Current status of carotid ultrasound in atherosclerosis

A self-supervised fusion network for carotid plaque ultrasound image classification

Carotid plaque classification from ultrasound images is crucial for predicting ischemic stroke risk. While deep learning has shown effectiveness, it heavily relies on substantial labeled datasets. Achieving high performance with limited labeled images is essential for clinical use. Self-supervised learning (SSL) offers a potential solution; however, the existing works mainly focus on constructing the SSL tasks, neglecting the use of multiple tasks for pretraining. To overcome these limitations, this study proposed a self-supervised fusion network (Fusion-SSL) for carotid plaque ultrasound image classification with limited labeled data. Fusion-SSL consists of two SSL tasks: classifying image block order (Ordering) and predicting image rotation angle (Rotating). A dual-branch residual neural network was developed to fuse feature presentations learned by the two tasks, which can extract richer visual boundary shape and contour information than a single task. In this experiment, 1270 carotid plaque ultrasound images were collected from 844 patients at Zhongnan Hospital (Wuhan, China). The results showed that Fusion-SSL outperforms single SSL methods across different percentages of labeled training data, ranging from 10 to 100%. Moreover, with only 40% labeled training data, Fusion-SSL achieved comparable results to a single SSL method (predicting image rotation angle) with 100% labeled data. These results indicate that Fusion-SSL could be beneficial for the classification of carotid plaques and the early warning of a stroke in clinical practice.

Psychological stress and the longitudinal progression of subclinical atherosclerosis

OBJECTIVE

In a midlife sample of adults, the present study tested the extent to which changes in psychological stress relate to the progression of subclinical cardiovascular disease over multiple years and explored the potential moderating role of cardiometabolic risk.

METHOD

Participants were screened to exclude those with clinical cardiovascular, respiratory, metabolic, and other chronic illnesses, as well as those taking psychotropic, cardiovascular, lipid, and glucose control medications. At baseline (N = 331) and then again at follow-up an average of 3 years later (N = 260), participants completed the 10-item Perceived Stress Scale, underwent assessments of their cardiometabolic risk, and underwent ultrasonography to measure carotid artery intima-media thickness (IMT), which is a surrogate indicator of subclinical atherosclerosis.

RESULTS

Regression models showed that the change in psychological stress from baseline to follow-up was positively associated with the corresponding change in IMT, with covariate control for age at baseline, sex at birth, and variability in length of follow-up across participants. Cardiometabolic risk factors did not statistically moderate this longitudinal association. In exploratory analyses, cardiometabolic risk factors also did not statistically mediate this association.

CONCLUSION

These longitudinal findings suggest that increases in psychological stress in midlife relate to corresponding increases in subclinical atherosclerosis. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Role of Cardiovascular Imaging in Risk Assessment: Recent Advances, Gaps in Evidence, and Future Directions

Optimal risk assessment for primary prevention remains highly challenging. Recent registries have highlighted major discrepancies between guidelines and daily practice. Although guidelines have improved over time and provide updated risk scores, they still fail to identify a significant proportion of at-risk individuals, who then miss out on effective prevention measures until their initial ischemic events. Cardiovascular imaging is progressively assuming an increasingly pivotal role, playing a crucial part in enhancing the meticulous categorization of individuals according to their risk profiles, thus enabling the customization of precise therapeutic strategies for patients with increased cardiovascular risks. For the most part, the current approach to patients with atherosclerotic cardiovascular disease (ASCVD) is homogeneous. However, data from registries (e.g., REACH, CORONOR) and randomized clinical trials (e.g., COMPASS, FOURIER, and ODYSSEY outcomes) highlight heterogeneity in the risks of recurrent ischemic events, which are especially higher in patients with poly-vascular disease and/or multivessel coronary disease. This indicates the need for a more individualized strategy and further research to improve definitions of individual residual risk, with a view of intensifying treatments in the subgroups with very high residual risk. In this narrative review, we discuss advances in cardiovascular imaging, its current place in the guidelines, the gaps in evidence, and perspectives for primary and secondary prevention to improve risk assessment and therapeutic strategies using cardiovascular imaging.

Development and validation of explainable machine-learning models for carotid atherosclerosis early screening

BACKGROUND

Carotid atherosclerosis (CAS), an important factor in the development of stroke, is a major public health concern. The aim of this study was to establish and validate machine learning (ML) models for early screening of CAS using routine health check-up indicators in northeast China.

