Quantification of carotid plaque lipid content with magnetic resonance T2 mapping in patients undergoing carotid endarterectomy

T1-T2 Mismatch Sign as a Predictor of Ipsilateral Ischemic Change After Carotid Artery Stenting

BACKGROUND

Magnetic resonance (MR)-plaque imaging reflects the characteristics of carotid plaque. We evaluated the relationship between MR-plaque images and ischemic change after carotid artery stenting (CAS).

METHODS

MR-plaque images were acquired from patients with carotid artery stenosis before CAS treatment. We calculated the relative signal intensity of plaque components compared with that of the sternocleidomastoid muscle and evaluated the presence/absence of T1-T2 mismatch and match sign. We then assessed the appearance of new ischemic lesions after CAS on diffusion-weighted imaging (DWI). Factors associated with the appearance of a high-intensity lesion on DWI were retrospectively analyzed.

RESULTS

A total of 64 patients with carotid artery stenoses treated with CAS were included in this study. In univariate analysis, T1-T2 mismatch sign was associated with the appearance of high-intensity lesions on DWI after CAS (odds ratio [OR], 12.00; 95% confidence interval [CI], 3.593-40.072; P < 0.0001), whereas T1-T2 match sign and high intensity on T2-weighted imaging were negatively associated (OR, 0.061, 95% CI, 0.007-0.502, P = 0.009 and OR, 0.085; 95% CI, 0.022-0.334, P = 0.0004, respectively). In multivariate logistic regression analysis, T1-T2 mismatch sign was independently associated with the appearance of a high-intensity lesion on DWI after CAS (OR, 16.695; 95% CI, 1.324-210.52; P = 0.0295).

CONCLUSIONS

T1-T2 mismatch sign on MR-plaque imaging is significantly associated with the appearance of new ischemic lesions after CAS. T1-T2 mismatch sign may be useful in considering treatment strategies for carotid artery stenosis.

10-channel phased-array coil for carotid wall MRI at 3T

BACKGROUND

Accurate assessment of plaque accumulation near the carotid bifurcation is important for the effective prevention and treatment of stroke. However, vessel and plaque delineation using MRI can be limited by low contrast-to-noise ratio (CNR) and long acquisition times. In this work, a 10-channel phased-array receive coil design for bilateral imaging of the carotid bifurcation using 3T MRI is proposed.

METHODS

The proposed 10-channel receive coil was compared to a commercial 4-channel receive coil configuration using data acquired from phantoms and healthy volunteers (N = 9). The relative performance of the coils was assessed, by comparing signal-to-noise ratio (SNR), noise correlation, g-factor noise amplification, and the CNR between vessel wall and lumen using black-blood sequences. Patient data were acquired from 12 atherosclerotic carotid artery disease patients.

RESULTS

The 10-channel coil consistently provided substantially increased SNR in phantoms (+77 ± 27%) and improved CNR in healthy carotid arteries (+62 ± 11%), or reduced g-factor noise amplification. Patient data showed excellent delineation of atherosclerotic plaque along the length of the carotid bifurcation using the 10-channel coil.

CONCLUSIONS

The proposed 10-channel coil design allows for improved visualization of the carotid arteries and the carotid bifurcation and increased parallel imaging acceleration factors relative to a commercial 4-channel coil design.

Advances in Cardiovascular Pharmacology in Atherosclerotic-Related Therapeutic Areas: Addressing Patients' Clinical Needs

Over the last three decades, a significant improvement has been achieved in reducing cardiovascular morbidity and mortality [...].

