Echolucent carotid plaques becomes more echogenic over time - a 3D ultrasound study

OBJECTIVES

We aimed to detect changes in carotid artery atherosclerotic plaque volume and echogenicity over time in patients with an acute thromboembolic event and in patients with chronic atherosclerotic disease, both treated with statin, using a novel 3D ultrasound system.

METHODS

We included two cohorts of patients; 70 patients, naïve to statin treatment, admitted with acute, first-time myocardial infarction (aMI) and 69 patients who had been on statin treatment for a minimum of 6-months with chronic peripheral arterial disease (cPAD). 3D ultrasound examination was performed at baseline and after 3- and 12-months. Plaque volume was quantified in 3D ultrasound plaque acquisitions and echogenicity was assessed using gray-scale median (GSM) and normalized with adventitia as reference.

RESULTS

The aMI group had darker plaques than the cPAD group at baseline (mean GSM: 60.98, standard deviation (SD): 24.09 vs 71.75, SD: 21.55; P=0.006), 3-months (63.64, SD: 20.47 vs 73.44, SD: 20.46; P=0.006) and at 12-months follow-up (59.25, SD: 18.07 vs 71.02, SD: 22.31; P=0.004). The differences were not significant after adjusting for traditional risk factors. Dividing both groups by the median GSM, the darkest half of the aMI group's had an increase in GSM mainly within the first 3-months (10.49, CI95%: 2.45 - 18.53; P=0.012) and hereafter remained unchanged at 12-months follow-up (-0.53, CI95%: -7.28 - 6.22, P=0.875). In the darkest cPAD group GSM also increased within 3-months (8.14, CI95%: 1.85 - 14.32, P=0.012) and hereafter stabilised till 12-months (-2.54, CI95%: -9.62 - 4.53, P=0.475). Plaque volume did not change in the aMI group from baseline (median: 55.41mm³, interquartile range (IQR): 24.24 - 84.31) to 12-months (58.67mm³, IQR: 31.81 - 93.51) (P=0.220) whereas there was a small decrease in the cPAD group from baseline (71.63mm³, IQR: 40.12 - 135.61) to 12-months (67.73mm³, IQR: 31.00 - 122.38) (P=0.026).

CONCLUSION

Assessed with the novel 3D matrix ultrasound system echolucent carotid plaque had increasing GSM within a 3-months period, indicating stabilization of the more vulnerable plaques in aMI and cPAD patients. Plaque volume decreased over 12-months follow-up in long-term statin treated patient with cPAD, but not during the first 12 months statin therapy in patients with aMI.

Predictors for High-Risk Carotid Plaque in Asymptomatic Korean Population

Aims

High-risk carotid plaque remains an important risk factor for atherosclerotic cardiovascular disease (ASCVD). We sought to evaluate the characteristics of carotid plaque and to find out the predictors for high-risk carotid plaque in asymptomatic Koreans.

Methods

Subjects (n = 801) without a history of ASCVD from 12 university hospitals in Korea underwent carotid ultrasound. The images were standardized at core laboratory. Morphologic characteristics of plaque were analyzed with laboratory and clinical characteristics. High-risk carotid plaque features included the highest quartile of carotid plaque score (cPS), irregular plaque surface, and hypoechoic and ulcerated plaque.

Results

The carotid plaque prevalence was 22.1% (177/801 persons, 293 plaques). The plaque was increased with age (p < 0.001) and conventional ASCVD risk estimator (p < 0.001) and the most frequently found in bulb (n = 190, 64.8%). The number of the highest quartile of cPS was 44/177 (24.9%). Irregular plaque was seen in 20.8% out of total plaque (61/293) and was more frequent in the high-risk 10-year ASCVD risk group than in the low-risk group (36.1% vs. 15.8%, p = 0.023). Hypoechoic and ulcerated plaques were seen in 14.3% (42/293) and 2% (6/293), respectively. The independent predictors for high-risk plaque were age (β = 0.052, p < 0.001), HbA1c (β = 0.182, p = 0.004), male (β = 0.118, p = 0.006), hypertension (β = 0.090, p = 0.032), and multiple plaques (OR: 4.810 (two plaques) and 8.621 (three plaques), all p < 0.001).

Conclusions

This study suggests that high-risk carotid plaque was seen in 12.4% (99/801). The high-risk plaque was associated with diabetes control status reflected by the HbA1c level as well as traditional risk factors in asymptomatic Korean population.

Association between periodontal disease and vulnerable plaque morphology in patients undergoing carotid endarterectomy

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Periodontal disease is associated with echolucent plaques.

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Periodontal disease is associated with increased macrophages in plaques.

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Periodontal disease is associated with decreased smooth muscle cells in plaques.

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Periodontal disease is associated with plaque instability.

Background

Periodontal disease (PD) is a chronic inflammatory oral condition with potentially important systemic sequelae. We sought to determine whether the presence of PD in patients with severe carotid disease was associated with morphological features consistent with carotid plaque instability.

Methods

A total of 52 dentate patients hospitalized for carotid endarterectomy (CEA) had standardized assessments of their periodontal status, including measurements of probing pocket depth (PPD), clinical attachment level (CAL) and bleeding on probing (BoP). Carotid plaque morphology was assessed by ultrasound using the gray scale median (GSM) score and by immunohistochemistry using anti-CD68 and anti-alpha-actin antibodies, markers for macrophages and smooth muscle cells (SMCs) respectively.

Results

In total 30/52 patients (58%) had PD. Significant associations were noted between low GSM on ultrasound and each mm in PPD (p = 0.001), each mm in CAL (p = 0.002) and with a 10% increase in BoP (p = 0.009). Using the standardized PERIO definition the association remained robust (aOR = 10.4 [95% CI:2.3–46.3], p = .002). Significant associations were also observed with high macrophage accumulation and each individual PD measure (p < 0.01 for PPD, CAL and BoP) and with the PERIO definition (aOR = 15 [95% CI:1.8–127.8], p = .01). Similarly, low SMC density was also significantly associated with individual measures of PD (p < 0.05 for PPD, CAL and BoP), but not with the PERIO definition (aOR 3.4 [95% CI:0.9–12.8], p = .07).