METHODS

A total of 69,601 health check-up records from the health examination center of the First Hospital of China Medical University (Shenyang, China) were collected between 2018 and 2019. For the 2019 records, 80% were assigned to the training set and 20% to the testing set. The 2018 records were used as the external validation dataset. Ten ML algorithms, including decision tree (DT), K-nearest neighbors (KNN), logistic regression (LR), naive Bayes (NB), random forest (RF), multiplayer perceptron (MLP), extreme gradient boosting machine (XGB), gradient boosting decision tree (GBDT), linear support vector machine (SVM-linear), and non-linear support vector machine (SVM-nonlinear), were used to construct CAS screening models. The area under the receiver operating characteristic curve (auROC) and precision-recall curve (auPR) were used as measures of model performance. The SHapley Additive exPlanations (SHAP) method was used to demonstrate the interpretability of the optimal model.

RESULTS

A total of 6315 records of patients undergoing carotid ultrasonography were collected; of these, 1632, 407, and 1141 patients were diagnosed with CAS in the training, internal validation, and external validation datasets, respectively. The GBDT model achieved the highest performance metrics with auROC of 0.860 (95% CI 0.839-0.880) in the internal validation dataset and 0.851 (95% CI 0.837-0.863) in the external validation dataset. Individuals with diabetes or those over 65 years of age showed low negative predictive value. In the interpretability analysis, age was the most important factor influencing the performance of the GBDT model, followed by sex and non-high-density lipoprotein cholesterol.

CONCLUSIONS

The ML models developed could provide good performance for CAS identification using routine health check-up indicators and could hopefully be applied in scenarios without ethnic and geographic heterogeneity for CAS prevention.

Carotid intima media thickness (CIMT) in adults in the AWI-Gen Nairobi site study: Profiles and predictors

BACKGROUND

Carotid intima media thickness (CIMT) is used as a marker of subclinical and asymptomatic atherosclerotic vascular disease. Increased CIMT is associated with future cerebrovascular and cardiovascular events. There is limited data on the profile and correlates of CIMT in Africa. The aim of this study was to describe the profile and correlates of CIMT in apparently normal younger-age adults in an urban setting in Kenya.

METHODS

This study used population-based data collected from 2003 adults between the ages of 40 and 60 years in two slums of Nairobi as part of a genetic study. CIMT was measured using LOGIQ e (GE Healthcare, CT, USA) ultrasound on both left and right carotid arteries, whereby maximum, mean, and minimum values were recorded. Age- and sex-specific CIMT measurements were calculated and their association with basic sociodemographic, behavioral and body composition indicators were investigated.

RESULTS

The median (IQR) CIMT were 0.58 (0.51, 0.66) and 0.59 (0.53, 0.66) in men and women, respectively. About 16% of the study population had CIMT greater than 0.7mm, the cut off for higher CIMT. Nearly 60% had CIMT values ≥75th percentile. Age, current use of alcohol, systolic blood pressure, subcutaneous fat thickness, pulse rate and pulse pressure were found to be the main predictors of CIMT in our study population.

CONCLUSION

This study provided population-based reference values and predictors for CIMT for an adult population living in urban poor settings in Kenya. Future studies need to consider biochemical and genetic predictors of CIMT in this population.

Cardiovascular/Stroke Risk Assessment in Patients with Erectile Dysfunction-A Role of Carotid Wall Arterial Imaging and Plaque Tissue Characterization Using Artificial Intelligence Paradigm: A Narrative Review

PURPOSE

The role of erectile dysfunction (ED) has recently shown an association with the risk of stroke and coronary heart disease (CHD) via the atherosclerotic pathway. Cardiovascular disease (CVD)/stroke risk has been widely understood with the help of carotid artery disease (CTAD), a surrogate biomarker for CHD. The proposed study emphasizes artificial intelligence-based frameworks such as machine learning (ML) and deep learning (DL) that can accurately predict the severity of CVD/stroke risk using carotid wall arterial imaging in ED patients.

METHODS

Using the PRISMA model, 231 of the best studies were selected. The proposed study mainly consists of two components: (i) the pathophysiology of ED and its link with coronary artery disease (COAD) and CHD in the ED framework and (ii) the ultrasonic-image morphological changes in the carotid arterial walls by quantifying the wall parameters and the characterization of the wall tissue by adapting the ML/DL-based methods, both for the prediction of the severity of CVD risk. The proposed study analyzes the hypothesis that ML/DL can lead to an accurate and early diagnosis of the CVD/stroke risk in ED patients. Our finding suggests that the routine ED patient practice can be amended for ML/DL-based CVD/stroke risk assessment using carotid wall arterial imaging leading to fast, reliable, and accurate CVD/stroke risk stratification.

SUMMARY

We conclude that ML and DL methods are very powerful tools for the characterization of CVD/stroke in patients with varying ED conditions. We anticipate a rapid growth of these tools for early and better CVD/stroke risk management in ED patients.

