New criteria for the sonographic diagnosis of a plaque ulcer in the extracranial carotid artery

Ultrasound-based carotid plaque characteristics combined with dynamic cerebral autoregulation: An imaging biomarker for cerebral ischemic events in patients with severe carotid artery stenosis

BACKGROUND

Atherosclerotic stenosis of the carotid artery is a major cause of ischemic stroke. We aimed to identify extracranial and intracranial features associated with cerebral ischemic events in patients with severe carotid artery stenosis using carotid ultrasonography and transcranial Doppler.

METHODS

We retrospectively enrolled 130 patients with severe carotid artery stenosis and 45 age- and sex-matched healthy controls. Extracranial carotid artery parameters included carotid plaque morphology, echogenicity, and the gray-scale median (GSM). Intracranial features, mainly dynamic cerebral autoregulation (dCA), were assessed using transfer function analysis. Correlations between extracranial and intracranial parameters and cerebral ischemic events were analyzed using univariate and multivariate logistic regression analyses. Receiver operating characteristic (ROC) curves were compared.

RESULTS

Sixty-six patients (50.8 %) experienced cerebral ischemic events upon admission. Extracranial features (proportion of ulcerated plaques and echogenicity classification) significantly differed between the asymptomatic and symptomatic groups. The mean GSM of carotid plaques (48.9 ± 17.3 vs. 62.1 ± 18.3, P < 0.001) and intracranial parameters were significantly lower in the symptomatic group. Plaque ulceration, hypoechoic plaques, and impaired dCA [lower ipsilateral phase at very-low frequency (VLF)] were independently associated with cerebral ischemic events in patients with severe carotid artery stenosis. The combined GSM and ipsilateral phase at VLF had the highest area under the ROC curve (0.784).

CONCLUSIONS

Combined extracranial and intracranial assessments may help predict cerebral ischemic events in patients with severe carotid artery stenosis. Ultrasound-based carotid plaque characteristics, combined with dynamic cerebral autoregulation, could be imaging biomarkers of cerebral ischemic events in patients with severe carotid artery stenosis.

Analysis of risk factors for carotid artery plaque in asymptomatic adults

OBJECTIVE

This study aimed to investigate the risk factors affecting the presence of carotid plaque in asymptomatic adults.

METHODS

Asymptomatic adults (age > 40 years, no symptoms of cardiovascular and cerebrovascular diseases) undergoing routine health examinations from physical examination department were included in this study. Carotid plaque was measured by Resona 7OB and Resona 8EXP color Doppler ultrasound and L9-3U and L4-5WU probes. The focal carotid intima-media thickness was greater than 1.1 mm, and the local protrusion of the artery wall into the artery lumen suggested the presence of carotid atherosclerotic plaque. According to their ultrasound results, 1077 asymptomatic adults were divided into a group with carotid plaque (477) and a group without carotid plaque (600).

RESULTS

A total of 1077 asymptomatic adults were included in this study, of whom 44.3% had carotid plaque. The proportion of men with carotid plaque was 84.5%. Multifactorial logistic analysis suggested that age, fasting blood glucose (FBG), total cholesterol (TC), homocysteine (Hcy) and male gender were risk factors for carotid atherosclerosis. The predictive probability of these risk factor indicators derived from the multifactorial model was calculated using receiver operating characteristic (ROC) curves with SPSS 25.0 software. The calculated area under the receiver operating characteristic curve (AUC) was 0.715 (95% CI, 0.685-0.746).

CONCLUSION

Age, FBG, TC, Hcy and male gender are risk factors for carotid atherosclerosis in asymptomatic adults. Gender differences in carotid atherosclerosis deserve further attention.

Brazilian Angiology and Vascular Surgery Society Guidelines for the treatment of extracranial cerebrovascular disease

Extracranial cerebrovascular disease has been the subject of intense research throughout the world, and is of paramount importance for vascular surgeons. This guideline, written by the Brazilian Society of Angiology and Vascular Surgery (SBACV), supersedes the 2015 guideline. Non-atherosclerotic carotid artery diseases were not included in this document. The purpose of this guideline is to bring together the most robust evidence in this area in order to help specialists in the treatment decision-making process. The AGREE II methodology and the European Society of Cardiology system were used for recommendations and levels of evidence. The recommendations were graded from I to III, and levels of evidence were classified as A, B, or C. This guideline is divided into 11 chapters dealing with the various aspects of extracranial cerebrovascular disease: diagnosis, treatments and complications, based on up-to-date knowledge and the recommendations proposed by SBACV.

