Noninvasive Coronary Plaque Imaging

Multimodal Intravascular Imaging of the Vulnerable Coronary Plaque

Vulnerable coronary plaques are atherosclerotic lesions which, due to their specific phenotype, are prone to plaque rupture and to cause acute coronary syndromes, with subsequent relevant morbidity and mortality. Strategies to break the chain link between plaque vulnerability and adverse clinical events include optimized pharmacologic prevention and potentially also preemptive percutaneous coronary interventions (previously defined as "plaque sealing" or "plaque passivation"). Various morphologic features of the vulnerable plaques have been described, including aspects regarding the large necrotic lipid content, the thin fibrous cap, the presence and extent of the presence of calcifications with small size and calcification angle, and as well as the large macrophage infiltration within the plaque. The detection of these features of plaque vulnerability is possible with intravascular imaging modalities such as intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and optical coherence tomography (OCT). This review explores the peculiarities of these three imaging modalities for the detection of vulnerable coronary plaque features.

Diagnostic Methods of Atherosclerotic Plaque and the Assessment of Its Prognostic Significance-A Narrative Review

Cardiovascular diseases (CVD) are a leading cause of death. The most notable cause of CVD is an atherosclerotic plaque. The aim of this review is to provide an overview of different diagnostic methods for atherosclerotic plaque relevant to the assessment of cardiovascular risk. The methods can be divided into invasive and non-invasive. This review focuses on non-invasive with attention paid to ultrasonography, contrast-enhanced ultrasonography, intravascular ultrasonography, and assessment of intima-media complex, coronary computed tomography angiography, and magnetic resonance. In the review, we discuss a number of Artificial Intelligence technologies that support plaque imaging.

Update on cardiac imaging: A critical analysis

Imaging is instrumental in diagnosing and directing the management of atherosclerosis. In 1958 the first diagnostic coronary angiography (CA) was performed, and since then further development has led to new methods such as coronary CT angiography (CTA), optical coherence tomography (OCT), positron tomography (PET), and intravascular ultrasound (IVUS). Currently, CA remains powerful for visualizing coronary arteries; however, recent studies show the benefits of using other non-invasive techniques. This review identifies optimum imaging techniques for diagnosing and monitoring plaque stability. This becomes even direr now, given the rapidly rising incidence of atherosclerosis in society today. Many acute coronary events, including acute myocardial infarctions and sudden deaths, are attributable to plaque rupture. Although fatal, these events can be preventable. We discuss the factors affecting plaque integrity, such as increased inflammation, medications like statins, and increased lipid content. Some of these precipitating factors are identifiable through imaging. However, we also highlight significant complications arising in some modalities; in CA this can include ventricular arrhythmia and even death. Extending this, we elucidated from the literature that risk can also vary based on the location of arteries and their plaques. Promisingly, there are less invasive methods being trialled for assessing plaque stability, such as Cardiac Magnetic Resonance Imaging (CMR), which is already in use for other cardiac diseases like cardiomyopathies. Therefore, future research focusing on using imaging modalities in conjunction may be sensible, to bridge between the effectiveness of modalities, at the expense of increased complications, and vice versa.

EXPRESSION OF GENES OF BIOMOLECULES ASSOCIATED WITH THE ETIOPATHOGENESIS OF ATHEROSCLEROSIS IN ATHEROSCLEROTIC PLAQUES OF CORONARY ARTERIES

Highlights

The study showed differences in the expression of a number of genes in atherosclerotic plaques of different types in patients with coronary atherosclerosis. The obtained data can become the basis for the development of test systems in order to determine the dynamics of the atherosclerotic process and detect signs of destabilization of the atherosclerotic plaque as early as possible.

 

Aim. To study the differential expression of genes encoding molecules associated with the etiopathogenesis of atherosclerosis by the method of genome-wide RNA sequencing in stable atherosclerotic plaque of fibrous type and unstable atherosclerotic plaque of dystopic-necrotic type.

Methods. The study was performed on samples of atherosclerotic plaques of patients with coronary atherosclerosis without acute coronary syndrome with stable angina pectoris of functional class II–IV (FC) at the age of 45-65 years. Tissue sampling of atherosclerotic plaques was performed intraoperatively in the presence of indications. Genome-wide RNA sequencing was performed using Illumina’s TruSeq RNA Sample Preparation Kit (Illumina, USA).

