Contrast-enhanced ultrasound of the carotid system: a review of the current literature

Sex-related differences in coronary and carotid vessel geometry, plaque composition and shear stress obtained from imaging

Atherosclerosis manifests itself differently in men and women with respect to plaque initiation, progression and plaque composition. The observed delay in plaque progression in women is thought to be related to the hormonal status of women. Also features associated with the vulnerability of plaques to rupture seem to be less frequently present in women compared to men. Current invasive and non-invasive imaging modalities allow for visualization of plaque size, composition and high risk vulnerable plaque features. Moreover, image based modeling gives access to local shear stress and shear stress-related plaque growth. In this review, current knowledge on sex-related differences in plaque size, composition, high risk plaque features and shear stress related plaque growth in carotid and coronary arteries obtained from imaging are summarized.

Determinants of Carotid Wall Echolucency in a Cohort of European High Cardiovascular Risk Subjects: A Cross-Sectional Analysis of IMPROVE Baseline Data

Echolucency, a measure of plaque instability associated with increased cardiovascular risk, can be assessed in both the carotid plaque and the plaque-free common carotid intima-media (IM) complex as a gray-scale median (plaque-GSM and IM-GSM, respectively). The impact of specific vascular risk factors on these two phenotypes remains uncertain, including the nature and extent of their influence. This study aims to seek the determinants of plaque-GSM and IM-GSM. Plaque-GSM and IM-GSM were measured in subjects from the IMPROVE study cohort (aged 54-79, 46% men) recruited in five European countries. Plaque-GSM was measured in subjects who had at least one IMTmax ≥ 1.5 mm (n = 2138), whereas IM-GSM was measured in all subjects included in the study (n = 3188). Multiple regression with internal cross-validation was used to find independent predictors of plaque-GSM and IM-GSM. Plaque-GSM determinants were plaque-size (IMTmax), and diastolic blood pressure. IM-GSM determinants were the thickness of plaque-free common carotid intima-media complex (PF CC-IMTmean), height, systolic blood pressure, waist/hip ratio, treatment with fibrates, mean corpuscular volume, treatment with alpha-2 inhibitors (sartans), educational level, and creatinine. Latitude, and pack-yearscode were determinants of both plaque-GSM and IM-GSM. The overall models explain 12.0% of plaque-GSM variability and 19.7% of IM-GSM variability. A significant correlation (r = 0.51) was found between plaque-GSM and IM-GSM. Our results indicate that IM-GSM is a weighty risk marker alternative to plaque-GSM, offering the advantage of being readily measurable in all subjects, including those in the early phases of atherosclerosis where plaque occurrence is relatively infrequent.

3-D Contrast-Enhanced Fusion Ultrasound for Accurate Volume Assessment of Vessel Lumen and Plaque in Carotid Artery Disease as Compared With Computed Tomography Angiography

OBJECTIVE

Three-dimensional contrast-enhanced fusion ultrasound (CEFUS) of atherosclerotic carotid arteries provides spatial visualization of the vessel lumen, creating a lumenography. As in 3-D computed tomography angiography (CTA), 3-D CEFUS outlines the contrast-filled lumen. Plaque and vessel contours are distinguished in 3-D CEFUS, allowing plaque volume quantification as a valid estimate of carotid plaque burden. Three-dimensional CEFUS is unproven in intermodality studies, vindicating the assessment of 3-D CEFUS applicability and comparing 3-D CEFUS and 3-D CTA lumenography as a proof-of-concept study.

METHODS

Using an ultrasound system with magnetic tracking, a linear array transducer and SonoVue contrast agent, 3-D CEFUS acquisitions were generated by spatial stitching of serial 2-D images. From 3-D CEFUS and 3-D CTA imaging, the atherosclerotic carotid arteries were reconstructed with lumenography in an offline software program for lumen and plaque volume quantification. Bland-Altman analysis was used for inter-image modality agreement.

RESULTS

The study included 39 carotid arteries. Mean lumen and plaque volume in 3-D CEFUS were 0.63 cm3 (standard deviation [SD]: 0.26) and 0.62 cm3 (SD: 0.26), respectively. Lumen volume differences between 3-D CEFUS and 3-D CTA were non-significant, with a mean difference of 0.01 cm3 (SD: 0.02, p = 0.26) and limits of agreement (LoA) range of ±0.11 cm3. Mean plaque volume difference was -0.12 cm3 (SD: 0.19, p = 0.006) with a LoA range of ±0.39 cm3.

CONCLUSION

There was strong agreement in lumenography between 3-D CEFUS and 3-D CTA. The interimage modality difference in plaque volumes was substantial because of challenging vessel wall definition in 3-D CTA. Three-dimensional CEFUS is viable in quantifying carotid plaque volume burden and can potentially monitor plaque development over time.

Accuracy of contrast-enhanced ultrasound in diagnosing extracranial carotid occlusion: A meta-analysis

AIM

This study aimed to assess the accuracy of contrast-enhanced ultrasound (CEUS) in detecting extracranial carotid artery occlusion.

MATERIALS AND METHODS

A systematic literature search was conducted in the Cochrane, PubMed, and EMBASE databases. Prospective or retrospective studies that reported sensitivity and specificity of CEUS for the diagnosis of carotid artery occlusion were selected. Eight studies (354 arteries) were included in the meta-analysis. A bivariate random-effect model was used to estimate overall sensitivity and specificity. The results were also summarized by developing a summary receiver operating characteristic (SROC) curve.

RESULTS

The overall sensitivity, specificity, positive, and negative likelihood ratios were 0.99 (95% CI: 0.83-1.00), 0.97 (95% CI: 0.90-0.99), 30.0 (95% CI: 9.8-91.4), and 0.01 (95% CI: 0.00-0.21), respectively; the odds ratio for diagnosis was 4,796 (95% CI: 119-192,584).

CONCLUSION

The diagnostic test accuracy suggests that CEUS is a reliable tool for diagnosis of extracranial carotid artery occlusion.

Multiparametric analysis of carotid body tumours: a pictorial essay

Carotid body tumours (CBT), also called carotid body paraganglioma, are highly vascular and histologically portray paraganglion cells. They are typically found at the carotid bifurcation and result in the splaying of the internal and external carotid arteries (ICA and ECA). Recent literature supports the role of chronic hypoxia in the etiology of CBT. This pictorial essay discusses how CBT is an uncommon etiology for common clinical problems such as transient ischemic attacks. It also discusses imaging techniques to precisely map out the tumour for surgical resection using advanced imaging modalities and techniques.

Application of Model-Building Based on Arterial Ultrasound Imaging Evaluation to Predict CHD Risk

Objective

Atherosclerotic is a chronic systemic disease that may occur in multiple vascular beds, including the carotid arteries, renal arteries, lower limb arteries, and cerebral vessels. Coronary atherosclerosis shares similar risk factors, pathogenesis, and pathophysiological basis with the atherosclerotic lesions of arteries at these sites. Arterial ultrasound assessment data were used to explore the correlation of atherosclerotic disease with CHD lesions and their severity and the number of lesion branches, as well as to evaluate its value in predicting CHD risk, in combination with traditional risk factors.

