Coronary CT angiography characteristics of OCT-defined thin-cap fibroatheroma: a section-to-section comparison study

Computed Tomography Angiography Characteristics of Thin-Cap Fibroatheroma in Patients With Diabetes

BACKGROUND

It was recently reported that thin-cap fibroatheroma (TCFA) detected by optical coherence tomography was an independent predictor of future cardiac events in patients with diabetes. However, the clinical usefulness of this finding is limited by the invasive nature of optical coherence tomography. Computed tomography angiography (CTA) characteristics of TCFA have not been systematically studied. The aim of this study was to investigate CTA characteristics of TCFA in patients with diabetes.

METHODS AND RESULTS

Patients with diabetes who underwent preintervention CTA and optical coherence tomography were included. Qualitative and quantitative analyses were performed for plaques on CTA. TCFA was assessed by optical coherence tomography. Among 366 plaques in 145 patients with diabetes, 111 plaques had TCFA. The prevalence of positive remodeling (74.8% versus 50.6%, P<0.001), low attenuation plaque (63.1% versus 33.7%, P<0.001), napkin-ring sign (32.4% versus 11.0%, P<0.001), and spotty calcification (55.0% versus 34.9%, P<0.001) was significantly higher in TCFA than in non-TCFA. Low-density noncalcified plaque volume (25.4 versus 15.7 mm3, P<0.001) and remodeling index (1.30 versus 1.20, P=0.002) were higher in TCFA than in non-TCFA. The presence of napkin-ring sign, spotty calcification, high low-density noncalcified plaque volume, and high remodeling index were independent predictors of TCFA. When all 4 predictors were present, the probability of TCFA increased to 82.4%.

CONCLUSIONS

The combined qualitative and quantitative plaque analysis of CTA may be helpful in identifying TCFA in patients with diabetes.

REGISTRATION INFORMATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04523194.

Nonobstructive epicardial coronary artery disease: an evolving concept in need of diagnostic and therapeutic guidance

For decades, we have been treating patients presenting with angina and concerning electrocardiographic changes indicative of ischemia or injury, in whom no culprit epicardial coronary stenosis was found during diagnostic coronary angiography. Unfortunately, the clinical outcomes of these patients were not better than those with recognized obstructive coronary disease. Improvements in technology have allowed us to better characterize these patients. Consequently, an increasing number of patients with ischemia and no obstructive coronary artery disease (INOCA) or myocardial infarction in the absence of coronary artery disease (MINOCA) have now gained formal recognition and are more commonly encountered in clinical practice. Although both entities might share functional similarities at their core, they pose significant diagnostic and therapeutic challenges. Unless we become more proficient in identifying these patients, particularly those at higher risk, morbidity and mortality outcomes will not improve. Though this field remains in constant flux, data continue to become available. Therefore, we thought it would be useful to highlight important milestones that have been recognized so we can all learn about these clinical entities. Despite all the progress made regarding INOCA and MINOCA, many important knowledge gaps continue to exist. For the time being, prompt identification and early diagnosis remain crucial in managing these patients. Even though we are still not clear whether intensive medical therapy alters clinical outcomes, we remain vigilant and wait for more data.

High-Risk Plaques on Coronary Computed Tomography Angiography: Correlation With Optical Coherence Tomography

BACKGROUND

Although patients with high-risk plaque (HRP) on coronary computed tomography angiography (CTA) are reportedly at increased risk for future cardiovascular events, individual HRP features have not been systematically validated against high-resolution intravascular imaging.

OBJECTIVES

The aim of this study was to correlate HRP features on CTA with plaque characteristics on optical coherence tomography (OCT).

METHODS

Patients who underwent both CTA and OCT before coronary intervention were enrolled. Plaques in culprit vessels identified by CTA were evaluated with the use of OCT at the corresponding sites. HRP was defined as a plaque with at least 2 of the following 4 features: positive remodeling (PR), low-attenuation plaque (LAP), napkin-ring sign (NRS), and spotty calcification (SC). Patients were followed for up to 3 years.

RESULTS

The study included 448 patients, with a median age of 67 years and of whom 357 (79.7%) were male, and 203 (45.3%) presented with acute coronary syndromes. A total of 1,075 lesions were analyzed. All 4 HRP features were associated with thin-cap fibroatheroma. PR was associated with all OCT features of plaque vulnerability, LAP was associated with lipid-rich plaque, macrophage, and cholesterol crystals, NRS was associated with cholesterol crystals, and SC was associated with microvessels. The cumulative incidence of the composite endpoint (target vessel nontarget lesion revascularization and cardiac death) was significantly higher in patients with HRP than in those without HRP (4.7% vs 0.5%; P = 0.010).

CONCLUSIONS

All 4 HRP features on CTA were associated with features of vulnerability on OCT. (Massachusetts General Hospital and Tsuchiura Kyodo General Hospital Coronary Imaging Collaboration; NCT04523194).

The role of computed tomography angiography in assessing the correlation between properties of coronary atherosclerotic plaque and blood lipids

BACKGROUND

Coronary atherosclerotic heart disease (CAHD) is the leading cause of death in developed countries.