Novel Applications for Invasive and Non-invasive Tools in the Era of Contemporary Percutaneous Coronary Revascularisation

Percutaneous coronary intervention (PCI) is an expanding treatment option for patients with coronary artery disease (CAD). It is considered the default strategy for the unstable presentation of CAD. PCI techniques have evolved over the last 4 decades with significant improvements in stent design, an increase in functional assessment of coronary lesions, and the use of intra-vascular imaging. Nonetheless, the morbidity and mortality related to CAD remain significant. Advances in technology have allowed a better understanding of the nature and progression of CAD. New tools are now available that reflect the pathophysiological changes at the level of the myocardium and coronary atherosclerotic plaque. Certain changes within the plaque would render it more prone to rupture leading to acute vascular events. These changes are potentially detected using novel tools invasively, such as near infra-red spectroscopy, or non-invasively using T2 mapping cardiovascular magnetic resonance imaging (CMR) and ¹⁸F-Sodium Fluoride positron emission tomography/ computed tomography. Similarly, changes at the level of the injured myocardium are feasibly assessed invasively using index microcirculatory resistance or non-invasively using T1 mapping CMR. Importantly, these changes could be detected immediately with the opportunity to tailor treatment to those considered at high risk. Concurrently, novel therapeutic options have demonstrated promising results in reducing future cardiovascular risks in patients with CAD. This Review article will discuss the role of these novel tools and their applicability in employing a mechanical and pharmacological treatment to mitigate cardiovascular risk in patients with CAD.

Intensive lipid-lowering therapy, time to think beyond low-density lipoprotein cholesterol

Statins have been shown to be effective in reducing cardiovascular events. Their magnitude of benefits has been proportionate to the reduction in low-density lipoprotein cholesterol (LDL-c). Intensive lipid-lowering therapies using ezetimibe and more recently proprotein convertase subtilisin kexin 9 inhibitors have further improved clinical outcomes. Unselective application of these treatments is undesirable and unaffordable and, therefore, has been guided by LDL-c level. Nonetheless, the residual risk in the post-statin era is markedly heterogeneous, including thrombosis and inflammation risks. Moreover, the lipo-protein related risk is increasingly recognised to be related to other non-LDL-c markers such as Lp(a). Emerging data show that intensive lipid-lowering therapy produce larger absolute risk reduction in patients with polyvascular disease, post coronary artery bypass graft and diabetes. Notably, these clinical entities share similar phenotype of large burden of atherosclerotic plaques. Novel plaque imaging may aid decision making by identifying patients with propensity to develop lipid rich plagues at multi-vascular sites. Those patients may be suitable candidates for intensive lipid lowering treatment.

Colchicine in Patients with Coronary Artery Disease with or Without Diabetes Mellitus: A Meta-analysis of Randomized Clinical Trials

BACKGROUND AND OBJECTIVES

Whether the anti-inflammatory drug colchicine has a differential treatment effect according to diabetes mellitus status in patients with coronary artery disease has never been studied. Therefore, the aim of the present meta-analysis was to evaluate whether the use of colchicine in patients with coronary artery disease with diabetes was associated with a higher magnitude of benefits compared to patients with coronary artery disease without diabetes.

METHODS

Electronic databases were searched through June 2020 to identify randomized clinical trials using colchicine in patients with coronary artery disease. Studies using blood biomarkers, such as troponin or high-sensitive C-reactive protein, as well as angiographic endpoints were excluded. The primary endpoint was major cardiovascular events as defined by the included studies.

RESULTS

In total, 11,594 patients from four randomized trials were included of whom 2278 (19.6%) had diabetes and 5540 (47.8%) presented with acute coronary syndrome. Colchicine was associated with almost twice the absolute risk reduction in patients with diabetes {absolute risk difference (ARD) - 3.94 [95% confidence interval (CI) - 1.28 to - 6.6], p = 0.004} compared with those without diabetes [ARD - 2.32 (95% CI - 1.32 to - 3.31), p < 0.001]. The magnitude of ARD between colchicine and placebo was significantly larger in patients with diabetes compared with patients without diabetes [ARD 1.62 (95% CI 1.43-1.81), p < 0.001]. When the analysis was restricted to patients presenting with acute coronary syndrome, the differential treatment effect of colchicine was more pronounced in patients with diabetes [ARD - 0.05 (95% CI - 0.08 to - 0.01), p = 0.02] compared with those without diabetes [ARD - 0.01 (95% CI - 0.02 to 0), p = 0.11].