A Powerful Paradigm for Cardiovascular Risk Stratification Using Multiclass, Multi-Label, and Ensemble-Based Machine Learning Paradigms: A Narrative Review

Background and Motivation: Cardiovascular disease (CVD) causes the highest mortality globally. With escalating healthcare costs, early non-invasive CVD risk assessment is vital. Conventional methods have shown poor performance compared to more recent and fast-evolving Artificial Intelligence (AI) methods. The proposed study reviews the three most recent paradigms for CVD risk assessment, namely multiclass, multi-label, and ensemble-based methods in (i) office-based and (ii) stress-test laboratories. Methods: A total of 265 CVD-based studies were selected using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) model. Due to its popularity and recent development, the study analyzed the above three paradigms using machine learning (ML) frameworks. We review comprehensively these three methods using attributes, such as architecture, applications, pro-and-cons, scientific validation, clinical evaluation, and AI risk-of-bias (RoB) in the CVD framework. These ML techniques were then extended under mobile and cloud-based infrastructure. Findings: Most popular biomarkers used were office-based, laboratory-based, image-based phenotypes, and medication usage. Surrogate carotid scanning for coronary artery risk prediction had shown promising results. Ground truth (GT) selection for AI-based training along with scientific and clinical validation is very important for CVD stratification to avoid RoB. It was observed that the most popular classification paradigm is multiclass followed by the ensemble, and multi-label. The use of deep learning techniques in CVD risk stratification is in a very early stage of development. Mobile and cloud-based AI technologies are more likely to be the future. Conclusions: AI-based methods for CVD risk assessment are most promising and successful. Choice of GT is most vital in AI-based models to prevent the RoB. The amalgamation of image-based strategies with conventional risk factors provides the highest stability when using the three CVD paradigms in non-cloud and cloud-based frameworks.

Three-dimensional ultrasound for carotid vessel wall volume measurement

Objectives:

The intima–media thickness (IMT) of the carotid artery can now be detected on a three-dimensional (3D) plane. The 3D vessel wall volume (VWV) more accurately represents vascular conditions. Through 3D ultrasound, we established a standardized method for carotid VWV measurement.

Materials and Methods:

A total of thirty patients without stroke or cardiovascular disease who received carotid duplex sonography were retrospectively reviewed. Gray-scale 3D images from the distal common carotid artery (CCA) to internal carotid artery on both sides were acquired using a single-sweep 3D transducer and analyzed offline by using the vascular plaque quantification function of the Philips QLAB software. Then, the 3D IMT(QLAB intima–media thickness [QIMT]), total plaque volume (TPV), and VWV were measured by a neurologist and a technician, and the interobserver variability was assessed.

Results:

The mean two-dimensional (2D) carotid IMT was 0.65 ± 0.12 mm. The mean QIMT, TPV, and VWV measured by observer 1 were 0.68 ± 0.18 mm, 26 ± 12 mm³, and 94 ± 10 mm³, respectively. The Bland–Altman plot of the mean differences between the QIMT, TPV, and VWV values measured by observers 1 and 2 showed that those of observer 2 were within two standard deviations of those of observer 1. Intraclass correlation coefficients (ICCs) indicated strong correlations in QIMT (ICC = 0.76), TPV (ICC = 0.85), and VWV (ICC = 0.90; P < 0.001) between observers 1 and 2. Both 2D IMT and 3D QIMT exhibited a positive linear correlation with age.

Conclusion:

This study established a standardized VWV measurement through 3D ultrasound. Reasonable interobserver differences were obtained within a 95% limit of agreement and high reliability (ICC = 0.90). The VWV 1 cm from the CCA bifurcation was quantified with a mean value of 94.2 mm³. Further studies on the 3D ultrasound quantification of carotid arteries are warranted.

A hybrid deep learning paradigm for carotid plaque tissue characterization and its validation in multicenter cohorts using a supercomputer framework

BACKGROUND

Early and automated detection of carotid plaques prevents strokes, which are the second leading cause of death worldwide according to the World Health Organization. Artificial intelligence (AI) offers automated solutions for plaque tissue characterization. Recently, solo deep learning (SDL) models have been used, but they do not take advantage of the tandem connectivity offered by AI's hybrid nature. Therefore, this study explores the use of hybrid deep learning (HDL) models in a multicenter framework, making this study the first of its kind.