OBJECTIVE

This study aimed to explore the correlation between the properties of coronary atherosclerotic plaque and blood lipids using computed tomography angiography (CTA).

METHODS

A total of 83 patients with coronary heart disease were included in this study (males: 50; females: 33; average age: [59 ± 8] years old). They were classified into the stable angina group and unstable angina group. Atherosclerotic plaques were classified as fatty plaques (soft plaques), fibrous plaques, and calcified plaques based on the computed tomography (CT) values. SPSS 17.0 statistical software was used to analyze the correlation between the properties of angina and the CT values of atherosclerotic plaques, blood lipids, and plaque properties, and then compared between the stable and unstable angina groups.

RESULTS

There were statistically significant differences in plaque properties between the stable and unstable angina groups (P< 0.001). During CTA examination, we found statistically significant differences in the CT density values of atherosclerotic plaques between the stable and unstable angina groups (P< 0.001). There were statistically significant differences between the properties of angina and the level of blood lipids (P< 0.05).

CONCLUSION

Anginal properties negatively correlated with calcified plaques and positively correlated with non-calcified plaques. Calcified plaques negatively correlated with total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and triglycerides (TG), and positively correlated with high-density lipoprotein cholesterol (HDL-C). Non-calcified plaques negatively correlated with HDL-C and positively correlated with TC, LDL-C, and TG.

Determination of lipid-rich plaques by artificial intelligence-enabled quantitative computed tomography using near-infrared spectroscopy as reference

BACKGROUND AND AIMS

Artificial intelligence quantitative CT (AI-QCT) determines coronary plaque morphology with high efficiency and accuracy. Yet, its performance to quantify lipid-rich plaque remains unclear. This study investigated the performance of AI-QCT for the detection of low-density noncalcified plaque (LD-NCP) using near-infrared spectroscopy-intravascular ultrasound (NIRS-IVUS).

METHODS

The INVICTUS Registry is a multi-center registry enrolling patients undergoing clinically indicated coronary CT angiography and IVUS, NIRS-IVUS, or optical coherence tomography. We assessed the performance of various Hounsfield unit (HU) and volume thresholds of LD-NCP using maxLCBI4mm ≥ 400 as the reference standard and the correlation of the vessel area, lumen area, plaque burden, and lesion length between AI-QCT and IVUS.

RESULTS

This study included 133 atherosclerotic plaques from 47 patients who underwent coronary CT angiography and NIRS-IVUS The area under the curve of LD-NCP<30HU was 0.97 (95% confidence interval [CI]: 0.93-1.00] with an optimal volume threshold of 2.30 mm3. Accuracy, sensitivity, and specificity were 94% (95% CI: 88-96%], 93% (95% CI: 76-98%), and 94% (95% CI: 88-98%), respectively, using <30 HU and 2.3 mm3, versus 42%, 100%, and 27% using <30 HU and >0 mm3 volume of LD-NCP (p < 0.001 for accuracy and specificity). AI-QCT strongly correlated with IVUS measurements; vessel area (r2 = 0.87), lumen area (r2 = 0.87), plaque burden (r2 = 0.78) and lesion length (r2 = 0.88), respectively.

CONCLUSIONS

AI-QCT demonstrated excellent diagnostic performance in detecting significant LD-NCP using maxLCBI4mm ≥ 400 as the reference standard. Additionally, vessel area, lumen area, plaque burden, and lesion length derived from AI-QCT strongly correlated with respective IVUS measurements.

Preventative Imaging with Coronary Computed Tomography Angiography

PURPOSE OF REVIEW

Coronary computed tomography angiography (CCTA) is the diagnostic modality of choice for patients with stable chest pain. In this review, we scrutinize the evidence on the use of CCTA for the screening of asymptomatic patients.

RECENT FINDINGS

Clinical evidence suggests that CCTA imaging enhances cardiovascular risk stratification and prompts the timely initiation of preventive treatment leading to reduced risk of major adverse coronary events. Visualization of coronary plaques by CCTA also helps patients to comply with preventive medications. The presence of non-obstructive plaques and total plaque burden are prognostic for cardiovascular events. High-risk plaque features and pericoronary fat attenuation index, enrich the prognostic output of CCTA on top of anatomical information by capturing information on plaque vulnerability and coronary inflammatory burden. Timely detection of atherosclerotic disease or coronary inflammation by CCTA can assist in the deployment of targeted preventive strategies and novel therapeutics to prevent cardiovascular disease.

Sex-specific associations of cardiovascular risk factors and coronary plaque composition for hemodynamically significant coronary artery stenosis: a coronary computed tomography angiography study

BACKGROUND

It has been reported that there are sex differences in plaque composition and hemodynamically significant stenosis. This study aimed to explore the impact of sex on cardiovascular risk factors for specific plaque compositions and hemodynamically significant stenosis.