Methods

A total of 363 inpatients with suspected CHD in the Department of Cardiology of the First Hospital of Harbin Medical University from November 2017 to June 2021 were selected. Patient clinical data, blood biochemical examination results, and ultrasound examination of neck vessels, abdominal arteries, and limb arteries were collected to obtain atherosclerosis assessment data. We then compared the differences between the CHD group and the control group, analyzed their correlation with CHD lesions and severity and the number of lesion branches, and evaluated the correlation with the coronary Gensini score. After adjustment for traditional risk factors, logistic regression was applied to analyze the relationship between arterial ultrasound assessment data and the risk of CHD. In addition, ROC plots were drawn to evaluate the risk of arterial ultrasound assessment data, combined with traditional risk factors, to predict CHD.

Results

With regard to abnormal blood biochemical index values, differences in lipids, HDL-C, FIB, CK-MB, hs-cTnI, BNP, and GGT were found between the CHD group and the control group. Carotid plaque count, abdominal aortic flow velocity, inferior mesenteric artery flow velocity, classification of the number of stenotic branches of abdominal aortic branch arteries, lower-extremity-artery plaque count, degree of lower-extremity-artery stenosis, and lower-extremity-artery AS were risk factors for arterial ultrasound assessment data of CHD. Carotid plaque count, carotid artery AS, inferior mesenteric artery flow velocity, abdominal aortic flow velocity, abdominal aortic plaque count, abdominal aortic branch artery stenosis branch classification, lower-extremity-artery plaque count, lower-extremity-artery stenosis branch classification, degree of lower-extremity-artery stenosis, and lower-extremity-artery AS, combined with traditional risk factors, were mostly more effective than traditional risk factor models in predicting CHD, its severity, and the number of branch lesions; moreover, the predictive value was higher. Specifically, carotid plaque count, carotid AS, lower-extremity-artery AS, the degree of stenosis of lower-extremity arteries, and abdominal aortic branch artery stenosis branch classification can be used as predictor variables for CHD risk. Among these variables, the carotid plaque count can be used as an independent predictor of CHD.

Conclusion

The incidence of arterial intima–media thickening (IMT), plaques, and stenosis can provide a reference for understanding the pattern of systemic atherogenesis and the distribution of atherosclerosis.

3D-Arterial analysis software and CEUS in the assessment of severity and vulnerability of carotid atherosclerotic plaque: a comparison with CTA and histopathology

Purpose

Our purpose is to assess Multiparametric Ultrasound (MPUS) efficacy for evaluation of carotid plaque vulnerability and carotid stenosis degree in comparison with Computed Tomography angiography (CTA) and histology.

Material and methods

3D-Arterial Analysis is a 3D ultrasound software that automatically provides the degree of carotid stenosis and a colorimetric map of carotid plaque vulnerability.

We enrolled 106 patients who were candidates for carotid endarterectomy. Prior to undergoing surgery, all carotid artery plaques were evaluated with Color-Doppler-US (CDUS), Contrast-Enhanced Ultrasound (CEUS), and 3D Arterial analysis (3DAA) US along with Computerized Tomographic Angiography (CTA) to assess the carotid artery stenosis degree. Post-surgery, the carotid specimens were fixed with 10% neutral buffered formalin solution, embedded in paraffin and used for light microscopic examination to assess plaque vulnerability morphological features.

Results

The results of the CTA examinations revealed 91 patients with severe carotid stenoses with a resultant diagnostic accuracy of 82.3% for CDUS, 94.5% for CEUS, 98.4% for 3DAA, respectively. The histopathological examination showed 71 vulnerable plaques with diagnostic accuracy values of 85.8% for CDUS, 93.4% for CEUS, 90.3% for 3DAA, 92% for CTA, respectively.

Conclusions

The combination of CEUS and 3D Arterial Analysis may provide a powerful new clinical tool to identify and stratify “at-risk” patients with atherosclerotic carotid artery disease, identifying vulnerable plaques. These applications may also help in the postoperative assessment of treatment options to manage cardiovascular risks.

Duplex ultrasound for diagnosing symptomatic carotid stenosis in the extracranial segments

BACKGROUND

Carotid artery stenosis is an important cause of stroke and transient ischemic attack. Correctly and rapidly identifying patients with symptomatic carotid artery stenosis is essential for adequate treatment with early cerebral revascularization. Doubts about the diagnostic value regarding the accuracy of duplex ultrasound (DUS) and the possibility of using DUS as the single diagnostic test before carotid revascularization are still debated.

OBJECTIVES

To estimate the accuracy of DUS in individuals with symptomatic carotid stenosis verified by either digital subtraction angiography (DSA), computed tomography angiography (CTA), or magnetic resonance angiography (MRA).

SEARCH METHODS

We searched CRDTAS, CENTRAL, MEDLINE (Ovid), Embase (Ovid), ISI Web of Science, HTA, DARE, and LILACS up to 15 February 2021. We handsearched the reference lists of all included studies and other relevant publications and contacted experts in the field to identify additional studies or unpublished data.

SELECTION CRITERIA

We included studies assessing DUS accuracy against an acceptable reference standard (DSA, MRA, or CTA) in symptomatic patients. We considered the classification of carotid stenosis with DUS defined with validated duplex velocity criteria, and the NASCET criteria for carotid stenosis measures on DSA, MRA, and CTA. We excluded studies that included < 70% of symptomatic patients; the time between the index test and the reference standard was longer than four weeks or not described, or that presented no objective criteria to estimate carotid stenosis.

DATA COLLECTION AND ANALYSIS

The review authors independently screened articles, extracted data, and assessed the risk of bias and applicability concerns using the QUADAS-2 domain list. We extracted data with an effort to complete a 2 × 2 table (true positives, true negatives, false positives, and false negatives) for each of the different categories of carotid stenosis and reference standards. We produced forest plots and summary receiver operating characteristic (ROC) plots to summarize the data. Where meta-analysis was possible, we used a bivariate meta-analysis model.

MAIN RESULTS

We identified 25,087 unique studies, of which 22 were deemed eligible for inclusion (4957 carotid arteries). The risk of bias varied considerably across the studies, and studies were generally of moderate to low quality. We narratively described the results without meta-analysis in seven studies in which the criteria used to determine stenosis were too different from the duplex velocity criteria proposed in our protocol or studies that provided insufficient data to complete a 2 × 2 table for at least in one category of stenosis. Nine studies (2770 carotid arteries) presented DUS versus DSA results for 70% to 99% carotid artery stenosis, and two (685 carotid arteries) presented results from DUS versus CTA in this category. Seven studies presented results for occlusion with DSA as the reference standard and three with CTA as the reference standard. Five studies compared DUS versus DSA for 50% to 99% carotid artery stenosis. Only one study presented results from 50% to 69% carotid artery stenosis. For DUS versus DSA, for < 50% carotid artery stenosis, the summary sensitivity was 0.63 (95% confidence interval [CI] 0.48 to 0.76) and the summary specificity was 0.99 (95% CI 0.96 to 0.99); for the 50% to 69% range, only one study was included and meta-analysis not performed; for the 50% to 99% range, the summary sensitivity was 0.97 (95% CI 0.95 to 0.98) and the summary specificity was 0.70 (95% CI 0.67 to 0.73); for the 70% to 99% range, the summary sensitivity was 0.85 (95% CI 0.77 to 0.91) and the summary specificity was 0.98 (95% CI 0.74 to 0.90); for occlusion, the summary sensitivity was 0.91 (95% CI 0.81 to 0.97) and the summary specificity was 0.95 (95% CI 0.76 to 0.99). For sensitivity analyses, excluding studies in which participants were selected based on the presence of occlusion on DUS had an impact on specificity: 0.98 (95% CI 0.97 to 0.99). For DUS versus CTA, we found two studies in the range of 70% to 99%; the sensitivity varied from 0.57 to 0.94 and the specificity varied from 0.87 to 0.98. For occlusion, the summary sensitivity was 0.95 (95% CI 0.80 to 0.99) and the summary specificity was 0.91 (95% CI 0.09 to 0.99). For DUS versus MRA, there was one study with results for 50% to 99% carotid artery stenosis, with a sensitivity of 0.88 (95% CI 0.70 to 0.98) and specificity of 0.60 (95% CI 0.15 to 0.95); in the 70% to 99% range, two studies were included, with sensitivity that varied from 0.54 to 0.99 and specificity that varied from 0.78 to 0.89. We could perform only a few of the proposed sensitivity analyses because of the small number of studies included.

