque burden and non-calcified plaque burden were independently related to the estimated cardiovascular risk. Plaque burden was also related to prognosis.

Use of cardiac CT amidst the COVID-19 pandemic and beyond: North American perspective

The COVID-19 pandemic has affected patient care deliver throughout the world, resulting in a greater emphasis on efficiently and safety. In this article, we discuss the experiences of several North American centers in utilizing cardiac CT during the pandemic. We also provide a case-based overview which highlights the advantages of cardiac CT in evaluating the following scenarios: (1) patients with possible myocardial injury versus myocardial infarction; (2) patients with acute chest pain; (3) patients with stable chest pain; (4) patients with possible intracardiac thrombus; (5) patients with valvular heart disease. For each scenario, we also provide an overview of various societies recommendations which have highlighted the use of cardiac CT during different phases of the COVID-19 pandemic. We hope that the advantages of cardiac CT that have been realized during the pandemic can help promote wider adoption of this technique and improved coverage and payment by payors.

Segmentation of coronary arteries images using global feature embedded network with active contour loss

Coronary heart disease (CHD) is a serious disease that endangers human health and life. In recent years, the morbidity and mortality of CHD are increasing significantly. Because of the particularity and complexity of medical image, it is challenging to segment coronary artery accurately and efficiently. This paper proposes a novel global feature embedded network for better coronary arteries segmentation in 3D coronary computed tomography angiography (CTA) data. The global feature combines multi-level layers from various stages of the network, which contains semantic information and detailed features, aiming to accurately segment target with precise boundary. In addition, we integrate a group of improved noisy activating functions with parameters into our network to eliminate the impact of noise in CTA data. And we improve the learning active contour model, which obtains a refined segmentation result with smooth boundary based on the high-quality score map produced by the networks. The experimental results show that the proposed framework achieved the state-of-the-art performance intuitively and quantitively.

Highlights of the 15th annual scientific meeting of the Society of Cardiovascular Computed Tomography

The 15th Society of Cardiovascular Computed Tomography (SCCT) annual scientific meeting (ASM) welcomed 770 digital attendees from 44 countries, over 2 days, with a program that included 30 sessions across three simultaneously streaming channels, 10 exhibitors and a diverse range of scientific abstracts. In addition, #SCCT2020 generated >5900 tweets from nearly 700 engaged social media participants resulting in an estimated 38 million digital impressions and becoming #1 trending medical meeting in social media in the world during the meeting time period. This article summarizes the many themes and topics of presentation and discussion in this meeting, and the many technical advances that are likely to impact future clinical practice in cardiovascular computed tomography.

Method to simulate distal flow resistance in coronary arteries in 3D printed patient specific coronary models

BACKGROUND

Three-dimensional printing (3DP) offers a unique opportunity to build flexible vascular patient-specific coronary models for device testing, treatment planning, and physiological simulations. By optimizing the 3DP design to replicate the geometrical and mechanical properties of healthy and diseased arteries, we may improve the relevance of using such models to simulate the hemodynamics of coronary disease. We developed a method to build 3DP patient specific coronary phantoms, which maintain a significant part of the coronary tree, while preserving geometrical accuracy of the atherosclerotic plaques and allows for an adjustable hydraulic resistance.

METHODS

Coronary computed tomography angiography (CCTA) data was used within Vitrea (Vital Images, Minnetonka, MN) cardiac analysis application for automatic segmentation of the aortic root, Left Anterior Descending (LAD), Left Circumflex (LCX), Right Coronary Artery (RCA), and calcifications. Stereolithographic (STL) files of the vasculature and calcium were imported into Autodesk Meshmixer for 3D model optimization. A base with three chambers was built and interfaced with the phantom to allow fluid collection and independent distal resistance adjustment of the RCA, LAD and LCX and branching arteries. For the 3DP we used Agilus for the arterial wall, VeroClear for the base and a Vero blend for the calcifications, respectively. Each chamber outlet allowed interface with catheters of varying lengths and diameters for simulation of hydraulic resistance of both normal and hyperemic coronary flow conditions. To demonstrate the manufacturing approach appropriateness, models were tested in flow experiments.