METHODS

Data regarding demographics and cardiovascular risk factors were collected. Hemodynamically significant stenosis was identified by a computed tomography-derived fractional flow reserve of ≤ 0.8. Associations among cardiovascular risk factors, plaque composition, and hemodynamically significant stenosis were assessed using a multivariate binary logistic regression analysis across sexes. The discriminating capacity of diverse plaque components for hemodynamically significant stenosis was assessed by area under the receiver-operating characteristics curve with 95% confidence intervals.

RESULTS

A total of 1164 patients (489 men and 675 women) were included. For men, hyperlipidemia and cigarette smoking were risk factors for each plaque component (all P < 0.05), and diabetes mellitus also predicted fibrotic components (P < 0.05). For women, risk factors for each plaque component were hypertension and diabetes mellitus (all P < 0.01). Nonetheless, hyperlipidemia (P < 0.05) was a specific risk factor for non-calcified components. Calcified components combined with fibrotic components showed superior discrimination of hemodynamically significant stenosis in men and calcified components alone in women (all P < 0.01). Hypertension (P < 0.01) was a risk factor for hemodynamically significant stenosis in women. In contrast, diabetes, hyperlipidemia, and cigarette smoking were risk factors for hemodynamically significant stenosis in men (all P < 0.05).

CONCLUSIONS

In men, hemodynamically significant stenosis was predicted by a combination of calcified and fibrotic components with multiple risk factors. In women, hemodynamically significant stenosis was predicted by calcified components caused by a single risk factor. It might be a key point to improve prognosis by more precise risk management between men and women, which needs to be proved by further prospective trials.

Accuracy and limitation of plaque detection by coronary CTA: a section-to-section comparison with optical coherence tomography

Plaques identified by Coronary CT angiography (CCTA) are important in clinical diagnosis and primary prevention. High-risk plaque features by CCTA have been extensively validated using optical coherence tomography (OCT). However, since their general diagnostic performance and limitations have not been fully investigated, we sought to compare CCTA with OCT among consecutive vessel sections. We retrospectively compared 188 consecutive plaques and 84 normal sections in 41 vessels from 40 consecutive patients referred for chest pain evaluation who had both CCTA and OCT with a median time lapse of 1 day. The distance to reference points were used to co-register between the modalities and the diagnostic performance of CCTA was evaluated against OCT. Plaque categories evaluated by CT were calcified, non-calcified and mixed. The diagnostic performance of CCTA was excellent for detecting any plaque identified by OCT with the sensitivity, specificity, negative and positive predictive values and accuracy of 92%, 98%, 99%, 84% and 93%, respectively. The lower than expected negative predictive value was due to failure of detecting sub-millimeter calcified (≤ 0.25 mm²) (N = 12) and non-calcified plaques (N = 4). Misclassification of plaque type accounted for majority of false negative findings (25/41, 61%) which was most prevalent among the mixed plaque (19/41, 46%). There was calcification within mixed plaques (N = 5) seen by CCTA but missed by OCT. Our findings suggest that CCTA is excellent at identifying coronary plaques except those sub-millimeter in size which likely represent very early atherosclerosis, although the clinical implication of very mild atherosclerosis is yet to be determined.

Pericoronary Adipose Tissue Radiomics from Coronary Computed Tomography Angiography Identifies Vulnerable Plaques

Pericoronary adipose tissue (PCAT) features on Computed Tomography (CT) have been shown to reflect local inflammation and increased cardiovascular risk. Our goal was to determine whether PCAT radiomics extracted from coronary CT angiography (CCTA) images are associated with intravascular optical coherence tomography (IVOCT)-identified vulnerable-plaque characteristics (e.g., microchannels (MC) and thin-cap fibroatheroma (TCFA)). The CCTA and IVOCT images of 30 lesions from 25 patients were registered. The vessels with vulnerable plaques were identified from the registered IVOCT images. The PCAT-radiomics features were extracted from the CCTA images for the lesion region of interest (PCAT-LOI) and the entire vessel (PCAT-Vessel). We extracted 1356 radiomic features, including intensity (first-order), shape, and texture features. The features were reduced using standard approaches (e.g., high feature correlation). Using stratified three-fold cross-validation with 1000 repeats, we determined the ability of PCAT-radiomics features from CCTA to predict IVOCT vulnerable-plaque characteristics. In the identification of TCFA lesions, the PCAT-LOI and PCAT-Vessel radiomics models performed comparably (Area Under the Curve (AUC) ± standard deviation 0.78 ± 0.13, 0.77 ± 0.14). For the identification of MC lesions, the PCAT-Vessel radiomics model (0.89 ± 0.09) was moderately better associated than the PCAT-LOI model (0.83 ± 0.12). In addition, both the PCAT-LOI and the PCAT-Vessel radiomics model identified coronary vessels thought to be highly vulnerable to a similar standard (i.e., both TCFA and MC; 0.88 ± 0.10, 0.91 ± 0.09). The most favorable radiomic features tended to be those describing the texture and size of the PCAT. The application of PCAT radiomics can identify coronary vessels with TCFA or MC, consistent with IVOCT. Furthermore, the use of CCTA radiomics may improve risk stratification by noninvasively detecting vulnerable-plaque characteristics that are only visible with IVOCT.