AUTHORS' CONCLUSIONS

This review provides evidence that the diagnostic accuracy of DUS is high, especially at discriminating between the presence or absence of significant carotid artery stenosis (< 50% or 50% to 99%). This evidence, plus its less invasive nature, supports the early use of DUS for the detection of carotid artery stenosis. The accuracy for 70% to 99% carotid artery stenosis and occlusion is high. Clinicians should exercise caution when using DUS as the single preoperative diagnostic method, and the limitations should be considered. There was little evidence of the accuracy of DUS when compared with CTA or MRA. The results of this review should be interpreted with caution because they are based on studies of low methodological quality, mainly due to the patient selection method. Methodological problems in participant inclusion criteria from the studies discussed above apparently influenced an overestimated estimate of prevalence values. Most of the studies included failed to precisely describe inclusion criteria and previous testing. Future diagnostic accuracy studies should include direct comparisons of the various modalities of diagnostic tests (mainly DUS, CTA, and MRA) for carotid artery stenosis since DSA is no longer considered to be the best method for diagnosing carotid stenosis and less invasive tests are now used as reference standards in clinical practice. Also, for future studies, the participant inclusion criteria require careful attention.

The Value of Contrast-Enhanced Ultrasound in the Evaluation of Carotid Web

Objectives

The purpose of this study was to investigate whether contrast-enhanced ultrasound (CEUS) is more advantageous than conventional ultrasound in the diagnosis of carotid web (CaW) and to compare the clinical characteristics of patients in different age groups.

Methods

Seventeen patients admitted to the hospital from October 2019 to December 2021 were included in our study. Patients were initially diagnosed with CaW using digital subtraction angiography (DSA), and conventional ultrasound and CEUS were completed. Baseline patient data were analyzed and compared between the <60 years old CaW group and the ≥60 years old CaW group to explore the differences between the two groups. Then, comparing the accuracy of conventional ultrasound and CEUS.

Results

A total of 17 CaW patients participated in this study, including 4 female patients (23.5%) and 13 male patients (76.5%), with an average age of 59.41 (±10.86) years. There were 9 patients (52.9%) with left CaW and 8 patients (47.1%) with right CaW. Acute ischemic stroke (AIS) occurred in 14 patients (82.4%). Thrombosis occurred in five of 17 patients (29.4%). There was a significant statistical difference about the thrombosis between the <60 years old CaW group and the ≥60 years old CaW group [<60 years group: 0 (0%), ≥60 years group: 5 (62.5%), P = 0.005]. Seven patients (41.2%) received medical management, nine patients (52.9%) had carotid artery stenting (CAS), and one patient (5.9%) had carotid endarterectomy (CEA). None of the patients had recurrent stroke during the follow-up period. The diagnostic rate of CaW and thrombus by CEUS was higher than that by conventional ultrasound, and there was a significant statistical difference in the diagnosis of thrombus between CEUS and conventional ultrasound (χ2 = 4.286, P = 0.038).

Conclusions

CEUS may have a higher diagnostic accuracy for CaW with thrombosis, and it has a higher clinical application prospect.

Synthetic role of miR-200b-3p, ABCD2 score, and carotid ultrasound in the prediction of cerebral infarction in patients with transient ischemic attack

BACKGROUND

Transient ischemic attack (TIA) is a major risk factor for the occurrence of cerebral infarction (CI). This study aimed to evaluate the predictive value of the synthetic role of miR-200b-3p, ABCD² score, and carotid ultrasound for CI onset in patients with TIA.

METHODS

Expression of miR-200b-3p was detected by reverse transcription quantitative PCR and carotid stenosis degree was evaluated using carotid ultrasound examination. Association of miR-200b-3p with ABCD² scores and carotid stenosis degree was assessed using t-test and chi-square test. Logistic regression analysis was used to judge the ability of miR-200b-3p, ABCD² score, and carotid ultrasound to predict the occurrence of CI. Receiver operating characteristic curve was used to analyze the diagnostic value of miR-200b-3p and the accuracy of miR-200b-3p, ABCD² score, and carotid ultrasound in predicting CI development.

RESULTS

Expression of serum miR-200b-3p was significantly increased in TIA patients compared with healthy controls, and had diagnostic value in TIA patients. Serum miR-200b-3p was significantly associated with dyslipidemia, ABCD² score, and carotid stenosis degree in TIA patients. ABCD² score, carotid stenosis degree, and serum miR-200b-3p were independently associated with CI onset, and the synthetic role of these three indicators had the best accuracy in the prediction of CI onset in TIA patients.

CONCLUSION

Serum miR-200b-3p expression was increased in TIA patients with considerable diagnostic value to screen TIA cases from healthy controls. Moreover, we speculated that the combination of miR-200b-3p, ABCD² score, and carotid stenosis degree by ultrasound may propose as an efficient predictive strategy for the prediction of CI in TIA patients.

A Review of Clinical Applications for Super-resolution Ultrasound Localization Microscopy

Microvascular structure and hemodynamics are important indicators for the diagnosis and assessment of many diseases and pathologies. The structural and functional imaging of tissue microvasculature in vivo is a clinically significant objective for the development of many imaging modalities. Contrast-enhanced ultrasound (CEUS) is a popular clinical tool for characterizing tissue microvasculature, due to the moderate cost, wide accessibility, and absence of ionizing radiation of ultrasound. However, in practice, it remains challenging to demonstrate microvasculature using CEUS, due to the resolution limit of conventional ultrasound imaging. In addition, the quantification of tissue perfusion by CEUS remains hindered by high operator-dependency and poor reproducibility. Inspired by super-resolution optical microscopy, super-resolution ultrasound localization microscopy (ULM) was recently developed. ULM uses the same ultrasound contrast agent (i.e. microbubbles) in CEUS. However, different from CEUS, ULM uses the location of the microbubbles to construct images, instead of using the backscattering intensity of microbubbles. Hence, ULM overcomes the classic compromise between imaging resolution and penetration, allowing for the visualization of capillary-scale microvasculature deep within tissues. To date, many in vivo ULM results have been reported, including both animal (kidney, brain, spinal cord, xenografted tumor, and ear) and human studies (prostate, tibialis anterior muscle, and breast cancer tumors). Furthermore, a variety of useful biomarkers have been derived from using ULM for different preclinical and clinical applications. Due to the high spatial resolution and accurate blood flow speed estimation (approximately 1 mm/s to several cm/s), ULM presents as an enticing alternative to CEUS for characterizing tissue microvasculature in vivo. This review summarizes the principles and present applications of CEUS and ULM, and discusses areas where ULM can potentially provide a better alternative to CEUS in clinical practice and areas where ULM may not be a better alternative. The objective of the study is to provide clinicians with an up-to-date review of ULM technology, and a practical guide for implementing ULM in clinical research and practice.