Conclusions

The presence of PD was significantly associated with both ultrasound and immunohistochemistry features of carotid plaque instability in patients undergoing CEA.

Imaging of the vulnerable carotid plaque: Role of imaging techniques and a research agenda

OBJECTIVES

Atherothrombosis in the carotid arteries is a main cause of ischemic stroke and may depend on plaque propensity to complicate with rupture or erosion, in turn related to vulnerability features amenable to in vivo imaging. This would provide an opportunity for risk stratification and-potentially-local treatment of more vulnerable plaques. We here review current information on this topic.

METHODS

We systematically reviewed the literature for concepts derived from pathophysiologic, histopathologic, and clinical studies on imaging techniques attempting at identifying vulnerable carotid lesions.

RESULTS

Ultrasound, MRI, CT, and nuclear medicine-based techniques, alone or with multimodality approaches, all have a link to pathophysiology and describe different-potentially complementary-aspects of lesions prone to complications. There is also, however, a true paucity of head-to-head comparisons of such techniques for practical implementation of a thorough and cost-effective diagnostic strategy based on evaluation of outcomes. Especially in asymptomatic patients, major international societies leave wide margins of indecision in the advice to techniques guiding interventions to prevent atherothrombotic stroke.

CONCLUSIONS

To improve practical management of such patients-in addition to the patient's vulnerability for systemic reasons-a more precise identification of the vulnerable plaque is needed. A better definition of the diagnostic yield of each imaging approach in comparison with the others should be pursued for a cost-effective translation of the single techniques. Practical translation to guide future clinical practice should be based on improved knowledge of the specific pathophysiologic correlates and on a comparative modality approach, linked to subsequent stroke outcomes.

Three-dimensional ultrasonographic evaluation of carotid artery plaque surface irregularity

INTRODUCTION

The aim of this study was to evaluate 3-dimensional (3D) ultrasonography (US) in determining the surface irregularity of carotid artery plaques.

MATERIAL AND METHODS

This study included 50 patients (20 females and 30 males) aged between 56 and 82 years with plaques in the carotid artery which were detected during routine neck ultrasound. Simultaneously these cases were evaluated in terms of plaque echogenicities and surface characteristics with 2D and 3D US.

RESULTS

3D imaging was successfully performed in 45 of the 50 cases and the technical success rate was 90%. A single plaque was detected in 64.4% of the patients, with the remaining 35.6% having more than one plaque. The lengths of the plaques ranged from 2 to 12 mm (mean: 3.98 ±1.70 mm); the widths ranged from 1.8 to 3.2 mm (mean: 2.11 ±0.37 mm). No significant difference was found between 2D and 3D plaque echo-structures (observer 1, p = 0.317; observer 2, p = 0.276), but there were significant differences between 2D and 3D plaque surface irregularities (observer 1, p = 0.002; observer 2, p = 0.004). The inter-observer agreement on 2D and 3D plaque echo-structure and surface irregularity was very good (k coefficients were 0.89 and 0.83, respectively, for echo-structure, and 0.91 and 0.95, respectively, for surface irregularity).

CONCLUSIONS

The present study shows that 3D US examination is a valuable non-invasive method for investigation of surface irregularity of carotid artery plaques.

Prospective Study About the Relationship Between CEUS of Carotid Intraplaque Neovascularization and Ischemic Stroke in TIA Patients

Objective: To evaluate the relationship between contrast-enhanced ultrasonography (CEUS) of carotid intraplaque neovascularization and ischemic stroke in transient ischemic attack (TIA) patients. Methods: A total of 112 TIA patients were selected for the study. Routine carotid ultrasonic examination was performed for all the patients. CEUS was carried out for consecutive patients with plaque thicker than 2.5 mm in carotid bifurcation and follow-up for at least 24 months. The number of patients with incurrence of ischemic stroke or recurrence of TIA was obtained during the follow-up period. To detect the risk factors for incurrence of ischemic stroke or recurrence of TIA in 24 months, multivariate logistic regression analyses were performed for all the risk factors in all the selected patients. Results: Ninety-one patients underwent CEUS and were followed up at least 24 months. There were statistical differences between recurrent and non-recurrent groups about hypertension, diabetes, hyperlipemia, smoking history, family history of stroke, medication compliance, two-dimensional ultrasound, and CEUS (P < 0.05). The higher CEUS intensity in the carotid plaque was, the higher was the possibility of ischemic stroke or recurrent TIA. Multivariate logistic regression analysis showed that the CEUS characteristics of carotid plaque such as linear enhancement or diffuse enhancement were independent risk factors for ischemic stroke or recurrent TIA in TIA patients (P < 0.05). Conclusion: For carotid plaques, CEUS could evaluate the infusion mode, which could reflect the neovascularization in plaques. CEUS could predict the incurrence of ischemic stroke or recurrence of TIA in TIA patients, which is useful information when making a clinical decision.

Contrast Enhanced Ultrasound (CEUS) Is Not Able to Identify Vulnerable Plaques in Asymptomatic Carotid Atherosclerotic Disease

OBJECTIVES

Contrast enhanced ultrasound (CEUS) has been suggested as an imaging tool for detection of asymptomatic carotid atherosclerotic disease (ACAD) at high risk of cerebral embolisation. The objective of this study was to evaluate CEUS and immunohistochemical (IHC) patterns in ACAD (i.e., without any neurologic symptoms in the last 6 months) and their correlations with histology.

METHODS

CEUS analysis was classified on a semiquantitative basis using a three-point classification scale. Plaque morphology was assessed using the American Heart Association (AHA) classification of atherosclerotic plaques, then accordingly assigned as non-vulnerable (AHA Type IV/V) or vulnerable (AHA Type VI). IHC analysis for intra-plaque neo-angiogenesis (IPN) was identified by CD34/VEGF immunostaining and classified on a semiquantitative basis using a four-point classification scale. Both CEUS and IHC analyses were performed and scored by single observers.