CONCLUSIONS

This meta-analysis underscores the heightened inflammatory risk associated with diabetes and highlights the need to target inflammatory pathways in these individuals irrespective of glucose-lowering drugs.

Micro Spectroscopic Photoacoustic (μsPA) imaging of advanced carotid atherosclerosis

Atherosclerosis is a lipid-driven and an inflammatory disease of the artery walls. The composition of atherosclerotic plaque stratifies the risk of a specific plaque to cause a cardiovascular event. In an optical resolution photoacoustic microscopy setup, of 45 μm resolution, we extracted plaque lipid photoacoustic (PA) spectral signatures of human endarterectomy samples in the range of 1150-1240 nm, using matrix assisted laser desorption ionization mass spectrometry imaging as a reference. We found plaque PA signals to correlate best with sphingomyelins and cholesteryl esters. PA signal spectral variations within the plaque area were compared to reference molecular patterns and absorption spectra of lipid laboratory standards. Variability in the lipid spectroscopic features extracted by principal component analysis of all samples revealed three distinct components with peaks at: 1164, 1188, 1196 and 1210 nm. This result will guide the development of PA-based atherosclerosis disease staging capitalizing on lipidomics of atherosclerotic tissue.

Multimodality imaging for the prevention of cardiovascular events: Coronary artery calcium and beyond

Atherosclerotic cardiovascular disease (ASCVD) has been the leading cause of death worldwide for more than a decade. Prevention is of utmost importance to reduce related mortality. The innovations in cardiovascular imaging technology, in addition to our improved understanding of coronary atherosclerosis pathogenesis, have resulted in cardiovascular imaging becoming one of the most influential tools for diagnosis and risk stratification in ASCVD. Although numerous publications have emerged on this topic, data that guide routine cardiology clinical practice currently focus on the utility of a limited number of such modalities, namely arterial ultrasonography and computed tomography. Herein, current evidence with respect to the role of multimodality cardiovascular imaging on ASCVD prevention will be reviewed.

Dyslipidemia Management in 2020: An Update on Diagnosis and Therapeutic Perspectives

Cardiovascular diseases are the leading cause of death in the modern world and dyslipidemia is one of the major risk factors. The current therapeutic strategies for cardiovascular diseases involve the management of risk factors, especially dyslipidemia and hypertension. Recently, the updated guidelines of dyslipidemia management were presented, and the newest data were included in terms of diagnosis, imaging, and treatment. In this targeted literature review, the researchers presented the most recent evidence on dyslipidemia management by including the current therapeutic goals for it. In addition, the novel diagnostic tools based on theranostics are shown. Finally, the future perspectives on treatment based on novel drug delivery systems and their potential to be used in clinical trials were also analyzed. It should be noted that dyslipidemia management can be achieved by the strict lifestyle change, i.e., by adopting a healthy life, and choosing the most suitable medication. This review can help medical professionals as well as specialists of other sciences to update their knowledge on dyslipidemia management, which can lead to better therapeutic outcomes and newer drug developments.

Meta-Analysis of Intensive Lipid-Lowering Therapy in Patients With Polyvascular Disease