Results. An increase in the level of gene expression in stable atherosclerotic plaques was noted for A2M, ADAMTS13, CSF3, CX3CL1, CXCL1, FGF2, GDF15, ICAM1, IL1A, IL1B, IL6, IL10, PDGFA, PTX3. There was an eightfold statistically significant increase in the level of CFD, CXCL16, FABP4, FLT3, IFNG, IL7, IL15, SELL, TGFA, THBD, TNNT1, VCAM1 and VEGFA gene expression (p<0,001) in unstable atherosclerotic plaques of dystrophic-necrotic type.

Conclusion. The study showed differences in the expression of a number of genes in atherosclerotic plaques of different types in patients with coronary atherosclerosis. The obtained data can become the basis for the development of test systems in order to determine the dynamics of the atherosclerotic process and detect signs of destabilization of the atherosclerotic plaque as early as possible.

Evolving concepts of the vulnerable atherosclerotic plaque and the vulnerable patient: implications for patient care and future research

Understanding the natural history of coronary artery atherosclerosis is necessary to determine prognosis and prescribe effective therapies. Traditional management of coronary artery disease has focused on the treatment of flow-limiting anatomical obstructions that lead to ischaemia. In most scenarios, revascularization of these atherosclerotic plaques has not substantially improved freedom from death or myocardial infarction, questioning the utility of contemporary revascularization strategies to improve prognosis. Advances in non-invasive and invasive imaging techniques have helped to identify the characteristics of obstructive and non-obstructive plaques that are precursors for plaque progression and future acute coronary syndromes as well as cardiac death. These 'vulnerable plaques' develop as a consequence of systemic inflammation and are prone to inducing thrombosis. Vulnerable plaques most commonly have a large plaque burden with a well-formed necrotic core and thin fibrous cap and are metabolically active. Perivascular adipose tissue might, in some patients, be used as a surrogate for coronary inflammation and predict future risk of adverse cardiac events. Vulnerable plaques can be identified in their quiescent state, offering the potential for therapeutic passivation. In this Review, we describe the biological and compositional features of vulnerable plaques, the non-invasive and invasive diagnostic modalities to characterize vulnerable plaques, the prognostic utility of identifying vulnerable plaques, and the future studies needed to explore the value of intensified pharmacological and focal treatments of vulnerable plaques.

Characteristics of Calcification and Their Association with Carotid Plaque Vulnerability

BACKGROUND

Carotid plaque vulnerability is one of the important features for evaluating the risk of subsequent ischemic stroke. Although magnetic resonance imaging (MRI) is the gold standard modality for evaluating plaque vulnerability, some patients cannot undergo MRI because of physical or economic issues. Computed tomography (CT) is more readily available. The purpose of this study was to establish a new category of calcification on CT and to assess its usefulness for detecting vulnerable plaque.

MATERIALS AND METHODS

We retrospectively evaluated consecutive patients who underwent plaque imaging using CT and MRI before carotid revascularization at our institute. Calcifications were classified into 4 types according to the new calcium classification. The patients were divided into 2 groups, the double layer sign (DLS)-positive group and the DLS-negative group. Signal intensity ratio (SIR) of carotid plaque was measured on MRI for evaluating plaque vulnerability and compared between type of calcification and SIR.

RESULTS

Among the 132 patients evaluated, 50 patients (62.5%) in DLS positive group and 16 patients (30.8%) in DLS negative group had calcification with vulnerable plaque (SIR > 1.47) (P < 0.01). Substantial interobserver agreement of type of calcification was observed (kappa, 0.79; P < 0.01). Multivariate analysis showed that DLS (odds ratio 3.03; 95% confidence interval 1.35-6.8; P < 0.01) and male sex (odds ratio 3.15; 95% confidence interval 1.02-9.68; P = 0.04) were independent predictors of vulnerable plaque.

CONCLUSIONS

DLS in our new classification of calcification on CT reliably detects vulnerable plaque and could thus be used in patients who cannot undergo MRI.

