Symptomatic carotid atherosclerotic disease: correlations between plaque composition and ipsilateral stroke risk

Quantitative evaluation using carotid ultrasonography-based high-frame-rate vector flow imaging in patients with low carotid stenosis

OBJECTIVE

To explore the role of quantitative evaluation using carotid ultrasonography (US)-based high-frame-rate vector flow (V Flow) imaging in patients with low carotid stenosis.

METHODS

This single-centre cross-sectional study consecutively recruited volunteers without carotid plaque and patients with low carotid stenosis from August 2022 to May 2023. Patients were divided into symptomatic and asymptomatic groups according to their head CT or MRI results within 8 weeks. All V Flow imaging examinations were performed using a Mindray Resona R9 US system. The wall shear stress (WSS) values, oscillatory shear index (OSI) values, and turbulence (Tur) indexes in the normal common carotid artery (CCA), normal carotid bifurcation (CB), and on the upstream and downstream surface of carotid plaque were measured. Pearson Chi-square test and Fisher exact test were used for counting data according to their type. For measurement data, independent sample t test and non-parametric rank sum test were used.

RESULTS

The results proved that patients have higher WSS values and Tur indexes of CB than volunteers, and higher WSS values were detected on the surface of the plaques in symptomatic patients. What's more, the downstream side of the plaque was more vulnerable to plaque rupture than the upstream side due to more dynamic blood flow.

CONCLUSION

Therefore, carotid US-based high-frame-rate V Flow imaging provides reliable mechanical biomarkers for assessing the haemodynamic change in patients with low stenosis. Our study may provide a new imaging tool for monitoring the progression of atherosclerosis and aiding the management of early atherosclerotic patients.

ADVANCES IN KNOWLEDGE

Our study firstly investigated the difference of V Flow parameters on the surface of carotid plaques between symptomatic and asymptomatic patients with low carotid stenosis, which is expected to provide haemodynamic information and the mechanical basis for plaque rupture.

Gray-Scale Median in Patients with Symptomatic and Asymptomatic Carotid Atherosclerosis-Risk Factors and Diagnostic Potential

BACKGROUND

The identification of clinical factors affecting the gray-scale median (GSM) and determination of GSM diagnostic utility for differentiating between symptomatic and asymptomatic internal carotid artery (ICA) stenosis.

METHODS

This study included 45 patients with asymptomatic and 40 patients with symptomatic ICA stenosis undergoing carotid endarterectomy (CEA). Echolucency of carotid plaque was determined using computerized techniques for the GSM analysis. Study groups were compared in terms of clinical risk factors, coexisting comorbidities, and used pharmacotherapy.

RESULTS

Mean GSM values in the symptomatic group were significantly lower than in the asymptomatic group (p < 0.001). Both in the univariate as well as in the multiple regression analysis, GSM was significantly correlated with D-dimers and fasting plasma glucose levels and tended to correlate with β-adrenoceptor antagonist use in the symptomatic group. In asymptomatic patients, GSM was associated with the presence of grade 2 and grade 3 hypertension, and tended to correlate with the use of metformin, sulfonylureas, and statin. Independent factors for GSM in this group remained as grade 3 hypertension and statin's therapy. The receiver operating characteristic (ROC) analysis revealed that GSM differentiated symptomatic from asymptomatic ICA stenosis with sensitivity and specificity of 73% and 80%, respectively.

CONCLUSION

The completely diverse clinical parameters may affect GSM in symptomatic and asymptomatic patients undergoing CEA, whose clinical characteristics were similar in terms of most of the compared parameters. GSM may be a clinically useful parameter for differentiating between symptomatic and asymptomatic ICA stenosis.

Vascular Calcification Heterogeneity from Bench to Bedside: Implications for Manifestations, Pathogenesis, and Treatment Considerations

Vascular calcification (VC) is the ectopic deposition of calcium-containing apatite within vascular walls, exhibiting a high prevalence in older adults, and those with diabetes or chronic kidney disease. VC is a subclinical cardiovascular risk trait that increases mortality and functional deterioration. However, effective treatments for VC remain largely unavailable despite multiple attempts. Part of this therapeutic nihilism results from the failure to appreciate the diversity of VC as a pathological complex, with unforeseeable variations in morphology, risk associates, and anatomical and molecular pathogenesis, affecting clinical management strategies. VC should not be considered a homogeneous pathology because accumulating evidence refutes its conceptual and content uniformity. Here, we summarize the pathophysiological sources of VC heterogeneity from the intersecting pathways and networks of cellular, subcellular, and molecular crosstalk. Part of these pathological connections are synergistic or mutually antagonistic. We then introduce clinical implications related to the VC heterogeneity concept. Even within the same individual, a specific artery may exhibit the strongest tendency for calcification compared with other arteries. The prognostic value of VC may only be detectable with a detailed characterization of calcification morphology and features. VC heterogeneity is also evident, as VC risk factors vary between different arterial segments and layers. Therefore, diagnostic and screening strategies for VC may be improved based on VC heterogeneity, including the use of radiomics. Finally, pursuing a homogeneous treatment strategy is discouraged and we suggest a more rational approach by diversifying the treatment spectrum. This may greatly benefit subsequent efforts to identify effective VC therapeutics.

Improving radiomic modeling for the identification of symptomatic carotid atherosclerotic plaques using deep learning-based 3D super-resolution CT angiography

Rationale and objectives

Radiomic models based on normal-resolution (NR) computed tomography angiography (CTA) images can fail to distinguish between symptomatic and asymptomatic carotid atherosclerotic plaques. This study aimed to explore the effectiveness of a deep learning-based three-dimensional super-resolution (SR) CTA radiomic model for improved identification of symptomatic carotid atherosclerotic plaques.

Materials and methods

A total of 193 patients with carotid atherosclerotic plaques were retrospectively enrolled and allocated into either a symptomatic (n = 123) or an asymptomatic (n = 70) groups. SR CTA images were derived from NR CTA images using deep learning-based three-dimensional SR technology. Handcrafted radiomic features were extracted from both the SR and NR CTA images and three risk models were developed based on manually measured quantitative CTA characteristics and NR and SR radiomic features. Model performances were assessed via receiver operating characteristic, calibration, and decision curve analyses.

Results

The SR model exhibited the optimal performance (area under the curve [AUC] 0.820, accuracy 0.802, sensitivity 0.854, F1 score 0.847) in the testing cohort, outperforming the other two models. The calibration curve analyses and Hosmer-Lemeshow test demonstrated that the SR model exhibited the best goodness of fit, and decision curve analysis revealed that SR model had the highest clinical value and potential patient benefits.

Conclusions

Deep learning-based three-dimensional SR technology could improve the CTA-based radiomic models in identifying symptomatic carotid plaques, potentially providing more accurate and valuable information to guide clinical decision-making to reduce the risk of ischemic stroke.

Assessment for Carotid Atherosclerotic Plaque Using Vessel Wall Magnetic Resonance Imaging: A Multireader ROC Study to Determine Optimal Sequence for Detecting Vessel Wall Calcification

INTRODUCTION

We aimed to compare conventional vessel wall MR imaging techniques and quantitative susceptibility mapping (QSM) to determine the optimal sequence for detecting carotid artery calcification.

METHODS

Twenty-two patients who underwent carotid vessel wall MR imaging and neck CT were enrolled. Four slices of 6-mm sections from the bilateral internal carotid bifurcation were subdivided into 4 segments according to clock position (0-3, 3-6, 6-9, and 9-12) and assessed for calcification. Two blinded radiologists independently reviewed a total of 704 segments and scored the likelihood of calcification using a 5-point scale on spin-echo imaging, FLASH, and QSM. The observer performance for detecting calcification was evaluated by a multireader, multiple-case receiver operating characteristic study. Weighted κ statistics were calculated to assess interobserver agreement.

RESULTS

QSM had a mean area under the receiver operating characteristic curve of 0.85, which was significantly higher than that of any other sequence (p < 0.01) and showed substantial interreader agreement (κ = 0.68). A segment with a score of 3-5 was defined as positive, and a segment with a score of 1-2 was defined as negative; the sensitivity and specificity of QSM were 0.75 and 0.87, respectively.

CONCLUSION

QSM was the most reliable MR sequence for the detection of plaque calcification.

Do neutrophil extracellular traps implicate in atheromatous plaques from carotid endarterectomy? Re-analyzes of cDNA microarray data by surgeons

Background

Carotid artery stenosis is the cause of 15% of strokes. Neutrophil extracellular traps (NETs) and peptidyl arginine deiminase 4 (PAD4) are believed to be involved in thrombosis. This pilot study described the differential expression profile of NETs between atheromatous plaques and surrounding tissues.

Methods

Microarray datasets of carotid plaques were obtained from Gene Expression Omnibus. The normalized data were processed into comma-separated value matrix files using spreadsheet software. Analyzes of microarray data were conducted using integrated differential expression and pathway analysis.

Result

The clustering results illustrated that the classifications of plaque and control had reasonable biological validity. Pathway analysis revealed the relevance of immune response, cell signaling, and other pathways. Differentially expressed genes were detected between carotid plaques and control specimens. However, enrichment analyzes did not reveal a difference in PAD4 expression between the groups and that NET implication was only found in one cDNA microarray dataset.

Discussion

This pilot study does not necessarily dismiss the possibility of a relationship between NETs and atherothrombotic stroke. Gene expression could differ between endothelial cells and atheromas, and further studies are needed.