RESULTS

Models were used successfully in flow experiments to simulate normal and hyperemic flow conditions. The inherent mean resistance of the chamber for the LAD, LCX, and RCA, were 1671, 1820, and 591 (dynes ∙ sec/ cm5), respectively. This was negligible when compared with estimates in humans, with the chamber resistance equating to 0.65-5.86%, 1.23-6.86%, and 0.05-1.67% of the coronary resistance for the LAD, LCX, and RCA, respectively at varying flow rates and activity states. Therefore, the chamber served as a means to simulate the compliance of the distal coronary trees and to allow facile coupling with a set of known resistance catheters to simulate various physical activity levels.

CONCLUSIONS

We have developed a method to create complex 3D printed patient specific coronary models derived from CCTA, which allow adjustable distal capillary bed resistances. This manufacturing approach permits comprehensive coronary model development which may be used for physiologically relevant flow simulations.

Percent atheroma volume: Optimal variable to report whole-heart atherosclerotic plaque burden with coronary CTA, the PARADIGM study

BACKGROUND AND AIMS

Different methodologies to report whole-heart atherosclerotic plaque on coronary computed tomography angiography (CCTA) have been utilized. We examined which of the three commonly used plaque burden definitions was least affected by differences in body surface area (BSA) and sex.

METHODS

The PARADIGM study includes symptomatic patients with suspected coronary atherosclerosis who underwent serial CCTA >2 years apart. Coronary lumen, vessel, and plaque were quantified from the coronary tree on a 0.5 mm cross-sectional basis by a core-lab, and summed to per-patient. Three quantitative methods of plaque burden were employed: (1) total plaque volume (PV) in mm³, (2) percent atheroma volume (PAV) in % [which equaled: PV/vessel volume * 100%], and (3) normalized total atheroma volume (TAV_norm) in mm³ [which equaled: PV/vessel length * mean population vessel length]. Only data from the baseline CCTA were used. PV, PAV, and TAV_norm were compared between patients in the top quartile of BSA vs the remaining, and between sexes. Associations between vessel volume, BSA, and the three plaque burden methodologies were assessed.

RESULTS

The study population comprised 1479 patients (age 60.7 ± 9.3 years, 58.4% male) who underwent CCTA. A total of 17,649 coronary artery segments were evaluated with a median of 12 (IQR 11-13) segments per-patient (from a 16-segment coronary tree). Patients with a large BSA (top quartile), compared with the remaining patients, had a larger PV and TAV_norm, but similar PAV. The relation between larger BSA and larger absolute plaque volume (PV and TAV_norm) was mediated by the coronary vessel volume. Independent from the atherosclerotic cardiovascular disease risk (ASCVD) score, vessel volume correlated with PV (P < 0.001), and TAV_norm (P = 0.003), but not with PAV (P = 0.201). The three plaque burden methods were equally affected by sex.

CONCLUSIONS

PAV was less affected by patient's body surface area then PV and TAV_norm and may be the preferred method to report coronary atherosclerotic burden.

Long-term health outcomes and cost-effectiveness of coronary CT angiography in patients with suspicion for acute coronary syndrome

BACKGROUND

Randomized trials have shown favorable clinical outcomes for coronary CT angiography (CTA) in patients with suspected acute coronary syndrome (ACS). Our goal was to estimate the cost-effectiveness of coronary CTA as compared to alternative management strategies for ACP patients over lifetime.