Evaluation of Turbulence Index and Flow Pattern for Atherosclerotic Carotid Stenosis: A High-Frame-Rate Vector Flow Imaging Study

OBJECTIVE

The emerging high-frame-rate vector flow imaging provides a new way of hemodynamic evaluation for complex blood flow. This study was aimed at exploring quantitatively the characteristics of complex flow with turbulence (Tur) index and analyzing flow patterns in atherosclerotic internal carotid artery stenosis (ICAS) using high-frame-rate vector flow imaging.

METHODS

This study prospectively included 60 patients with ICAS. Tur values in different segments of stenosis and cardiac phases were compared. Spearman correlation analysis was performed between clinical plaque characteristics with turbulence grading by ln(Tur). Three complex flow patterns were qualitatively drawn on vector flow mode, and the rates of detection of flow patterns in different stenosis groups and ulceration groups were compared.

RESULTS

Highly disordered blood flow was observed in the stenotic (Tur [M, QR] = 12.5%, 21.5%) and distal segment (15.4%, 27.2%), particularly during systole (21.0%, 30.7%, 33.3%, 38.7%, p < 0.05). Spearman correlation analysis revealed that stenosis rate was correlated with turbulence grading in the stenotic (ρ = 0.65, p < 0.05) and distal segment (ρ = 0.79, p < 0.05), and ulcer formation was correlated with turbulence grading in the stenotic segment (ρ = 0.58, p < 0.05). The overall rate of detection of three flow patterns was higher in the severe stenosis group (22/22) versus the mild to moderate stenosis group (21/38) (p < 0.001) and in the ulcer group (21/23) versus the non-ulcer group (23/37) (p < 0.001).

CONCLUSION

High-frame-rate vector flow imaging was helpful in assessing the severity and characteristics of flow turbulence. Lumen geometric factors could affect flow turbulence and blood flow patterns around the plaque. This would provide important hemodynamic information for the detection of high-risk plaque.

Novel Imaging-Based Biomarkers for Identifying Carotid Plaque Vulnerability

Carotid artery disease has traditionally been assessed based on the degree of luminal narrowing. However, this approach, which solely relies on carotid stenosis, is currently being questioned with regard to modern risk stratification approaches. Recent guidelines have introduced the concept of the "vulnerable plaque," emphasizing specific features such as thin fibrous caps, large lipid cores, intraplaque hemorrhage, plaque rupture, macrophage infiltration, and neovascularization. In this context, imaging-based biomarkers have emerged as valuable tools for identifying higher-risk patients. Non-invasive imaging modalities and intravascular techniques, including ultrasound, computed tomography, magnetic resonance imaging, intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy, have played pivotal roles in characterizing and detecting unstable carotid plaques. The aim of this review is to provide an overview of the evolving understanding of carotid artery disease and highlight the significance of imaging techniques in assessing plaque vulnerability and informing clinical decision-making.

The utility of ultrasound and computed tomography in the assessment of carotid artery plaque vulnerability-A mini review

As the burden of cardiovascular and cerebrovascular events continues to increase, emerging evidence supports the concept of plaque vulnerability as a strong marker of plaque rupture, and embolization. Qualitative assessment of the plaque can identify the degree of plaque instability. Ultrasound and computed tomography (CT) have emerged as safe and accurate techniques for the assessment of plaque vulnerability. Plaque features including but not limited to surface ulceration, large lipid core, thin fibrous cap (FC), intraplaque neovascularization and hemorrhage can be assessed and are linked to plaque instability.

Advances in Noninvasive Carotid Wall Imaging with Ultrasound: A Narrative Review

Carotid atherosclerosis is a major cause for stroke, with significant associated disease burden morbidity and mortality in Western societies. Diagnosis, grading and follow-up of carotid atherosclerotic disease relies on imaging, specifically ultrasound (US) as the initial modality of choice. Traditionally, the degree of carotid lumen stenosis was considered the sole risk factor to predict brain ischemia. However, modern research has shown that a variety of other imaging biomarkers, such as plaque echogenicity, surface morphology, intraplaque neovascularization and vasa vasorum contribute to the risk for rupture of carotid atheromas with subsequent cerebrovascular events. Furthermore, the majority of embolic strokes of undetermined origin are probably arteriogenic and are associated with nonstenosing atheromas. Therefore, a state-of-the-art US scan of the carotid arteries should take advantage of recent technical developments and should provide detailed information about potential thrombogenic (/) and emboligenic arterial wall features. This manuscript reviews recent advances in ultrasonographic assessment of vulnerable carotid atherosclerotic plaques and highlights the fields of future development in multiparametric arterial wall imaging, in an attempt to convey the most important take-home messages for clinicians performing carotid ultrasound.