RESULTS

Fifty-eight consecutive asymptomatic patients (mean age 73 years, 33 males) undergoing carotid endarterectomy were included in the final analysis. Nineteen had AHA Class IV/V plaques, and the remaining 39 had AHA Class VI plaques. There were two main findings of the study: (a) histologically proven vulnerable plaques compared with histologically proven non-vulnerable plaques had denser IPN (p = .004), but did not show more pronounced contrast enhancement; (b) the correlation between IHC analysis and CEUS analysis was significant for both vulnerable and non-vulnerable plaques (p = .04 and p = .01, respectively), but it was direct for AHA Type IV/V plaques and inverse for AHA Type VI plaques.

CONCLUSIONS

The main findings of the study were that histologically proven vulnerable plaques (i.e., AHA Class VI) as compared with histologically proven non-vulnerable plaques (i.e., AHA Class IV/V) had denser neo-vascularisation, but not more pronounced contrast enhancement.

The Growing Field of Imaging of Atherosclerosis in Peripheral Arteries

In the past decades, peripheral arteries have represented a model for the comprehension of atherosclerosis as well as for the development of new diagnostic imaging modalities and therapeutic strategies. Peripheral arteries may represent a window to study atherosclerosis. Pathology has prominently contributed to move the clinical and research attention from the arterial lumen stenosis and angiography to morphological and functional imaging techniques. Evidence from large and prospective cohort or randomized controlled studies is still modest. Nevertheless, several emerging imaging investigations represent a potential tool for a comprehensive "in vivo" evaluation of the entire natural history of peripheral atherosclerosis. This constitutes a demanding assignment, as it would be desirable to obtain both single-lesion focused and extensive arterial system views to achieve the most accurate prognostic information. Our narrative review rests upon the fundamental pathological evidence, summarizing the rapidly growing field of imaging of atherosclerosis in peripheral arteries and presenting a selection of both currently available and emerging imaging techniques.

Relationship between Plaque Echo, Thickness and Neovascularization Assessed by Quantitative and Semi-quantitative Contrast-Enhanced Ultrasonography in Different Stenosis Groups

The aim of this study was to determine the relationship between plaque echo, thickness and neovascularization in different stenosis groups using quantitative and semi-quantitative contrast-enhanced ultrasound (CEUS) in patients with carotid atherosclerosis plaque. A total of 224 plaques were divided into mild stenosis (<50%; 135 plaques, 60.27%), moderate stenosis (50%-69%; 39 plaques, 17.41%) and severe stenosis (70%-99%; 50 plaques, 22.32%) groups. Quantitative and semi-quantitative methods were used to assess plaque neovascularization and determine the relationship between plaque echo, thickness and neovascularization. Correlation analysis revealed no relationship of neovascularization with plaque echo in the groups using either quantitative or semi-quantitative methods. Furthermore, there was no correlation of neovascularization with plaque thickness using the semi-quantitative method. The ratio of areas under the curve (RAUC) was negatively correlated with plaque thickness (r = -0.317, p = 0.001) in the mild stenosis group. With the quartile method, plaque thickness of the mild stenosis group was divided into four groups, with significant differences between the 1.5-2.2 mm and ≥3.5 mm groups (p = 0.002), 2.3-2.8 mm and ≥3.5 mm groups (p <0.001) and 2.9-3.4 mm and ≥3.5 mm groups (p <0.001). Both semi-quantitative and quantitative CEUS methods characterizing neovascularization of plaque are equivalent with respect to assessing relationships between neovascularization, echogenicity and thickness. However, the quantitative method could fail for plaque <3.5 mm because of motion artifacts.

Evaluation of carotid plaque echogenicity based on the integral of the cumulative probability distribution using gray-scale ultrasound images

OBJECTIVE

Carotid plaque echogenicity is associated with the risk of cardiovascular events. Gray-scale median (GSM) of the ultrasound image of carotid plaques has been widely used as an objective method for evaluation of plaque echogenicity in patients with atherosclerosis. We proposed a computer-aided method to evaluate plaque echogenicity and compared its efficiency with GSM.

METHODS

One hundred and twenty-five carotid plaques (43 echo-rich, 35 intermediate, 47 echolucent) were collected from 72 patients in this study. The cumulative probability distribution curves were obtained based on statistics of the pixels in the gray-level images of plaques. The area under the cumulative probability distribution curve (AUCPDC) was calculated as its integral value to evaluate plaque echogenicity.

RESULTS

The classification accuracy for three types of plaques is 78.4% (kappa value, κ = 0.673), when the AUCPDC is used for classifier training, whereas GSM is 64.8% (κ = 0.460). The receiver operating characteristic curves were produced to test the effectiveness of AUCPDC and GSM for the identification of echolucent plaques. The area under the curve (AUC) was 0.817 when AUCPDC was used for training the classifier, which is higher than that achieved using GSM (AUC = 0.746). Compared with GSM, the AUCPDC showed a borderline association with coronary heart disease (Spearman r = 0.234, p = 0.050).

CONCLUSIONS

Our experimental results suggest that AUCPDC analysis is a promising method for evaluation of plaque echogenicity and predicting cardiovascular events in patients with plaques.

Classification of Carotid Plaque Echogenicity by Combining Texture Features and Morphologic Characteristics

OBJECTIVES

Anechoic carotid plaques on sonography have been used to predict future cardiovascular or cerebrovascular events. The purpose of this study was to investigate whether carotid plaque echogenicity could be assessed objectively by combining texture features extracted by MaZda software (Institute of Electronics, Technical University of Lodz, Lodz, Poland) and morphologic characteristics, which may provide a promising method for early prediction of acute cardiovascular disease.

METHODS

A total of 268 plaque images were collected from 136 volunteers and classified into 85 hyperechoic, 83 intermediate, and 100 anechoic plaques. About 300 texture features were extracted from histogram, absolute gradient, run-length matrix, gray-level co-occurrence matrix, autoregressive model, and wavelet transform algorithms by MaZda. The morphologic characteristics, including degree of stenosis, maximum plaque intima-media thickness, and maximum plaque length, were measured by B-mode sonography. Statistically significant features were selected by analysis of covariance. The most discriminative features were obtained from statistically significant features by linear discriminant analysis. The K-nearest neighbor classifier was used to classify plaque echogenicity based on statistically significant and most discriminative features.