A Dual-modal Imaging Method Combining Ultrasound and Electromagnetism for Simultaneous Measurement of Tissue Elasticity and Electrical Conductivity

The mechanical and electrical properties of soft tissues are relative to soft tissues' pathological state. Modern medical imaging devices have shown a trend to multi-modal imaging, which will provide complementary functional information to improve the accuracy of disease diagnosis. However, no method or system can simultaneously measure the mechanical and electrical properties of the soft tissue. In this study, we proposed a novel dual-modal imaging method integrated by shear wave elasticity imaging (SWEI) and Magneto-acousto-electrical tomography (MAET) to measure soft tissue's elasticity and conductivity simultaneously. A dual-modal imaging system based on a linear array transducer is built, and the imaging performances of MAET and SWEI were respectively evaluated by phantoms experiment and \textit{in vitro} experiment. Conductivity phantom experiments show that the MAET in this dual-modal system can image conductivity gradient as low as 0.4 S/m. The phantom experiments show that the reconstructed 2-D elasticity maps of the phantoms with inclusions with a diameter larger than 5 mm are relatively accurate. \textit{In vitro} experiments show that the elasticity parameter can significantly distinguish the changes in tissue before and after heating. This study first proposes a method that can simultaneously obtain tissue elasticity and electrical conductivity to the best of our knowledge. Although this paper just carried out the proof of concept experiments of the new method, it demonstrates great potential for disease diagnosis in the future.

Application progress of multiple imaging modalities in Takayasu arteritis

Takayasu arteritis (TA) is a chronic, idiopathic, granulomatous large vessel vasculitis of unknown etiology. The clinical manifestations of TA are incredibly variable, mainly depending on the location of the lesions. In the light of its insidious progress and the diversity of clinical manifestations, a substantial proportion of patients might experience a considerable delay in diagnosis, which leads to irreversible malignant complications, highlighting the importance of early diagnosis. There has been accumulating evidence that early identification of disease is pivotal to initiate timely therapy and ameliorate the prognosis. Therefore, this review discusses and summarizes the latest evidence on the application progress of multiple imaging modalities.

Ultrasound Methods in the Evaluation of Atherosclerosis: From Pathophysiology to Clinic

Atherosclerosis is a key pathological process that causes a plethora of pathologies, including coronary artery disease, peripheral artery disease, and ischemic stroke. The silent progression of the atherosclerotic disease prompts for new surveillance tools that can visualize, characterize, and provide a risk evaluation of the atherosclerotic plaque. Conventional ultrasound methods—bright (B)-mode US plus Doppler mode—provide a rapid, cost-efficient way to visualize an established plaque and give a rapid risk stratification of the patient through the Gray–Weale standardization—echolucent plaques with ≥50% stenosis have a significantly greater risk of ipsilateral stroke. Although rather disputed, the measurement of carotid intima-media thickness (C-IMT) may prove useful in identifying subclinical atherosclerosis. In addition, contrast-enhanced ultrasonography (CEUS) allows for a better image resolution and the visualization and quantification of plaque neovascularization, which has been correlated with future cardiovascular events. Newly emerging elastography techniques such as strain elastography and shear-wave elastography add a new dimension to this evaluation—the biomechanics of the arterial wall, which is altered in atherosclerosis. The invasive counterpart, intravascular ultrasound (IVUS), enables an individualized assessment of the anti-atherosclerotic therapies, as well as a direct risk assessment of these lesions through virtual histology IVUS.

Carotid Intraplaque Neovascularization Predicts Ischemic Stroke Recurrence in Patients with Carotid Atherosclerosis

INTRODUCTION

This study aimed to examine whether intraplaque neovascularization (IPN) of carotid plaques, as characterized by contrast-enhanced ultrasound (CEUS), is associated with ischemic stroke recurrence in patients with carotid atherosclerosis.

METHODS

We conducted a prospective study of consecutive patients with a recent stroke and at least one atherosclerotic plaque in the carotid artery on the side consistent with symptoms. All patients underwent CEUS after their first admission. IPN was graded on the basis of the presence and location of microbubbles within each plaque.

RESULTS

We eventually included 155 patients, all of whom underwent IPN analysis. After a follow-up of 24 months, we recorded 25 (16.1%) stroke recurrences in the whole population. All the recurrences occurred in patients presenting IPN. There was significant difference in the IPN between the 2 groups (p = 0.002). In the final Cox proportional-hazards multivariable models, IPN of grade 2 was independently associated with the risk of stroke recurrence (HR = 4.535; 95% CI: 1.892-10.870; p = 0.001). This association remained after adjusting for the degree of carotid stenosis (HR = 3.491; 95% CI: 1.410-8.646; p = 0.007).

CONCLUSIONS

IPN was an independent predictor of stroke recurrence in patients with a recent ischemic stroke and carotid atherosclerosis. In predicting stroke recurrence, IPN may be an earlier indicator than carotid stenosis and may help stratify the risk of stroke recurrence.

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.

Advances in Multimodality Carotid Plaque Imaging: AJR Expert Panel Narrative Review

Contemporary imaging methods provide detailed visualization of carotid athero-sclerotic plaque, enabling a major evolution of in vivo carotid plaque imaging evaluation. The degree of luminal stenosis in the carotid artery bifurcation, as assessed by ultrasound, has historically served as the primary imaging feature for determining ischemic stroke risk and the potential need for surgery. However, stroke risk may be more strongly driven by the presence of specific characteristics of vulnerable plaque, as visualized on CT and MRI, than by traditional ultrasound-based assessment of luminal narrowing. This review highlights six promising imaging-based plaque characteristics that harbor unique information regarding plaque vulnerability: maximum plaque thickness and volume, calcification, ulceration, intraplaque hemorrhage, lipid-rich necrotic core, and thin or ruptured fibrous cap. Increasing evidence supports the association of these plaque characteristics with risk of ischemic stroke, although these characteristics have varying suitability for clinical implementation. Key aspects of CT and MRI protocols for carotid plaque imaging are also considered. Practical next steps and hurdles are explored for implementing routine imaging assessment of these plaque characteristics in addition to, or even as replacement for, traditional assessment of the degree of vascular stenosis on ultrasound, in the identification of individuals at high risk of ischemic stroke.

Diagnostic Value of Contrast-Enhanced Ultrasound for Differential Diagnosis of Malignant and Benign Soft Tissue Masses: A Meta-Analysis

This meta-analysis was aimed at investigating the value of using contrast-enhanced ultrasound (CEUS) in the differential diagnosis of benign and malignant soft tissue masses (STMs). Relevant studies published before March 24, 2020 were identified through a comprehensive search of PubMed, Ovid, Cochrane and Web of Science. According to the inclusion criteria, five studies were selected comprising 746 patients. In the differential diagnosis of benign and malignant STMs, the pooled sensitivity and specificity of CEUS were 76% (95% confidence interval [CI]: 71%-81%; heterogeneity [I²] = 74.5%) and 67% (95% CI: 62%-71%; I² = 36.5%), respectively. The diagnostic odds ratio was 7.37 (95% CI: 3.78%-14.35; I² = 66.6%). The overall area under the curve was 0.77 (standard error: 0.0392). Subgroup analysis revealed that different index tests of CEUS resulted in different diagnostic performance. Importantly, CEUS is an effective method for the differential diagnosis between benign and malignant STMs.