Identification Markers of Carotid Vulnerable Plaques: An Update

Vulnerable plaques have been a hot topic in the field of stroke and carotid atherosclerosis. Currently, risk stratification and intervention of carotid plaques are guided by the degree of luminal stenosis. Recently, it has been recognized that the vulnerability of plaques may contribute to the risk of stroke. Some classical interventions, such as carotid endarterectomy, significantly reduce the risk of stroke in symptomatic patients with severe carotid stenosis, while for asymptomatic patients, clinically silent plaques with rupture tendency may expose them to the risk of cerebrovascular events. Early identification of vulnerable plaques contributes to lowering the risk of cerebrovascular events. Previously, the identification of vulnerable plaques was commonly based on imaging technologies at the macroscopic level. Recently, some microscopic molecules pertaining to vulnerable plaques have emerged, and could be potential biomarkers or therapeutic targets. This review aimed to update the previous summarization of vulnerable plaques and identify vulnerable plaques at the microscopic and macroscopic levels.

The Correlation Between Collagen Types and Ultrasound Feature Score in Evaluating the Vulnerability of Carotid Artery Plaque

Objectives: To investigate whether ultrasound score has clinical value in identifying carotid artery-vulnerable plaque and the impacts of collagen distribution on the stability of plaque.

Materials and Methods: Standard carotid artery ultrasound examinations were performed in 51 patients with carotid artery plaques before carotid endarterectomy. Hematoxylin-eosin staining and Sirius red–picric acid staining of plaque sections were performed to analyze the pathological features and collagen distribution. All plaques were classified into vulnerable and stable groups by pathological features. Ultrasound scores, cap thickness, and the ratios of different collagen types were recorded and analyzed between two groups and different parts of plaques.

Results: Ultrasound scores of the vulnerable group were higher than those of the stable group (4.35 ± 1.23 vs. 2.09 ± 1.04, P = 0.001). AUC was 0.894 (best cutoff point three) in differentiating vulnerable and stable plaques. Compared with the stable group, the fibrous caps of the vulnerable group were thinner (P = 0.012); the area ratios of collagen type I to all collagen in the vulnerable group were lower (P = 0.033); however, the area ratios of collagen type IV to all collagen were higher (P = 0.026). Compared with downstream shoulders, the ultrasound scores of upstream shoulders of plaque were higher (P = 0.001), the fibrous caps of upstream shoulders were thinner (P = 0.001), and the area ratios of collagen type I to all collagen were lower (P = 0.022).

Conclusion: Ultrasound score could have a clinical value in identifying vulnerable carotid artery plaque, and the collagen distribution could impact the stability of plaques, especially collagen type I and type IV. The results also prompted that the upstream shoulders were more vulnerable than the downstream shoulders.

Plaque Length Predicts the Incidence of Microembolic Signals in Acute Anterior Circulation Stroke

Microembolic signals (MES) of the carotid artery are associated with plaque destabilization and reoccurrence of stroke. Previous studies have focused primarily on the degree of carotid artery stenosis and plaque components, and the relationship between plaque length and microembolic sign has received little attention. We aimed to find the association between carotid plaque length (CPL) and the presence of MES. We conducted a retrospective observational cross-sectional study. A total of 84 acute anterior-circulation ischemic stroke/transient ischemic attack (TIA) patients with carotid artery atherosclerosis were classified into an MES-positive (MES+) group and MES-negative (MES−) group. We measured multiple parameters of carotid plaque size (length, thickness) in each patient and evaluated the relationship between different plaque parameters and occurrence of MES. We found that male, carotid artery stenosis (CAS), CPL, carotid plaque thickness (CPT), and intima-media thickness (IMT) of the carotid artery were each significantly different between two groups (all P < 0.05). The multivariate analysis showed CPL (odds ratio (OR), 1.109; 95% CI, 1.044–1.177; P = 0.001) to be independently associated with the presence of MES. The areas under the ROC curves (AUCs) for CPL for predicting MES were 0.777 (95% CI, 0.640–0.914; P < 0.001). The cutoff value of CPL for predicting MES was 16.7 mm, with a sensitivity of 88.2% and a specificity of 77.6%. We found that CPL was a meaningful independent predictor of MES. Therefore, CPL may be useful for risk stratification of long and nonstenotic plaques in anterior circulation stroke.