RESULTS

A total of 30 statistically significant features were selected among the plaques, and 2 most discriminative features were obtained from the statistically significant features. The classification accuracy rates for 3 types of plaques based on statistically significant and most discriminative features were 72.03% (κ= 0.571; P < .001) and 88.14% (κ= 0.820; P < .001), respectively. The receiver operating characteristic curve for identifying anechoic plaques showed an area under the curve of 0.918 when the most discriminative features were used to train the classifier.

CONCLUSIONS

It is feasible to classify carotid plaque echogenicity by combining texture features extracted from sonograms by MaZda and morphologic characteristics.

Contrast-enhanced ultrasound imaging of intraplaque neovascularization and its correlation to plaque echogenicity in human carotid arteries atherosclerosis

BACKGROUND

Currently the most widely accepted predictor of stroke risk in patients with carotid atherosclerosis is the degree of stenoses. Plaque echogenicity on ultrasound imaging (US) and intraplaque neovascularization (IPNV) are becoming recognized as factors of plaque vulnerability. Aim of the study was to investigate the correlation between the echogenicity of the carotid atherosclerosis by standard US and the degree of IPNV by contrast enhanced US (CEUS).

METHODS

We recruited 45 consecutive subjects with an asymptomatic ≥50% carotid artery stenoses. Carotid plaque echogenicity at standard US was visually graded according to Gray-Weale classification (GW) and measured by the grayscale median (GSM), a semi-automated measurement performed by Adobe Photoshop©. On CEUS imaging IPNV was graded by different point scales according to the visual appearance of contrast within the plaque as follows: CEUS_A (1=absent; 2=present); CEUS_B (increasing IPNV from 1 to 3); and CEUS_C (increasing IPNV from 0 to 3).

RESULTS

The correlation between echogenicity by GW and IPNV grading was as follows: CEUS_B (-0.130 p .423), CEUS_C (-0.108, p .509), CEUS_A (0.021, p .897). The correlation between echogenicity by GSM measurement and IPNV was as follows: using a CEUS_A (-0.125, p .444), CEUS_C (-0.021, p .897) (0.005, p .977). No correlation was found statistically significant.

CONCLUSION

Our results display that there is no significant correlation between plaque echogenicity and IPNV. The small sample number and the multifaceted pathophysiology of the atherosclerotic plaque may explain the absence of statistically significantly correlation. Curtailing vulnerability explanation to either IPNV or echolucency may be misleading.

Echogenicity of the Common Carotid Artery Intima-Media Complex in Stroke

The grey-scale median of the common carotid artery intima-media complex (IM-GSM) characterizes arterial wall composition, and a low IM-GSM is associated with increased cardiovascular mortality in the elderly. We aimed to determine differences in the IM-GSM between a cohort with cerebrovascular disease and a healthy cohort. Eighty-two healthy individuals (control group: 63.2 ± 8.7 y) and 96 patients with either stroke or transient ischemic attacks (CRVD group: 68.6 ± 9.8 y) were studied. Common carotid artery intima-media thickness and IM-GSM obtained by ultrasound were analyzed using semi-automated edge-detection software. The IM-GSM was significantly lower in the CRVD group than in the control group (106 ± 24 vs. 124 ± 27 au, p < 0.001). The IM-GSM was similar for the infarct and non-infarct sides in CRVD. In the pooled cohort of all participants, the lower the quartile of IM-GSM, the greater were the carotid artery intima-media thickness and carotid artery remodeling. These results suggest the presence of an altered atherosclerotic phenotype in the intima-media complex of CRVD patients that can be detected by ultrasound.

Ultrasound and Biochemical Diagnostic Tools for the Characterization of Vulnerable Carotid Atherosclerotic Plaque

Stroke is a leading cause of morbidity and mortality worldwide, and characterization of vulnerable carotid plaque remains the spearhead of scientific research. Plaque destabilization, the key factor that induces the series of events leading to the clinical symptoms of carotid artery disease, is a consequence of complex mechanical, structural and biochemical processes. Novel imaging and molecular markers have been studied as predictors of disease outcome with promising results. The aim of this review is to present the current state of research on the association between ultrasound-derived echogenicity indices and blood parameters indicative of carotid plaque stability and activity. Bibliographic research revealed that there are limited available data. Among the biomarkers studied, those related to oxidative stress, lipoproteins and diabetes/insulin resistance are associated with echolucent plaques, whereas adipokines are associated with echogenic plaques. Biomarkers of inflammation and coagulation have not exhibited any conclusive relationship with plaque echogenicity, and it is not possible to come to any conclusion regarding calcification-, apoptosis- and neo-angiogenesis-related parameters because of the extremely limited bibliographic data.

Ultrasound imaging for risk assessment in atherosclerosis

Atherosclerosis and its consequences like acute myocardial infarction or stroke are highly prevalent in western countries, and the incidence of atherosclerosis is rapidly rising in developing countries. Atherosclerosis is a disease that progresses silently over several decades before it results in the aforementioned clinical consequences. Therefore, there is a clinical need for imaging methods to detect the early stages of atherosclerosis and to better risk stratify patients. In this review, we will discuss how ultrasound imaging can contribute to the detection and risk stratification of atherosclerosis by (a) detecting advanced and early plaques; (b) evaluating the biomechanical consequences of atherosclerosis in the vessel wall;

Imaging of atherosclerotic plaques in obesity: excessive fat accumulation, plaque progression and vulnerability

Obesity is becoming a major health issue in the world due to sedentary lifestyles and increasing intake of Western diets. Obesity is associated with metabolic abnormalities and atherosclerotic cardiovascular diseases. Adipose tissue has been increasingly considered to play a critical role in inducing metabolic disturbances and promoting atherogenesis. Arterial wall imaging permits direct visualization of atheroma burden in various vascular beds. In addition, recent advances in imaging technology help characterize components, microstructures and functional features of atherosclerotic plaques. These imaging modalities have contributed to elucidating factors associated with atherosclerosis in obese patients. Also, it provides opportunities to evaluate the effect of novel therapies on plaques in the setting of obesity. The findings of recent imaging studies and the clinical implications will be reviewed.