METHODS

Markov microsimulation model was developed to compare cost-effectiveness of competitive strategies for ACP patients: 1) coronary CTA, 2) standard of care (SOC), 3) AHA/ACC Guidelines, and 4) expedited emergency department (ED) discharge protocol with outpatient testing. ROMICAT-II trial was used to populate the model with low to intermediate risk of ACS patient data, whereas diagnostic test-, treatment effect-, morbidity/mortality-, quality of life- and cost data were obtained from the literature. We predicted test utilization, costs, 1-, 3-, 10-year and over lifetime cardiovascular morbidity/mortality for each strategy. We determined quality adjusted life years (QALY) and incremental cost-effectiveness ratio. Observed outcomes in ROMICAT-II were used to validate the short-term model.

RESULTS

Estimated short-term outcomes accurately reflected observed outcomes in ROMICAT-II as coronary CTA was associated with higher costs ($4,490 vs. $2,513-$4,144) and revascularization rates (5.2% vs. 2.6%-3.7%) compared to alternative strategies. Over lifetime, coronary CTA dominated SOC and ACC/AHA Guidelines and was cost-effective compared to expedited ED protocol ($49,428/QALY). This was driven by lower cardiovascular mortality (coronary CTA vs. expedited discharge: 3-year: 1.04% vs. 1.10-1.17; 10-year: 5.06% vs. 5.21-5.36%; respectively).

CONCLUSION

Coronary CTA in patients with suspected ACS renders affordable long-term health benefits as compared to alternative strategies.

Left Main Coronary Artery Thrombus Diagnosed and Managed With Coronary Computed Tomography Angiography and Fractional Flow Reserve Derived From Computed Tomography

Left main coronary artery thrombus (LMCA-T) is a rare disease state and diagnosed with invasive coronary angiography (ICA). We present a case of LMCA-T diagnosed with coronary computed tomography angiography (CTA) and treated without ICA in a patient who presented to a hospital in the middle of war zone in Erbil, Iraqi Kurdistan. Coronary CTA performed 1 month later demonstrated resolution of the thrombus. Fractional flow reserve computed from computed tomography (FFR-CT; HeartFlow, Redwood City, CA) performed retrospectively confirmed that the clot was not hemodynamically significant at the time of diagnosis. This case demonstrates the diagnostic capabilities of coronary CTA and FFR-CT when ICA is not readily available.

Low Iodine Contrast Injection for CT Acquisition Prior to Transcatheter Aortic Valve Replacement: Aorta Assessment and Screening for Coronary Artery Disease

RATIONALE AND OBJECTIVES

To assess both the complete aorta and coronary artery disease (CAD) using low iodine contrast computed-tomography angiography before transcatheter aortic valve replacement.

MATERIALS AND METHODS

84 patients underwent computed-tomography angiography before transcatheter aortic valve replacement: 42 with standard iodine injection protocol (P1:120 mL); 42 with a low dose iodine injection protocol (P2:60 mL). Mean attenuation and subjective image quality were rated at different levels of the aorta, iliac and coronary arteries. Sensitivity, specificity, negative and positive predictive values for depiction of CAD were calculated according to the coronary angiography.

RESULTS

Mean attenuation was significantly higher in P1 for the ascending aorta (p < 0.001). No significant difference was observed regarding image quality of the aortic valve (p = 0.876), the ascending aorta (p = 0.306), or the abdominal aorta (p = 1.0). Diagnostic image quality of coronary arteries was excellent for P1 and P2 (94.6% vs 96.5%, p = 0.08). Sensitivity, specificity, negative and positive predictive values, and accuracy for depiction of CAD were excellent for P1 and P2 (100% vs 100%; 79% vs 86%, 70% vs 87%, 100% vs 100% and 86% vs 93%) without significant differences (p = 0.93; p = 0.58; p = 0.90; p = 1.0; p = 0.74), respectively.

CONCLUSION

Despite a difference in aortic mean attenuation, a reduced iodine injection protocol showed similar image quality and detection of CAD in comparison with a standard injection protocol.