Do Carotid Plaque Ulcers Heal? Potential Detection of Carotid Artery Plaque Healing by Carotid Ultrasound Imaging

OBJECTIVES

Carotid plaque ulcers confer an increased risk for stroke/ transient ischemic attacks in both symptomatic and asymptomatic carotid artery stenosis. Little is known about the healing rates of ulcers or the development of new ulcers. Carotid Duplex studies are noninvasive and easily repeatable tests to monitor progression of carotid stenosis and plaque morphology. Our aim was to determine the prevalence and healing rates of ultrasound-detected carotid plaque ulcers.

METHODS

We retrospectively reviewed 5837 carotid Duplex studies performed in an outpatient ultrasound laboratory affiliated with the neurological department of an academic center. A total of 3215 patients underwent a first carotid ultrasound Duplex study, and 2622 follow-up studies were done. Carotid ulcer was defined as a 2 mm deep surface indentation in a carotid plaque with a well-defined back wall, as determined by multimodal ultrasound imaging techniques.

RESULTS

The prevalence of carotid plaque ulcers among the 3215 patients with a first ultrasound study was 3% (82/3215). The mean follow-up was 42 ± 30 months, and the median number of follow-up studies was 6. Among patients with ulcers, follow-up studies were available in 65/82 patients. During the follow-up period, 28/65 (43%) ulcers healed. Among all 2622 follow-up studies, 45 patients developed a new ulcer.

CONCLUSIONS

Duplex-detected carotid plaque ulcer prevalence is low. The carotid ulcers healed in approximately half of patients during follow-up. Factors associated with ulcer healing and development remain poorly understood.

Ultrasound Assessment of Extracranial Carotids and Vertebral Arteries in Acute Cerebral Ischemia

Assessing ischemic etiology and mechanism during the acute phase of an ischemic stroke is crucial in order to tailor and monitor appropriate treatment and determine prognosis. Cervical Duplex Ultrasound (CDU) has evolved since many years as an excellent screening tool for the evaluation of extracranial vasculature. CDU has the advantages of a low cost, easily applicable, bed side examination with high temporal and spatial resolution and without exposing the patients to any significant complications. It represents an easily repeatable test that can be performed in the emergency room as a first-line examination of cervical artery pathology. CDU provides well validated estimates of the type of the atherosclerotic plaque, the degree of stenosis, as well as structural and hemodynamic information directly about extracranial vessels (e.g., subclavian steal syndrome) and indirectly about intracranial circulation. CDU may also aid the diagnosis of non-atherosclerotic lesions of vessel walls including dissections, arteritis, carotid-jugular fistulas and fibromuscular dysplasias. The present narrative review outlines all potential applications of CDU in acute stroke management and also highlights its potential therapeutic implications.

Contrast imaging ultrasound for the detection and characterization of carotid vulnerable plaque

Not only the degree of luminal narrowing but also the plaque morphology and composition play an important role in risk stratification of carotid atherosclerotic lesions. During the last few years, carotid contrast-enhanced ultrasound (CEUS) has emerged as a valuable imaging tool to assess such vulnerable carotid plaques. This review article discussed the use of CEUS for the detection of carotid plaque irregularities and ulcerations as well as the quantification of intraplaque neovascularization and its correlation with histology and inflammatory biomarkers. Apart from evaluating for markers of vulnerable carotid plaques, CEUS enhancement is directly associated with past cerebrovascular events. More importantly, preliminary evidence has shown that CEUS could be used to predict future cerebrovascular and cardiovascular events. Despite the progress in CEUS imaging for carotid atherosclerotic disease, past studies still suffer from the retrospective nature, small sample size, and a lack of matched, well controlled prospective studies. In the future, large multi-center prospective studies addressing the relationship between CEUS findings and patient clinical outcomes in carotid atherosclerotic disease are warranted.

Attenuation Coefficient Parameter Computations for Tissue Composition Assessment of Carotid Atherosclerotic Plaque in Vivo