Atorvastatin treatment and carotid plaque morphology in first-ever atherosclerotic transient ischemic attack/stroke: a case-control study

BACKGROUND

A relationship between echolucency of carotid plaques and the consequent risk of ipsilateral ischemic stroke has been observed. An aggressive lipid-lowering therapy may increase the echogenicity of carotid plaque in patients with elevated low-density lipoprotein cholesterol levels. The aim of this study is to prospectively evaluate the long-term effect of high-dose atorvastatin on carotid plaque morphology in patients with first-ever transient ischemic attack or stroke.

METHODS

All patients with symptomatic first ischemic atherosclerotic cerebrovascular event occurred within the previous 10 days were enrolled. Carotid Doppler ultrasound of the neck vessels with 7-11 MHz probe for the definition of the atherosclerotic carotid framework was performed. The analysis of the gray-scale median (GSM) of each plate was carried out with image processing software.

RESULTS

A total of 240 symptomatic plaques were included and divided into 3 groups: 80 in group A (atorvastatin 80 mg), 80 in group B (atorvastatin 40 mg), and 80 to group C (no atorvastatin). GSM score increases significantly more extensive in group A than in group B (+48.65 vs. +39.46, P < .02) and group C (+48.65 vs. 19.3, P = .0002). An inverse association between reduction of low-density lipoprotein and the increase in the GSM score (r = -.456, P = .007) has been observed. Moreover, the reduction of high-sensitive C-reactive protein correlates inversely with the increase of the GSM (r = -.398, P = .021).

CONCLUSIONS

Dose-dependent effect of atorvastatin on symptomatic carotid plaque morphology may suggest a specific role of this drug in the atherosclerotic stroke prevention.

The impact of variability in ultrasound settings on the measured echolucency of the carotid intima-media

BACKGROUND

B-mode ultrasound measurements of the echolucency of the carotid intima-media may hold information on cardiovascular risk. The information obtained from this measurement may depend on which gain settings are used. We studied the effect of gain settings on echolucency measurements and its consequences on risk factor relations and treatment effects.

METHODS

We used two approaches. In the first, we examined the relationship between calibration, gain and common grey-scale median (GSM) from repeated ultrasound images obtained from four healthy individuals at gain settings ranging from -20 to 20 dB. In the second, we evaluated the effect of gain settings on the relation of risk factors and statin treatment with common GSM, using images from 325 participants of the Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin (METEOR) study with documented gain settings. Echolucency of the carotid intima-media was measured from ultrasound images using PaintShop Pro and Artery Measurement Software and expressed as GSM.

RESULTS

In healthy individuals, common GSM increased with increments in gain setting, primarily when the measurements were not calibrated. In the METEOR study sample, age and sex were significantly related to gain setting. The risk factor relations with common GSM were of the same magnitude and direction after adjustment for gain setting. Furthermore, adjustment for gain setting did not alter the rates of GSM change over time.

CONCLUSION

Extreme variability in gain settings has a major impact on the echolucency measurements of the far wall common carotid intima-media. Calibration should be used to adjust for these effects of gain settings. Variability in gain settings, however, seems limited in real practice and did not change the direction and magnitude of the relations under study. However, as age and sex are major determinants of gain settings, adjustment for or stratification by age and sex is recommended in studies into echolucency of the carotid intima-media in situations in which gain settings are unknown.

Vulnerable atherosclerotic carotid plaque evaluation by ultrasound, computed tomography angiography, and magnetic resonance imaging: an overview

Ischemic syndromes associated with carotid atherosclerotic disease are often related to plaque rupture. The benefit of endarterectomy for high-grade carotid stenosis in symptomatic patients has been established. However, in asymptomatic patients, the benefit of endarterectomy remains equivocal. Current research seeks to risk stratify asymptomatic patients by characterizing vulnerable, rupture-prone atherosclerotic plaques. Plaque composition, biology, and biomechanics are studied by noninvasive imaging techniques such as magnetic resonance imaging, computed tomography, ultrasound, and ultrasound elastography. These techniques are at a developmental stage and have yet to be used in clinical practice. This review will describe noninvasive techniques in ultrasound, magnetic resonance imaging, and computed tomography imaging modalities used to characterize atherosclerotic plaque, and will discuss their potential clinical applications, benefits, and drawbacks.

An assessment of the vulnerability of carotid plaques: a comparative study between intraplaque neovascularization and plaque echogenicity

BACKGROUND

Carotid plaque echolucency as detected by Color Doppler ultrasonography (CDUS) has been used as a potential marker of plaque vulnerability. However, contrast-enhanced ultrasound (CEUS) has recently been shown to be a valuable method to evaluate the vulnerability and neovascularization within carotid atherosclerotic plaques. The aim of this study was to compare CEUS and CDUS in the assessment of plaque vulnerability using transcranial color Doppler (TCD) monitoring of microembolic signals (MES) as a reference technique.

METHODS

A total of 46 subjects with arterial stenosis (≥ 50%) underwent a carotid duplex ultrasound, TCD monitoring of MES and CEUS (SonoVue doses of 2.0 mL) within a span of 3 days. The agreement between the CEUS, CDUS, and MES findings was assessed with a chi-square test. A p-value less than 0.05 was considered statistically significant.

RESULTS

Neovascularization was observed in 30 lesions (44.4%). The vascular risk factors for stroke were similar and there were no age or gender differences between the 2 groups. Using CEUS, MES were identified in 2 patients (12.5%) within class 1 (non-neovascularization) as opposed to 15 patients (50.0%) within class 2 (neovascularization) (p = 0.023). CDUS revealed no significant differences in the appearance of the MES between the 2 groups (hyperechoic and hypoechoic) (p = 0.237).