Heavy macrophage infiltration identified by optical coherence tomography relates to plaque rupture

OBJECTIVE

Risk stratification plays a critical role in patients with asymptomatic carotid atherosclerotic stenosis. Heavy macrophage infiltration (HMC) is an important factor of plaque destabilization. However, in vivo imaging technologies and screening criteria for HMC remain limited. We aimed to (i) introduce algorithms for in vivo detection of macrophage infiltrations using optical coherence tomography (OCT) and (ii) to investigate the threshold of HMC and its association with plaque vulnerability.

METHODS

Ex vivo OCT images were co-registered with histopathology in 282 cross-sectional pairs from 19 carotid endarterectomy specimens. Of these, 197 randomly selected pairs were employed to define the parameters, and the remaining 85 pairs were used to evaluate the accuracy of the OCT-based algorithm in detecting macrophage infiltrations. Clinical analysis included 93 patients receiving carotid OCT evaluation. The prevalence and burden of macrophage infiltration were analyzed. Multivariable and subgroup analysis were performed to investigate the association between HMC and plaque rupture.

RESULTS

The sensitivity and specificity of algorithm for detecting macrophage infiltration were 88.0% and 74.9%, respectively. Of 93 clinical patients, ruptured plaques exhibited higher prevalence of macrophage infiltration than nonruptured plaques (83.7% [36/43] vs 32.0% [16/50], p < 0.001). HMC was identified when the macrophage index was greater than 60.2 (sensitivity = 74.4%, specificity = 84.0%). Multivariable analysis showed that HMC and multiple calcification were independent risk factors for non-lipid-rich plaque rupture.

INTERPRETATION

This study provides a novel approach and screening criteria for HMC, which might be valuable for atherosclerotic risk stratification.

Combined near infrared photoacoustic imaging and ultrasound detects vulnerable atherosclerotic plaque

Atherosclerosis is an inflammatory process resulting in the deposition of cholesterol and cellular debris, narrowing of the vessel lumen and clot formation. Characterization of the morphology and vulnerability of the lesion is essential for effective clinical management. Here, near-infrared auto-photoacoustic (NIRAPA) imaging is shown to detect plaque components and, when combined with ultrasound imaging, to differentiate stable and vulnerable plaque. In an ex vivo study of photoacoustic imaging of excised plaque from 25 patients, 88.2% sensitivity and 71.4% specificity were achieved using a clinically-relevant protocol. In order to determine the origin of the NIRAPA signal, immunohistochemistry, spatial transcriptomics and spatial proteomics were co-registered with imaging and applied to adjacent plaque sections. The highest NIRAPA signal was spatially correlated with bilirubin and associated blood-based residue and with the cytoplasmic contents of inflammatory macrophages bearing CD74, HLA-DR, CD14 and CD163 markers. In summary, we establish the potential to apply the NIRAPA-ultrasound imaging combination to detect vulnerable carotid plaque and a methodology for fusing molecular imaging with spatial transcriptomic and proteomic methods.

The Value of Multimodal Ultrasonic Scoring System in the Diagnosis of Carotid Vulnerable Plaque: A Comparative Study With Pathology

BACKGROUND AND AIMS

Vulnerable plaques are closely related to ischemic stroke. To investigate the diagnostic value of multimodal plaque vulnerability ultrasound scoring system (PV-USS) using histopathology as the gold standard.

METHODS

A total of 45 subjects who would be underwent carotid endarterectomy were recruited. The postoperative specimens were examined by histopathology. All responsible plaques were scanned dynamically in multiple sections by carotid ultrasound to measure maximum thickness and lumen stenotic degree, as well as, the echo, homogeneity, surface morphology, and echo type were observed. The above two-dimensional (2D) ultrasonic features were systematically scored, that is, PV-USS2D . Combined with contrast-enhanced ultrasonography (CEUS), neovascularization grade in plaque was scored, which is PV-USS2D+CEUS .

RESULTS

According to the pathological results, 45 subjects were divided into vulnerable plaque group (27 cases, 60%) and non-vulnerable plaque group (18 cases, 40%). PV-USS2D and PV-USS2D+CEUS in vulnerable plaque group were higher than those in non-vulnerable plaque group (PV-USS2D : 9.44 ± 2.10 vs 7.22 ± 1.73; PV-USS2D+CEUS: 12.37 ± 2.10 vs 8.28 ± 1.81, P < .001). ROC curve analysis showed that the AUC of PV-USS2D and PV-USSCEUS was 0.783 and 0.929, respectively (P < .001). The best cutoff values of PV-USS2D and PV-USS2D+CEUS were, respectively, 9.5 (the maximum Youden index was 0.425, the sensitivity was 48.1%, the specificity was 94.4%) and 10.5 (the maximum Youden index was 0.667, the sensitivity was 77.8%, the specificity was 88.9%).

CONCLUSIONS

Ultrasound scoring system may be used as an effective method to evaluate the vulnerability of plaque. The diagnostic efficiency of PV-USS2D+CEUS is more higher than PV-USS2D .

[Correlations between plaque characteristics and cerebral blood flow in patients with moderate to severe carotid stenosis using magnetic resonance vessel wall imaging]

OBJECTIVE

To investigate the correlations between carotid plaque characteristics and cerebral blood flow (CBF) in patients with unilateral moderate to severe carotid stenosis using high-resolution magnetic resonance imaging (HR-MRI) and 3D pseudo-continuous arterial spin labeling (3D pcASL).

METHODS

A total of 43 patients with unilateral moderate to severe carotid stenosis were recruited. The degree of carotid stenosis, maximum wall thickness (Max WT) and normalized wall index (NWI) were measured using HR-MRI. The plaque characteristics were analyzed. Presence or absence of plaque components including intraplaque hemorrhage (IPH), lipid-rich necrotic nucleus (LRNC), calcification and ulcer were identified, and the grades of calcification and LRNC were recorded. CBF values within the region of interest representing the bilateral middle cerebral artery distribution were acquired using 3D pcASL. Paired sample t test was used to compare the differences of CBF values between the index side and the contralateral side. Spearman correlation analysis was conducted to evaluate the correlations of CBF values with the degree of carotid stenosis, Max WT and NWI. The differences of CBF values between the patients with or without IPH and ulcer were compared using Mann-Whitney U test. Different levels of calcification and LRNC were compared by Kruskal-Wallis test, respectively.

RESULTS

The ave-rage degree of carotid stenosis at the index side was 77.30%±11.79%. The mean CBF value of the index side was (46.77±11.65) mL/(100 g·min), and that of the contralateral side was (49.92±9.95) mL/(100 g·min), and the difference was statistically significant (t=-2.474, P=0.017). The mean Max WT and NWI of the carotid plaques at the index side was (6.40±1.87) mm and 62.91%±8.87%, respectively. There were no significant correlations of CBF values with the degrees of stenosis, Max WT and NMI (P>0.05). Plaque composition analysis showed that the CBF values of the index side were different when there was calcification or not and the degrees of calcification were different (P=0.030), but there were no differences between the CBF values on the index sides with or without IPH, ulcer and LRNC.

CONCLUSION

In patients with unilateral moderate to severe carotid stenosis, calcification might affect CBF perfusion. When there is no calcification, the plaque components need attention.

Machine learning-based identification of symptomatic carotid atherosclerotic plaques with dual-energy computed tomography angiography

OBJECTIVE

This study aimed to develop and validate a machine learning model incorporating both dual-energy computed tomography (DECT) angiography quantitative parameters and clinically relevant risk factors for the identification of symptomatic carotid plaques to prevent acute cerebrovascular events.

METHODS

The data of 180 patients with carotid atherosclerosis plaques were analysed from January 2017 to December 2021; 110 patients (64.03±9.58 years old, 20 women, 90 men) were allocated to the symptomatic group, and 70 patients (64.70±9.89 years old, 50 women, 20 men) were allocated to the asymptomatic group. Overall, five machine learning models using the XGBoost algorithm, based on different CT and clinical features, were developed in the training cohort. The performances of all five models were assessed in the testing cohort using receiver operating characteristic curves, accuracy, recall rate, and F1 score.

RESULTS

The shapley additive explanation (SHAP) value ranking showed fat fraction (FF) as the highest among all CT and clinical features and normalised iodine density (NID) as the 10th. The model based on the top 10 features from the SHAP measurement showed optimal performance (area under the curve [AUC] .885, accuracy .833, recall rate .933, F1 score .861), compared with the other four models based on conventional CT features (AUC .588, accuracy .593, recall rate .767, F1 score .676), DECT features (AUC .685, accuracy .648, recall rate .667, F1 score .678), conventional CT and DECT features (AUC .819, accuracy .740, recall rate .867, F1 score .788), and all CT and clinical features (AUC .878, accuracy .833, recall rate .867, F1 score .852).

CONCLUSION

FF and NID can serve as useful imaging markers of symptomatic carotid plaques. This tree-based machine learning model incorporating both DECT and clinical features could potentially comprise a non-invasive method for identification of symptomatic carotid plaques to guide clinical treatment strategies.