Quantitative ultrasound has been used to assess carotid plaque tissue composition. Here, we compute the attenuation coefficient (AC) in vivo with the optimum power spectral shift estimator (OPSSE) and reference phantom method (RPM), extract AC parameters and form parametric maps. Differences between OPSSE and RPM AC parameters are computed. Relationships between AC parameters, surgical scores and histopathology assessments are examined. Kendall's τ correlations between OPSSE AC and surgical scores are significant, including those between cholesterol and Standard Deviation (adjusted p = 0.038); thrombus and Minimum (adjusted p = 0.002), Maximum (adjusted p = 0.021) and Standard Deviation (adjusted p = 0.001); ulceration and Average (adjusted p = 0.033), Median (unadjusted p = 0.013), Maximum (unadjusted p = 0.039) and Mode (adjusted p = 0.009). The strongest correlations with histopathology are percentage cholesterol and Median OPSSE (unadjusted p = 0.007); percentage hemorrhage and Minimum OPSSE (adjusted p < 0.001); hemosiderin score and Median OPSSE (adjusted p = 0.010); and percentage calcium and Percentage Non-physical RPM Pixels (unadjusted p = 0.014). Kruskal-Wallis H and Dunn's post hoc tests have the ability to distinguish between groups (p < 0.05). Results suggest AC parameters may assist in vivo evaluation of carotid plaque vulnerability.

Carotid artery imaging: The study of intra-plaque vascularization and hemorrhage in the era of the "vulnerable" plaque

Intraplaque hemorrhage (IPH) is one of the main factors involved in atherosclerotic plaque (AP) instability. Its recognition is crucial for the correct staging and management of patients with carotid artery plaques to limit ischemic stroke. Imaging plays a crucial role in identifying IPH, even if the great variability of intraplaque vascularization and the limitations of our current imaging technologies make it difficult. The intent of this review is to give a general overview of the main features of intraplaque vascularization and IPH on Ultrasound (US), Computed Tomography (CT), Magnetic Resonance (MR) and Nuclear Medicine, and a brief description on the future prospectives.

Vascular ultrasound, the potential of integration of multiparametric ultrasound into routine clinical practice

Introduction

Ultrasound has traditionally been regarded as the first-line imaging modality for screening, diagnostic evaluation and monitoring treatment and disease progression of vascular pathology, including both the arterial and the venous branch of the vascular system. Albeit of its well-tolerated nature, wide availability and low cost, ultrasound above all, has the advantage of providing the clinician with clinically significant information related to both intraluminal irregularities and extravascular disease. Ultrasound has the potential not only to anatomically describe tissues but also to assess physiology by evaluating blood flow characteristics in real time.

Discussion

The already fundamental role of ultrasound has been even more expanded with the introduction of newer techniques like contrast-enhanced ultrasound, tissue-elastography and 3D ultrasound and the incorporation of research advances into clinical practice. The purpose of this review is to present and discuss some of the latest advances in the field of vascular ultrasound in attempt to illustrate how the adoption of multiparametric ultrasound into everyday clinical practice could address the patient's needs. Pathology and applications discussed include carotid and aortic disease, portal and peripheral venous abnormalities.

Conclusion

Widespread availability of modern technology in ultrasound devices has made the application of contrast-enhanced ultrasound, tissue elastography and 3D ultrasound feasible options, ready to contribute to the diagnostic performance of the ultrasonographic technique.

Three-Dimensional Echographic Evaluation of Carotid Artery Disease

The introduction of three-dimensional echography (3D echo) in vascular field is not recent, but it still remains a seldom-used technique because of the costs of ultrasound probe and the need of dedicated laboratories. Therefore, despite significant prognostic implications, the high diagnostic accuracy in plaque definition, and the relative ease of use, 3D echo in vascular field is a niche technique. The purpose of this review is mainly clinical and intends to demonstrate the potential strength of a 3D approach, including technical aspects, in order to present to clinicians and imagers the appealing aspects of a noninvasive and radiation-free methodology with relevant diagnostic and prognostic correlates in the assessment of carotid atherosclerosis. A comprehensive literature search (since 1990s to date) using the PubMed, MEDLINE, and Cochrane libraries databases has been conducted. Articles written in English have been assessed, including reviews, clinical trials, meta-analyses, and interventional/observational studies. Manual cross-referencing was also performed, and relevant references from selected articles were reviewed. The search was limited to studies conducted in humans. Search terms, retrieved also with PubMed Advanced search and AND/OR Boolean operators (mainly in title and abstract), included three-dimensional, echo, stroke/transient ischemic attack, predictors, carotid, imaging, and biomarkers.