Background Polyvascular atherosclerotic disease is associated with an increased risk of future cardiovascular events. Intensive lipid-lowering therapy (ILT) may mitigate this risk. The aims of this study-level meta-analysis were to examine the effects of ILT in patients with polyvascular disease and whether baseline low-density lipoprotein cholesterol (LDL-C) may determine the level of benefit. Methods and Results Electronic databases were searched through January 2020 to identify randomized controlled trials of treatments targeting upregulation of LDL-C receptors (ie, statins, ezetimibe, and PCSK9 [proprotein convertase subtilisin-kexin type 9] inhibitors). The primary end point was major adverse vascular events as defined by the included studies. A total of 94 362 patients (14 821 [18.6%] with polyvascular disease) from 7 studies were included. In patients with monovascular disease, ILT was associated with a 13% reduction in the primary end point (rate ratio [RR] 0.87; 95% CI, 0.81-0.93 [P=0.0002]) (absolute RR, 1.8%) compared with less ILT, while patients with polyvascular disease had 15% relative RR (0.85; 95% CI, 0.80-0.90 [P<0.00001]) (absolute RR, 6.5%) (P=0.66 for interaction). When factoring LDL-C, unlike patients with monovascular disease, the relative benefits of ILT, compared with less ILT, in patients with polyvascular disease were comparable with LDL-C >100 mg/dL (RR, 0.85; 95% CI, 0.80-0.90 [P<0.00001]) and LDL-C <100 mg/dL (RR, 0.88; 95% CI, 0.81-0.96 [P=0.003]) (P=0.23 for interaction). Conclusions Patients with polyvascular disease experienced comparable benefits to those with monovascular disease in response to ILT. The benefits of ILT in patients with polyvascular disease were not dependent on baseline LDL-C, challenging the approach of using LDL-C as a prerequisite to commence ILT for this high-risk subgroup.

Navigator-based reacquisition and estimation of motion-corrupted data: Application to multi-echo spin echo for carotid wall MRI

PURPOSE

To assess whether artifacts in multi-slice multi-echo spin echo neck imaging, thought to be caused by brief motion events such as swallowing, can be corrected by reacquiring corrupted central k-space data and estimating the remainder with parallel imaging.

METHODS

A single phase-encode line (ky = 0, phase-encode direction anteroposterior) navigator echo was used to identify motion-corrupted data and guide the online reacquisition. If motion corruption was detected in the 7 central k-space lines, they were replaced with reacquired data. Subsequently, GRAPPA reconstruction was trained on the updated central portion of k-space and then used to estimate the remaining motion-corrupted k-space data from surrounding uncorrupted data. Similar compressed sensing-based approaches have been used previously to compensate for respiration in cardiac imaging. The g-factor noise amplification was calculated for the parallel imaging reconstruction of data acquired with a 10-channel neck coil. The method was assessed in scans with 9 volunteers and 12 patients.

RESULTS

The g-factor analysis showed that GRAPPA reconstruction of 2 adjacent motion-corrupted lines causes high noise amplification; therefore, the number of 2-line estimations should be limited. In volunteer scans, median ghosting reduction of 24% was achieved with 2 adjacent motion-corrupted lines correction, and image quality was improved in 2 patient scans that had motion corruption close to the center of k-space.

CONCLUSION

Motion-corrupted echo-trains can be identified with a navigator echo. Combined reacquisition and parallel imaging estimation reduced motion artifacts in multi-slice MESE when there were brief motion events, especially when motion corruption was close to the center of k-space.

Construction of dual nanomedicines for the imaging and alleviation of atherosclerosis

Magnetic resonance imaging (MRI) is an essential tool for the diagnosis of atherosclerosis, a chronic cardiovascular disease. MRI primarily uses superparamagnetic iron oxide (SPIO) as a contrast agent. However, SPIO integrated with therapeutic drugs has rarely been studied. In this study, we explored biocompatible paramagnetic iron-oxide nanoparticles (NPs) in a complex with low pH-sensitive cyclodextrin for the diagnostic imaging and treatment of atherosclerosis. The NPs were conjugated with profilin-1 antibody (PFN1) to specifically target vascular smooth muscle cells (VSMCs) in the atherosclerotic plaque and integrated with the anti-inflammatory drug, rapamycin. The PFN1-CD-MNPs were easily binded to the VSMCs, indicating their good biocompatibility and low renal toxicity over the long term. Ex vivo near-infrared fluorescence (NIRF) imaging and in vivo MRI indicated the accumulation of PFN1-CD-MNPs in the atherosclerotic plaque. The RAP@PFN1-CD-MNPs alleviated the progression of arteriosclerosis. Thus, PFN1-CD-MNPs served not only as multifunctional imaging probes but also as nanovehicles for the treatment of atherosclerosis.