Pericoronary adipose tissue radiomics from coronary CT angiography identifies vulnerable plaques characteristics in intravascular OCT

Pericoronary adipose tissue (PCAT) features on CT have been shown to reflect local inflammation, and signals increased cardiovascular risk. Our goal was to determine if PCAT radiomics extracted from coronary CT angiography (CCTA) images are associated with intravascular optical coherence tomography (IVOCT)-identified vulnerable plaque characteristics (e.g., microchannels [MC] and thin-cap fibroatheroma [TCFA]). CCTA and IVOCT images of 30 lesions from 25 patients were registered. Vessels with vulnerable plaques were identified from the registered IVOCT images. PCAT radiomics features were extracted from CCTA images for the lesion region of interest (PCAT-LOI) and the entire vessel (PCAT-Vessel). We extracted 1356 radiomics features, including intensity (first-order), shape, and texture features. Features were reduced using standard approaches (e.g., high feature correlation). Using stratified three-fold cross-validation with 1000 repeats, we determined the ability of PCAT radiomics features from CCTA to predict IVOCT vulnerable plaque characteristics. In identification of TCFA lesions, PCAT-LOI and PCAT-Vessel radiomics models performed comparably (AUC±standard deviation 0.78±0.13, 0.77±0.14). For identification of MC lesions, PCAT-Vessel radiomics model (0.89±0.09) was moderately better associated than that of PCAT-LOI model (0.83±0.12). Both PCAT-LOI and PCAT-Vessel radiomics models also similarly identified coronary vessels thought to be highly vulnerable (i.e., both TCFA and MC) (0.88±0.10, 0.91±0.09). Favorable radiomics features tended to be those describing texture and size of PCAT. PCAT radiomics can identify coronary vessels with TCFA or MC, consistent with IVOCT. CCTA radiomics may improve risk stratification by noninvasively detecting vulnerable plaque characteristics that are only visible with IVOCT.

Relationship between sexual differences and cardiovascular risk factors in the prevalence of asymptomatic coronary disease

BACKGROUND

This study investigated the sexual differences of coronary artery disease (CAD) prevalence and its association with cardiovascular risk factors in the asymptomatic population.

METHODS

In total 6434 asymptomatic participants without known CAD (1740 women and 4694 men) underwent coronary computed tomography angiography (CCTA). The prevalence of significant CAD (diameter stenosis ≥50%) and other CCTA findings were compared by sex, and its influence on CAD was investigated in groups stratified by the number of cardiovascular risk factors, including age (>55 years), hypertension, diabetes, dyslipidemia, and current smoking.

RESULTS

The prevalence of current smokers, hypertension, and diabetes were higher in men than women. The mean coronary artery calcium score was 13.1 ± 58.4 for women and 51.1 ± 158.2 for men; the coronary atherosclerosis burden indices were significantly higher in men than women. Significant CAD was identified in 65 women (3.7%) and 429 men (9.1%), showing a significant association (adjusted odds ratio [OR] 2.38, P < 0.001). The relatively higher risk for significant CAD in men was observed in patients with fewer risk factors, and the risk difference was not significant in patients with many risk factors (adjusted ORs: 7.69, 3.37, 1.71, 1.31, and 0.88 in patients with 0, 1, 2, 3, and 4-5 risk factors, respectively). The association between sex and risk factor groups was significant (P < 0.001).

CONCLUSIONS

In the asymptomatic population, a significantly higher CAD prevalence was noted in men than women. However, women with a high number of cardiovascular risk factors showed a CAD prevalence similar to that of men.

Prediction of acute myocardial infarction by multi-parameter coronary computed tomography angiography

AIM

To investigate the performance of multi-parameter coronary computed tomography angiography (CCTA), including stenosis, plaque qualitative-quantitative characteristics, and fractional flow reserve derived from CCTA (FFRct), to predict acute myocardial infarction (AMI) and build a combined model.

MATERIALS AND METHODS

Thirty patients with AMI 90 days after CCTA and 120 matched patients without AMI were enrolled retrospectively. Multiple CCTA parameters were analysed and compared. Independent risk factors were obtained through univariate and multivariate regression analyses, after which a multi-parameter model was built.

RESULTS

A total of 150 patients were analysed successfully. The multi-parameter CCTA model (area under the curve, 0.944; p<0.001) had a higher predictive value than each single parameter (p<0.001, all). Independent risk factors were intra-plaque dye penetration (IDP; odds ratio [OR], 8.373; p=0.002), lipid plaque volume (LPV; OR, 1.263; p<0.001), and FFRct ≤0.83 (OR, 8.092; p=0.001).

CONCLUSION

This one-stop multi-parameter CCTA model, comprising IDP, LPV, and FFRct as independent risk factors, has good performance to predict AMI.

Physiologic and compositional coronary artery disease extension in patients with takotsubo syndrome assessed using artificial intelligence: an optical coherence tomography study

BACKGROUND

Takotsubo syndrome (TTS) is an acute and reversible ventricular motion abnormality without epicardial coronary obstruction. Optical flow ratio (OFR) is an approach to evaluate the coronary stenosis significance based on three-dimensional optical coherence tomography (3D-OCT). The aim of this study is to utilize OCT and an artificial intelligence plaque characterization model to show the prevalence and composition of atherosclerotic disease in coronary vessels of patients with TTS.