Ultrasonographical Features Associated with Progression of Atherosclerosis in Patients with Moderate Internal Carotid Artery Stenosis

Carotid artery stenosis (CAS) is a leading cause of ischemic stroke. Plaque stabilization is a major management approach. Information about the ultrasonographical and clinical features associated with the progression of moderate internal carotid artery (ICA) stenosis (50-69%) could assist with prognostication and risk factor modifications. We evaluated 287 patients with moderate ICA stenosis (50-69%) and subsequently evaluated them at follow-up points at 12, 24, and 36 months. Patients were divided into three groups according to the degree of ICA stenosis: progression (70-99%, n = 48), stable (50-69%, n = 210), and regression (< 50%, n = 29). Responsible plaque thickness (RPT) across groups during follow-up was compared using a repeated measure ANOVA test. An ordinal regression was subsequently applied to identify risk factors for atherosclerosis progression. Male (P = 0.04), hypoechoic plaque (P < 0.01), smoking (P = 0.02), plaque ulceration (P = 0.05), and contralateral severe CAS or occlusions (P = 0.04) on ultrasound was more frequent in the progression group vs. other two groups. The ordinal regression revealed that only hypoechoic plaque (OR, 7.03; 95% CI, 3.34-14.81; P < 0.01) and contralateral ICA severe stenosis or occlusion (OR, 2.86; 95% CI, 1.41-5.80; P < 0.01) were independently associated with stenosis progression, while statin use was inversely associated with stenosis progression (OR, 0.26; 95% CI, 0.13-0.54; P < 0.01). Of note, symptomatic vs. asymptomatic moderate CAS at baseline was not associated with progression. For patients with moderate CAS, hypoechoic plaque, contralateral severe stenosis or occlusion on ultrasonography, and statin use are independently related to stenosis progression. Statin use may delay the progression of carotid stenosis.

Swirling of microbubbles: Demonstration of a new finding of carotid plaque ulceration on contrast-enhanced ultrasound explaining the arterio-arterial embolism mechanism

Carotid plaque ulceration is a well-established feature of vulnerability, associated with high risk for neurological symptoms. From a pathogenetic point of view, the mechanism responsible for occurrence of symptomatology relies on the aggregation of platelets within the ulcer cavity, activation of coagulation mechanism, formation of thrombus and arterio-arterial embolization of thrombotic material in the central nervous system. Many imaging modalities including unenhanced ultrasound, computed tomographic angiography and magnetic resonance angiography have been used to image and diagnose carotid plaque ulceration with varying success. Contrast-enhanced ultrasound has been recently introduced in the study of carotid disease offering improved flow visualization and better plaque surface delineation. We present a case where contrast-enhanced ultrasound visualized the swirling pattern of movement of the microbubbles within the ulcer cavity. These findings illustrate the underlying hemodynamic mechanism of arterio-arterial embolization and can be proposed as a new finding of plaque ulcerations on contrast-enhanced ultrasound.

Imaging of the ulcerated carotid atherosclerotic plaque: a review of the literature

Abstract

Carotid atherosclerotic disease constitutes a major modern health problem whose diagnosis primarily relies on imaging. Grading of stenosis has been long used as the main factor for risk stratification and guiding of management. Nevertheless, increasing evidence has shown that additional plaque characteristics such as plaque composition and surface morphology play an important role in the occurrence of symptoms, justifying the term “vulnerable plaque”. Carotid plaque surface characteristics either in the form of surface irregularities or ulceration represent an important factor of vulnerability and are associated with the occurrence of neurologic symptoms. The delineation of the carotid plaque surface can be performed with virtually all imaging modalities including ultrasound, contrast-enhanced ultrasound, multi-detector computed tomography angiography, magnetic resonance angiography and the traditional reference method of angiography. These techniques have shown varying levels of diagnostic accuracy for the identification of ulcerated carotid plaques or plaque surface irregularities. As a consequence and given its high clinical significance, radiologists should be familiar with the various aspects of this entity, including its definition, classification, imaging findings on different imaging modalities and associations. The purpose of this review is to present the current literature regarding carotid plaque ulcerations and present illustrative images of ulcerated carotid plaques.

Teaching Points

• Plaque surface and ulceration represent risk factors for stroke in carotid disease.

• Characterisation of the plaque surface and ulcerations can be performed with every modality.

• US is the first-line modality for carotid disease and identification of ulcerations.

• The administration of microbubbles increases US accuracy for diagnosis of carotid ulceration.

• MDCTA and MRA are valuable for diagnosing ulceration and evaluating plaque composition.

Current status of carotid ultrasound in atherosclerosis

Cardiovascular disease (CVD) primarily caused by atherosclerosis is a major cause of death and disability in developed countries. Sonographic carotid intima-media thickness (CIMT) is widely studied as a surrogate marker for detecting subclinical atherosclerosis for risk prediction and disease progress to guide medical intervention. However, there is no standardized CIMT measurement methodology in clinical studies resulting in inconsistent findings, thereby undermining the clinical value of CIMT. Increasing evidences show that CIMT alone has weak predictive value for CVD while CIMT including plaque presence consistently improves the predictive power. Quantification of plaque burden further enhances the predictive power beyond plaque presence. Sonographic carotid plaque characteristics have been found to be predictive of cerebral ischaemic events. With advances in ultrasound technology, enhanced assessment of carotid plaques is feasible to detect high-risk/vulnerable plaques, and provide risk assessment for ischemic stroke beyond measurement of luminal stenosis.