Combined near infrared photoacoustic imaging and ultrasound detects vulnerable atherosclerotic plaque

Atherosclerosis is an inflammatory process resulting in the deposition of cholesterol and cellular debris, narrowing of the vessel lumen and clot formation. Characterization of the morphology and vulnerability of the lesion is essential for effective clinical management. Photoacoustic imaging has sufficient penetration and sensitivity to map and characterize human atherosclerotic plaque. Here, near infrared photoacoustic imaging is shown to detect plaque components and, when combined with ultrasound imaging, to differentiate stable and vulnerable plaque. In an ex vivo study of photoacoustic imaging of excised plaque from 25 patients, 88.2% sensitivity and 71.4% specificity were achieved using a clinically-relevant protocol. In order to determine the origin of the near-infrared auto-photoacoustic (NIRAPA) signal, immunohistochemistry, spatial transcriptomics and proteomics were applied to adjacent sections of the plaque. The highest NIRAPA signal was spatially correlated with bilirubin and associated blood-based residue and inflammatory macrophages bearing CD74, HLA-DR, CD14 and CD163 markers. In summary, we establish the potential to apply the NIRAPA-ultrasound imaging combination to detect vulnerable carotid plaque.

Precision Medicine in Neurocritical Care for Cerebrovascular Disease Cases

Scientific advances have informed many aspects of acute stroke care but have also highlighted the complexity and heterogeneity of cerebrovascular diseases. While practice guidelines are essential in supporting the clinical decision-making process, they may not capture the nuances of individual cases. Personalized stroke care in ICU has traditionally relied on integrating clinical examinations, neuroimaging studies, and physiologic monitoring to develop a treatment plan tailored to the individual patient. However, to realize the potential of precision medicine in stroke, we need advances and evidence in several critical areas, including data capture, clinical phenotyping, serum biomarker development, neuromonitoring, and physiology-based treatment targets. Mathematical tools are being developed to analyze the multitude of data and provide clinicians with real-time information and personalized treatment targets for the critical care management of patients with cerebrovascular diseases. This review summarizes research advances in these areas and outlines principles for translating precision medicine into clinical practice.

Oxidative Stress as a Reliable Biomarker of Carotid Plaque Instability: A Pilot Study

Background: Predicting stroke risk in patients with carotid artery stenosis (CS) remains challenging. Circulating biomarkers seem to provide improvements with respect to risk stratification. Methods: Study patients who underwent carotid endarterectomy were categorized into four groups according to symptomatology and compared as follows: symptomatic with asymptomatic patients; and asymptomatic patients including amaurosis fugax (AF) (asymptomatic + AF group) with patients with a transient ischemic attack (TIA) or brain stroke (BS) (hemispheric brain stroke group). Carotid specimens were histologically analyzed and classified based on the American Heart Classification (AHA) standard. As a marker of OS, the plasma levels of malondialdehyde (MDA) were measured. Comparisons of MDA plasma levels between groups were analyzed. Results: In total, 35 patients were included in the study. There were 22 (63%) patients in the asymptomatic group and 13 (37%) in the symptomatic group. Atheromatous plaque (p = 0.03) and old hemorrhage (p = 0.05), fibrous plaque (p = 0.04), myxoid changes (p = 0.02), plaques without hemorrhage (p = 0.04), significant neovascularization (p = 0.04) and AHA classification (p = 0.006) had significant correlations with clinical presentation. There were 26 (74%) patients in the asymptomatic group and 9 (26%) in the hemispheric brain stroke group. Atheromatous plaque (p = 0.02), old hemorrhage (p = 0.05) and plaques without neovascularization (p = 0.02), fibrous plaque (p = 0.03), plaques without hemorrhage (p = 0.02) and AHA classification (p = 0.01) had significant correlations with clinical presentation. There was no significant difference between symptomatic and asymptomatic groups with respect to MDA plasma levels (p = 0.232). A significant difference was observed when MDA plasma levels were compared to asymptomatic + AF and the hemispheric stroke group (p = 0.002). Conclusions: MDA plasma level correlates with the risk of hemispheric stroke (TIA or BS) and is a reliable marker of plaque vulnerability in carotid artery stenosis.

Spectral analysis of ultrasound backscatter for non-invasive measurement of plaque composition

Carotid atherosclerotic plaque composition may be an important indication of patient risk for future cerebrovascular events. Ultrasound spectral analysis has the potential to provide a robust measure of plaque composition in vivo if the backscatter transfer function can be sufficiently isolated from the effects of attenuation from overlying tissue, receive and transmit transfer functions from the ultrasound system and transducer, and diffraction. This study examines the usefulness of the nonlinearly generated second harmonic portion of the backscatter signal and the effects of a variety of attenuation compensation techniques for noninvasively characterizing human carotid plaque using spectral analysis and machine learning. Post-beamformed ultrasound backscatter radiofrequency (RF) data were acquired from 6 normal subjects and 119 carotid endarterectomy patients prior to surgery. Plaque obtained following surgery was histologically processed, and regions of interest (ROI) corresponding to homogenous tissue types (fibrous/fibro-lipidic, hemorrhagic and/or necrotic core and calcified) were selected from RF data. Both the harmonic and fundamental power spectra for each ROI was obtained and normalized by data from a uniform phantom (0.5 dB/cm-MHz slope of attenuation). Additional attenuation compensation approaches were compared to simply using the reference phantom: (1) optimum power spectral shift estimation, (2) one-step adventitial, or (3) two-step adventitial. Spectral parameters extracted from both the fundamental and harmonic estimates of the backscatter transfer function of 363 ROI's from 152 plaque specimens were used to train and test random forest and support vector machine classification models. The best results came from using spectral parameters derived from both the fundamental and second harmonic bands with a predictive accuracy of 65-68%, kappa statistic of 0.49-0.54, and accuracies of 84% for fibrous, 68-74% for hemorrhagic and/or necrotic core, and 78-81% for calcified ROI's. The result indicated that the nonlinearly generated second harmonic portion of backscatter is useful for carotid plaque tissue characterization and that a reference phantom approach with a 0.5 dB/cm-MHz slope of attenuation works as well as more complicated approaches.

Diagnostic Performance of Contrast-Enhanced Ultrasound and High-Resolution Magnetic Resonance Imaging for Carotid Atherosclerotic Plaques: A Systematic Review and Meta-Analysis

OBJECTIVES

The aim of this meta-analysis was to evaluate the diagnostic value of contrast-enhanced ultrasound (CEUS) and high-resolution magnetic resonance imaging (HR-MRI) in patients with carotid vulnerable plaques.

METHODS

A systematic review was conducted in PubMed, Embase, Cochrane Library, and Web of Science using the search terms carotid artery, atherosclerotic plaque, CEUS, contrast-enhanced ultrasound, HR-MRI, and high-resolution magnetic resonance. Studies published since the establishment of the library until December 2021 were retrieved. The statistical analyses were performed with Meta-DiSc version 1.4. Beyond that, the potential sources of heterogeneity for CEUS and HR-MRI were explored.

RESULTS

Nine articles were included in this study. For CEUS, the pooled sensitivity and specificity for detecting carotid vulnerable plaques 91% (95% confidence interval [CI]: 84%, 95%) and 67% (95% CI: 54%, 79%), respectively. For HR-MRI, the pooled sensitivity and specificity were 78% (95% CI: 72%, 83%) and 65% (95% CI, 56%, 73%), respectively. The area under the summary receiver operating characteristic curve for CEUS and HR-MRI were 0.9218 and 0.8129, respectively. However, the difference in diagnostic accuracy between CEUS and HR-MRI diagnostic accuracy was not statistically significant.

CONCLUSIONS

The study shows that the sensitivity of CEUS was higher than that of HR-MRI, and the specificity was similar to HR-MRI. CEUS and HR-MRI provide a similar diagnostic yield in detecting a vulnerable plaque. Thus, CEUS may be a useful tool for the diagnosis of carotid vulnerable plaques.

Clinical Application of High-Frame-Rate Vector Flow Imaging in Evaluation of Carotid Atherosclerotic Stenosis

OBJECTIVE

This study seeks to evaluate the value of the high-frame-rate vector flow imaging technique in assessing the hemodynamic changes of carotid atherosclerotic stenosis in aging people (>60 years old).

METHODS

Aging patients diagnosed with carotid atherosclerotic stenosis who underwent carotid high-frame-rate vector flow imaging examination were prospectively enrolled. A Mindray Resona7s ultrasound machine equipped with high-frame-rate vector flow function was used for ultrasound evaluation. First, B mode ultrasound and color Doppler flow imaging were used to evaluate carotid stenosis. Then, the vector arrows and flow streamline detected by V Flow were analyzed and the wall shear stress values (Pa) at the carotid stenosis site were measured. All patients were divided into symptomatic and asymptomatic groups according to whether they had acute/subacute stroke or other clinical symptoms within 2 weeks before ultrasound examination. The results of digital subtraction angiography or computed tomography angiography were used as the gold standard. The stenosis rate was calcified, according to North American Symptomatic Carotid Endarterectomy Trial criteria. The diagnostic values of wall shear stress, conventional ultrasound, and the combined diagnosis in carotid atherosclerotic stenosis were compared.

RESULTS

Finally, 88 patients with carotid atherosclerotic plaque were enrolled (71 males (80.7%), mean age 67.6 ± 5.4 years). The success rate of high-frame-rate vector flow imaging was 96.7% (88/91). The WSS value of symptomatic carotid stenosis (1.4 ± 0.15 Pa) was significantly higher than that of asymptomatic carotid stenosis (0.80 ± 0.08 Pa) (p < 0.05). Taking the wall shear stress value > 0.78 Pa as the diagnostic criteria for symptomatic carotid atherosclerotic plaque, the area under receiver operating characteristic curves was 0.79 with 87.1% sensitivity and 69.6% specificity. The area under receiver operating characteristic curves of the combined diagnosis (0.966) for differentiating severe carotid atherosclerotic stenosis was significantly higher than that of conventional ultrasound and WSS value, with 89.7% sensitivity and 93.2% specificity (p < 0.05).