METHODS

This is a retrospective and observational study which enrolled patients with TTS who underwent coronary angiography and OCT examination. OCT images were analyzed for tissue characterization and OFR computation using a novel artificial intelligence algorithm.

RESULTS

A total of 37 patients and 49 vessels were studied. All patients were imaged in the left anterior descending coronary artery (LAD) and about two-thirds were also imaged in the left circumflex coronary artery (LCX). Most patients were women (n = 35), and apical was the most common takotsubo type. Tissue composition analysis yielded the following overall plaque types: fibrous (67.1%), lipid (15.5%), and calcium (3.77%). The mean OFR for LAD and LCX was 0.97 ± 0.04 and 0.98 ± 0.02, respectively.

CONCLUSION

Utilizing automatic plaque characterization on OCT images by artificial intelligence, we found that TTS patients have coronary artery disease (i.e. presence of lipid, calcified, or fibrous tissue). The advent of artificial intelligence methods may allow for large-scale studies of patients with TTS.

Predicting major adverse cardiac events based on multi-parameter coronary computed tomography angiography

OBJECTIVE

To build a nomogram model to improve the prediction of major adverse cardiac events (MACE) using multi-parameter coronary computed tomography angiography (CCTA).

METHODS

All patients underwent CCTA. Those who developed MACE 90 days later but within 2 years between January 2008 and December 2018 were retrospectively enrolled as MACE group, while those without MACE were 1:1 propensity score matched in the control group. CCTA stenosis, plaque qualitative-quantitative characteristics, and fractional flow reserve derived from computed tomography angiography (FFRct) were analyzed and compared between the two groups. The independent risk factors for predicting MACE were obtained through univariate and multivariate regression analysis, after which multi-parameter models were built to predict MACE. Finally, the nomogram for predicting MACE was created using the independent risk factors from multivariate regression analysis.

RESULTS

A total of 483 vessels in 260 patients were successfully analyzed. The combination of CCTA stenosis, plaque qualitative-quantitative characteristics, and FFRct (AUC = 0.922, P<0.001) showed a higher predictive value compared to CCTA stenosis alone, FFRct alone, plaque qualitative-quantitative characteristics alone, CCTA stenosis combined with plaque qualitative-quantitative characteristics, and CCTA stenosis combined with FFRct (all P <0.001). Independent risk factors were CCTA stenosis ≥50%, low attenuation plaque, positive remodeling, napkin ring sign, lipid plaque volume proportion, and FFRct. Subsequently, a nomogram was created using these independent risk factors.

CONCLUSIONS

The multi-parameter CCTA model has improved performance in predicting MACE. Nomogram for predicting MACE, which includes these factors, represents a practical and easy-to-use method in the clinical setting. This article is protected by copyright. All rights reserved.

Effect of long-term intensive cholesterol control on the plaque progression in elderly based on CTA cohort study

OBJECTIVES

To investigate the long-term effects of intensive LDL cholesterol-lowering treatments on lumen stenosis severity, plaque calcification, spotty calcifications, percent calcified plaque volume (PCPV), and Agatston coronary artery calcium score (CACS) based on coronary computed tomography angiography (CCTA) in elderly patients.

METHODS

A total of 240 patients over 60 years old (comprising 754 lesions) who underwent serial CCTA were retrospectively enrolled in this 5-year cohort study. Patients were divided into three groups: an intensive lipid-lowering group, a lipid-lowering group, and a control group. The stenosis severity, plaque volume (PV), plaque composition, PCPV, and high-risk plaque (HRP) presence were quantitatively analyzed. The CACS was calculated at baseline and follow-up.

RESULTS

All patients were male with an average age of 66.8 ± 5.8 years old. Over time, increases in the percentages of obstructive coronary lesions (p < 0.001) were observed. Compared with those at baseline, the percentage of obstructive lesions remained unchanged (p = 0.077), and the percentage of spotty calcifications significantly decreased (p < 0.05) at the follow-up CCTA scan in the intensive lipid-lowering group. Patients in the intensive lipid-lowering group demonstrated a higher progression in calcified PV, CACS, and PCPV (all p < 0.05), and a significantly greater attenuation in fibrous-fatty and lipid-rich PV (all p < 0.05) than patients in other groups.

CONCLUSIONS

The PV and contents increased gradually with time in all groups. Intensive LDL-C lowering was associated with slower progression of stenosis severity and reduction of high-risk plaque features, with increased plaque calcification and higher progression in PCPV. Comprehensive serial plaque evaluations by CCTAs may contribute to further refinement of risk stratification and reasonable lipid-lowering treatment in elderly patients.

KEY POINTS

• Intensive LDL-C lowering increased coronary calcification and percent calcified plaque volume progression. • Comprehensive serial plaque evaluations by serial CCTAs may help to refine risk stratification.