Sonographic Detection of Abnormal Plaque Motion of the Carotid Artery: Its Usefulness in Diagnosing High-Risk Lesions Ranging from Plaque Rupture to Ulcer Formation

We investigated the feasibility of using sonography of abnormal plaque motion to diagnose high-risk carotid lesions ranging from plaque rupture to ulcer formation. Fifty consecutive carotid arteries of 49 patients (71 ± 7 y, 37 males) who underwent carotid endarterectomy were investigated by carotid sonography to find a plaque concavity (sonographic ulcer [SU]), fine trembling motion inside the plaque (FTMI) and systolic retractive motion of the plaque surface (SRMS). Plaque rupture or ulcer, necrotic core and intra-plaque hemorrhage were determined at carotid endarterectomy. Twenty-two SUs, 41 cases of FTMI and 20 cases of SRMS were detected by carotid sonography. The sensitivity and specificity of SU in diagnosing plaque rupture or ulcer at carotid endarterectomy were 48% and 90%, and those of FTMI were 93% and 60%. Plaques with SRMS more frequently had both a necrotic core and intra-plaque hemorrhage than those without SRMS (80% vs. 30%, p = 0.0005). Abnormal plaque motion detected by carotid sonography is useful in detecting a ruptured or ulcerated plaque with a necrotic core and/or hemorrhage.

Contemporary carotid imaging: from degree of stenosis to plaque vulnerability

Carotid artery stenosis is a well-established risk factor of ischemic stroke, contributing to up to 10%-20% of strokes or transient ischemic attacks. Many clinical trials over the last 20 years have used measurements of carotid artery stenosis as a means to risk stratify patients. However, with improvements in vascular imaging techniques such as CT angiography and MR angiography, ultrasonography, and PET/CT, it is now possible to risk stratify patients, not just on the degree of carotid artery stenosis but also on how vulnerable the plaque is to rupture, resulting in ischemic stroke. These imaging techniques are ushering in an emerging paradigm shift that allows for risk stratifications based on the presence of imaging features such as intraplaque hemorrhage (IPH), plaque ulceration, plaque neovascularity, fibrous cap thickness, and presence of a lipid-rich necrotic core (LRNC). It is important for the neurosurgeon to be aware of these new imaging techniques that allow for improved patient risk stratification and outcomes. For example, a patient with a low-grade stenosis but an ulcerated plaque may benefit more from a revascularization procedure than a patient with a stable 70% asymptomatic stenosis with a thick fibrous cap. This review summarizes the current state-of-the-art advances in carotid plaque imaging. Currently, MRI is the gold standard in carotid plaque imaging, with its high resolution and high sensitivity for identifying IPH, ulceration, LRNC, and inflammation. However, MRI is limited due to time constraints. CT also allows for high-resolution imaging and can accurately detect ulceration and calcification, but cannot reliably differentiate LRNC from IPH. PET/CT is an effective technique to identify active inflammation within the plaque, but it does not allow for assessment of anatomy, ulceration, IPH, or LRNC. Ultrasonography, with the aid of contrast enhancement, is a cost-effective technique to assess plaque morphology and characteristics, but it is limited in sensitivity and specificity for detecting LRNC, plaque hemorrhage, and ulceration compared with MRI. Also summarized is how these advanced imaging techniques are being used in clinical practice to risk stratify patients with low- and high-grade carotid artery stenosis. For example, identification of IPH on MRI in patients with low-grade carotid artery stenosis is a risk factor for failure of medical therapy, and studies have shown that such patients may fair better with carotid endarterectomy (CEA). MR plaque imaging has also been found to be useful in identifying revascularization candidates who would be better candidates for CEA than carotid artery stenting (CAS), as high intraplaque signal on time of flight imaging is associated with vulnerable plaque and increased rates of adverse events in patients undergoing CAS but not CEA.