Secondary cardiac risk stratifying tests after coronary computed tomography angiography in emergency department patients

BACKGROUND

Several large trials demonstrated that coronary computed tomography angiography (CTA) in a triage strategy could lead to increased secondary cardiac risk stratifying testing (SCRST). Whether this is true for routine clinical care remains unclear. We measured SCRSTs after coronary CTA was implemented in our emergency department (ED) practice by CTA result, and if locally existing management recommendations for a structured post CTA diagnostic strategy were followed.

METHODS

This single site retrospective cohort study included all our ED patients who received coronary CTA between October 1, 2012 and September 30, 2016. SCRST's included functional cardiac tests and invasive coronary angiography (ICA), performed during the ED coronary CTA visit or related admission.

RESULTS

A total of 1916 subjects were included with a mean age of 52.9 ± 10.8 years. Of their coronary CTAs, 179 were positive (severe stenosis, occlusion or ventricular wall motion abnormalities; 9.3%), 105 intermediate (moderate stenosis; 5.5%), 1611 negative (no to mild obstructive CAD; 84.1%) and 21 non-diagnostic (1.1%). SCRSTs were performed in 237 (overall 12.4%, noninvasive in 5.6%, ICA in 6.7%). After positive coronary CTA, 73.7% of subjects received SCRSTs. For intermediate, negative and non-diagnostic CTAs this was 72.4%, 1.1% and 47.6% respectively. Management conformed to local management recommendations in 96.2% of cases.

CONCLUSION

In spite of previous trials, rates of secondary cardiac risk stratifying tests after routine clinical ED coronary CTA are low, especially in patients with negative coronary CTA. Structured management guidelines for post coronary CTA, and adherence to these guidelines, appear essential.

Highlights of the Twelfth Annual Scientific Meeting of the Society of Cardiovascular Computed Tomography

The 12th Annual Scientific Meeting of the SCCT, held from July 6 to July 9 in Washington, DC, was one of the largest to date with 724 attendants from 34 countries, 130 invited talks, 4 "Read with the Experts" sessions, 42 oral abstracts presented, 20 rapid fire posters and 164 poster presentations with the abstracts of all of these published in the JCCT. This article summarises the many themes and topics of presentation and discussion in this meeting, and the many technical advances that are likely to impact future clinical practice and feature in future meetings.

A quick glance at selected topics in this issue

A quick glance at selected topics in this issue" aims to highlight selected articles and provide a quick review to the readers.

CAD-RADS(TM) Coronary Artery Disease - Reporting and Data System. An expert consensus document of the Society of Cardiovascular Computed Tomography (SCCT), the American College of Radiology (ACR) and the North American Society for Cardiovascular Imaging (NASCI). Endorsed by the American College of Cardiology

The intent of CAD-RADS - Coronary Artery Disease Reporting and Data System is to create a standardized method to communicate findings of coronary CT angiography (coronary CTA) in order to facilitate decision-making regarding further patient management. The suggested CAD-RADS classification is applied on a per-patient basis and represents the highest-grade coronary artery lesion documented by coronary CTA. It ranges from CAD-RADS 0 (Zero) for the complete absence of stenosis and plaque to CAD-RADS 5 for the presence of at least one totally occluded coronary artery and should always be interpreted in conjunction with the impression found in the report. Specific recommendations are provided for further management of patients with stable or acute chest pain based on the CAD-RADS classification. The main goal of CAD-RADS is to standardize reporting of coronary CTA results and to facilitate communication of test results to referring physicians along with suggestions for subsequent patient management. In addition, CAD-RADS will provide a framework of standardization that may benefit education, research, peer-review and quality assurance with the potential to ultimately result in improved quality of care.