Role of cardiac CT in the diagnostic evaluation and risk stratification of patients with myocardial infarction and non-obstructive coronary arteries (MINOCA): rationale and design of the MINOCA-GR study

INTRODUCTION

Myocardial infarction with non-obstructive coronary arteries (MINOCA) occurs in 5%-15% of all patients with acute myocardial infarction. Cardiac MR (CMR) and optical coherence tomography have been used to identify the underlying pathophysiological mechanism in MINOCA. The role of cardiac CT angiography (CCTA) in patients with MINOCA, however, has not been well studied so far. CCTA can be used to assess atherosclerotic plaque volume, vulnerable plaque characteristics as well as pericoronary fat tissue attenuation, which has not been yet studied in MINOCA.

METHODS AND ANALYSIS

MINOCA-GR is a prospective, multicentre, observational cohort study based on a national registry that will use CCTA in combination with CMR and invasive coronary angiography (ICA) to evaluate the extent and characteristics of coronary atherosclerosis and its correlation with pericoronary fat attenuation in patients with MINOCA. A total of 60 consecutive adult patients across 4 participating study sites are expected to be enrolled. Following ICA and CMR, patients will undergo CCTA during index hospitalisation. The primary endpoints are quantification of extent and severity of coronary atherosclerosis, description of high-risk plaque features and attenuation profiling of pericoronary fat tissue around all three major epicardial coronary arteries in relation to CMR. Follow-up CCTA for the evaluation of changes in pericoronary fat attenuation will also be performed. MINOCA-GR aims to be the first study to explore the role of CCTA in combination with CMR and ICA in the underlying pathophysiological mechanisms and assisting in diagnostic evaluation and prognosis of patients with MINOCA.

ETHICS AND DISSEMINATION

The study protocol has been approved by the institutional review board/independent ethics committee at each site prior to study commencement. All patients will provide written informed consent. Results will be disseminated at national meetings and published in peer-reviewed journals.

TRIAL REGISTRATION NUMBER

NCT4186676.

Dual-energy CT plaque characteristics of post mortem thin-cap fibroatheroma in comparison to infarct-related culprit lesions

Improvement of non-invasive identification of high-risk plaque may increase the preventive options of acute coronary syndrome. To describe the characteristics of thin-cap fibroatheroma (TCFA) in a post mortem model in comparison to characteristics of culprit lesions in patients with non-ST-elevation-myocardial-infarction (NSTEMI) using the dual energy computed tomography (DECT). Three post mortem hearts were prepared with iodine-contrast, inserted in a Kyoto phantom and scanned by DECT. Six TCFA were identified using histopathological analysis (cap thickness < 65 μm and necrotic core > 10% of the plaque area). In the NSTEMI group, 29 patients were scheduled to DECT prior to coronary angiography and invasive treatment. Culprit lesions were identified blinded for the patient history by two independent invasive cardiologists using the coronary angiography. The DECT analysis of TCFA and culprit lesions was performed retrospectively with determination of effective atomic number (Effective-Z), Hounsfield Unit (HU), plaque type (non-calcified, predominantly non-calcified, predominantly calcified or calcified), spotty calcification,, plaque length, plaque volume and plaque burden and the remodeling index. The Effective-Z, HU and plaqueburden were significantly different between TCFA and culprit lesions (P < 0.05).The TCFA plaques were more calcified in comparison to culprit lesions (P < 0.05). No significant difference in the other plaque characteristics was observed. The use of DECT demonstrated different Effective-Z values and different characteristics of post mortem TCFA in comparison to in vivo culprit lesions. This finding may highlight, that not all TCFA should be considered as vulnerable.

Application of Artificial Intelligence to Cardiovascular Computed Tomography

Cardiovascular computed tomography (CT) is among the most active fields with ongoing technical innovation related to image acquisition and analysis. Artificial intelligence can be incorporated into various clinical applications of cardiovascular CT, including imaging of the heart valves and coronary arteries, as well as imaging to evaluate myocardial function and congenital heart disease. This review summarizes the latest research on the application of deep learning to cardiovascular CT. The areas covered range from image quality improvement to automatic analysis of CT images, including methods such as calcium scoring, image segmentation, and coronary artery evaluation.

CT texture analysis of vulnerable plaques on optical coherence tomography

PURPOSE

To explore whether CT texture analysis can identify thin-cap fibroatheroma (TCFA) determined by optical coherence tomography (OCT).

METHODS

Thirty-three patients with 43 lesions who underwent both CCTA and OCT within 3 months were retrospectively included. 12 conventional CT-derived plaque features, fat attenuation index (FAI) and 1691 plaque radiomics features were extracted to discriminate TCFA lesions and non-TCFA lesions determined by OCT. Minimum redundancy and maximum relevance (mRMR) method was employed to select radiomics features. The top ranked features were used to construct a forward stepwise logistic radiomics model. The performance of radiomics model was compared with the conventional high-risk plaque (HRP) features model and FAI model for the detection of TCFA.