Retinal embolization after carotid endarterectomy and stenting for carotid artery stenosis

To compare the incidence of retinal arterial embolism after carotid endarterectomy (CEA) or carotid artery stenting (CAS) as a treatment for carotid artery stenosis and to determine the risk factors for retinal artery embolization, this study included all consecutive severe carotid artery stenosis patients (70-99%), diagnosed by digital subtraction angiography, who underwent CEA or CAS between February 2014 and July 2014. The study included 61 patients in the CEA group and 71 patients in the CAS group. None of the patients developed a stroke or myocardial infarction or died within 7 days of the surgery. A total of 15 patients exhibited retinal embolization including three patients who underwent CEA. None of these emboli caused symptoms. After undergoing CAS, 12 patients exhibited retinal embolization and one of the 12 patients suffered a decrease in visual acuity and visual field after CAS. The retinal embolization rate was 4.9% in the CEA group which was lower than the 16.9% rate in the CAS group (p=0.031). In addition, the retinal embolization rate in the ulcerated plaque group was higher than that in the non-ulcerated plaque group (p=0.007). Ulcerated plaques (odds ratio [OR] 5.043; 95% confidence interval [CI] 1.476-17.225; p=0.010) and CAS (OR 4.248; 95% CI 1.104-16.343; p=0.035) were independent predictors of retinal embolization. Although retinal embolization during CEA and CAS is common at our center, symptomatic embolization is not. The presence of ulcerated plaques and CAS were independent predictors of retinal embolization.

Imaging of functional and structural alterations of large arteries after acute ischaemic atherothrombotic stroke or acute coronary syndromes

BACKGROUND

Non-invasive methods allow the evaluation of structural and functional arterial abnormalities. So far, no study has focused on the comparison of vascular parameters by type of cardiovascular event.

METHODS

In this pilot study, cardiovascular risk factors, carotid parameters, carotid-to-femoral pulse wave velocity (PWV), brachial flow-mediated dilation and ambulatory blood pressure were assessed in patients who presented with acute coronary syndromes (ACS) or ischaemic atherothrombotic stroke (IAS). Groups were matched for age and gender.

RESULTS

Prevalences of hypertension, diabetes and dyslipidaemia and heredity, smoking and body mass index were similar in the ACS (n=50) and IAS (n=50) groups. Carotid intima-media thickness (IMT) and PWV were significantly higher in the IAS vs. ACS group (769±180 vs. 701±136 μm; P=0.039 and 12.5±3.5 vs. 10.7±2.4 m/s; P=0.006). Carotid distensibility was significantly lower in the IAS vs. ACS group (16.2±3.2 vs. 18.9±7.6 10(-3)/kPa; P=0.02). These differences persisted after adjustment for blood pressure for carotid distensibility but not for PWV. The prevalences of endothelial dysfunction and carotid plaques were not significantly different in the ACS and IAS groups (86% and 74%; 80% and 78%). In a multivariable model, carotid distensibility remained associated with ACS (odds ratio 1.19; 95% confidence interval 1.03-1.38; P=0.016).

CONCLUSIONS

Stiffness and carotid wall thickness were higher in IAS than in ACS patients. These differences may support the interest in new therapeutic targets for cardiovascular secondary prevention.

NCT NO

NCT00926874.

Quantitative assessment of carotid plaque surface irregularities and correlation to cerebrovascular symptoms

Background

The purpose of this study was to determine whether surface irregularities measured from ultrasound images of carotid artery plaques and quantified using a novel method, correlate with the presence of ipsilateral hemispheric cerebrovascular symptoms.

Methods

A plaque surface irregularity index (SII) was measured in 47 carotid artery plaques (32 subjects, stenosis range 10% -95%, 49% symptomatic) using ultrasound image sequences spanning several cardiac cycles. The differences in the distribution of SII in plaques with ipsilateral hemispheric symptoms versus those without symptoms and the correlation between the SII of plaques and the degrees of stenosis of the corresponding arteries were assessed. Diagnostic performance of plaque SII was evaluated on its own and in combination with the degree of stenosis.

Results

The mean SII was significantly greater for plaques with ipsilateral hemispheric symptoms (1.89 radians/mm) than for asymptomatic plaques (1.67 radians/mm, p = 0.03). There was no statistically significant association between the SII and the degree of stenosis (p = 0.30). SII predicted the presence of cerebrovascular symptoms with an accuracy of 66% (sensitivity 65%, specificity 67%) on its own and with an accuracy of 83% (sensitivity 96%, specificity 71%) in combination with the degree of stenosis.

Conclusions

Quantitative assessment of carotid plaque surface irregularities using a novel SII parameter correlates with the presence ipsilateral hemispheric cerebrovascular symptoms and may increase diagnostic performance beyond that provided by the degree of stenosis.