Assessment of coronary in-stent restenosis: value of subtraction coronary computed tomography angiography

In conventional coronary computed tomography angiography (CCTA), metal artifacts are frequently observed where stents are located, making it difficult to evaluate in-stent restenosis. This study was conducted to investigate whether subtraction CCTA can improve diagnostic accuracy in the evaluation of in-stent restenosis. Subtraction CCTA was performed using 320-row CT in 398 patients with previously placed stents who were able to hold their breath for 25 s and in whom mid-diastolic prospective one-beat scanning was possible. Among these patients, 126 patients (94 men and 32 women, age 74 ± 8 years) with 370 stents who also underwent invasive coronary angiography (ICA) were selected as the subjects of this study. With ICA findings considered the gold standard, conventional CCTA was compared against subtraction CCTA to determine whether subtraction can improve diagnostic accuracy in the evaluation of in-stent restenosis. When non-assessable stents were considered to be stenotic, the diagnostic accuracy in the evaluation of in-stent restenosis was 62.7 % for conventional CCTA and 89.5 % for subtraction CCTA. When the non-assessable stents were considered to be non-stenotic the diagnostic accuracy was 90.3 % for conventional CCTA and 94.31 % for subtraction CCTA. When subtraction CCTA was used to evaluate only the 138 stents that were judged to be non-assessable by conventional CCTA, 116 of these stents were judged to be assessable, and the findings for 109 of them agreed with those obtained by ICA. Even for stents with an internal diameter of 2.5-3 mm, the lumen can be evaluated in more than 80 % of patients. Subtraction CCTA provides significantly higher diagnostic accuracy than conventional CCTA in the evaluation of in-stent restenosis.

Preoperative evaluation for coronary atherosclerosis with computed tomography angiography in intravenous drug users: an emerging indication in the face of a growing threat

The purpose of this study was to describe the application of coronary computed tomography angiography (CCTA) in evaluation of patients with history of intravenous drug use (IDU). An IRB approved retrospective review was performed of all patients who had a prior history of IDU and presenting with endocarditis who had undergone CCTA. Demographic characteristics and cardiovascular risk factors were collected. In addition, we reviewed CCTA reports for dosimetric parameters, calcium score, and atherosclerotic burden. There were 32 patients (25 males) included in this study with a mean age of 38 ± 10.8 years. The average BMI for the study group was 26.5 ± 4.9. 44 % of patients had evidence of atherosclerotic disease on coronary CTA. Mean calcium score was 175 ± 487. Median total exam effective dose was 4.8 mSv (range: 3.3-7.3 mSv). In spite of their relatively young age and BMI at the upper limits of normal, patients with history of IDU have atherosclerosis and coronary CTA can be utilized to screen these patients and may be helpful for risk stratification prior to noncoronary surgical procedures. Given the recent rise in IDU, this may become a growing indication for CCTA.

Effects of intensive lipid-lowering therapy on coronary plaques composition in patients with acute myocardial infarction: Assessment with serial coronary CT angiography

BACKGROUND

Statins have been shown to possess favourable effects on the cardiovascular system with stabilization of the vulnerable plaque. We sought to assess the effects of early aggressive statin treatment on plaque composition in patients with acute myocardial infarction (AMI), using serial assessment with coronary CT-angiography (CTA).

METHODS

In a prospective randomized blinded endpoint trial patients with AMI were randomized to an intensive lipid lowering treatment receiving statin loading with 80 mg rosuvastatin followed by 40 mg daily or standard statin therapy according to current guidelines. Patients were assessed with CTA at baseline and after 12 months with evaluation of plaque volume and composition.

RESULTS

In total, 140 patients with AMI were randomized and plaque composition was assessed in 96 patients. In the intensive care group LDL-level was median 1.3 [0.9; 1.5] mmol/l at 12 months follow-up and 2.0 [1.7; 2.4] mmol/l in the usual care group, p < 0.001. Plaque volume increased over 12 months with 43.5 (±225.8) mm(3) in the intensive care group and 19.1 (±190.2) mm(3) in the usual care group, p = 0.57. Plaque composition changed over 12 months with an increase in total dense calcium volume by 11.1 (±39.6) mm(3), corresponding to a 23% increase, in the intensive care group and a decreased by -0.4 (±26.6) mm(3) in the usual care group, p < 0.001. Necrotic core volume increased 26.8 (±122.1) mm(3) in the intensive care group and 25.2 (±80.1) mm(3) in the usual care group, p = 0.94.