RESULTS

Out of 1691 features, 35 features were significantly different between TCFA and non-TCFA lesions (all p＜0.05) while only low attenuation plaque (LAP) was more frequent in TCFA group (p = 0.004). There was no significant difference in FAI between TCFA and non-TCFA lesions. Five features were ultimately integrated into the radiomics model after mRMR analysis, which demonstrated significantly higher AUC for the detection of TCFA (0.952; 95 % CI: 0.897-1.000) compared with the conventional HRP features model (0.621; 95 % CI: 0.469-0.773, p < 0.001) and FAI model (0.52; 95 % CI: 0.33-0.70, p < 0.001).

CONCLUSION

CT texture analysis performs better at identifying TCFA determined by OCT compared with conventional CT-derived plaque parameters and FAI. Texture analysis may serve as a potential non-invasive method of evaluating vulnerable plaque.

Coronary Computed Tomography (CT) Angiography Characteristics of High-Risk Plaque: Correlation with Stress Myocardial Perfusion Imaging in Patients with Moderate Coronary Stenosis

Background

The aim of this study was to investigate the ability of coronary computed tomographic angiography (CCTA) characteristics of high-risk plaque (HRP) in moderate stenosis to improve differentiation of myocardial ischemia detected by stress CT perfusion (CTP) imaging.

Material/Methods

Sixty-two patients with coronary plaques and moderate stenosis confirmed by invasive coronary angiography (ICA) had stress CTP and 26 of these patients were found to have myocardial ischemia. The other 36 patients without myocardial ischemia were defined as controls. Characteristics of major plaques on CCTA images of the ischemia and non-ischemia groups were analyzed and compared.

Results

Differences between the 2 groups were observed in plaque volume, burden and rough inner surface necrotic core volume, plaque-lipid interface and plaque length. In a multivariable analysis, plaque burden and necrotic core volume were significantly associated with myocardial ischemia: plaque burden odds ratio (OR) was 1.28 (95% confidence interval [CI], 1.12–1.48); necrotic core volume OR was 1.78 (95% CI, 1.03–1.34). Compared with other quantitative measurements, optimized thresholds for plaque burden (area under the curve was 0.852) and necrotic core volume (area under the curve was 0.730) showed significantly higher diagnostic performance for ischemia with threshold values of 60.8% and 11.25 mm³, respectively.

Conclusions

CCTA characteristics of major plaques may improve the discrimination of ACS patients with myocardial ischemia on stress CTP.

Prognostic Value of Coronary Computed Tomography Angiography-derived Morphologic and Quantitative Plaque Markers Using Semiautomated Plaque Software

PURPOSE

In this study, we analyzed the prognostic value of coronary computed tomography angiography-derived morphologic and quantitative plaque markers and plaque scores for major adverse cardiovascular events (MACEs).

MATERIALS AND METHODS

We analyzed the data of patients with suspected coronary artery disease (CAD). Various plaque markers were obtained using a semiautomated software prototype or derived from the results of the software analysis. Several risk scores were calculated, and follow-up data concerning MACE were collected from all patients.

RESULTS

A total of 131 patients (65±12 y, 73% male) were included in our study. MACE occurred in 11 patients within the follow-up period of 34±25 months.CAD-Reporting and Data System score (odds ratio [OR]=11.62), SYNTAX score (SS) (OR=1.11), Leiden-risk score (OR=1.37), segment involvement score (OR=1.76), total plaque volume (OR=1.20), and percentage aggregated plaque volume (OR=1.32) were significant predictors for MACE (all P≤0.05). Moreover, the difference of the corrected coronary opacification (ΔCCO) correlated significantly with the occurrence of MACE (P<0.0001). The CAD-Reporting and Data System score, SS, and Leiden-risk score showed substantial sensitivity for predicting MACE (90.9%). The SS and Leiden-risk score displayed high specificities of 80.8% and 77.5%, respectively. These plaque markers and risk scores all provided high negative predictive value (>90%).

CONCLUSION

The coronary computed tomography angiography-derived plaque markers of segment involvement score, total plaque volume, percentage aggregated plaque volume, and ΔCCO, and the risk scores exhibited predictive value for the occurrence of MACE and can likely aid in identifying patients at risk for future cardiac events.

Cardiac Computed Tomography

Unstable coronary plaques that are prone to erosion and rupture are the major cause of acute coronary syndromes. Our expanding understanding of the biological mechanisms of coronary atherosclerosis and rapid technological advances in the field of medical imaging has established cardiac computed tomography as a first-line diagnostic test in the assessment of suspected coronary artery disease, and as a powerful method of detecting the vulnerable plaque and patient. Cardiac computed tomography can provide a noninvasive, yet comprehensive, qualitative and quantitative assessment of coronary plaque burden, detect distinct high-risk morphological plaque features, assess the hemodynamic significance of coronary lesions and quantify the coronary inflammatory burden by tracking the effects of arterial inflammation on the composition of the adjacent perivascular fat. Furthermore, advances in machine learning, computational fluid dynamic modeling, and the development of targeted contrast agents continue to expand the capabilities of cardiac computed tomography imaging. In our Review, we discuss the current role of cardiac computed tomography in the assessment of coronary atherosclerosis, highlighting its dual function as a clinical and research tool that provides a wealth of structural and functional information, with far-reaching diagnostic and prognostic implications.

