Risk prediction of cerebrovascular events with carotid plaque magneitc resonance analysis: A meta-analysis

Lipidomic Approaches in Common and Rare Cerebrovascular Diseases: The Discovery of Unconventional Lipids as Novel Biomarkers

Stroke remains a major cause of death and disability worldwide. Identifying new circulating biomarkers able to distinguish and monitor common and rare cerebrovascular diseases that lead to stroke is of great importance. Biomarkers provide complementary information that may improve diagnosis, prognosis and prediction of progression as well. Furthermore, biomarkers can contribute to filling the gap in knowledge concerning the underlying disease mechanisms by pointing out novel potential therapeutic targets for personalized medicine. If many "conventional" lipid biomarkers are already known to exert a relevant role in cerebrovascular diseases, the aim of our study is to review novel "unconventional" lipid biomarkers that have been recently identified in common and rare cerebrovascular disorders using novel, cutting-edge lipidomic approaches.

MR Imaging of Carotid Artery Atherosclerosis: Updated Evidence on High-Risk Plaque Features and Emerging Trends

MR imaging is well-established as the criterion standard for carotid artery atherosclerosis imaging. The capability of MR imaging to differentiate numerous plaque components has been demonstrated, including those features that are associated with a high risk of sudden changes, thrombosis, or embolization. The field of carotid plaque MR imaging is constantly evolving, with continued insight into the imaging appearance and implications of various vulnerable plaque characteristics. This article will review the most up-to-date knowledge of these high-risk plaque features on MR imaging and will delve into 2 major emerging topics: the role of vulnerable plaques in cryptogenic strokes and the potential use of MR imaging to modify carotid endarterectomy treatment guidelines.

Association of symptomatic atherosclerotic carotid arteries with plaque areas showing low densities on CTA

BACKGROUND AND PURPOSE

Intraplaque hemorrhage (IPH) is a key feature of vulnerable carotid atherosclerotic plaque (CAP), associated with low densities (<25 Hounsfield unit, HU) on CTA. This study aimed to analyze CAP on routine CTA performed in patients with symptomatic and asymptomatic carotid stenosis undergoing carotid endarterectomy (CEA) by assessing HU of the CAP area showing the lowest density (CAPALD) using radiological tools available in daily clinical practice, and to compare CAPALD values between symptomatic and asymptomatic carotids.

MATERIAL AND METHODS

We retrospectively screened pre-operative CTA scans of 206 consecutive adult patients undergoing CEA for symptomatic or asymptomatic stenosis. CAPALD values were compared between symptomatic and asymptomatic carotids. Asymptomatic carotids included arteries contralateral to the symptomatic CEA artery, and asymptomatic stenotic arteries undergoing CEA and their contralateral arteries. Carotids were excluded when <30% stenosis, or when CAP could not be identified or CAPALD not measured.

RESULTS

In total, 95 symptomatic and 112 asymptomatic carotids (derived from 174 patients) were analysed. In multivariate analysis, symptomatic arteries showed more severe stenosis (median 70% vs. 67%, p=0.0228) and lower CAPALD values (median 17 vs. 25 HU, p=0.049), whereas degree of stenosis and CAPALD values were not correlated (rho=-0.02, p=0.77). HU values <25 were more frequent in symptomatic than asymptomatic carotids (68% vs. 47%, p=0.0022).

CONCLUSION

On CTA, symptomatic carotids are associated with CAP areas with low densities. CTA analysis of CAP may be interesting to help identifying vulnerable plaques at risk for future stroke, especially in patients lacking strict indications for CEA based on the current guidelines.

Relation of Carotid Plaque Features Detected with Ultrasonography-Based Radiomics to Clinical Symptoms

Carotid plaque is one of the predominant causes of stroke. We sought to build a nomogram using ultrasonography (US)-based radiomics and clinical features for identification of symptomatic carotid plaques. We prospectively enrolled 548 patients (mean age ± standard deviation, 63 ± 10 years; 373 men) were randomly divided into training and test cohorts. Clinical and conventional US features of carotid plaques were used to generate a clinical and conventional US model. US-based radiomics model was constructed by extracting radiomics features from grayscale and strain elasticity images. Multivariate logistic regression was performed using the radiomics scores together with clinical and conventional US data, and a final nomogram was subsequently developed. The performance of the final nomogram was assessed with respect to discrimination and clinical usefulness in the training of the test cohorts and contrast-enhanced US test cohort. All the radiomics scores were significantly higher in patients with symptomatic carotid plaques. The US-based radiomics model [area under the curve (AUC) = 0.930 and 0.922 for training and test cohorts, respectively] and final nomogram (AUC = 0.927 and 0.919, respectively) outperformed the clinical and conventional US model (AUC = 0.723 and 0.580, respectively). The decision curve analysis indicated that the final nomogram was clinically useful. In patients undergoing the contrast-enhanced US, the prevalence of plaque enhancement was higher in high-risk patients than in low-risk patients based on the final nomogram-score (P = 0.008). Nomogram has a high diagnostic performance for identification of symptomatic carotid plaques.