CONCLUSION

This study provides preliminary evidence to suggest that intraplaque neovascularization detected by CEUS is associated with the presence of MESs, where as plaque echogenicity on traditional CDUS does not. These findings argue that CEUS may better identify high-risk plaques.

Carotid plaque characteristics and disease activity in rheumatoid arthritis

OBJECTIVE

Carotid plaques (CP) are predictive of acute coronary syndrome in patients with rheumatoid arthritis (RA), suggesting that atherosclerotic plaques in these patients are vulnerable. The objective of our study was to characterize vulnerability of CP in patients with RA compared to a control population, and between RA patients with different levels of disease activity.

METHODS

Ultrasound examination of carotid arteries was performed in 152 patients with RA and 89 controls. CP echolucency was evaluated by the Gray-Scale Median (GSM) technique. Lower GSM values indicate higher vulnerability of plaques. CP characteristics were compared between RA patients with active disease and in remission, and between patients and controls. All analyses were performed with adjustment for confounding factors (sex, age, smoking, and blood pressure). Poisson regression analysis was used for count data, mixed modeling for GSM and area per plaque, and analysis of covariance for minimum GSM value per patient.

RESULTS

Patients with RA more frequently had CP (median 2, range 0, 4) compared with controls (median 1, range 0, 3; p < 0.001), after adjustment for age and sex. Patients with active RA disease according to the Clinical Disease Activity Index (CDAI) had lower median GSM (p = 0.03), minimum GSM (p = 0.03), and a larger CP area (although the latter finding was not significant; p = 0.27), compared with patients with RA in remission. These findings were not confirmed for other disease measures (Simplified Disease Activity Index, Disease Activity Score-28, C-reactive protein, erythrocyte sedimentation rate).

CONCLUSION

Patients with RA had more CP compared with controls and patients in CDAI remission, and controls had more stable CP than patients with active disease; these findings point to the importance of achieving remission in RA.

Increased age, high body mass index and low HDL-C levels are related to an echolucent carotid intima-media: the METEOR study

INTRODUCTION

Echolucent plaques are related to a higher cardiovascular risk. Studies to investigate the relationship between echolucency and cardiovascular risk in the early stages of atherosclerosis are limited. We studied the relationship between cardiovascular risk factors and echolucency of the carotid intima-media in low-risk individuals.

METHODS

Data were analysed from the Measuring Effects on Intima-Media Thickness: an Evaluation of Rosuvastatin (METEOR) study, a randomized placebo-controlled trial including 984 individuals which showed that rosuvastatin attenuated the rate of change of carotid intima-media thickness (CIMT). In this post hoc analysis, duplicate baseline ultrasound images from the far wall of the left and right common carotid arteries were used for the evaluation of the echolucency of the carotid intima-media, measured by grey-scale median (GSM) on a scale of 0-256. Low GSM values reflect echolucent, whereas high values reflect echogenic structures. The relationship between baseline GSM and cardiovascular risk factors was evaluated using linear regression models.

RESULTS

Mean baseline GSM (± SD) was 84 ± 29. Lower GSM of the carotid intima-media was associated with older age, high body mass index (BMI) and low levels of high-density lipoprotein cholesterol (HDL-C) [beta -4.49, 95% confidence interval (CI) -6.50 to -2.49; beta -4.51, 95% CI -6.43 to -2.60; beta 2.45, 95% CI 0.47 to 4.42, respectively]. Common CIMT was inversely related to GSM of the carotid intima-media (beta -3.94, 95% CI -1.98 to -5.89).

CONCLUSION

Older age, high BMI and low levels of HDL-C are related to echolucency of the carotid intima-media. Hence, echolucency of the carotid intima-media may be used as a marker of cardiovascular risk profile to provide more information than thickness alone.

Sonographic characteristics of carotid artery plaques: Implications for follow-up planning?

The aim of our study was to analyze the ultrasound characteristics of carotid plaques in an outpatient population and to determine their implications for planning the ultrasound follow-up.

MATERIALS AND METHODS

We studied 747 consecutive outpatients (397 [53%] of whom were women) who underwent color Doppler sonography of the carotid arteries. Most of the patients presented multiple cardiovascular risk factors or were being followed-up for carotid artery stenosis.

RESULTS

Stenosis ranging from 1% to 69% was observed at the level of the right internal carotid arteries (ICA) in 419 (56.1%) of the 747 patients and in the left ICA in 408 of 747 (54.5%). One hundred twenty-four (29.5%) of the 419 RICA plaques and 77 (18.8%) of the 408 LICA plaques were classified as type 1 or type 2 according to the modified Gray-Weale classification.

CONCLUSIONS

Type 1 and type 2 plaques, which are referred to as "vulnerable plaques," were found in 160 (21.4%) of the 747 patients we examined. These patients should be subjected to closer ultrasound follow-up, even if they have only moderate carotid artery stenosis.

Echolucency of carotid plaques and cerebrovascular events

OBJECTIVES

To assess the relationship between carotid plaque echogenicity and degree of stenosis with acute and chronic stroke.

METHODS

A retrospective study of cerebral MRI and carotid B-mode and Doppler ultrasonography in 60 patients with stroke. Plaque echogenicity was graded as echolucent (1), predominantly echolucent (2), predominantly echogenic (3), or echogenic (4). Sonographic findings were compared between patients with acute (group 1) and chronic (group 2) stroke.

RESULTS

In group 1 (n = 39 patients), the carotid plaques were grade 1 in 21, grade 2 in 22, grade 3 in 9, and grade 4 in 4 carotid arteries. In group 2 (n = 21), the carotid plaques were grade 1 in 2, grade 2 in 8, grade 3 in 4, and grade 4 in 11 carotid arteries. Plaque echogenicity was lower in group 1 than in group 2 (p < 0.05). Plaque echolucency was associated independently with acute stroke from the degree of stenosis.

CONCLUSIONS

Patients with acute infarcts have predominantly echolucent plaques, regardless of the degree of stenosis.