Cardiac MR: From Theory to Practice

Cardiovascular disease (CVD) is the leading single cause of morbidity and mortality, causing over 17. 9 million deaths worldwide per year with associated costs of over $800 billion. Improving prevention, diagnosis, and treatment of CVD is therefore a global priority. Cardiovascular magnetic resonance (CMR) has emerged as a clinically important technique for the assessment of cardiovascular anatomy, function, perfusion, and viability. However, diversity and complexity of imaging, reconstruction and analysis methods pose some limitations to the widespread use of CMR. Especially in view of recent developments in the field of machine learning that provide novel solutions to address existing problems, it is necessary to bridge the gap between the clinical and scientific communities. This review covers five essential aspects of CMR to provide a comprehensive overview ranging from CVDs to CMR pulse sequence design, acquisition protocols, motion handling, image reconstruction and quantitative analysis of the obtained data. (1) The basic MR physics of CMR is introduced. Basic pulse sequence building blocks that are commonly used in CMR imaging are presented. Sequences containing these building blocks are formed for parametric mapping and functional imaging techniques. Commonly perceived artifacts and potential countermeasures are discussed for these methods. (2) CMR methods for identifying CVDs are illustrated. Basic anatomy and functional processes are described to understand the cardiac pathologies and how they can be captured by CMR imaging. (3) The planning and conduct of a complete CMR exam which is targeted for the respective pathology is shown. Building blocks are illustrated to create an efficient and patient-centered workflow. Further strategies to cope with challenging patients are discussed. (4) Imaging acceleration and reconstruction techniques are presented that enable acquisition of spatial, temporal, and parametric dynamics of the cardiac cycle. The handling of respiratory and cardiac motion strategies as well as their integration into the reconstruction processes is showcased. (5) Recent advances on deep learning-based reconstructions for this purpose are summarized. Furthermore, an overview of novel deep learning image segmentation and analysis methods is provided with a focus on automatic, fast and reliable extraction of biomarkers and parameters of clinical relevance.

18F-Sodium fluoride uptake is associated with severity of atherosclerotic stenosis in stable ischemic heart disease

BACKGROUND

Increased uptake of 18F-Sodium fluoride (18F-NaF) PET has potential to identify atherosclerotic plaques that are vulnerable to rupture. Whether 18F-NaF PET can evaluate the significance of atherosclerotic plaque in patients with stable coronary artery disease is less clear. We evaluated 18F-NaF PET uptake in coronary arteries in patients without acute coronary artery syndrome to determine the association of 18F-NaF signal uptake with severity of coronary stenosis.

METHODS AND RESULTS

We retrospectively identified 114 patients who received both regadenoson stress 82Rb myocardial perfusion PET and 18F-NaF PET study with an average interval of 5 months. Out of this cohort, forty-one patients underwent invasive coronary angiography. In a patient-based analysis, patients with ischemic regadenoson stress 82Rb PET had significantly higher coronary 18F-NaF uptake than patients with normal myocardial perfusion (P < .01). Among the 41 patients who underwent coronary angiography, per-vessel 18F-NaF uptake in both obstructive and nonobstructive coronary arteries was significantly higher than in normal coronary arteries (P < .05) regardless of the severity of coronary calcification. There was poor correlation between calcification and 18F-NaF uptake in coronary arteries (r = 0.41) CONCLUSION: Coronary arterial 18F-NaF uptake is associated with coronary stenosis severity in patients with stable coronary artery disease. 18F-NaF PET studies may be useful for characterizing coronary atherosclerotic plaques.

Abdominal subcutaneous adipose tissue negatively associates with subclinical coronary artery disease in men with psoriasis

Objective

Understand the relationship between abdominal subcutaneous adipose tissue (ASAT) and coronary atherosclerosis defined as noncalcified and lipid-rich necrotic core burden in psoriasis.

Methods

We performed a cross-sectional study of 232 participants (92 women) with psoriasis and without known cardiovascular disease. Participants underwent coronary computed tomography angiography to characterize coronary atherosclerosis burden and low dose abdominal computed tomography to quantify subcutaneous and visceral adipose tissue. Fat depot volumes were first adjusted for each participant's BMI (ASAT_adjBMI).