Impact of H-Type Hypertension on Intraplaque Neovascularization Assessed by Contrast-Enhanced Ultrasound

Aim: H-type hypertension is connected with carotid atherosclerotic plaques and stroke, whereas neovascularization is a dominant contributor to plaque vulnerability. However, the correlation between H-type hypertension and plaque vulnerability remains unclear. This study aims to explore the influence of H-type hypertension on intraplaque neovascularization (IPN).

Methods: We enrolled 235 patients with carotid plaques into the investigation and classified them into four groups: H-type hypertension group, simple hypertension group, isolated hyperhomocysteinemia group, and control group. Contrast-enhanced ultrasound (CEUS) was performed on them and IPN was evaluated using semi-quantitative visual grading: grade 1 (no microbubbles or microbubbles limited to the adventitial side and/or shoulder of plaque) and, grade 2 (diffused microbubbles within plaque or microbubbles enter plaque core). To analyze the correlation between H-type hypertension and the degree of plaque enhancement, logistic regression was used.

Results: Compared with those with CEUS grade 1 plaques, those with CEUS grade 2 plaques had higher frequency of ischemic stroke (29.0% vs. 45.1%, P ＜0.05), hypertension (41.0% vs. 56.3%, P ＜0.05), and H-type hypertension (18.0% vs. 29.6%, P ＜0.05). No significant differences existed in plaque morphology, plaque echogenicity, and the severity of carotid artery stenosis between the degree of plaque enhancement (all P ＞0.05). H-type hypertension (multivariate-adjusted OR: 3.036, 95% CI: 1.258–7.329) was independently connected with the degree of plaque enhancement even after adjusting for other covariates.

Conclusion: H-type hypertension is expressly connected with the degree of plaque enhancement and may facilitate plaque vulnerability. Our findings may offer a new insight for treating vulnerable plaque, lowering blood pressure, and lowering homocysteine equally crucial.

Carotid plaque vulnerability on magnetic resonance imaging and risk of future ischemic events: a systematic review and meta-analysis

INTRODUCTION

Magnetic resonance imaging (MRI) can characterize carotid plaque features, including intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), and thin/ruptured fibrous cap (TRFC), that have increased tendency to cause future cerebrovascular ischemic events. We performed a systematic review and meta-analysis of studies evaluating association of MRI-identified high-risk plaque features, including IPH, LRNC, and TRFC, with risks of subsequent ischemic events of stroke, transient ischemic attack (TIA), or amaurosis fugax (AF) over follow-up duration of ≥3 months.

EVIDENCE ACQUISITION

Multiple databases were searched for relevant publications between January 2000 and March 2020. Studies reporting outcomes of future ischemic events of stroke, TIA, or AF for individual MRI-identified high-risk carotid plaque features over follow-up duration of ≥3 months were included. Random effects meta-analysis was performed to estimate odds ratios (OR) and 95% confidence intervals (CI) comparing outcomes between MRI-positive and MRI-negative groups.

EVIDENCE SYNTHESIS

Fifteen studies including 2350 patients were included. The annual rate of future ischemic events was 11.9% for MRI-positive IPH, 5.4% for LRNC, and 5.7% for TRFC. IPH, LRNC, and TRFC were associated with increased risk of future ischemic events (OR 6.37; 95% CI, 3.96 to 10.24), (OR 4.34; 95% CI, 1.65 to 11.42), and (OR 10.60, 95% CI 3.56 to 31.58), respectively.

CONCLUSIONS

The current study findings strengthen the assertion that MRI-positive "high-risk" or "vulnerable" plaque features, including IPH, LRNC, and/or TRFC can predict risks of future ischemic events of stroke, TIA, or AF.