CONCLUSION

As a non-invasive imaging method, the high-frame-rate vector flow imaging technique showed potential value in the preoperative assessment of the symptomatic carotid atherosclerotic stenosis and diagnosing carotid atherosclerotic stenosis in aging patients.

Comparison of cardiovascular biomarker expression in extracellular vesicles, plasma and carotid plaque for the prediction of MACE in CEA patients

Extracellular vesicles (EV) are a novel biomarker source for diagnosis and prognosis of cardiovascular disease. A protein comparison of plasma EVs in relation to blood plasma and atherosclerotic plaque has not been performed but would provide insight into the origin and content of biomarker sources and their association with atherosclerotic progression. Using samples of 88 carotid endarterectomy patients in the Athero-Express, 92 proteins (Olink Cardiovascular III panel) were measured in citrate plasma, plasma derived LDL-EVs and atherosclerotic plaque. Proteins were correlated between sources and were related to pre-operative stroke and 3-year major adverse cardiovascular events (MACE). Plasma and EV proteins correlated moderately on average, but with substantial variability. Both showed little correlation with plaque, suggesting that these circulating biomarkers may not originate from the latter. Plaque (n = 17) contained most differentially-expressed proteins in patients with stroke, opposed to EVs (n = 6) and plasma (n = 5). In contrast, EVs contained most differentially-expressed proteins for MACE (n = 21) compared to plasma (n = 9) and plaque (n = 1). EVs appear to provide additional information about severity and progression of systemic atherosclerosis than can be obtained from plasma or atherosclerotic plaque.

Application value of shear-wave elastography combined with monochrome superb microvascular imaging in renal allograft chronic rejection

BACKGROUND

Conventional ultrasound (US), which include gray scale US and Doppler US, is the first-line imaging modality for the evaluation of renal allograft; however, conventional US indicators have limitations.

OBJECTIVE

To explore the application value of shear-wave elastography (SWE) combined with monochrome superb microvascular imaging (mSMI) in renal allograft chronic rejection (CR).

METHODS

From November 2021 to February 2022 in the Lanzhou University Second Hospital, the US features of 54 patients with renal allograft were retrospectively analyzed. Patients were categorized into two groups: stable group(n = 44) and CR group(n = 10), with clinical diagnosis as reference standard. The vascular index (VI) on mSMI and parenchymal stiffness were measured in the middle cortex of all renal allografts and receiver operating characteristic (ROC) curves were drawn to evaluate the feasibility of differentiation. Statistically significant US features and biochemical indicators such as creatinine were scored, and the results of the scores were analyzed by ROC curve.

RESULTS

The VI on mSMI of the stable group (49.5±2.0) was significantly greater than that of the CR group (33.8±5.9) (P = 0.028). There was a statistically significant difference in parenchymal stiffness between stable group (16.2kPa±1.2) and CR group (33.9kPa±6.6) (P = 0.027). The sensitivity was 90% and specificity was 81.8% of the scores in the differentiation of stable group from CR group (cut-off value, 2; P = 0.000).

CONCLUSION

SWE combined with mSMI may help differentiate stable renal allograft from renal allograft CR and have the potential application value in the diagnosis of renal allograft CR.

Assessment of plaque vulnerability in carotid atherosclerotic plaques using contrast-enhanced ultrasound

Background

Atherosclerotic carotid plaques are one of the most important causes of stroke. Apart from the severity of stenosis, there are certain plaque characteristics such as neovascularization and, surface ulceration which makes a plaque vulnerable. This study was performed to study the plaque characteristics using contrast-enhanced ultrasound (CEUS) and evaluate their association with presence of ischemic cerebrovascular symptoms in these patients.

Methods

This study included patients presenting at a tertiary care center, having carotid plaques causing >60% stenosis. CEUS was performed for assessment of intraplaque neovascularity and plaque surface characteristics. These plaque features were then evaluated for their association with presence of ischemic cerebrovascular symptoms in patients.

Results

Sixty plaques were studied in 50 patients. Thirty-two plaques were associated with ischemic cerebrovascular symptoms. On CEUS, intraplaque neovascularization was seen in 38 of the 60 plaques studied (63.3%). There was statistically significant association of intraplaque neovascularity and plaque surface characteristics with presence of ischemic cerebrovascular symptoms.

Conclusion

CEUS allows better characterization of plaque surface characteristics and also depicts plaque neovascularization, which helps in determining the plaque vulnerability. It should be used as an adjunct to ultrasound and doppler assessment of carotid plaques.

Carotid Stenosis Patients with a Remote History of Cerebrovascular Events have Increased Risk of Major Adverse Events Over Asymptomatic Patients

INTRODUCTION

Asymptomatic patients with a remote history of transient ischemic attack (TIA) or stroke are not well studied as a separate population from asymptomatic patients with no prior history of TIA or stroke. We compared in-hospital outcomes following transcarotid artery revascularization (TCAR) and transfemoral carotid artery stenting (TFCAS) among symptomatic, remote history of neurologic symptoms, and asymptomatic patients.

METHODS

Data from patients in the Vascular Quality Initiative database undergoing TCAR (Jan 2017 to Apr 2020) or TFCAS (May 2005 to Apr 2020) was analyzed. Symptomatic status was defined as TIA and/or stroke occurring within 180 days prior to procedure. Asymptomatic status was divided into patients with no history of TIA/stroke (asymptomatic) and TIA/stroke occurring more than 180 days prior to procedure (remote history of neurologic symptoms). Student's T-test and Pearson Chi-Squared test were used to compare baseline patient characteristics and outcomes. Multivariate logistic regression was used to adjust for significant between-group differences in baseline characteristics.

RESULTS

There were 7,158 patients who underwent TCAR (symptomatic: 2,574; asymptomatic: 3,689; asymptomatic with a remote history of neurologic symptoms: 895) and 18,023 patients who underwent TFCAS (symptomatic: 6,195; asymptomatic: 10,333; asymptomatic with a remote history of neurologic symptoms: 1,495). Regardless of symptom status, the mean patient age was 73 years for TCAR and 69 years for TFCAS. 64% of patients in the study were male and 36% of patients were female. Mean long-term follow up data ranged between 208 to 331 days within the three patient groups. Carotid stenosis patients with a remote history of neurologic symptoms had higher rates of TIA, stroke, TIA/stroke, stroke/death, and stroke/death/MI than asymptomatic patients, and these rates were similar to those of symptomatic patients. Comparing TCAR and TFCAS among remote history of neurologic symptom patients, there were statistically significant reductions in the odds of stroke/death (OR: 0.46, 95% CI: 0.27-0.84, P = 0.011) and stroke/death/MI (OR: 0.51, 95% CI: 0.30-0.87, P = 0.013) after TCAR. This was likely driven by the increased rate of death for TFCAS remote history of neurologic symptoms patients (0.9%) compared to asymptomatic patients (0.6%).

CONCLUSION

Asymptomatic patients with a remote history of TIA/stroke do not have the same outcomes as asymptomatic patients without a history of TIA/stroke and are at higher risk of adverse in-hospital events. Patients with a remote history of TIA/stroke have increased risk of in-hospital death after TFCAS and may benefit from TCAR.

Quantitative comparison between carotid plaque hardness and histopathological findings: an observational study

Background

Plaque hardness in carotid artery stenosis correlates with cerebral infarction. This study aimed to quantitatively compare plaque hardness with histopathological findings and identify the pathological factors involved in plaque hardness.

Methods

This study included 84 patients (89 lesions) undergoing carotid endarterectomy (CEA) at our institution. Plaque hardness was quantitatively measured immediately after excision using a hardness meter. Collagen and calcification were evaluated as the pathological factors. Collagen was stained with Elastica van Gieson stain, converted to a gray-scale image, and displayed in a 256-step histogram. The median gray-scale median (GSM) was used as the collagen content. The degree of calcification was defined by the hematoxylin–eosin stain as follows: "0:" no calcification, "1:" scattered microcalcification, or "2:" calcification greater than 1 mm or more than 2% of the total calcification. Carotid echocardiographic findings, specifically echoluminance or the brightness of the narrowest lesion of the plaque, classified as hypo-, iso-, or hyper-echoic by comparison with the intima-media complex surrounding the plaque, and clinical data were reviewed.

Results

Plaque hardness was significantly negatively correlated with GSM [Spearman's correlation coefficient: -0.7137 (p < 0.0001)]: the harder the plaque, the higher the collagen content. There were significant differences between plaque hardness and degree of calcification between "0" and "2" (p = 0.0206). For plaque hardness and echoluminance (hypo-iso-hyper), significant differences were found between hypo-iso (p = 0.0220), hypo-hyper (p = 0.0006), and iso-hyper (p = 0.0015): the harder the plaque, the higher the luminance. In single regression analysis, GSM, sex, and diabetes mellitus were significant variables, and in multiple regression analysis, only GSM was extracted as a significant variable.

Conclusions

Plaque hardness was associated with a higher amount of collagen, which is the main component of the fibrous cap. Greater plaque hardness was associated with increased plaque stability. The degree of calcification may also be associated with plaque hardness.