Diagnostic Accuracy of 320-Row Computed Tomography for Characterizing Coronary Atherosclerotic Plaques: Comparison with Intravascular Optical Coherence Tomography

BACKGROUND/PURPOSE

This study sought to determine the diagnostic accuracy of 320-row computed tomography (320CT) for characterizing coronary atherosclerotic plaques in comparison with optical coherence tomography (OCT).

METHODS/MATERIALS

From 32 patients, 42 coronary segments were evaluated and co-registered by both 320CT and OCT. 320CT vulnerable plaque characteristics included low attenuation plaque (LAP) (<30HU), napkin-ring sign (NRS), positive remodeling (PR) and spotty calcification (SC). The presence of macrophage, neovascularization and cholesterol crystals was also determined by OCT.

RESULTS

Minimal lumen area was 2.78 ± 1.23 mm by OCT and 3.29 ± 1.49 mm by 320CT (p < 0.001). Noncalcified plaques were classified accordingly by both methods in 88.2% of the cases (p = 0.005). There was no association between any 320CT plaque type and OCT fibroatheroma (p = 0.62). The combination of 2 or more of the 320CT vulnerable plaque characteristics was associated with the presence of macrophage (74.2 vs. 25.8%; p = 0.034) and cholesterol crystals (85.7 vs. 14.3%; p = 0.04), but not with neovascularization (p = 0.65). The presence of all four characteristics demonstrated an accuracy of 75.1% for detecting OCT fibroatheroma.

CONCLUSIONS

320CT is useful for non-invasive evaluation of calcified and noncalcified tissue characteristics of coronary atheroma. The combination of all four 320CT vulnerable plaque characteristics provided the highest accuracy for detecting fibroatheromas.

SUMMARY

320CT is useful for non-invasive evaluation of calcified and noncalcified tissue characteristics of coronary atheroma. The combination of all 320CT vulnerable plaque characteristics (low attenuation plaque (<30HU), napkin-ring sign, positive remodeling and spotty calcification) provided the highest accuracy for detecting fibroatheromas compared to optical coherence tomography.

Aortic and Internal Carotid Atherosclerosis in Patients with Carotid Stenosis: Semiautomatic Volumetric Analysis of Low-Attenuation Plaque on Curved Planar Reformations Using MDCT Angiographic Data

This retrospective study included 65 patients who underwent multidetector computed tomography (MDCT) carotid angiography; 28 patients were <70 years old (group 1), and 37 were ≥70 years old (group 2). Each low-attenuation (<30 Hounsfield units [HU]) plaque volume (LPV) and total uncalcified plaque volume ([TUPV] ≤150 HU) were semiautomatically measured on each aortic arch and internal carotid artery (ICA) curved planar reformations (CPR), using MDCT angiographic data. Correlation coefficients were employed to assess the impact of each plaque volume on various factors including ICA stenosis. The correlations (r > 0.5) were observed between aortic LPV and each ICA stenosis ratio and >30% stenosis in group 1, between aortic TUPV and male gender in group 1, and between ICA-TUPV and each aortic TUPV or the largest plaque thickness in group 2. Marginal correlations were observed between hyperlipidemia and aortic LPV and ICA-TUPV in group 1. There was no association between cerebral infarction and the aortic and ICA plaques. Both the aortic arch and ICA plaque volumes can be measured clinically. The increasing aortic LPV may be a significant factor associated with the development of ICA stenosis in patients younger than 70 years old.

Semiautomatic Volumetry of Low Attenuation of Thoracic Aortic Plaques on Curved Planar Reformations Using MDCT Angiographic Data with 0.5 mm Collimation

To evaluate the relationship of aortic low attenuation plaque volume (LAPV) on multidetector computed tomography (MDCT) with the abdominal aortic aneurysm (AAA), the coronary arterial disease (CAD, ≥50% stenosis), severe (≥90% stenosis) CAD, hypertension, and long-term (≥10 years) hypertension. Curved planar reformations (CPR) of three segments (the ascending, the arch, and the upper descending aorta) of the thoracic aorta were generated with attenuation-dependent color codes to measure LAPV with 0~29 HU and total noncalcified plaque volume (TNPV) with 0~150 HU in 95 patients. Correlation coefficients were employed to assess the impact of each LAPV and TNPV on AAA, CAD, severe CAD, hypertension, and long-term hypertension. Each Mean LAPV/cm and TNPV/cm was statistically greater in the aortic arch than the ascending (p < 0.001 on each) or the proximal descending segment (p < 0.001 on each). LAPV in the aortic arch has moderate correlations with AAA, severe CAD, and long-term hypertension (r = 0.643, 0.639, 0.662, resp.). Plaque volumes in each aortic segment can be measured clinically and the increasing LAPV in the arch may be a significant factor associated with the development of severe atherosclerosis underlying AAA, severe CAD, and long-term hypertension.