Correlation of MRI-detected vulnerable carotid plaques with clinical presentation: a systematic review and meta-analysis

INTRODUCTION

To determine the association between magnetic resonance imaging (MRI)-detected vulnerable Carotid Plaques and clinical presentation related to ipsilateral carotid artery territory.

EVIDENCE ACQUISITION

We searched three databases including Ovid MEDLINE, Ovid EMBASE, and Scopus from 2000 to 2018 for studies that evaluated vulnerable carotid plaques by MRI defined as intraplaque hemorrhage (IPH), lipid-rich necrotic core (LRNC), or thinning/rupture of the fibrous cap (TRFC). Data on study characteristics, clinical presentation, and MRI findings were extracted. Publication bias, methodologic quality, and study heterogeneity were assessed. Random-effects meta-analysis model was used to estimate incidence rate ratio (IRR) and 95% confidence intervals (CI) of MRI-detected vulnerable carotid plaque between symptomatic and asymptomatic arteries.

EVIDENCE SYNTHESIS

Of 2855 studies, 33 studies containing 6210 participants with 8401 assessed arteries were included. Overall, the risk of bias was moderate in 13, and low in 20 studies. The prevalence of MRI-positive IPH, TRFC, and LRNC were higher in symptomatic groups compared with the asymptomatic groups. In 11 studies that compared vulnerable carotid plaques between symptomatic and asymptomatic groups, symptomatic presentation was correlated with increased risk of IPH (IRR=1.57; 95% CI: 1.24-1.99), TRFC (IRR=2.26; 95% CI: 1.83 to 3.76), and LRNC (IRR=1.95; 95% CI: 1.28 to 2.97), respectively.

CONCLUSIONS

The presence of MRI-positive vulnerable carotid plaques including IPH, LRNC, and TRFC is positively associated with symptomatic clinical presentation. Therefore, carotid plaque MRI might be a useful risk stratification tool in determining the risk of ischemic stroke.

Effect of cigarette smoking on carotid artery atherosclerosis: a community-based cohort study

Cigarette smoking is closely associated with the development of cardiovascular diseases. However, the relationship between cigarette smoking and subclinical atherosclerosis has not been fully studied. We sought to clarify the association between cigarette smoking and carotid intima-media thickness (cIMT) in a general Japanese population. Among 1,209 participants who received a medical check-up with cardiovascular examination at our institution, 450 participants (37.2%) were smokers (including both past and current smokers). We evaluated cIMT as a marker of subclinical atherosclerosis. The value of cIMT and rate of carotid plaque defined as IMT ≥ 1.1 mm did not differ between smokers and never smokers. However, the rate of carotid high-risk atheroma, defined as carotid artery atheroma including hypoechoic dominant and ulceration, was significantly higher among smokers than never smokers (30.4%, vs 23.6%, p = 0.009). Even after adjustment for covariates, cigarette smoking was independently associated with high-risk atheroma formation (odds ratio 1.384, 95% CI 1.019-1.880; p = 0.038). The value of cIMT and the rate of high-risk atheroma were significantly higher in smokers than never smokers in the subgroup of participants aged ≥ 60 years, whereas the rate of high-risk atheroma only was higher in smokers than never smokers in the subgroup of participants aged < 60 years. In conclusion, the development of high-risk carotid artery atheroma may precede the thickening of cIMT in cigarette smokers, which suggests the novel insight for the pathological mechanism underlying cardiovascular events and cigarette smoking.

Determination of Ultrastructural Properties of Human Carotid Atherosclerotic Plaques by Scanning Acoustic Microscopy, Micro-Computer Tomography, Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy

Microcalcification is the precursor of vulnerability of plaques in humans. Visualization of such small structures in vivo with high spatial resolution is an unsolved issue. The goal of this study is to evaluate the potential of scanning acoustic microscopy (SAM) in the determination of atherosclerotic plaques with calcifications by validating this technique with micro-computer tomography (micro-CT), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The fibrocalcific plaques were obtained from 12 different patients and initially examined with micro-CT. The images exhibited calcifications within these plaques. For imaging with SAM, approximately 5 μm thick slices were prepared. Sound speed values within calcified regions were measured to be greater than the ones in collagen-rich regions. These fibrocalcific plaques were also examined with SEM and EDS revealing collagen and calcium deposition within these samples. The consistency of the results obtained by all of the modalities involved in our study is an indication of the potential of SAM as a clinical tool for the diagnosis of vulnerable plaques.