METHODS

We hypothesize that HDL techniques perform better than SDL and transfer learning (TL) techniques. We propose two kinds of HDL frameworks: (i) the fusion of two SDLs (Inception with ResNet) or (ii) 10 other kinds of tandem models that fuse SDL with ML. The system Atheromatic™ 2.0_HDL (AtheroPoint, CA, USA) was designed on an augmentation framework and three kinds of loss functions (cross-entropy, hinge, and mean-square-error) during training to determine the best optimization paradigm. These 11 combined HDL models were then benchmarked against one SDL model and five types of TL models; thus, this study considers a total of 17 AI models.

RESULTS

Among the 17 AI models, the best performing HDL system was that comprising CNN and decision tree (DT), as its accuracy and area-under-the-curve were 99.78 ± 1.05% and 0.99 (p<0.0001), respectively. These values are 6.4% and 3.2% better than those recorded for the SDL and TL models, respectively. We validated the performance of the HDL models with diagnostics odds ratio (DOR) and Cohen and Kappa statistics; here, HDL outperformed DL and TL by 23% and 7%, respectively. The online system ran in <2 s.

CONCLUSION

HDL is a fast, reliable, and effective tool for characterizing the carotid plaque for early stroke risk stratification.

Switching from boosted PIs to dolutegravir in HIV-infected patients with high cardiovascular risk: 48 week effects on subclinical cardiovascular disease

BACKGROUND

Switching from boosted PIs to dolutegravir in virologically suppressed HIV-infected patients with high cardiovascular risk significantly decreased total cholesterol and other proatherogenic lipid fractions at 48 weeks. The impact of this strategy on subclinical cardiovascular disease is unknown.

METHODS

NEAT022 is a European, multicentre, open-label, randomized, non-inferiority trial. HIV-infected adults aged >50 years or with a Framingham score >10% were eligible if plasma HIV RNA was <50 copies/mL for >24 weeks on a boosted PI-based regimen. Patients were randomized 1:1 to switch from boosted PIs to dolutegravir or to continue on boosted PIs. Common carotid arteries intima-media thickness (CIMT) and pulse wave velocity (PWV) were measured following a standardized protocol in a subgroup of NEAT022 study participants at baseline and at Week 48.

RESULTS

One hundred and fifty-six patients participated in the ultrasonography and arterial stiffness substudies, respectively. In each substudy, population characteristics did not differ between arms and matched those of the main study. At 48 weeks, patients who switched to dolutegravir had lower mean progression of both right (+4 versus +14.6 μm) and left (-6.1 versus +1.6 μm) CIMT and also a smaller increase in mean PWV (+0.18 versus +0.39 m/s) than patients continuing on boosted PIs, although differences were not statistically significant. CIMT trends were consistent across Framingham score, age and country. Inconsistent effects were seen in arterial stiffness.

CONCLUSIONS

Relative to continuing on boosted PIs, switching to dolutegravir in virologically suppressed patients with high cardiovascular risk showed consistent favourable although non-significant trends on CIMT progression at 48 weeks.

Vulnerable Plaque Is More Prevalent in Male Individuals at High Risk of Stroke: A Propensity Score-Matched Study

OBJECTIVES

To assess the gender differences in the prevalence of carotid vulnerable plaques in high-risk individuals for stroke in a multicenter, cross-sectional study.

METHODS

In the year 2015, 18595 residents who were at the age of 40 or older participated in a face-to-face study in eight communities in southwestern China. Totally 2,644 participants at high risk of stroke were enrolled. Before and after propensity score matching (PSM), the prevalence of carotid plaques and vulnerable plaques were compared between men and women. Multivariate analyses were applied to explore the association between the gender and carotid plaques. Stratified analyses and interaction tests were performed to identify factors that might modify the association between the gender and carotid plaques.

RESULTS

Among 2644 high-risk individuals enrolled, there were 1,202 (45.5%) men and 1442 (54.5%) women. Carotid plaques were detected in 904 (34.2%) participants, while vulnerable plaques were found in 425 (16.1%) participants. Before PSM, carotid plaques were more prevalent in male individuals than the female (36.7% vs. 32.1%, p = 0.01), as well as vulnerable plaque (20.0% vs. 12.8%, p < 0.01). Men tend to have a higher prevalence of vulnerable plaques in multivariate analyses (adjusted OR 1.70, 95% CI 1.10-2.62, p = 0.02). Stratified analyses and interaction tests demonstrated that the association between male sex and vulnerable carotid plaque did not change by age, family history of stroke, histories of chronic disease, smoking status, drinking status, physical activity, and BMI (all p for interaction > 0.05). After PSM, vulnerable plaques were still more prevalent in male individuals than the female (17.03% vs. 12.07%, p = 0.032).

CONCLUSION

Male individuals had a higher risk of vulnerable carotid plaque independent of classical vascular risk factors. Whether there is a gender-specific association between variations in genes related to inflammation, lipid metabolis, and endothelial function and plaque vulnerability needs to be further studied.