Carotid artery endarterectomy in patients with symptomatic non-stenotic carotid artery disease

Object

We sought to determine the safety and efficacy in secondary stroke prevention of carotid endarterectomy (CEA) in patients with symptomatic non-stenotic carotid artery disease (SyNC).

Methods

This was a single-centre retrospective case series. All patients who underwent CEA for unilateral anterior circulation cerebrovascular events with ipsilateral <50% carotid stenosis from 2002 to 2020 were included. Imaging hallmarks including the degree of luminal stenosis and the presence of various vulnerable plaque characteristics (eg, intraplaque haemorrhage (IPH) on MR angiography, ulceration or low-density plaque on CT angiography) were assessed. The presence of vulnerable plaque characteristics was compared between arteries ipsilateral to the ischaemic event and contralateral arteries. The prevalence of perioperative/intraoperative complications, as well as recurrent ischaemic events at follow-up was determined.

Results

Thirty-two patients were included in the analysis, of which 25.0% were female. Carotid arteries ipsilateral to an ischaemic event had a significantly higher prevalence of IPH when compared with contralateral arteries (80.0% vs 0.0%; p<0.001). There were no intraoperative complications. One patient (3.1%) developed symptoms of transient ipsilateral ischaemia 1 day following CEA which resolved without treatment. In a median follow-up of 18.0 months (IQR 5.0–36.0), only one patient (3.1%) experienced a transient neurologic deficit with complete resolution (annualised rate of recurrent stroke after CEA of 1.5% for a total follow-up of 788 patient-months following CEA). All other patients (31/32, 96.9%) were free of recurrent ischaemic events.

Conclusion

CEA appears to be safe and well-tolerated in patients with SyNC. Additional studies with larger cohorts and longer follow-up intervals are needed in order to determine the role of CEA in this patient population.

Preoperative antithrombotic treatment in acutely symptomatic carotid artery stenosis

OBJECTIVES

Early recurrence of cerebral ischemia in acutely symptomatic carotid artery stenosis can precede revascularization. The optimal antithrombotic regimen for this high-risk population is not well established. Although antiplatelet agents are commonly used, there is limited evidence for the use of anticoagulants. We sought to understand the safety and efficacy of short-term preoperative anticoagulants in secondary prevention of recurrent cerebral ischemic events from acutely symptomatic carotid stenosis in patients awaiting carotid endarterectomy (CEA).

MATERIALS AND METHODS

A retrospective query of a prospective single institution registry of carotid revascularization was performed. Patients who presented with acute ischemic stroke or transient ischemic attack (TIA) attributable to an ipsilateral internal carotid artery stenosis (ICA) were included. Antiplatelet (AP) only and anticoagulation (AC) treatment arms were compared. The primary outcome was a composite of preoperative recurrent ischemic stroke or TIA. The primary safety outcome was symptomatic intracranial hemorrhage.

RESULTS

Out of 443 CEA patients, 342 were in the AC group and 101 in the AP group. Baseline characteristics between groups (AC vs AP) were similar apart from age (71±10.5 vs 73±9.5, p=0.04), premorbid modified Rankin scale (mRS) score (1.0±1.2 vs 1.4±1.3, p=0.03) and stroke as presenting symptom (65.8 vs 53.5%, p=0.02). Patients in the AC group had a lower incidence of recurrent stroke/TIA (3.8 vs 10.9%, p=0.006). One patient had symptomatic intracranial hemorrhage in the AC group, and none in the AP group. In multivariate analysis controlling for age, premorbid mRS, stroke severity, degree of stenosis, presence of intraluminal thrombus (ILT) and time to surgery, AC was protective (OR 0.30, p=0.007). This effect persisted in the cohort exclusively without ILT (OR 0.23, p=0.002).

CONCLUSIONS

Short term preoperative anticoagulation in patients with acutely symptomatic carotid stenosis appears safe and effective compared to antiplatelet agents alone in the prevention of recurrent cerebral ischemic events while awaiting CEA.

Immune system and atherosclerosis: Hostile or friendly relationship

Coronary artery disease has remained a major health challenge despite enormous progress in prevention, diagnosis, and treatment strategies. Formation of atherosclerotic plaque is a chronic process that is developmentally influenced by intrinsic and extrinsic determinants. Inflammation triggers atherosclerosis, and the fundamental element of inflammation is the immune system. The immune system involves in the atherosclerosis process by a variety of immune cells and a cocktail of mediators. It is believed that almost all main components of this system possess a profound contribution to the atherosclerosis. However, they play contradictory roles, either protective or progressive, in different stages of atherosclerosis progression. It is evident that monocytes are the first immune cells appeared in the atherosclerotic lesion. With the plaque growth, other types of the immune cells such as mast cells, and T lymphocytes are gradually involved. Each cell releases several cytokines which cause the recruitment of other immune cells to the lesion site. This is followed by affecting the expression of other cytokines as well as altering certain signaling pathways. All in all, a mix of intertwined interactions determine the final outcome in terms of mild or severe manifestations, either clinical or subclinical. Therefore, it is of utmost importance to precisely understand the kind and degree of contribution which is made by each immune component in order to stop the growing burden of cardiovascular morbidity and mortality. In this review, we present a comprehensive appraisal on the role of immune cells in the atherosclerosis initiation and development.

Carotid Plaques From Symptomatic Patients With Mild Stenosis Is Associated With Intraplaque Hemorrhage

Carotid plaque vulnerability features beyond the degree of stenosis may play a key role in the pathogenesis and recurrence of ischemic cerebrovascular events. This study sought to compare intraplaque hemorrhage (IPH) as a marker of plaque vulnerability in symptomatic patients with mild (<50%), moderate (50%-69%), and severe (≥70%) carotid artery stenosis. We included patients who experienced ischemic cerebrovascular events with no other identifiable sources and underwent carotid endarterectomy for mild (n=32), moderate (n=47), and severe (n=58) carotid artery stenosis. The degree of stenosis and imaging hallmarks were assessed by computed tomography angiography or magnetic resonance angiography. Plaque specimens were stained with hematoxylin and eosin and Movat pentachrome staining. Carotid plaques of patients with mild stenosis had a higher extent of IPH (%) on tissue analysis compared with patients with moderate (mild, 15.7% [interquartile range, 7.8%-26.7%]; moderate, 3.9% [0.0%-9.2%]; P<0.001) and severe carotid artery stenosis (mild, 15.7% [interquartile range, 7.8%-26.7%]; severe, 2.5% [interquartile range, 0.0%-11.2%]; P<0.001). When considering the degree of carotid artery stenosis as a continuous variable, a lower lumen narrowing was associated with higher extent of IPH (P<0.001; R, -0.329). Our major finding is the association of IPH with mild carotid artery stenosis based on histological analysis. The current study may suggest that IPH potentially plays a role in the mechanism of stroke in patients with nonobstructive carotid stenosis.

Environmental Contaminants Acting as Endocrine Disruptors Modulate Atherogenic Processes: New Risk Factors for Cardiovascular Diseases in Women?

The number of aged individuals is increasing worldwide, rendering essential the comprehension of pathophysiological mechanisms of age-related alterations, which could facilitate the development of interventions contributing to “successful aging” and improving quality of life. Cardiovascular diseases (CVD) include pathologies affecting the heart or blood vessels, such as hypertension, peripheral artery disease and coronary heart disease. Indeed, age-associated modifications in body composition, hormonal, nutritional and metabolic factors, as well as a decline in physical activity are all involved in the increased risk of developing atherogenic alterations that raise the risk of CVD development. Several factors have been reported to play a role in the alterations observed in muscle and endothelial cells and that lead to increased CVD, such as genetic pattern, smoking and unhealthy lifestyle. Moreover, a difference in the risk of these diseases in women and men has been reported. Interestingly, in the past decades attention has been focused on a potential role of several pollutants that disrupt human health by interfering with hormonal pathways, and more specifically in non-communicable diseases such as obesity, diabetes and CVD. This review will focus on the potential alteration induced by Endocrine Disruptors (Eds) in the attempt to characterize a potential role in the cellular and molecular mechanisms involved in the atheromatous degeneration process and CVD progression.

A narrative review of plaque and brain imaging biomarkers for stroke risk stratification in patients with atherosclerotic carotid artery disease

Objective

In this narrative review, we aim to review imaging biomarkers that carry the potential to non-invasively guide stroke risk stratification for treatment optimization.

Background

Carotid atherosclerosis plays a fundamental part in the occurrence of ischemic stroke. International guidelines select the optimal treatment strategy still mainly based on the presence of clinical symptoms and the degree of stenosis for stroke prevention in patients with atherosclerotic carotid plaques. These guidelines, based on randomized controlled trials that were conducted three decades ago, recommend carotid revascularization in symptomatic patients with high degree of stenosis versus a conservative approach for most asymptomatic patients. Due to optimization of best medical therapy and risk factor control, it is suggested that a subgroup of symptomatic patients is at lower risk of stroke and may not benefit from revascularization, whereas a selective subgroup of high-risk asymptomatic patients would benefit from this procedure.

Methods

A literature search was performed for articles published up to December 2020 using PubMed, EMBASE and Scopus. Based on the literature found, change in stenosis degree and volume, plaque echolucency, plaque surface, intraplaque haemorrhage, lipid-rich necrotic core, thin fibrous cap, inflammation, neovascularization, microembolic signals, cerebrovascular reserve, intracranial collaterals, silent brain infarcts, diffusion weighted imaging lesions and white matters lesions have the potential to predict stroke risk.