Results

In women, there was a positive correlation between ASAT_adjBMI and systemic inflammation as assessed by hs-C-reactive protein (r=0.30; p=.004) and GlycA (r=0.29; p=.007) as well as total cholesterol (r=0.24; p=.02) and low-density lipoprotein cholesterol (r=0.22; p=.04). In men, ASAT_adjBMI correlated with hs-C-reactive protein (r=0.18; p=.04) and insulin resistance (r=0.17; p=.04). In models fully adjusted for traditional cardiovascular risk factors, ASAT_adjBMI negatively associated with noncalcified and lipid-rich necrotic core burden in men (β= -0.17; p=.03, β= -0.20; p=.03, respectively), but not women (β= -0.06; p=.57, β= 0.09; p=.49, respectively) with psoriasis.

Conclusions

For a given BMI, ASAT negatively associated with coronary atherosclerosis burden in male participants with psoriasis. The observed sex-specific effects warrant further study of ASAT in states of chronic inflammation.

High-risk coronary plaque in SLE: low-attenuation non-calcified coronary plaque and positive remodelling index

Background

Positive remodelling index and presence of low-attenuation non-calcified plaque (LANCP) are characteristic vessel changes in unstable coronary plaques. We sought to characterise these high-risk plaque features in patients with systemic lupus erythematosus (SLE) and to compare them with controls.

Methods

A total of 72 patients who satisfied the SLICC classification criteria for SLE had coronary CT angiography (CCTA) studies, 30 of which had follow-up CCTA, as screening for occult coronary atherosclerotic disease in asymptomatic individuals. A total of 100 consecutive controls with no known history of lupus, heart disease or revascularisation who had two coronary CT angiograms at least 1 year apart were included in the study. These were asymptomatic patients referred by their primary physicians for screening of coronary artery disease and the screening interval was decided by the primary physicians. The methodology for image acquisition was identical.

Results

LANCP burden at baseline was significantly greater in patients with SLE compared with controls. LANCP volume was significantly greater in patients over 60 years of age (p<0.05) and in those with current prednisone dose >10 mg/day. LANCP burden remained stable over follow-up. There were no significant differences in remodelling index compared with controls.

Conclusion

This is the first study describing high-risk CCTA features of coronary plaque in patients with SLE. Both LANCP and positive remodelling are common in SLE. These characteristic vessel changes may identify patients with SLE at increased risk of cardiovascular events and those in need for more frequent cardiac monitoring.

Subclinical Liver Disease is Associated with Subclinical Atherosclerosis in Psoriasis: Results from Two Observational Studies

Psoriasis is associated with a higher risk of liver diseases. We investigated the impact of hepatic steatosis (European cohort) and hepatic inflammation (United States cohort) on subclinical atherosclerosis. In the European cohort (n=76 psoriasis participants and 76 controls), non-alcoholic fatty liver disease (NAFLD), assessed by the sonographic hepatorenal index (SHRI), was more prevalent in psoriasis than controls (61% vs 45%; p=.04). Psoriasis participants with NAFLD had a higher prevalence of subclinical atherosclerosis (ultrasonographic presence of plaque in femoral or carotid arteries) than psoriasis without NAFLD (61% vs 23%; p=.006) and controls with NAFLD (61% vs 32%; p<.05). SHRI was a determinant of subclinical atherosclerosis in psoriasis (OR, 3.5; p=.01). In the United States cohort, (n=162 psoriasis participants who underwent positron emission tomography and coronary CT angiography), those with high hepatic ¹⁸F-FDG uptake had higher noncalcified (1.3 (0.49 mm²) vs 1.0 (0.40 mm²)), fibrofatty (0.23 (0.15 mm²) vs 0.11 (0.087 mm²)), and lipid rich necrotic core (4.3 (2.3 mm²) vs 3.0 (1.7 mm²)) coronary burden (all p<.001,). Hepatic ¹⁸F-FDG uptake associated with noncalcified (β=0.28; p<.001), fibrofatty (β=0.49; p<.001) and lipid rich necrotic core (β=0.28; p=.003) burden. These results demonstrate the downstream cardiovascular effects of subclinical liver disease in psoriasis.

Metabolic syndrome and its factors are associated with noncalcified coronary burden in psoriasis: An observational cohort study

BACKGROUND

Psoriasis is associated with a heightened risk of cardiovascular disease and higher prevalence of metabolic syndrome.

OBJECTIVE

Investigate the effect of metabolic syndrome and its factors on early coronary artery disease assessed as noncalcified coronary burden by coronary computed tomography angiography in psoriasis.