Relative Estimate of Revised Cardiovascular Risk Combining Traditional and Non-traditional Image-based CV Markers: A Kerala Based Study

BACKGROUND

Non-traditional image markers can improve the traditional cardiovascular risk estimation, is untested in Kerala based participants.

OBJECTIVE

To identify the relationship between the 'Modified CV risk' categories with traditional and non-traditional image-based risk markers. The correlation and improvement in reclassification, achieved by pooling atherosclerotic non-traditional markers with Intermediate (≥7.5% and <20%) and High (≥20%) 10-year participants is evaluated.

METHODS

The cross-sectional study with 594 participants has the ultrasound measurements recorded from the medical archives of clinical locations at Ernakulum district, Kerala. With carotid Intima-Media Thickness (cIMT) measurement, the Plaque (cP) complexity was computed using selected plaque characteristics to compute the carotid Total Plaque Risk Score (cTPRS) for superior risk tagging. Statistical analysis was done using RStudio, the classification accuracy was verified using the decision tree algorithm.

RESULTS

The mean age of the participants was (58.14±10.05) years. The mean cIMT was (0.956±0.302) mm, with 65.6% plaque incidence. With 94.90% variability around its mean, the Multinomial Logistic Regression model identifies cIMT and cTPRS, age, diabetics, Familial Hypercholesterolemia (FH), Hypertension treatment, the presence of Rheumatoid Arthritis (RA), Chronic Kidney Disease (CKD) as significant (p<0.05). cIMT and cP were found significant for 'Intermediate High', 'High' and 'Very High' 'Modified CV risk' categories. However, age, diabetes, gender and use of hypertension treatment are significant for the 'Intermediate' 'Modified CV risk' category. The overall performance of the MLR model was 80.5%. The classification accuracy verified using the decision tree algorithm has 78.7% accuracy.

CONCLUSION

The use of atherosclerotic markers shows a significant correlation suitable for a nextlevel reclassification of the traditional CV risk.

The association between urine di-(2-ethylhexyl) phthalate metabolites, global DNA methylation, and subclinical atherosclerosis in a young Taiwanese population

Di-(2-ethylhexyl) phthalate (DEHP) has been utilized in many products for years. DEHP exposure has been linked to cardiovascular diseases (CVD) and its risk factors. Recent evidence has found a crucial role for epigenetics, including DNA methylation, in CVD. Moreover, DEHP exposure has proved to alter DNA methylation in epidemiological studies. However, the interplay between DEHP exposure, global DNA methylation, and atherosclerosis has never been reported. In this current study, we enrolled 793 participants (12-30 years) from a Taiwanese population to investigate the association between concentrations of DEHP metabolites, 5mdC/dG (global DNA methylation marker) and the carotid intima-media thickness (CIMT). The results showed urine mono-2-ethylhexyl phthalate (MEHP) level was positively correlated with 5mdC/dG and CIMT, respectively. In logistic regression models, the odds ratios (OR) of thicker CIMT (greater than 75^th percentile) with one unit increase in ln-MEHP level was higher when levels of 5mdC/dG were above 50%. In structural equation model, the result showed urine MEHP levels are directly associated with CIMT. Moreover, MEHP had an indirect association with CIMT through the 5mdC/dG after adjusting other confounding effects. In the current study, urine DEHP metabolite levels were positively correlated with 5mdC/dG, and CIMT. Our results showed DEHP had a direct and indirect association with CIMT through the 5mdC/dG. The finding implies that DNA methylation may mediate the association between DEHP exposures and subclinical atherosclerosis in this young population. Future effort is needed to elucidate the causal relationship between DEHP exposure, DNA methylation and CVD.

Carotid plaques and neurological impairment in patients with acute cerebral infarction

OBJECTIVE

To determine whether the coexistence of carotid atherosclerosis plaque affects the neurological function of cerebral infarction.

METHODS

A total of 1078 patients with acute cerebral infarction were enrolled, all patients were divided into carotid plaque group (n = 702) and non-carotid plaque group (n = 376). Meanwhile, all patients were divided into mild group (n = 624) and moderate to severe group (n = 454). The difference of the incidence of carotid plaque between the mild and moderate to severe group was analyzed.

RESULTS

In the 1078 patients with cerebral infarction, the NIHSS score in the carotid plaque group was significantly higher than that in the non-carotid plaque group (P<0.05). The number of mild cases without carotid artery plaque group was larger than that of plaque group (P<0.05), and the number of moderate to severe cases in carotid plaque group was larger than that in non-plaque group (P<0.05). In patients with carotid atherosclerotic plaque, the risk of moderate to severe cerebral infarction was 2.11 times higher than that without carotid artery plaque. Lastly, patients with single plaques were 1.82 times more likely to develop moderate to severe cerebral infarction than those without carotid plaque, while patients with multiple carotid plaques were 2.41 times higher to get moderate or severe cerebral infarction than those without carotid plaque.