Conclusions

The applicability of imaging biomarkers needs to be further improved before the potential synergistic prognostic ability of imaging biomarkers can be verified on top of the clinical biomarkers. In the future, the routine and combined assessment of both plaque and brain imaging biomarkers might help to improve optimization of treatment strategies in individual patients with atherosclerotic carotid artery disease.

Shear-Wave Elastography Enables Identification of Unstable Carotid Plaque

Shear-wave elastography (SWE) is a novel ultrasound technique for quantifying tissue elasticity. The aim of this study was to identify differences in atherosclerotic plaque elasticity measured using SWE among individuals with symptomatic, asymptomatic progressive and asymptomatic stable carotid plaques. Consecutive patients from the Atherosclerotic Plaque Characteristics Associated with a Progression Rate of the Plaque and a Risk of Stroke in Patients with the Carotid Bifurcation Plaque Study were screened for this research. Neurosonography examination of carotid arteries was performed to identify plaque stenosis of ≥50% using B-mode ultrasound and SWE imaging to measure the mean, maximal and minimal elasticity. The set consisted of 97 participants-74 with asymptomatic stable stenosis, 12 with asymptomatic progressive stenosis and 11 with symptomatic stenosis. The mean elasticity in the asymptomatic stable plaque group was significantly higher than in the asymptomatic progressive (52.2 vs. 30.4 kPa; p < 0.001) and symptomatic (52.2 vs. 36.4 kPa; p = 0.033) plaque groups. No significant differences were found between asymptomatic progressive and symptomatic (p > 0.1) plaque groups. Asymptomatic stable, asymptomatic progressive and symptomatic plaques did not differ in echogenicity, calcifications, homogeneity, occurrence of ulcerated surface, or intra-plaque hemorrhage (p > 0.05 in all cases). SWE was a helpful modality for differentiating between stable and unstable atherosclerotic plaques in carotid arteries.

The endocrine disruptor cadmium: a new player in the pathophysiology of metabolic diseases

Cadmium (Cd), a highly toxic heavy metal, is found in soil, environment and contaminated water and food. Moreover, Cd is used in various industrial activities, such as electroplating, batteries production, fertilizers, while an important non-occupational source is represented by cigarette smoking, as Cd deposits in tobacco leaves. Since many years it is clear a strong correlation between Cd body accumulation and incidence of many diseases. Indeed, acute exposure to Cd can cause inflammation and affect many organs such as kidneys and liver. Furthermore, the attention has focused on its activity as environmental pollutant and endocrine disruptor able to interfere with metabolic and energy balance of living beings. Both in vitro and in vivo experiments have demonstrated that the Cd-exposure is related to metabolic diseases such as obesity, diabetes and osteoporosis even if human studies are still controversial. Recent data show that Cd-exposure is associated with atherosclerosis, hypertension and endothelial damage that are responsible for cardiovascular diseases. Due to the large environmental diffusion of Cd, in this review, we summarize the current knowledge concerning the role of Cd in the incidence of metabolic and cardiovascular diseases.

Aortic Valve Sclerosis as an Important Predictor of Long-Term Mortality in Patients With Carotid Atheromatous Plaque Requiring Carotid Endarterectomy

Background: A strong association between aortic valve sclerosis (AVSc), the earliest manifestation of calcific aortic valve disease, and atherosclerosis exists. The aim of the study was to evaluate the predictive capabilities of AVSc on long-term all-cause mortality, in patients requiring carotid endarterectomy (CEA).

Methods and Results: 806 consecutive CEA patients were enrolled. Preoperative echocardiography was used to assess AVSc. Computed tomography angiography was applied for plaque characterization. Kaplan-Meier curves, Cox linear regression, and area under the receiving operator characteristic (AUC) curve analyses were used to evaluate the predictive capability of AVSc. Overall, 348 of 541 patients had AVSc (64%). Age, diabetes, and estimated glomerular filtration rate (eGFR) were associated with AVSc. In the 5-year follow-up, AVSc group had a mortality rate of 16.7% while in no-AVSc group was 7.8%. Independent predictors of all-cause mortality were age, sex, eGFR, left ventricular ejection fraction, and AVSc. After adjustments, AVSc was associated with a significant increase in all-cause mortality risk (hazard ratio, HR = 1.9; 95%CI: 1.04–3.54; p = 0.038). We stratify our cohort based on carotid atheromatous plaque-type: soft, calcified, and mixed-fibrotic. In patients with mixed-fibrotic plaques, the mortality rate of AVSc patients was 15.5% compared to 2.4% in no-AVSc patients. In this group, AVSc was associated with an increased long-term all-cause mortality risk with an adjusted HR of 12.8 (95%CI: 1.71–96.35; p = 0.013), and the AUC, combing eGFR and AVSc was 0.77 (p < 0.001).

Conclusions: Our findings indicate that AVSc together with eGFR may be used to improve long-term risk stratification of patients undergoing CEA surgery.

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.

YKL-40 Is Associated With Ultrasound-Determined Carotid Atherosclerotic Plaque Instability

Background and Aims: YKL-40, an inflammatory biomarker, has been reported to be involved in the process and progression of atherosclerosis. Several studies have investigated the association between YKL-40 and plaque and suggested YKL-40 might be a potential biomarker for plaque instability. This study aimed to investigate the association between YKL-40 and carotid plaque instability. Methods: Based on a community-based study in Beijing from February 2014 to May 2016, 1,132 participants with carotid plaques were enrolled in this study. Data on demographics and medical history were collected through face-to-face interviews, and fasting blood samples were collected and stored. We used ultrasound to evaluate the presence of carotid plaque and its instability. The level of YKL-40 was measured by enzyme-linked immunosorbent assay (ELISA). Multivariate logistic regression analysis was performed to investigate the association between YKL-40 level and carotid atherosclerotic plaque instability. Results: The mean age of the 1,132 participants was 58.0 (52.0-64.0) years, and 560 (49.5%) were male. Unstable plaques were detected in 855 (75.53%) participants. YKL-40 level was classified into four groups according to its quartile: quartile 1: <25.47 ng/mL, quartile 2: 25.47-39.53 ng/mL, quartile 3: 39.53-70.55 ng/mL, quartile 4: ≥70.55 ng/mL. After adjusting for age, sex, smoking, alcohol drinking, medical history, triglycerides, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, homocysteine, high-sensitivity C-reactive protein, and plaque thickness, the top quartiles of YKL-40 level were significantly associated with unstable plaque (quartile 3: OR 2.10, 95% CI 1.29-3.40; quartile 4: OR 1.70, 95% CI 1.04-2.80). Conclusion: This study found that YKL-40 was associated with carotid plaque instability determined by ultrasound. Individuals with high YKL-40 may have a higher risk of unstable carotid plaque.

Feasibility of ex vivo fluorescence imaging of angiogenesis in (non-) culprit human carotid atherosclerotic plaques using bevacizumab-800CW

Vascular endothelial growth factor-A (VEGF-A) is assumed to play a crucial role in the development and rupture of vulnerable plaques in the atherosclerotic process. We used a VEGF-A targeted fluorescent antibody (bevacizumab-IRDye800CW [bevacizumab-800CW]) to image and visualize the distribution of VEGF-A in (non-)culprit carotid plaques ex vivo. Freshly endarterectomized human plaques (n = 15) were incubated in bevacizumab-800CW ex vivo. Subsequent NIRF imaging showed a more intense fluorescent signal in the culprit plaques (n = 11) than in the non-culprit plaques (n = 3). A plaque received from an asymptomatic patient showed pathologic features similar to the culprit plaques. Cross-correlation with VEGF-A immunohistochemistry showed co-localization of VEGF-A over-expression in 91% of the fluorescent culprit plaques, while no VEGF-A expression was found in the non-culprit plaques (p < 0.0001). VEGF-A expression was co-localized with CD34, a marker for angiogenesis (p < 0.001). Ex vivo near-infrared fluorescence (NIRF) imaging by incubation with bevacizumab-800CW shows promise for visualizing VEGF-A overexpression in culprit atherosclerotic plaques in vivo.

Middle cerebral artery pressure laterality in patients with symptomatic ICA stenosis

An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔPMCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59-80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔPMCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔPMCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔPMCA and ΔQICA (r = 0.85, p<0.001) and ΔQACA (r = 0.71, p<0.001), respectively. The correlation to ΔQMCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.

Red and White Thrombus Characteristics in Patients Undergoing Carotid Endarterectomy

OBJECTIVE

The study aimed to compare the characteristics of red and white thrombi in patients undergoing carotid endarterectomy.

MATERIAL AND METHODS

The study was conducted in 81 patients with ischemic stroke who underwent carotid endarterectomy for carotid artery stenosis. Carotid plaques were graded by two pathologists. Thrombus materials were divided into two groups: white and red. The parameters of assessment were plaque rupture, lipid core, fibrous cap thickness, inflammation, intraplaque hemorrhage, calcification, necrotic core, and neovascularization. Normally distributed data were evaluated using Mann-Whitney U and Chi-squared tests.