A promising tool to tackle the risk of cerebral vascular disease, the emergence of novel carotid wall imaging

Stroke is a heterogeneous vascular disease. Carotid artery atherosclerosis is associated with almost one-quarter of ischemic strokes. Moreover, a large percentage of preventable strokes are currently attributed to carotid atherosclerosis. Over the past three decades, the management of carotid artery disease has evolved. The benefits of carotid revascularization alongside medical therapy have early been recognized. Nonetheless, the debate regarding the optimal strategy is still ongoing, particularly in patients with asymptomatic carotid artery disease. One of the challenges is the use of luminal stenosis to quantify the severity of the carotid artery disease and to guide decision-making regarding invasive revascularization. Characterizing carotid atherosclerotic plaque is a promising tool to identify vulnerable plaque. Certain features such as large lipid core have already been linked to acute vascular events, not only at the plaque level but also to predict systemic cardiovascular events. Recently, a quantitative T2 mapping magnetic resonance imaging technique was developed and validated against histology. The ability to accurately quantify plaque lipid content using this technique opens several new opportunities. In this review articles, we will discuss the current challenges in the management of carotid artery disease and the future roles of T2 mapping to aid therapeutic options. These roles may include how to determine the mode of invasive carotid revascularization in symptomatic patients. Moreover, there may be a rational to use T2 mapping as a risk stratification tool in asymptomatic patients with carotid artery stenosis. It may also provide an opportunity to stage atherosclerosis and identify patients with coronary atherosclerosis who may benefit maximally from intensive lipid interventions.

Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) Inhibitors, Reality or Dream in Managing Patients with Cardiovascular Disease

BACKGROUND

Statins have been a major keystone in the management of patients with atherosclerotic cardiovascular disease. The benefits of inhibiting HMG CoA reductase, via statins, were translated into reduction in LDL-c with proportionate decrease in cardiovascular events in response to the magnitude of LDL-c reduction. Despite major advances in pharmacological treatments, including the use of high-dose statins, there are urgent need to further reduce future cardiovascular risk. This is in particularly important since 1 out of 5 high-risk atherosclerotic patients who achieve low LDL-c return with a second cardiovascular event within five years. Although this residual risk post-statin is largely heterogeneous, lowering LDL-c beyond 'normal' or guidelines-recommended level using novel therapies has resulted in further reduction in cardiovascular events.

OBJECTIVE

The current review will discuss the use of PCSK9 inhibitors in patients with atherosclerotic disease. PCSK9 inhibitors are a new class of lipid-lowering drugs that are either fully human monoclonal antibodies (evolocumab and alirocumab) or humanised monoclonal antibodies (bococizumab) that effectively reduce LDL-c to unprecedented level. By blocking circulating PCSK9, these drugs would preserve LDL receptors and prevent them from cellular degradation. This process promotes recycling of LDL receptors back to hepatocytes surface, leading into further reduction of LDL-c. Combining PCSK9 inhibitors with statin have led into lower LDL-c, reduction in plaque volume and more importantly reduction in future cardiovascular events.

CONCLUSION

These drugs are very promising, nonetheless, the unselective approach of applying these monoclonal antibodies may not prove to be cost-effective and potentially exposing some patients to unnecessary side effects.

Current concepts in atherosclerosis

Atherosclerosis is a complex disease process. It is increasingly recognised that both lipoprotein retention and inflammatory cellular components are intricately related in the initiation and development of atherosclerotic plaque. LDL-c (cholesterol) has been long established as a cause for atherosclerosis; additionally, inflammatory cells such as monocytes and subsequently foam cells have also been directly linked to the progression of atherosclerotic disease. Emerging data suggest that structures outside vascular intima and media are also closely related to atherosclerosis. Perivascular adipose tissue (PVAT) may be a determinant of the inflammatory status of the atherosclerotic plaque. All these features are becoming extremely relevant as therapies against atherosclerosis are targeting both lipid retention and inflammation. Recently, there has been some success in these novel therapies, such as the proprotein convertase subtilisin-kexin type 9 (PCSK-9) inhibitor evolocumab and the interleukin-1ß neutralising antibody, canakinumab, in reducing cardiovascular events when added to standard therapy such as statin. This review will discuss the pathogenesis of atherosclerosis, including some novel features, and its management using new anti-atherosclerotic drugs.