Effect of rosuvastatin on the echolucency of the common carotid intima-media in low-risk individuals: the METEOR trial

BACKGROUND

The echolucency of the carotid intima-media is related to increased cardiovascular risk factor levels, morbidity, and mortality. The aim of this study was to assess the effect of statins on the echolucency of the common carotid intima-media in a low-risk population.

METHODS

Data from the Measuring Effects on Intima-Media Thickness: An Evaluation of Rosuvastatin study were used. Ultrasound images from the far walls of the left and right common carotid arteries were used for evaluation of the echolucency of the carotid intima-media, measured by grayscale median (GSM). Low GSM values reflect echolucent structures, whereas high values reflect echogenic structures. The primary end point was the difference in the annual rate of change in GSM between rosuvastatin and placebo.

RESULTS

Two-year change in GSM did not significantly differ between rosuvastatin and placebo in the total population, with a mean difference in the rate of change in GSM of 1.13 (95% confidence interval, -1.00 to 3.25). The effect of rosuvastatin differed across quintiles of baseline GSM values (P for interaction = .01). In the lowest quintile (n = 175) (i.e., in those with the most echolucent intima-media), the difference in the rate of change in GSM between rosuvastatin and placebo was 4.18 (95% confidence interval, -0.23 to 8.58). Increases in GSM were significantly related to decreasing low-density lipoprotein cholesterol levels in the lowest quintile (β = 0.76; 95% confidence interval, 0.26 to 1.25).

CONCLUSIONS

Treatment with rosuvastatin did not affect the echolucency of the arterial wall in all low-risk individuals. However, a potential effect of rosuvastatin on the echolucency of the common carotid intima-media is most likely to be found in individuals with echolucent arterial walls at baseline.

The relation between carotid plaque echogenicity and oxidative stress marker 8-iso-prostaglandin F2α

Echolucent plaques are associated with high risk of ischemic cerebrovascular events. Oxidative stress has been implicated in the process of atherosclerotic plaque development from initiation to progression. We assessed the relation between carotid plaque echogenicity and urinary 8-iso-prostaglandin F2α, as an index of oxidative stress. This cross-sectional study was conducted prospectively on 290 consecutive outpatients. Each patient was evaluated for carotid plaque echogenicity using the gray-scale median at the maximal thickness plaque and urinary 8-iso-prostaglandin F2α using enzyme linked immunosorbent assay. By Pearson correlation analysis, we found significant negative linear relation between gray-scale median values and the urinary 8-iso-prostaglandin F2α levels (r = -0.133, p = 0.023). This correlation remained significant after adjustment for atherosclerotic risk factors, thickness of the maximal plaque and medication use (β = -0.137, p = 0.031). We herein show that higher levels of urinary 8-iso-prostaglandin F2α is associated with lower plaque echogenicity.

Patient preference survey in the management of asymptomatic carotid stenosis

OBJECTIVES

Carotid stenosis accounts for 20% of ischemic strokes and can be managed with pharmacotherapy alone or in conjunction with carotid endarterectomy or stenting. The management of asymptomatic carotid stenosis is controversial amongst physicians. The aim of this study was to explore patient preferences for the potential management options using a standardized scenario to minimize clinician bias. These data will then be used to facilitate comparison with existing published data on physicians' preferences in the management of asymptomatic carotid stenosis.

METHODS

A patient information booklet and questionnaire was developed, validated, and distributed to patients who were identified as candidates for carotid screening duplex based on the presence of peripheral arterial, coronary, or aneurismal disease. Patients were asked to imagine their duplex revealed a 70% unilateral carotid stenosis. Five-year stroke or death risks of 11% were quoted for best medical therapy. The perioperative stroke or death rates quoted were 3% for endarterectomy and 3% to 5% for stenting, based on best current evidence. No physician interaction was allowed to minimize clinician bias. Responses for treatment preference and reasoning were analyzed using appropriate statistical methods. Results from this survey were then compared with a previously published poll of physician preference.

RESULTS

One hundred two questionnaires were analyzed with a 94% response rate: 48% chose pharmacotherapy alone, 30% selected carotid endarterectomy, and 22% opted for stenting. The preference for pharmacotherapy alone over either intervention, and for endarterectomy, over stenting was consistent in subgroup analyses by age, gender, prior stroke, family history of stroke, and smoking status.

CONCLUSION

In this scenario, patients were split equally between medical and surgical treatment of asymptomatic carotid stenosis. This was identical to a recent poll of physicians. Tools for risk assessment and the results of the SPACE2, ACST2, and ACT1 trials would benefit patients and physicians making this important treatment decision.

Comparison of carotid arterial morphology and plaque composition between patients with acute coronary syndrome and stable coronary artery disease: a high-resolution magnetic resonance imaging study

The purpose of this study was to evaluate the differences in carotid arterial morphology and plaque composition between patients with acute coronary syndrome (ACS) and patients with stable coronary artery disease (SCAD). Twenty-eight patients (12 ACS patients and 16 SCAD patients) underwent carotid high-resolution MRI examination using a 3.0-Tesla (3.0T) MRI scanner. The indicators of carotid arterial morphology included the maximum total vessel area (Max-TVA), mean TVA, minimum lumen area (Min-LA), mean LA, maximum wall area (Max-WA), mean WA, maximum wall thickness (Max-WT), mean WT, maximum normalized wall index (Max-NWI), mean NWI, and maximum stenosis (Max-stenosis). The indicators of plaque composition included the prevalence and mean area percentage (%) of lipid-rich necrotic core (LRNC), calcification (Ca), intraplaque hemorrhage (IPH), and fibrous cap rupture (FCR). None of the indicators of carotid arterial morphology had significant differences (all P > 0.05) between the ACS and SCAD patients. The prevalence and plaque composition area percentage of LRNC, Ca, and IPH did not exhibit significant differences between the two groups. However, carotid plaques in the ACS patients presented a higher prevalence of FCR than SCAD patients (P < 0.05). This study revealed a similar carotid arterial morphology between ACS and SCAD patients. However, FCR is more common in carotid plaques with ACS than in those with SCAD. Ruptured carotid plaques may be a forewarning factor for those patients who are at high risk of ACS.