Contrast-Enhanced Ultrasound: Identification of Neovascularization Permits Characterization of Vulnerable Carotid Plaques

Objective:

Carotid atherosclerotic vascular disease (ASVD) represents an ongoing health problem and is responsible for a significant proportion of all cerebral ischemic events (CIEs).

Method:

A review of the literature was performed on the application of contrast-enhanced ultrasound (CEUS) to enhance the diagnosis of ASVD and further avoid CIEs.

Results:

Cerebral ischemic events are those resulting from reduction or cessation of perfusion to localized regions of the brain made manifest by neurological, typically stroke-like, symptoms. Traditional triplex ultrasound evaluation is a reliable and widely established method of identifying carotid ASVD lesions and grading the accompanying degree of focal stenoses and their hemodynamic impact. While this information plays an integral role in determining management of patients with significant carotid ASVD, it is less useful in classifying individual lesions as “vulnerable” or not. Vulnerable lesions are those that, based on their histological and morphological features, predispose a patient to an increased risk of a CIE due to plaque or thrombus embolization.

Conclusions:

The addition of CEUS to carotid artery diagnostic studies offers new potential in identifying vulnerable plaques and predicting which patients will progress to sequelae associated with a cerebral ischemic event.

Usefulness of Carotid Ultrasonography for Risk Stratification of Cerebral and Cardiovascular Disease

Carotid ultrasonography is useful for the assessments of the risk stratification for stroke or coronary artery disease, because it is a simple, repeatable, and noninvasive procedure. The carotid intima-media thickness (IMT), which is assessed using carotid ultrasonography, is a widely used surrogate marker for the severity of atherosclerosis. Several large clinical studies showed that increased carotid IMT is associated with the future stroke or cardiovascular events. In addition, in many clinical trials, it has been adopted for surrogate markers of clinical endpoints of medical intervention. Moreover, carotid ultrasonography allows the measurement of the presence and characteristics of plaques and the severity of carotid artery stenosis. The unstable morphology of plaque, such as hypoechoic, ulcer, and mobility, is associated with future ischemic stroke events. The screening tool of asymptomatic carotid artery stenosis is also important, although whether routine carotid ultrasonography assessment is recommended in the general population remains controversial. The screening of carotid artery stenosis using ultrasonography is essential for not only daily clinical settings but also management of patients with acute ischemic stroke. The patients with atherothrombotic stroke with severe internal carotid artery stenosis should be considered to surgical intervention, and duplex ultrasound approach is important to estimate for the severity of carotid stenosis. Physicians should keep in mind the usefulness of carotid ultrasonography for risk stratification of cerebral and cardiovascular disease based on various aspects. In addition, visual assessment or dynamic changes using carotid ultrasonography could provide the various and valuable insights in clinical settings.

Carotid plaque imaging profiling in subjects with risk factors (diabetes and hypertension)

Carotid artery stenosis (CAS) due to the presence of atherosclerotic plaque (AP) is a frequent medical condition and a known risk factor for stroke, and it is also known from literature that several risk factors promote the AP development, in particular aging, smoke, male sex, hypertension, hyperlipidemia, smoke, diabetes type 1 and 2, and genetic factors. The study of carotid atherosclerosis is continuously evolving: even if the strategies of treatment still depends mainly on the degree of stenosis (DoS) determined by the plaque, in the last years the attention has moved to the study of the plaque components in order to identify the so called "vulnerable" plaque: features like the fibrous cap status and thickness, the volume of the lipid-rich necrotic core and the presence of intraplaque hemorrhage (IPH) are risk factors for plaque rupture, that can be studied with modern imaging techniques. The aim of this review is to give a general overview of the principle histological and imaging features of the subcomponent of carotid AP (CAP), focalizing in particular on the features of CAP of patients affected by hypertension and diabetes (in particular type 2 diabetes mellitus).

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

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

Characteristics of the carotid plaque in hypertensive patients with hyperhomocysteinemia using multimode ultrasound

BACKGROUND

Ischemic stroke is related to the level of total homocysteine and the stability of carotid atherosclerotic plaque. In this study, the characteristics of carotid plaque in hypertensive patients with hyperhomocysteinemia were preliminarily studied by conventional ultrasound, contrast-enhanced ultrasound and virtual touch image quantification.

METHODS

Hypertensive patients (n=196) hospitalised in the Department of Neurology and Cardiology of our hospital from April 2016 to February 2019 were studied to compare and analyse differences in general clinical data, conventional ultrasound, contrast-enhanced ultrasound and virtual touch image quantification between hypertension with hyperhomocysteinemia and hypertension with normal tHcy.

RESULTS

1. There was no statistical difference in other clinical data, except fasting blood sugar (P=0.021) and the history of cerebral infarction (P=0.0001). 2. There were significant differences in plaque thickness, stenosis degree, contrast-enhanced ultrasound level, The maximum shear wave velocity (SWVmax) , the minimum shear wave velocity (SWVmin) and the mean shear wave velocity (SWVmean) (P<0.05), except intima-media thickness between the two groups (t=0.160, P=0.873). 3. Blood tHcy level in hypertensive patients with hyperhomocysteinemia was positively correlated with carotid plaque thickness, stenosis degree and contrast-enhanced ultrasound level (r=0.349, 0.647, 0.421), but negatively correlated with SWVmax, SWVmin and SWVmean (r=-0.348, -0.409, -0.393).

CONCLUSIONS

Ultrasonography can reflect the vulnerability of hypertensive patients with hyperhomocysteinemia, providing reliable and comprehensive information for the prevention and treatment of stroke in hypertensive patients with hyperhomocysteinemia.

Improved Detection of Molecular Markers of Atherosclerotic Plaques Using Sub-Millimeter PET Imaging

Since atherosclerotic plaques are small and sparse, their non-invasive detection via PET imaging requires both highly specific radiotracers as well as imaging systems with high sensitivity and resolution. This study aimed to assess the targeting and biodistribution of a novel fluorine-18 anti-VCAM-1 Nanobody (Nb), and to investigate whether sub-millimetre resolution PET imaging could improve detectability of plaques in mice. The anti-VCAM-1 Nb functionalised with the novel restrained complexing agent (RESCA) chelator was labelled with [¹⁸F]AlF with a high radiochemical yield (>75%) and radiochemical purity (>99%). Subsequently, [¹⁸F]AlF(RESCA)-cAbVCAM1-5 was injected in ApoE^-/- mice, or co-injected with excess of unlabelled Nb (control group). Mice were imaged sequentially using a cross-over design on two different commercially available PET/CT systems and finally sacrificed for ex vivo analysis. Both the PET/CT images and ex vivo data showed specific uptake of [¹⁸F]AlF(RESCA)-cAbVCAM1-5 in atherosclerotic lesions. Non-specific bone uptake was also noticeable, most probably due to in vivo defluorination. Image analysis yielded higher target-to-heart and target-to-brain ratios with the β-CUBE (MOLECUBES) PET scanner, demonstrating that preclinical detection of atherosclerotic lesions could be improved using the latest PET technology.