T2 mapping MRI technique quantifies carotid plaque lipid, and its depletion after statin initiation, following acute myocardial infarction

BACKGROUND & AIMS

A recently-validated, highly-sensitive T2 mapping magnetic resonance (MRI) technique accurately quantifies carotid plaque lipid. The aims of this study were to determine: (i) the extent of carotid plaque lipid in patients with acute coronary syndromes (ACS); (ii) the effects of initiation of high-intensity statin on plaque lipid content and (iii) whether plaque lipid content is related to standard or 'functional' blood lipid measurements.

METHODS

Statin naïve subjects presenting with ACS underwent carotid artery MRI at 3 T scanner to quantify plaque lipid. Patients were subsequently commenced on high dose statin as part of clinical care and underwent a second MRI after three months. Plaque composition was measured using objective semi-automated techniques.

RESULTS

23 out of 24 patients had measurable lipid. Three months after statin initiation there was a significant reduction in carotid lipid percentage [from 10.3% (7.2-14.2) to 7.4% (5.4-10.0), p = 0.002] and a significant increase in fibrous percentage [from 83.3% ± 6.6-85.5% ± 4.8, p = 0.039]. None of the studied functional blood biomarkers were related to either baseline carotid plaque lipid content or its propensity to change with statin treatment.

CONCLUSIONS

T2-mapping demonstrated depleted carotid plaque lipid following the initiation of high-intensity statin treatment. Standard or 'functional' blood biomarkers were dissociated from plaque lipid content or changes with treatment. These findings further reinforce the importance of disease characterisation over risk factor assessment. Subject to clinical trial findings, quantification of plaque lipid may provide the basis for an approach to identify patients suitable for intensive lipid reduction regimes.

The relationship of perivascular adipose tissue and atherosclerosis in the aorta and carotid arteries, determined by magnetic resonance imaging

BACKGROUND AND AIMS

Imaging studies have relied on the 'overall' volumetric quantification of perivascular adipose tissue. We sought to assess the relationship of circumferential distribution between perivascular adipose tissue and adjacent wall thickness of carotid and aortic arteries using dedicated magnetic resonance imaging sequences.

METHODS

Vessel wall and perivascular adipose tissue were acquired using magnetic resonance imaging (1.5 T). Co-registered images were segmented separately, and measurements of both perivascular adipose tissue and vessel wall were obtained along radii of the vessel spaced at angles of 5° each.

RESULTS

In total, 29 patients were recruited. Perivascular adipose tissue thickness of the aorta was 3.34 ± 0.79 mm with specific pattern of 'double peaks' distribution, while carotid perivascular adipose tissue had no identifiable pattern with thickness of 0.8 ± 0.91 mm. Although statistically significant, the correlation between perivascular adipose tissue thickness and wall thickness in carotid arteries with normal (r = 0.040, p = 0.001) or with abnormal wall thickness (r = -0.039, p = 0.015) was merely nominal. Similarly, perivascular adipose tissue of the aorta had very weak correlation with normal aortic wall thickness (r = 0.010, p = 0.008) but not with the abnormal ones (r = -0.05, p = 0.29).

CONCLUSION

Dissociation between the spatial distribution of perivascular adipose tissue and arterial wall thickening in the aorta and carotid arteries does not support that perivascular adipose tissue has a causal role in promoting atherosclerotic plaque via a paracrine route. Yet, perivascular adipose tissue functional properties were not examined in this study.