CONCLUSIONS

Early aggressive lipid lowering therapy significantly increases dense calcium volume in patients with AMI.

Management of Coronary Artery Calcium and Coronary CTA Findings

Coronary artery calcium (CAC) testing and coronary computed tomography angiography (CTA) have significant data supporting their ability to identify coronary artery disease (CAD) and classify patient risk for atherosclerotic cardiovascular disease (ASCVD). Evidence regarding CAC use for screening has established an excellent prognosis in patients with no detectable CAC, and the ability to risk re-classify the majority of asymptomatic patients considered intermediate risk by traditional risk scores. While data regarding the ideal management of CAC findings are limited, evidence supports statin consideration in patients with CAC > 0 and individualized aspirin therapy accounting for CAD risk factors, CAC severity, and factors which increase a patient's risk of bleeding. In patients with stable or acute symptoms undergoing coronary CTA, a normal CTA predicts excellent prognosis, allowing reassurance and disposition without further testing. When CTA identifies nonobstructive CAD (<50 % stenosis), observational data support consideration of statin use/intensification in patients with extensive plaque (at least four coronary segments involved) and patients with high-risk plaque features. In patients with both nonobstructive and obstructive CAD, multiple studies have now demonstrated an ability of CTA to guide management and improve CAD risk factor control. Still, significant under-treatment of cardiovascular risk factors and high-risk image findings remain, among concerns that CTA may increase invasive angiography and revascularization. To fully realize the impact of atherosclerosis imaging for ASCVD prevention, patient engagement in lifestyle changes and the modification of ASCVD risk factors remain the foundation of care. This review provides an overview of available data and recommendations in the management of CAC and CTA findings.

Effect of statin treatment on coronary plaque progression - a serial coronary CT angiography study

OBJECTIVES

Statins have been shown to reduce plaque progression using data on intravascular ultrasound, carotid intima-media thickness and coronary artery calcium scans. However, there is little data on effects of statins on plaque progression using Coronary CTA. The objective is to evaluate the effect of statin therapy on plaque progression using serial Coronary CTA (CCTA).

METHODS

The study included 100 consecutive patients who underwent serial Coronary CTA (mean follow up: 406 ± 92 days) for evaluation of CAD without known prior heart disease or revascularization. We performed volumetric assessment of low attenuation plaque (LAP < 30 Hounsfield units), non-calcified (NCP) and calcified plaque volumes at baseline and follow up scans for vessels >2 mm in diameter. Patients who received statins were compared to those that did not.

RESULTS

Total plaque progression was significantly reduced among statin user compared to non-statin users (-33.3 mm(3) ± 90.5 vs. 31.0 mm(3) ± 84.5, p = 0.0006). Statin users had significantly reduced progression of NCP volume (-47.7 mm(3) ± 71.9 vs. 13.8 mm(3) ± 76.6, p < 0.001) and significantly reduced progression of LAP volume (-12.2 mm(3) ± 19.2 vs. 5.9 mm(3) ± 23.1, p < 0.0001). When we compared for remodeling index, no statistical difference was found between the two groups (p = 0.25) and a non-significant trend toward calcium progression (29.3 mm(3) ± 67.9 vs. 10.0 mm(3) ± 53.2, p = 0.133). After adjustment for cardiovascular risk factors, mean plaque volume difference between statin and non-statin users was statistically significant for both LAP and NCP volumes (-18.1, 95% CI: -26.4, -9.8 for LAP; -101.7, 95% CI: -162.1, -41.4 for NCP; p < 0.001) respectively.

CONCLUSION

Statin therapy resulted in significantly lower progression of LAP and NCP plaques compared to non-statin users.