Plaque neovascularization detected with contrast-enhanced ultrasound predicts ischaemic stroke recurrence in patients with carotid atherosclerosis

BACKGROUND AND PURPOSE

Plaque neovascularization is a hallmark of carotid plaque vulnerability. With contrast-enhanced ultrasound (CEUS) it is possible to visualize plaque neovessels in vivo. Our aim was to determine if CEUS-detected neovessels were associated with stroke recurrences in patients with a recent stroke and carotid atherosclerosis.

METHODS

We conducted a prospective study of consecutive patients with a recent stroke and at least one atherosclerotic plaque in the internal carotid artery on the side consistent with symptoms. All of our patients underwent a carotid ultrasound examination including a CEUS study. Neovascularization was graded into three categories according to the extent of neovessels. During the follow-up, we recorded stroke recurrences. A multivariable Cox regression analysis was performed to evaluate predictors of recurrence.

RESULTS

We included 78 patients whose mean age was 74.3 ± 10.4 years. There were 29 (37.2%) patients with a low-grade stenosis (<50%). The remainder presented moderate (50%-69%) or high-grade (≥70%) stenosis. CEUS was not interpretable in 35.9% of the patients, mainly due to calcium shadows. We detected neovascularization in 80% of the plaques. After a median follow-up of 14.1 (interquartile range, 9.5-19.6) months, there were 15 (19.2%) stroke recurrences. In the Cox regression analysis, CEUS-detected neovascularization was independently associated with the risk of stroke recurrence, even after adjusting for the degree of stenosis (hazard ratio, 6.57; 95% confidence interval, 1.66-26.01).

CONCLUSION

In patients with an anterior circulation ischaemic stroke and carotid atherosclerosis, plaque neovascularization detected with CEUS was an independent predictor of stroke recurrence.

Choosing the right therapy for a patient with asymptomatic carotid stenosis

Introduction: Most patients with asymptomatic carotid stenosis (ACS) now have a lower risk with intensive medical therapy than with stenting (CAS) or endarterectomy (CEA); the annual risk of stroke or death with intensive medical therapy is ~ 0.5%, vs. a periprocedural risk with CAS of ~ 2.5-4.1% with CAS, and ~ 1.4-1.8% with CEA. The excess risk of CAS is greater in older patients.Areas covered: Discussed are the need for intensive medical therapy, the nature of intensive medical therapy, approaches to identifying the few patients with ACS who could benefit from CEA or CAS, and which patients would be better suited to CEA vs. CAS.Expert opinion: All patients with ACS are at high risk of cardiovascular events, soshould receive intensive medical therapy including lifestyle modification, intensive lipid-lowering, B vitamins to lower homocysteine (using methylcobalamin rather than cyanocobalamin), and appropriate antithrombotic therapy. High-risk patients who could benefit from intervention can be identified by clinical and imaging features including transcranial Doppler embolus detection, ulceration, intraplaque hemorrhage, reduced cerebrovascular reserve, plaque echolucency, silent infarction on brain imaging, and progression of stenosis. Most patients whose risk of stroke warrants intervention would be better treated with CEA than with CAS.

Ultrasonography for the diagnosis of extra-cranial carotid occlusion - diagnostic test accuracy meta-analysis

Background: The correct diagnosis of internal carotid artery (ICA) occlusion is crucial as it limits unnecessary intervention, whereas correct identification of patients with severe ICA stenosis is paramount in decision making and selecting patients who would benefit from intervention. We aimed to evaluate the accuracy of ultrasonography (US) in the diagnosis of ICA occlusion. Methods: We conducted a systematic review in compliance with the Preferred Reporting Items for a Systematic Review and Meta-analysis (PRISMA) of diagnostic test accuracy studies. We interrogated electronic bibliographic sources using a combination of free text and thesaurus terms to identify studies assessing the diagnostic accuracy of US in ICA occlusion. We used a mixed-effects logistic regression bivariate model to estimate summary sensitivity and specificity. We developed hierarchical summary receiver operating characteristic (HSROC) curves. Results: We identified 23 studies reporting a total of 5,675 arteries of which 722 were proven to be occluded by the reference standard. The reference standard was digital subtraction or cerebral angiography in all but two studies, which used surgery to ascertain a carotid occlusion. The pooled estimates for sensitivity and specificity were 0.97 (95% confidence interval (CI) 0.94 to 0.99) and 0.99 (95% CI 0.98 to 1.00), respectively. The diagnostic odds ratio was 3,846.15 (95% CI 1,375.74 to 10,752.65). The positive and negative likelihood ratio were 114.71 (95% CI 58.84 to 223.63) and 0.03 (95% CI 0.01 to 0.06), respectively. Conclusions: US is a reliable and accurate method in diagnosing ICA occlusion. US can be used as a screening tool with cross-sectional imaging being reserved for ambiguous cases.

Does Quantification of Carotid Plaque Surface Irregularities Better Detect Symptomatic Plaques Compared to the Subjective Classification?

OBJECTIVES

To evaluate the interobserver agreement of color Doppler ultrasound (CDUS) and contrast-enhanced ultrasound (CEUS) for quantification of carotid plaque surface irregularities and to correlate objective and subjective measures with stroke occurrence.

METHODS

This work was an observational study involving 54 patients with 62 internal carotid artery or carotid bulb plaques (31 symptomatic) undergoing CDUS and CEUS between February 2016 and February 2018, with retrospective interpretation of prospectively acquired data. Plaques were included if causing moderate (50%-69%) or severe (70%-99%) stenosis based on velocity criteria, and their surface was classified as smooth, irregular, or ulcerated based on CEUS. The surface irregularities were quantified in the form of a surface irregularity index by 2 observers, based on CDUS and CEUS. The surface irregularity index was evaluated for interobserver agreement with CDUS and CEUS and correlated with the occurrence of stroke, as was the subjective characterization of the plaque surface.

RESULTS

Color Doppler ultrasound and CEUS showed good interobserver agreement (intraclass correlation coefficients, 0.979 and 0.952, respectively). Plaques were characterized as smooth in 30.6% of cases, irregular in 50%, and ulcerated in 19.4%. The subjective classification of the plaque surface did not correlate with stroke occurrence (P > .05, χ² ). Surface irregularity index values were significantly higher for symptomatic plaques with both CDUS and CEUS (P < .05).

CONCLUSIONS

Color Doppler ultrasound and CEUS can quantify carotid plaque surface irregularities with good interobserver agreement. The resulting quantitative measure was significantly higher in symptomatic plaques, whereas the subjective characterization of plaque surface failed to differ between symptomatic and asymptomatic plaques.

General principles and overview of vascular contrast-enhanced ultrasonography

Ultrasonography (US) is the first-line modality for the evaluation of vascular pathology. Although well-established for many diseases, US has inherent limitations that can occasionally hinder an accurate diagnosis. The value of US was improved by the introduction of microbubbles as ultrasonographic contrast agents (UCAs) and the emergence of contrast-enhanced ultrasonography (CEUS), following the introduction of second-generation UCAs and the emergence of modern contrast-specific techniques. CEUS offers valuable information about vascular disease, both on a macrovascular and a microvascular level, with well-established applications for carotid disease, post-interventional follow-up of abdominal aortic aneurysms, and the assessment of portal vein thrombosis. The purpose of this review is to discuss the principles of CEUS and to present an overview of its vascular applications.