CONCLUSIONS

The incidence of carotid atherosclerotic plaques may be related to neurological deficits in patients with acute cerebral infarction.

Subclinical left ventricular dysfunction assessed by two-dimensional speckle tracking echocardiography in asymptomatic patients with carotid stenosis

The relationship between subclinical left ventricular (LV) dysfunction and atherosclerosis may have been underestimated in the past, which might be responsible for the high incidence of premature death in individuals with carotid stenosis. We sought to evaluate the underlying myocardial dysfunction in asymptomatic carotid stenosis patients using speckle tracking echocardiography (STE). Fifty patients with carotid stenosis ≥ 50% and a preserved LV ejection fraction (LVEF), and 45 controls without carotid stenosis who were matched in terms of vascular comorbidities were enrolled. All participants underwent carotid ultrasound and echocardiographic examination. The global LV longitudinal strain (GLS) was measured using STE. Compared with the control group, the e' of the mitral annular velocity and GLS were decreased in asymptomatic carotid stenosis patients (p < 0.05), however, the LVEF was well preserved. Based on a predefined cutoff for subclinical LV systolic dysfunction that was defined at a GLS <  - 18%, this dysfunction was detected in 22 patients with carotid stenosis (44%) and in 10 patients in the control group (22%) (p < 0.05). The GLS was negatively correlated with the levels of low-density lipoprotein cholesterol (r =  - 0.356, p < 0.05) and triglyceride (r =  - 0.396, p < 0.05). In conclusion, LV diastolic and systolic functioning were significantly decreased in patients with asymptomatic carotid stenosis, and dyslipidemia likely contributed to the subclinical LV dysfunction in these patients. Our findings indicated the importance of detecting LV subclinical dysfunction and early intervention in this patient population.

Evaluation of subclinical atherosclerosis by ultrasound radiofrequency data technology in patients with Behçet's disease

AIM

We aimed to evaluate subclinical atherosclerosis based on carotid intima-media thickness (CIMT) and arterial stiffness measurements in patients with Behçet's disease (BD), using ultrasound (US) radiofrequency (RF) data technology.

METHODS

We included 33 BD patients and 33 healthy controls in this study. The participants did not have any primary cardiovascular risk factors, such as diabetes mellitus, hypertension, hyperlipidemia and obesity. All participants were evaluated using Doppler ultrasonography. Arterial stiffness and CIMT measurements were performed in bilateral common carotid arteries using the US RF data technology.

RESULTS

The right, left and mean CIMT values were similar between the patient and control groups (P > 0.05). There was also no statistically significant difference in the right side α and β stiffness indices despite higher values in the patient group (P > 0.05). The right, left and mean distensibility coefficient (DC) and compliance coefficient (CC) values of the patient group were significantly lower than the control group (P < 0.05). The left and mean α- and β-stiffness indices, and the right, left and mean pulse wave velocity (PWV) values were significantly higher in the patient group (P < 0.05). We found higher mean CIMT and PWV values, and α- and β-stiffness indices in patients with mucocutaneous involvement compared with those with major organ involvement, while the mean DC and CC values were lower in the former. However, these results did not reach a statistically significant level.

CONCLUSION

This study demonstrated evidence of subclinical atherosclerosis in BD in the absence of major atherosclerotic risk factors.

Acoustic field simulation method for arbitrarily shaped transducer with dynamically refined sub-elements

Background

Simulation of the emitted acoustic field is crucial to the design of ultrasound transducers. The method based on the spatial impulse response (SIR) and aperture discretization provides a powerful tool to study the acoustic field emitted by a transducer with complex aperture geometry and sophisticated apodization/excitation pattern.

Methods

In this work, a new method based on the dynamically refined sub-elements (SE) is employed to discrete the aperture and generate the SIR. Then, these SIRs are convoluted with the excitation pulse to get the acoustic pressure (AP) signal. When calculating the SIR with this method, the slowly changed time flight from a SE to a field point (FP) is approximated with a step function, and the fast changed length of intersection between a SE and a spherical wave centered at a FP is accurately estimated with the areas of the sub-parts (SP) which are given by the dynamically refined SE.

Results

Simulations of the acoustic field created by a focusing transducer array and a hollow structured point focusing transducer indicate that the proposed new method can give similar data accuracy with a sampling frequency 16 times lower than the conventional time tracing SE (TTSE) based method. The computational cost is also reduced by nearly one order of magnitude.