METHODS

This cross-sectional study consisted of 260 participants with psoriasis and coronary computed tomography angiography characterization. Metabolic syndrome was defined according to the harmonized International Diabetes Federation criteria.

RESULTS

Of the 260 participants, 80 had metabolic syndrome (31%). The metabolic syndrome group had a higher burden of cardiometabolic disease, systemic inflammation, noncalcified coronary burden, and high-risk coronary plaque. After adjusting for Framingham risk score, lipid-lowering therapy, and biologic use, metabolic syndrome (β = .31; P < .001) and its individual factors of waist circumference (β = .33; P < .001), triglyceride levels (β = .17; P = .005), blood pressure (β = .18; P = .005), and fasting glucose (β = .17; P = .009) were significantly associated with noncalcified coronary burden. After adjusting for all other metabolic syndrome factors, blood pressure and waist circumference remained significantly associated with noncalcified coronary burden.

LIMITATIONS

Observational nature with limited ability to control for confounders.

CONCLUSIONS

In psoriasis, individuals with metabolic syndrome had more cardiovascular disease risk factors, systemic inflammation, and noncalcified coronary burden. Efforts to increase metabolic syndrome awareness in psoriasis should be undertaken to reduce the heightened cardiovascular disease risk.

Coronary Magnetic Resonance Angiography: Technical Innovations Leading Us to the Promised Land?

Coronary artery disease remains the leading cause of cardiovascular morbidity and mortality. Invasive X-ray angiography and coronary computed tomography angiography are established gold standards for coronary luminography. However, they expose patients to invasive complications, ionizing radiation, and iodinated contrast agents. Among a number of imaging modalities, coronary cardiovascular magnetic resonance (CMR) angiography may be used in some cases as an alternative for the detection and monitoring of coronary arterial stenosis, with advantages including its versatility, excellent soft tissue characterization, and avoidance of ionizing radiation and iodinated contrast agents. In this review, we explore the recent advances in motion correction, image acceleration, and reconstruction technologies that are bringing coronary CMR angiography closer to widespread clinical implementation.

A review of serial coronary computed tomography angiography (CTA) to assess plaque progression and therapeutic effect of anti-atherosclerotic drugs

Change in coronary artery plaque on serial catheter intravascular ultrasound (IVUS) is an established technique to monitor the therapeutic effect of drugs on coronary atherosclerosis. Recent advances in coronary computed tomography angiography (CTA) now allow for non-invasive assessment of change in coronary plaque. Because coronary CTA is noninvasive, it enables clinical trials with lower-risk populations, higher retention rates, and lower costs. This review presents an overview of serial coronary CTA as a noninvasive imaging technique to gauge the therapeutic effect of anti-atherosclerotic therapies. Furthermore, it reviews the increasing use of serial CTA as an imaging endpoint in completed and ongoing clinical trials.

Network Medicine: A Clinical Approach for Precision Medicine and Personalized Therapy in Coronary Heart Disease

Early identification of coronary atherosclerotic pathogenic mechanisms is useful for predicting the risk of coronary heart disease (CHD) and future cardiac events. Epigenome changes may clarify a significant fraction of this "missing hereditability", thus offering novel potential biomarkers for prevention and care of CHD. The rapidly growing disciplines of systems biology and network science are now poised to meet the fields of precision medicine and personalized therapy. Network medicine integrates standard clinical recording and non-invasive, advanced cardiac imaging tools with epigenetics into deep learning for in-depth CHD molecular phenotyping. This approach could potentially explore developing novel drugs from natural compounds (i.e. polyphenols, folic acid) and repurposing current drugs, such as statins and metformin. Several clinical trials have exploited epigenetic tags and epigenetic sensitive drugs both in primary and secondary prevention. Due to their stability in plasma and easiness of detection, many ongoing clinical trials are focused on the evaluation of circulating miRNAs (e.g. miR-8059 and miR-320a) in blood, in association with imaging parameters such as coronary calcifications and stenosis degree detected by coronary computed tomography angiography (CCTA), or functional parameters provided by FFR/CT and PET/CT. Although epigenetic modifications have also been prioritized through network based approaches, the whole set of molecular interactions (interactome) in CHD is still under investigation for primary prevention strategies.