An Ultrasonographic Multiparametric Carotid Plaque Risk Index Associated with Cerebrovascular Symptomatology: A Study Comparing Color Doppler Imaging and Contrast-Enhanced Ultrasonography

BACKGROUND AND PURPOSE

Various ultrasonographic features of carortid plaques have been associated with the occurence of stroke, highlighting the need for multi-parametric assessment of plaque's vulnerability. Our aim was to compare ultrasonographic multiparametric indices using color Doppler imaging and contrast-enhanced sonography between symptomatic and asymptomatic carotid plaques.

MATERIALS AND METHODS

This was a cross-sectional observational study recruiting 54 patients (72.2% male; median age, 61 years) undergoing sonography and contrast-enhanced sonography. Patients were included if a moderately or severely stenotic internal carotid artery plaque was detected, with the plaque being considered symptomatic if it was ipsilateral to a stroke occuring within the last 6 months. A vulnerability index, previously described by Kanber et al, combined the degree of stenosis, gray-scale median, and a quantitative measure of surface irregularities (surface irregularity index) derived from color Doppler imaging and contrast-enhanced ultrasonography, resulting in 2 vulnerability indices, depending on the surface irregularity index used. Mann-Whitney U and t tests were used to compare variables between groups, and receiver operating characteristic curves were used to compare diagnostic accuracy.

RESULTS

Sixty-two plaques were analyzed (50% symptomatic), with a mean degree of stenosis of 68.9%. Symptomatic plaques had a significantly higher degree of stenosis (mean, 74.7% versus 63.1%; P < .001), a lower gray-scale median (13 versus 38; P = .001), and a higher Kanber vulnerability index based both on color Doppler imaging (median, 61.4 versus 16.5; P < .001) and contrast-enhanced ultrasonography (median, 88.6 versus 25.2; P < .001). The area under the curve for the detection of symptomatic plaques was 0.772 for the degree of stenosis alone, 0.783 for the vulnerability index-color Doppler imaging, and 0.802 for the vulnerability index-contrast-enhanced ultrasonography, though no statistical significance was achieved.

CONCLUSIONS

Symptomatic plaques had a higher degree of stenosis, lower gray-scale median values, and higher values of the Kanber vulnerability index using both color Doppler imaging and contrast-enhanced ultrasonography for plaque surface delineation.

Contrast-enhanced Ultrasonography for Monitoring Arterial Inflammation in Takayasu Arteritis

OBJECTIVE

To evaluate the utility of contrast-enhanced ultrasound (CEUS) compared with 18F-fluorodeoxyglucose-positron emission tomography (FDG-PET) in assessing vessel inflammation of Takayasu arteritis (TA).

METHODS

This is a retrospective analysis of 71 patients with TA who had undergone carotid CEUS. Twenty-two of 71 patients underwent FDG-PET after CEUS. Clinical disease activity was assessed by Kerr criteria and the Indian Takayasu Clinical Activity Score 2010 (ITAS2010). We investigated the correlation between carotid vascularization on CEUS and clinical data. The consistency of carotid CEUS and PET data has been analyzed for TA disease activity.

RESULTS

There was a statistically significant correlation between the results of CEUS and ITAS2010 (p = 0.004) or Kerr criteria (p < 0.001). According to ITAS2010, thirty-four of 71 patients with TA were clinically inactive. Assessment of 34 TA patients with clinically inactive disease yielded 11 CEUS scans that showed active lesions (visual grade ≥ 2) in the left or right carotid artery. In 22 cases that underwent CEUS and FDG-PET, 12 were active and 10 were inactive on the basis of ITAS2010. Moreover, bilateral carotid CEUS vascularization score positively correlated with vascular FDG uptake in these patients with TA (p = 0.004). When vascular inflammation was defined as FDG uptake with visual grade ≥ 2, carotid CEUS showed sensitivity of 100% and specificity of 80%.

CONCLUSION

For TA patients with clinically inactive disease, CEUS could help clinicians to identify active lesions in the carotid vascular region. Carotid CEUS may be a rapid and cost-effective imaging tool in the followup of patients with TA.

Multiparametric ultrasound evaluation with CEUS and shear wave elastography for carotid plaque risk stratification

PURPOSE

To assess the diagnostic effectiveness of Multiparametric ultrasound (MPUS), which includes color Doppler ultrasound (CDUS), CEUS and Shear wave elastography (SWE), for evaluating carotid plaque as compared with CT-angiography (CTA) and histology.

MATERIALS AND METHODS

Forty-three consecutive patients scheduled to undergo carotid endarterectomy underwent MPUS. Then, after periods ranging from 2 days to 2 weeks, all underwent CTA. Each plaque was classified by means of dedicated scores for CEUS and SWE as compared with CTA features. At surgery, each plaque was removed in a single fragment to facilitate histological analysis, which evaluated 4 features: extension of the lipid core, thickness of the fibrous cap, inflammatory infiltrate (CD68 + and CD3 + markers) and the presence of intraplaque microvessels. For the CEUS, SWE and CTA, the following values for identifying plaque vulnerability were evaluated: sensitivity, specificity, accuracy, negative predictive value (NPV), positive predictive value (PPV) and Area under the curve (AUC). Cohen's kappa was used to evaluate the concordance between measurements in the different imaging methods. A p < 0.05 was considered statistically significant.

RESULTS

At histology, 31 out of 43 plaques were identified as vulnerable because of the presence of at least one of the following criteria: fibrous cap < 200 μm, lipid core, intraplaque hemorrhage, inflammatory infiltrate or intraplaque neovascularization. CTA showed a sensitivity of 87.1%, a specificity of 100%, a PPV of 100%, an NPV of 75% and an AUC of 93.5%. SWE showed a sensitivity of 87.1%, a specificity of 66.7%, a PPV of 87.1%, an NPV of 66.7% and an AUC of 76.9%. CEUS showed a sensitivity of 87.1%, a specificity of 58.3%, a PPV of 84.4%, an NPV of 63.6% and an AUC of 72.7%.

CONCLUSIONS

Multiparametric ultrasound is an effective modality to obtain comprehensive information on carotid plaques. Further studies are needed to determine whether it can be considered a diagnostic standard.

Atherosclerotic plaque instability in carotid arteries: miR-200c as a promising biomarker

Early recognition of vulnerable carotid plaques could help in identifying patients at high stroke risk, who may benefit from earlier revascularisation. Nowadays, different biomarkers of plaque instability have been unravelled, among these miRNAs are promising tools for the diagnosis and treatment of atherosclerosis. Inflammation, reactive oxygen species (ROS) and endothelial dysfunction play a key role in unstable plaques genesis. We showed that miR-200c induces endothelial dysfunction, ROS production and a positive mechanism among miR-200c and miR-33a/b, two miRNAs involved in atherosclerosis progression. The goal of the present study was to determine whether miR-200c could be an atherosclerosis biomarker. Carotid plaques of patients that underwent carotid endarterectomy (CEA) were assayed for miR-200c expression. miR-200c was up-regulated in carotid plaques (n=22) and its expression was higher in unstable (n=12) compared with stable (n=10) plaques. miR-200c positively correlated with instability biomarkers (i.e. monocyte chemoattractant protein-1, cicloxigenase-2 (COX2), interleukin 6 (IL6), metalloproteinase (MMP) 1 (MMP1), 9 (MMP9)) and miR-33a/b. Moreover, miR-200c negatively correlated with stability biomarkers (i.e. zinc finger E-box binding homoeobox 1 (ZEB1), endothelial nitric oxide (NO) synthase (eNOS), forkhead boxO1 (FOXO1) and Sirtuin1 (SIRT1)) (stable plaques = 15, unstable plaques = 15). Circulating miR-200c was up-regulated before CEA in 24 patients, correlated with miR-33a/b and decreased 1 day after CEA. Interestingly, 1 month after CEA, circulating miR-200c is low in patients with stable plaques (n=11) and increased to control levels, in patients with unstable plaques (n=13). Further studies are needed to establish whether miR-200c represents a circulating biomarker of plaque instability. Our results show that miR-200c is an atherosclerotic plaque progression biomarker and suggest that it may be clinically useful to identify patients at high embolic risk.