Conclusions

A new method is proposed to simulate the acoustic field emitted by transducers with complex geometrical structure and sophisticated apodization/excitation patterns. The required sampling frequency with the new algorithm is greatly reduced compared to that of the conventional TTSE-based method; thus, the efficiency of the acoustic field calculation is improved significantly.

Topography of Vertebral Artery Origin Plaques: Characteristics and Determinants

BACKGROUND

Atherosclerotic plaques located at the vertebral artery ostium (VAo) are a mechanism for posterior circulation stroke, but little is known about VAo plaque topography and formation. In this study, we describe the topography of atherosclerotic plaques involving the origin of the vertebral artery (VA).

METHODS

Cross-sectional analyses of extracranial duplex studies were performed, and VAo plaques were classified based on their topography in 3 groups: (1) exclusively at the VA ostium; (2) predominantly subclavian, with extension into the vertebral ostium; and (3) predominantly ostial, with extension into the subclavian artery). Chi-square and analysis of variance tests were performed to investigate the association between VAo plaque topography and continuous and categorical variables, respectively.

RESULTS

A total of 99 of 481 (21%) ultrasound duplex studies showed VAo plaques. The majority of the plaques (60%) were found to extend from the subclavian to the ostium. Plaques occurred more frequently at the medial wall of the VAo. No vascular risk factors were associated with plaque formation; however, women were more likely to have plaques involving predominantly or exclusively the VAo (P = .004).

CONCLUSIONS

We describe 3 different patterns of VAo involvement in patients with ostial atherosclerotic VA disease. VAo plaques occurred almost exclusively at the medial wall of the vessel. Women had more plaques involving predominantly the origin. Prospective studies are needed to investigate the clinical significance of these findings.

The importance of blood flow volume in the brain-supplying arteries for the clinical management - the impact of collateral circulation

Aim: An assessment of increased compensatory blood flow in the brain-supplying arteries in patients with significant carotid artery stenosis. Materials and methods: Doppler ultrasound was performed in 218 patients over 60 years of age to evaluate both the degree of brain-supplying artery stenosis as well as the blood flow volume balance in all vessels supplying the brain: the internal carotid artery, the external carotid artery and the vertebral artery. The control group included 94 patients with no stenosis in the extracranial segments and no neurological manifestations, in whom blood flow values were calculated (the internal carotid artery – 290 mL/min, the external carotid artery – 125 mL/min, the vertebral artery – 80 mL/min); the total mean blood flow in the brain-supplying arteries was 985 mL/min. A 33% increase in blood flow was considered compensatory. In addition to the control group, 30 patients with asymptomatic stenosis of less than 50% and 12 patients after endarterectomy with mean blood flow of 920 mL/min and 960 mL/min, as well as two groups of particular interest to us, i.e. 38 patients with no compensatory blood flow increase despite significant stenosis (>50%) with mean blood flow of 844 mL/min and 44 patients with similar stenosis and with compensatory blood flow increase up to 1174 mL/min were included in the analysis. Results: Comparison of the two groups showed several significant differences: increased blood flow (118% vs. 86% of the norm) in patients with compensated stenosis, an increased number of asymptomatic patients (70% vs. 37%) and a threefold increase in the number of patients with occlusions (15 : 5) in the group of patients with increased blood supply to the brain. Conclusions: All potential blood-supplying vessels, including the external carotid artery, are involved in brain tissue perfusion in some of the patients with significant stenosis. Determining the degree of compensation may have an important impact on the indications for surgical treatment, which will make a valuable contribution to the current criteria (asymptomatic/symptomatic patients).

Arterial Phantoms with Regional Variations in Wall Stiffness and Thickness

Regional wall stiffening and thickening are two common pathological features of arteries. To account for these two features, we developed a new arterial phantom design framework to facilitate the development of vessel models that contain a lesion segment whose wall stiffness and thickness differ from those of other segments. This new framework is based on multi-part injection molding principles that sequentially casted the lesion segment and the flank segments of the vessel model using molding parts devised with computer-aided design tools. The vessel-mimicking material is created from polyvinyl alcohol cryogel, and its acoustic properties are similar to those of arteries. As a case demonstration, we fabricated a stenosed three-segment phantom composed of a central lesion segment (5.1-mm diameter, 1.95-mm wall thickness, 212.6-kPa elastic modulus) and two flank segments (6.0-mm diameter, 1.5-mm wall thickness, 133.7-kPa elastic modulus). B-mode imaging confirmed the difference in thickness between the lesion segment and flank segments of the phantom. Also, Doppler-based vessel wall displacement analysis revealed that when pulsatile flow was fed through the phantom (carotid pulse; 27 mL/s peak flow rate), the lesion segment distended less compared with the flank segments. Specifically, the three-beat averaged peak wall displacement in the lesion segment was measured as 0.28 mm, and it was significantly smaller than that of the flank segments (0.60 mm). It is anticipated that this new multi-segment arterial phantom can serve as a performance testbed for the evaluation of local arterial stiffness estimation algorithms.