RESULTS

The ratio of white and red thrombus was 19.8% and 80.2%, respectively. Lipid core, plaque rupture, necrotic core, neovascularization, intraplaque hemorrhage, obstruction, and inflammation were observed more in red thrombus, which were statistically significant. Calcification and fibrous cap thickness were not statistically significant in the two groups. Moreover, intimal smooth muscle cells were present in all thrombus types.

CONCLUSION

In our study, we found that red thrombi had more unstable characteristics than white thrombi. Thus, the risk for ischemic cerebrovascular events is more in red thrombi. However, this finding cannot be generalized due to the small number of patients in this study. Therefore, studies involving more patients are needed.

Outcomes after transfemoral carotid artery stenting stratified by preprocedural symptom status

OBJECTIVE

The available data on outcomes after transfemoral carotid artery stenting (TFCAS) originate from the early experience with TFCAS. Although most previous studies stratified outcomes according to a symptomatic or asymptomatic presentation, they often did not specify the degree of presenting neurologic injury. We previously reported that the outcomes after carotid endarterectomy differed according to neurologic injury severity, the contemporary perioperative outcomes of TFCAS stratified by the specific presenting symptom status are unknown.

METHODS

Patients with data in the Vascular Quality Initiative database who had undergone TFCAS from 2016 to 2020 were included. We stratified patients according to their preprocedural symptom status as asymptomatic, formerly symptomatic (last symptoms >180 days before the procedure), or recently symptomatic (symptoms <180 days before the procedure). The symptoms included stroke, hemispheric transient ischemic attack (TIA), and ocular TIA. We compared the occurrence of in-hospital stroke or death (stroke/death) among the asymptomatic, formerly symptomatic, and specific subtypes of recently symptomatic patients. Multivariable logistic regression models were constructed to adjust for the baseline differences among the groups.

RESULTS

Of the 9807 included patients, 2650 (27%) had had recent stroke, 842 (9%), recent hemispheric TIA, and 360 (4%), recent ocular TIA. In addition, 795 patients (8%) were formerly symptomatic and 5160 (53%) were asymptomatic. The patients with recent stroke had a perioperative stroke/death rate of 5.5%, higher than that of patients with recent hemispheric TIA (2.4%; P < .001) or recent ocular TIA (2.8%; P = .03) and asymptomatic patients (1.4%; P < .001). The stroke/death rate was greater for patients with recent ocular TIA than for asymptomatic patients (2.8% vs 1.4%; P = .04). Formerly symptomatic patients had higher stroke/death rates compared with asymptomatic patients (3.5% vs 1.4%; P < .001). On multivariable-adjusted analysis, recent stroke was associated with higher stroke/death compared with recent hemispheric TIA (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.6-4.3; P < .001) and asymptomatic status (OR, 4.1; 95% CI, 3.0-5.6; P < .001) and demonstrated a trend toward higher stroke/death compared with recent ocular TIA (OR, 2.0; 95% CI, 1.0-3.9; P = .06). Furthermore, asymptomatic status was associated with lower stroke/death compared with formerly symptomatic status (OR, 0.4; 95% CI, 0.2-0.6; P < .001).

CONCLUSIONS

For patients undergoing TFCAS, recent stroke was associated with greater odds of in-hospital stroke/death after TFCAS compared with recent hemispheric TIA. Also, formerly symptomatic status was associated with greater odds of stroke/death compared with asymptomatic status. These findings support further symptom stratification by the degree of the presenting neurologic injury in the preoperative risk assessment.

Carotid Intraplaque Neovascularization on Contrast-Enhanced Ultrasound Correlates with Cardiovascular Events and Poor Prognosis: A Systematic Review and Meta-analysis

The goal of this meta-analysis is to investigate whether carotid intraplaque neovascularization (IPN) on contrast-enhanced ultrasound (CEUS) correlates with past cardiovascular events (CVEs) and prognosis. The present meta-analysis included 22 studies involving 3232 patients. The pooled analysis revealed that the presence of IPN was significantly associated with a higher incidence of future CVEs (pooled relative risk = 3.28, 95% confidence interval [CI]: 2.28-4.73) and a lower event-free probability (pooled hazard ratio = 2.51, 95% CI: 1.48-4.27). The presence of IPN was significantly associated with higher rates of past cardiac events (odds ratio = 4.25, 95% CI: 2.48-7.29) and past cerebrovascular accidents (odds ratio = 4.83, 95% CI: 2.66-8.78). Our results suggest that carotid IPN on CEUS significantly correlates with past cardiac events and cerebrovascular accidents and can predict future CVEs. Carotid CEUS is useful in CVE risk stratification.

Identification of high-risk carotid plaque with MRI-based radiomics and machine learning

OBJECTIVES

We sought to build a high-risk plaque MRI-based model (HRPMM) using radiomics features and machine learning for differentiating symptomatic from asymptomatic carotid plaques.

MATERIALS AND METHODS

One hundred sixty-two patients with carotid stenosis were randomly divided into training and test cohorts. Multi-contrast MRI including time of flight (TOF), T1- and T2-weighted imaging, and contrast-enhanced imaging was done. Radiological characteristics of the carotid plaques were recorded and calculated to build a traditional model. After extracting the radiomics features on these images, we constructed HRPMM with least absolute shrinkage and selection operator algorithm in the training cohort and evaluated its performance in the test cohort. A combined model was also built using both the traditional and radiomics features. The performance of all the models in the identification of high-risk carotid plaque was compared.

RESULTS

Intraplaque hemorrhage and lipid-rich necrotic core were independently associated with clinical symptoms and were used to build the traditional model, which achieved an area under the curve (AUC) of 0.825 versus 0.804 in the training and test cohorts. The HRPMM and the combined model achieved an AUC of 0.988 versus 0.984 and of 0.989 versus 0.986 respectively in the two cohorts. Both the radiomics model and combined model outperformed the traditional model, whereas the combined model showed no significant difference with the HRPMM.

CONCLUSIONS

Our MRI-based radiomics model can accurately distinguish symptomatic from asymptomatic carotid plaques. It is superior to the traditional model in the identification of high-risk plaques.

KEY POINTS

• Carotid plaque multi-contrast MRI stores other valuable information to be further exploited by radiomics analysis. • Radiomics analysis can accurately distinguish symptomatic from asymptomatic carotid plaques. • The radiomics model is superior to the traditional model in the identification of high-risk plaques.

Carotid intraplaque haemorrhage: pathogenesis, histological classification, imaging methods and clinical value

Vulnerable carotid atherosclerotic plaques are characterised by several risk factors, such as inflammation, neovascularization and intraplaque haemorrhage (IPH). Vulnerable plaques can lead to ischemic events such as stroke. Many studies reported a relationship between IPH, plaque rupture, and ischemic stroke. Histology is the gold standard to evaluate IPH, but it required carotid endarterectomy (CEA) surgery to collect the tissue sample. In this context, several imaging methods can be used as a non-invasive way to evaluate plaque vulnerability and detect IPH. Most imaging studies showed that IPH is associated with plaque vulnerability and stroke, with magnetic resonance imaging (MRI) being the most sensitive and specific to detect IPH as a predictor of ischemic events. These conclusions are however still debated because of the limited number of patients included in these studies; further studies are required to better assess risks associated with different IPH stages. Moreover, IPH is implicated in plaque vulnerability with other risk factors which need to be considered to predict ischemic risk. In addition, MRI sequences standardization is required to compare results from different studies and agree on biomarkers that need to be considered to predict plaque rupture. In these circumstances, IPH detection by MRI could be an efficient clinical method to predict stroke. The goal of this review article is to first describe the pathophysiological process responsible for IPH, its histological detection in carotid plaques and its correlation with plaque rupture. The second part will discuss the benefits and limitations of imaging the carotid plaque, and finally the clinical interest of imaging IPH to predict plaque rupture, focusing on MRI-IPH.

Significance of high resolution MRI in the identification of carotid plaque

The stability of carotid artery plaque serves a key role in the occurrence of stroke. The present study was based on the recruitment of patients with acute ischemic cerebrovascular disease. High-resolution magnetic resonance imaging (HR-MRI) was used to identify the nature of carotid artery plaque, and the results were then used to manage the high-risk group of stroke. The patients were divided equally into a symptomatic group (36 cases) and an asymptomatic group (36 cases). According to the degree of carotid artery stenosis, the patients were divided into mild, moderate and severe stenosis groups, each group comprising 12 patients, and HR-MRI was performed. The proportion of patients with vulnerable plaque in the symptomatic group was higher compared with that in the asymptomatic group (P<0.05). The more severe the stenosis, the higher the proportion of vulnerable plaque that was identified (P<0.05). Compared with carotid ultrasound, HR-MRI was indicated to have the capability to both identify and quantify the different components in the plaque, allowing an assessment of its properties. In conclusion, the present study demonstrated that carotid HR-MRI is able to distinguish and quantify the different components of plaque, which may prove to be helpful for the hierarchical management of a population at high risk of stroke.

Plaque burden assessment and attenuation measurement of carotid atherosclerotic plaque using virtual monoenergetic images in comparison to conventional polyenergetic images from dual-layer spectral detector CT

PURPOSE

To compare virtual monoenergetic images (VMIs) with conventional polyenergetic images (PI) of Dual-layer spectral detector CT angiography (DLCTA) in plaque burden assessment and attenuation measurement of carotid atherosclerotic plaques.