Standardized definitions and clinical endpoints in carotid artery and supra-aortic trunk revascularization trials

BACKGROUND

Endovascular therapy has emerged as a promising alternative to open surgery for stroke prevention in patients with obstructive disease of the supra-aortic arteries. Although most previous studies have used similar safety and efficacy endpoints, differences in definitions, timing of assessments, and standards of reporting have hampered direct comparisons across various trials.

METHODS AND RESULTS

The DEFINE group, an informal collaboration of multidisciplinary physicians, involved in the therapy of patients with obstructive disease of the supra-aortic arteries in Europe and the United States reviewed the current literature and, after extensive correspondence and meetings, proposed the definitions outlined in the present manuscript. Three meetings including all authors of the manuscript, along with representatives of the United States Food and Drug Administration (FDA) and commercial device manufacturers were held in Barcelona, Spain, in May 2008, in Munich, Germany, in July 2008, and in New York in November 2008. The proposed definitions encompass baseline clinical and anatomic characteristics, clinical and radiologic outcomes, complications, standards of reporting, and timing of assessment.

CONCLUSIONS

Considering the broad consensus between the multidisciplinary scientific members and the regulatory authorities, the proposed definitions are expected to find adoption in future clinical investigations. These definitions can be applied to both endovascular and open surgery trials and will allow reliable comparisons between these two revascularization methods.

Correlation of carotid artery atherosclerotic lesion echogenicity and severity at standard US with intraplaque neovascularization detected at contrast-enhanced US

PURPOSE

To correlate echogenicity and severity of atherosclerotic carotid artery lesions at standard ultrasonography (US) with the degree of intraplaque neovascularization at contrast material-enhanced (CE) US.

MATERIALS AND METHODS

This HIPAA-compliant study was approved by the local ethics committee, and all patients provided informed consent. A total of 175 patients (113 [65%] men, 62 [35%] women; mean age, 67 years ± 10 [standard deviation]) underwent standard and CE US of the carotid artery. Lesion echogenicity (class I to IV), degree of stenosis, and maximal lesion thickness were evaluated for each documented atherosclerotic lesion. The degree of intraplaque neovascularization at CE US was categorized as absent (grade 1), moderate (grade 2), or extensive (grade 3). Correlation of neovascularization with echogenicity, degree of stenosis, and maximal lesion thickness was made by using Spearman ρ and χ(2) test for trend.

RESULTS

In a total of 293 atherosclerotic lesions, echogenicity was inversely correlated with grade of intraplaque neovascularization (ρ = -0.199, P < .001). More echolucent lesions had a higher degree of neovascularization compared with more echogenic ones (P < .001). The degree of stenosis was significantly correlated with grade of intraplaque neovascularization (ρ = 0.157, P = .003). Lesions with higher degree of stenosis had higher grade of neovascularization (P = .008), and maximal lesion thickness increased with the grade of neovascularization (P < .001) and was significantly correlated with grade of neovascularization (ρ = 0.233, P < .001).

CONCLUSION

Neovascularization visualized with CE US correlates with lesion severity and with morphologic features of plaque instability, contributing to the concept that more vulnerable plaques are more likely to have a greater degree of neovascularization. Therefore, CE US may be a valuable tool for further risk stratification of echolucent atherosclerotic lesions and carotid artery stenosis of different degrees.

SUPPLEMENTAL MATERIAL

http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.10101008/-/DC1.

Ultrasonographic measurements of subclinical carotid atherosclerosis in prediction of ischemic stroke

Carotid intima-media thickness (IMT) and plaque measurements are widely used to quantify atherosclerosis and assess the risk of future stroke, and are used as surrogate endpoints for clinical disease. In recent years, it has become clear that carotid IMT and plaque reflect biologically and genetically different aspects of the atherosclerotic process, and are differentially related to risk factors and cardiovascular disease. Plaques are focal manifestations of atherosclerosis while increased IMT represents mainly hypertensive medial hypertrophy. Several prospective studies have showed that IMT and plaque measurements, such as total plaque area and plaque number, are predictive of future stroke. Plaque echogenicity predicts future stroke independent of plaque size. The contribution of IMT and plaque measurements in individual stroke risk prediction in the general population seems to be limited, but may be useful as a tool for individual stratification of high-risk patients.

Correlation of carotid plaque neovascularization detected by using contrast-enhanced US with clinical symptoms

PURPOSE

To determine the correlation between the degree of plaque enhancement with contrast agent microbubbles and clinical symptoms in patients with carotid atherosclerotic plaque.

MATERIALS AND METHODS

The study was approved by the hospital ethical committee, and informed consent was obtained from all patients. One hundred four patients (83 men: mean age, 64 years +/- 9 [standard deviation]; 21 women: mean age, 61 years +/- 10) with carotid plaques were studied with standard and contrast material-enhanced ultrasonography (US). Contrast enhancement in the plaque was evaluated with visual interpretation and quantitative analysis.

RESULTS

Among the 104 patients, 35 (34%) had transient ischemic attack and/or cerebrovascular ischemic stroke. Plaque enhancement was found in 28 (80%) of 35 symptomatic patients and in 21 (30%) of 69 asymptomatic patients (P < .001). Enhanced intensity in the plaque (13.9 dB +/- 6.4) and the ratio of enhanced intensity in the plaque to that in the lumen of the carotid artery (0.54 +/- 0.23) in symptomatic patients were significantly greater than those in asymptomatic patients (8.8 dB +/- 5.2 [P < .001] and 0.33 +/- 0.19 [P < .001], respectively). Sensitivity and specificity were 74% and 62%, respectively, for enhanced intensity in the plaque (cutoff value, 10.0 dB) and 74% and 75%, respectively, for ratio of enhanced intensity in the plaque to that in the lumen of the carotid artery (cutoff value, 0.46).

CONCLUSION

Symptomatic patients had more intense contrast agent enhancement in the plaque than asymptomatic patients, suggesting that contrast-enhanced carotid US may be used for plaque risk stratification.