3D Ultrasound Imaging: Fast and Cost-effective Morphometry of Musculoskeletal Tissue

The developmental goal of 3D ultrasound imaging (3DUS) is to engineer a modality to perform 3D morphological ultrasound analysis of human muscles. 3DUS images are constructed from calibrated freehand 2D B-mode ultrasound images, which are positioned into a voxel array. Ultrasound (US) imaging allows quantification of muscle size, fascicle length, and angle of pennation. These morphological variables are important determinants of muscle force and length range of force exertion. The presented protocol describes an approach to determine volume and fascicle length of m. vastus lateralis and m. gastrocnemius medialis. 3DUS facilitates standardization using 3D anatomical references. This approach provides a fast and cost-effective approach for quantifying 3D morphology in skeletal muscles. In healthcare and sports, information on the morphometry of muscles is very valuable in diagnostics and/or follow-up evaluations after treatment or training.

Early Detection System of Vascular Disease and Its Application Prospect

Markers of imaging, structure, and function reflecting vascular damage, integrating a long time accumulation effect of traditional and unrecognized cardiovascular risk factors, can be regarded as surrogate endpoints of target organ damage before the occurrence of clinical events. Prevention of cardiovascular disease requires risk stratification and treatment of traditional risk factors, such as smoking, hypertension, hyperlipidemia, and diabetes. However, traditional risk stratification is not sufficient to provide accurate assessment of future cardiovascular events. Therefore, vascular injury related parameters obtained by ultrasound or other noninvasive devices, as a surrogate parameter of subclinical cardiovascular disease, can improve cardiovascular risk assessment and optimize the preventive treatment strategy. Thus, we will summarize the research progress and clinical application of early assessment technology of vascular diseases in the present review.

Lipoprotein-associated phospholipase A2: a new marker to determine cardiovascular risk in hypercholesterolemic dyslipidaemic children

Background

Inflammation and hypercholesterolaemia contribute to atherosclerotic changes which can start in childhood. Children with hyperlipidaemias are at high risk for early coronary atherosclerosis. This study evaluates the relationship between lipoprotein-associated phospholipase A2 (Lp-PLA2), carotid intima-media thickness (CIMT) and flow-mediated dilatation in hypercholesterolaemic dyslipidaemic children.

Methods

We performed a case–control study consisting of 43 cases, aged 2 to 17 years, and 24 age-matched controls. Fasting blood samples were obtained from both groups for the measurement of a lipid profile (total cholesterol, LDL-C, HDL-C and triglycerides) and Lp-PLA2 in mass units. The latter was determined with a turbidimetric immunoassay method (PlacTest, DiaDexus Inc.) applied to an automated analyser. CIMT and flow-mediated dilatation measurements were undertaken by a paediatric cardiologist, using high-resolution B-mode ultrasonography.

Results

Total cholesterol, LDL-C and Lp-PLA2 concentrations were significantly higher in the cases than in the controls ( p < 0.001 for all three parameters). While CIMT values were also significantly higher in the patients compared to the controls ( P = 0.001), flow-mediated dilatation values were significantly lower ( P = 0.001). We found positive correlations between Lp-PLA2 and total cholesterol ( r = 0.41, P = 0.001), Lp-PLA2 and LDL-C ( r = 0.36, P = 0.004), Lp-PLA2 and CIMT ( r = 0.44, P = 0.019) and LDL-C and CIMT ( r = 0.41, P = 0.032); there were negative correlations between Lp-PLA2 and flow-mediated dilatation ( r = −0.15, P = 0.045), total cholesterol and flow-mediated dilatation ( r = −0.45, P = 0.017), LDL-C and flow-mediated dilatation ( r = −0.51, P = 0.006) and CIMT and flow-mediated dilatation ( r = −0.45, P = 0.016).

Conclusion

Lp-PLA2 concentrations are significantly elevated in hypercholesterolaemic dyslipidaemic children. Given the association of Lp-PLA2 with markers of atherosclerosis (total cholesterol, LDL-C, CIMT and flow-mediated dilatation), the finding of increased concentrations of Lp-PLA2 could be used to identify early atherosclerotic changes in hypercholesterolaemic dyslipidaemic children and may inform their clinical management.