METHODS

Supra-aortic DLCTA imaging of thirty patients (8 female, mean ages 63.1 ± 7.5 years) were respectively reviewed. Lumen area, wall area, and calcified area of plaques were outlined and recorded. Normalized wall index (NWI) was calculated for plaque burden and compared between PI and different VMIs. The attenuation of the non-calcified, calcified area of the plaques, sternocleidomastoid muscle (SCM), as well as Z effective values were measured and compared.

RESULTS

Fifty carotid plaques (27 left, 23 right) of thirty patients were analyzed. The average values of lumen, wall, calcified areas and NWI on PI were 34.50 ± 20.57mm², 47.61 ± 19.94 mm², 5.25 mm² (1.35- 51.86 mm²), and 0.59 ± 0.16 respectively. No significant difference was found in the lumen area (p = 0.314), wall area (p = 0.600), and NWI (p = 0.980) between different VMIs and PI. A significant difference was found in the calcified area between VMIs and PI (p = 0.009). Attenuations of non-calcified and calcified components in carotid plaques were comparable to PI for 50-120 keV (all: p > 0.05) and 60-120 keVs (all p > 0.05), respectively. Z Effective values for non-calcified, calcified and SCM were 7.67 ± 0.42, 11.70 ± 1.22, and 7.45 ± 0.12, respectively.

CONCLUSIONS

Carotid plaque burden assessment was comparable between PI and VMIs at 40-120 keVs. Attenuations of non-calcified components in carotid plaques were comparable to PI for 50-120 keV VMIs of DLCTA. VMIs might provide more information on carotid plaque features.

Utility of Complementary Magnetic Resonance Plaque Imaging and Contrast-Enhanced Ultrasound to Detect Carotid Vulnerable Plaques

Background We aimed to improve the assessment quality of plaque vulnerability with combined use of magnetic resonance imaging and contrast-enhanced ultrasound ( CEUS ). Methods and Results We prospectively enrolled 71 patients with internal carotid artery stenosis who underwent carotid endarterectomy and performed preoperative CEUS and magnetic resonance plaque imaging. We distinguished high-signal-intensity plaques ( HIP s) and non- HIP s based on magnetization-prepared rapid acquisition with gradient echo images. We graded them according to the CEUS contrast effect and compared the CEUS images with the carotid endarterectomy specimens. Among the 70 plaques, except 1 carotid endarterectomy tissue sample failure, 59 were classified as HIP s (43 symptomatic) and 11 were classified as non- HIP s (5 symptomatic). Although the magnetization-prepared rapid acquisition with gradient echo findings alone had no significant correlation with symptoms ( P=0.07), concomitant use of magnetization-prepared rapid acquisition with gradient echo and CEUS findings did show a significant correlation ( P<0.0001). CEUS showed that all 5 symptomatic non- HIP s had a high-contrast effect. These 5 plaques were histopathologically confirmed as vulnerable, with extensive neovascularization but only a small amount of intraplaque hemorrhage. Conclusions Complementary use of magnetic resonance imaging and CEUS to detect intraplaque hemorrhage and neovascularization in plaques can be useful for evaluating plaque vulnerability, consistent with the destabilization process associated with neovessel formation and subsequent intraplaque hemorrhage.

Evaluation of Carotid Plaque Rupture and Neovascularization by Contrast-Enhanced Ultrasound Imaging: an Exploratory Study Based on Histopathology

A significant portion of ischemic stroke is on account of emboli caused by fibrous cap rupture of vulnerable plaque with intraplaque neovascularization as a significant triggering factor to plaque vulnerability. Contrast-enhanced ultrasound (CEUS) could offer detailed information on plaque surface and intraplaque microvascular. This study aims to comprehensively assess the value of CEUS for the detection of plaque rupture and neovascularization in histologically verified plaques that had been removed from the patients who had undergone carotid endarterectomy (CEA). Fifty-one consecutive subjects (mean age, 67.0 ± 6.5 years; 43 [84.3%] men) scheduled for CEA were recruited. Standard ultrasound and CEUS were performed prior to surgery. Based on the direction of the contrast agents that diffuse within the plaques, plaques were divided as "inside-out" direction (contrast agents diffuse from the artery lumen towards the inside of the plaque) and non-inside-out direction. Plaque enhancement was assessed by using a semi-quantitative grading scale (grade 1: no enhancement; grade 2: moderate enhancement; grade 3: extensive enhancement). Plaques were evaluated for histopathologic characteristics according to Oxford Plaque Study (OPS) standard postoperative. Intraplaque neovascularization as manifested by the appearance of CD34-positive microvessels was characterized in terms of microvessel density (MVD), microvessel area (MVA), and microvessel shape (MVS). In 51 plaques, the sensitivity, specificity, positive, and negative predictive values of contrast agent inside-out direction diffusion for the detection of plaque fibrous cap rupture were 87.5%, 92.6%, 91.3%, and 89.3%, respectively. The incidence of cap rupture was significantly higher in contrast agent inside-out direction diffusion than non-inside-out direction diffusion (73.9% vs 25.0%, p < 0.001), and inside-out direction diffusion did exhibit higher frequency of vulnerable plaques (OPS grades 3-4) (95.7% vs 53.6%, p = 0.001). Multivariate logistic regression analysis revealed the contrast agent inside-out direction diffusion as an independent correlate to plaque rupture (OR 8.5, 95% CI 2.4-30.1, p = 0.001). With increasing plaque enhancement, plaque MVD (p < 0.001), plaque MVA (p = 0.012), and percentage of highly irregular-shaped microvessels increased (p < 0.001). Contrast agent inside-out direction diffusion could indicate plaque rupture. The increase in plaque enhancement paralleled increased, larger, and more irregular-shaped microvessels, which may suggest an increased risk of plaque vulnerability.

Clinical considerations and recommendations for OCT-guided carotid artery stenting

Introduction: Optical Coherence Tomography (OCT) is an intravascular imaging providing high-resolution images of morphological features of arterial wall. Nowadays, OCT is an accepted intravascular modality to study coronary arteries, stent implantation, and vessel injury. In the last decade, an increasing interest have been focused on the application of OCT in carotid arteries.Areas covered: Literature evidence in the application of OCT in carotid arteries still remains debated. So far, OCT has been used as a research tool, aiming to evaluate atherosclerotic plaques' features and stents' behavior after implantation. This paper is intended to summarize clinical evidences and practices in the use of OCT in carotid arteries district and during CAS procedures. Literature review was completed via Pubmed search using Keywords.Expert opinion: CAS is a safe and effective procedure when performed by trained physicians with a tailored approach. In this scenario, ambiguous pictures at ultrasound, angiography, and IVUS might be clarified using OCT.By providing unprecedented microstructural information on atherosclerotic plaques, OCT may identify the features of vulnerable carotid plaque and, by identifying possible defects after stent implantation as malapposition and plaque prolapse, it may help the tailoring approach to CAS.

A Systematic Review for the Design of In Vitro Flow Studies of the Carotid Artery Bifurcation

PURPOSE

In vitro blood flow studies in carotid artery bifurcation models may contribute to understanding the influence of hemodynamics on carotid artery disease. However, the design of in vitro blood flow studies involves many steps and selection of imaging techniques, model materials, model design, and flow visualization parameters. Therefore, an overview of the possibilities and guidance for the design process is beneficial for researchers with less experience in flow studies.

METHODS

A systematic search to in vitro flow studies in carotid artery bifurcation models aiming at quantification and detailed flow visualization of blood flow dynamics results in inclusion of 42 articles.

RESULTS

Four categories of imaging techniques are distinguished: MRI, optical particle image velocimetry (PIV), ultrasound and miscellaneous techniques. Parameters for flow visualization are categorized into velocity, flow, shear-related, turbulent/disordered flow and other parameters. Model materials and design characteristics vary between study type.

CONCLUSIONS

A simplified three-step design process is proposed for better fitting and adequate match with the pertinent research question at hand and as guidance for less experienced flow study researchers. The three consecutive selection steps are: flow parameters, image modality, and model materials and designs. Model materials depend on the chosen imaging technique, whereas choice of flow parameters is independent from imaging technique and is therefore only determined by the goal of the study.

Left Common Carotid Artery Biomechanical Properties in Individuals over 80 years: Women Have Stiffer Vessels

BACKGROUND

Considering the longevity of the worldwide population, the cardiovascular diseases deserve particular attention, especially the carotid artery disease in the ≥80-year-old population. The stiffness of the common carotid artery, for example, has been showed in numerous clinical studies as a marker of increased risk of stroke, dementia, and depression. Besides, with the emergence of new surgical techniques such as the transcarotid artery revascularization that uses the common carotid artery as a workstation, the biomechanical and histological features of this vessel, more than ever, must be detailed.

METHODS

Left common carotid artery fragments from 9 cadaver donors (≥80 years old) were evaluated. Biomechanical (failure stress, tension, and strain) and histological (percentage of collagen and elastic fibers) features of these samples were analyzed with special focus on gender differences.

RESULTS

Statistically significant differences in biomechanical and histological features between the genders were observed. The percentage of collagen fiber in intima (P = 0.008) and media (P = 0.041) layers was significantly lower in men than in women. A higher elasticity (failure strain) of the specimens in male gender was also observed (P = 0.025). No significant difference was observed in the layers thickness between the genders regardless which part of the arterial wall was considered.

CONCLUSIONS

These biomechanical and histological findings could be the responsible for the higher left common carotid artery stiffness observed among ≥80-year-old women when compared with men in numerous clinical studies in literature.