A comparative study of color Doppler imaging and contrast-enhanced ultrasound for the detection of ulceration in patients with carotid atherosclerotic disease

OBJECTIVES

To evaluate the diagnostic accuracy of color Doppler imaging (CDI) and contrast-enhanced ultrasound (CEUS) for diagnosing carotid ulceration, having multi-detector computed tomography angiography (MDCTA) as the reference method.

METHODS

Patients with carotid disease referred for ultrasound (US), either due to the occurrence of neurovascular symptoms or for screening purposes, were included in this study if at least one plaque causing moderate (50-69%) or severe (70-99%) internal carotid artery stenosis was detected. Carotid US with CDI technique, CEUS, and MDCTA were performed in all patients, investigating the presence of ulceration. The agreement between modalities was evaluated using kappa statistics.

RESULTS

The study population included 54 patients (median age 62 years, inter-quartile range 16.2) and 66 carotid arteries. The mean degree of stenosis was 68.5% (SD 12.2%) while 47.1% of plaques were symptomatic. MDCTA characterized 28.8% of plaques as smooth, 45.5% irregular, and 24.3% ulcerated. Flow reversal was detected with CDI in 65.5% of ulcerations, while swirling of the microbubbles and neovessels adjacent to the ulcer were detected with CEUS in 17.64%. The agreement for ulceration diagnosis was moderate between CDI and CEUS (kappa 0.473) and between CDI and MDCTA (kappa 0.473) and very good between CEUS and MDCTA (kappa 0.921). The sensitivity, specificity, and positive and negative predictive values of CDI for the diagnosis of ulceration were 41.2%, 97.95%, 87.5%, 82.8% respectively, while CEUS respective measures were 94.1%, 97.95%, 94.1%, and 97.95%.

CONCLUSION

CEUS outperformed CDI in terms of agreement with MDCTA and diagnostic accuracy for the diagnosis of ulcerated carotid plaque.

KEY POINTS

• Superficial ulceration is a significant feature of carotid plaque vulnerability. • Color Doppler imaging has the potential to demonstrate carotid plaque ulceration but is characterized by limited sensitivity and moderate agreement with the reference method of multi-detector computed tomography angiography. • Contrast-enhanced ultrasound outperforms color Doppler imaging in terms of sensitivity for the detection of carotid plaque ulceration and in agreement with the reference method of multi-detector computed tomography angiography.

Evolving clinical applications of contrast-enhanced ultrasound (CEUS) in the abdominal aorta

Ultrasound (US) represents the initial modality in the workup of abdominal aortic pathology based on the plethora of advantages including widespread availability, low cost, safety profile and repeatability. However, US has inherent limitations including limited spatial information of pathologic processes to neighboring structures, lower sensitivity to slow blood flow and aortic luminal irregularities. For evaluation of aortic pathology angiography has long been considered the gold standard. Non-invasive cross-sectional imaging techniques like computed tomography angiography (CTA) and magnetic resonance angiography (MRA) have gradually replaced interventional angiography for the evaluation of aorta, currently being regarded as the diagnostic imaging modalities of choice for diagnosis of virtually every aortic disease. Interventional angiography is currently primarily performed for treatment purposes of aortic pathology. The introduction of microbubbles as ultrasonographic contrast agents has rendered contrast-enhanced ultrasound (CEUS) an evolving valuable complementary technique with markedly increased diagnostic accuracy for certain aortic applications. CEUS is characterized by the potential to be performed in patients with impaired renal function. Due to its superior spatial and temporal resolution, ability for prolonged scanning and dynamic and real-time imaging, it provides clinically significant additional information compared to the standard Duplex US. The purpose of this paper is to discuss the currently available literature regarding abdominal aortic applications of CEUS, briefly elaborate on CEUS technique and safety and present cases in order to illustrate the added value in aortic pathologies. Conditions discussed include abdominal aortic aneurysm (AAA), aneurysm rupture, aneurysm surveillance after endovascular repair, dissection and aortitis.

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

Introduction

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

Discussion

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

Conclusion

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

Transcranial Doppler ultrasound in neurocritical care

Multimodality monitoring is a common practice in caring for neurocritically ill patients, and consists mainly in clinical assessment, intracranial pressure monitoring and using several imaging methods. Of these imaging methods, transcranial Doppler (TCD) is an interesting tool that provides a non-invasive, portable and radiation-free way to assess cerebral circulation and diagnose and follow-up (duplex method) intracranial mass-occupying lesions, such as hematomas and midline shift. This article reviews the basics of TCD applied to neurocritical care patients, offering a rationale for its use as well as tips for practitioners.

Carotid Doppler ultrasonography as a screening tool of early atherosclerotic changes in children and young adults with β-thalassemia major

PURPOSE

β-thalassemia major (β-TM) patients had an increased incidence of cardiovascular complications secondary to iron overload. They showed early carotid atherosclerosis as showed by increased carotid intima media thickness (CIMT) that may occur early even when significant iron overload is absent. We aimed to test the diagnostic performance of CIMT measurement by Doppler ultrasonography as a structural indicator for premature atherosclerosis in β-TM patients.

METHODS

Case-control study included 42 β-TM patients (24 males and 18 females) aged from 3 to 30 years and 36 age- and sex-matched healthy controls. Carotid Duplex was used for measurement of CIMT in all subjects.

RESULTS

The frequency of abnormal CIMT among patients was 19%. Mean CIMT of right anterior wall was 0.8 ± 0.16 (range 0.5-1.2) mm, of right posterior wall was 0.80 ± 0.17 (range 0.5-1.2), of right lateral wall was 0.8 ± 0.17 (range 0.5-1.1) mm. CIMT of left anterior wall ranged from 0.5 to 1.2 with mean 0.81 ± 0.17, CIMT of left posterior wall ranged from 0.5 to 1.1 with mean 0.80 ± 0.17 mm. Mean CIMT of left lateral wall was 0.81 ± 0.18 mm (range 0.5-1.2). CIMT of right anterior, right posterior and left anterior walls were thicker in patients compared to controls (P = 0.003, 0.015, < 0.001, respectively). There was no observable difference in CIMT between males and females, splenectomised and non-splenectomised, or well and poorly chelated subgroups (P > 0.05). CIMT of right lateral wall correlated with the disease duration (r = 0.3, P = 0.04).

CONCLUSIONS

Carotid ultrasound was a useful tool to detect subclinical atherosclerosis thorough CIMT evaluation in B-thalassemia major patients. B-thalassemia major children proved to have an increased CIMT regardless the state of iron overload.

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

Abstract

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

Teaching Points

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

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

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

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

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