Background and purpose: A significant proportion of ischemic strokes are caused by emboli from unstable carotid artery plaques with intraplaque neovascularization (IPN) as a key feature of plaque instability. IPN is not detectable with conventional Doppler ultrasound.Contrast-enhanced ultrasound (CEUS) can visualize IPN, but it`s use is limited in clinical practice because it requires an intravenous injection of contrast. Superb microvascular imaging (SMI) without contrast uses an algorithm to remove clutter and motion wall artefacts whilst preserving low velocity blood flow signals, enabling visualization of IPN. Our aim was to assess the feasibility of SMI for the detection of IPN.Methods: Thirty-one patients with >50% carotid stenosis were included; twenty-two patients were symptomatic and 9 asymptomatic. All patients underwent conventional carotid ultrasound, CEUS, SMI and blood tests. CEUS and SMI findings were compared and correlated to histological plaque assessments after endarterectomy.Results: There was significant positive correlation between a IPN visual 5-level classification of SMI and a semi-quantitative analysis of CEUS, (p<0.001, r=0.911). Plaques with higher SMI grades had higher numbers of neo-vessels quantified at histology, (p=0.041, r=0.460).Hypoechoic plaques had higher grades of IPN on both CEUS and SMI, (p<0.001). Higher visual IPN counts on SMI were associated with (i) Increased areas of inflammation (p=0.043, r=0,457), (ii) Combined rank scores of granulation tissue, inflammation and lipids (p=0.02, r=0.494) at histology, and (iii) Higher peak-intensity values on quantitative CEUS (p=0.042, r=0.514).
Cardiovascular disease is estimated to be the leading cause of death, globally causing 14 million deaths each year. Stroke remains a massive public health problem and there is an increasing need for better strategies for the prevention and treatment of this disease. At least 20% of ischemic strokes are thromboembolic in nature, caused by a thromboembolism from an atherosclerotic plaque at the carotid bifurcation or the internal carotid artery. Current clinical guidelines for both primary and secondary prevention of stroke in patients with carotid stenosis caused by atherosclerotic plaques remain reliant on general patient characteristics (traditional risk factors for stroke) and static measures of the degree of artery stenosis. Patients with similar traditional risk factors, however, have been found to have different risk of stroke, and it has in recent years become increasingly clear that the degree of artery stenosis alone is not the best estimation of stroke risk. There is a need for new methods for the assessment of stroke risk to improve risk prediction for the individual patient. This review aims to give an overview of new methods available for the identification of carotid plaque instability and the assessment of stroke risk.
Background: A significant proportion of ischemic strokes are caused by emboli from atherosclerotic, unstable carotid artery plaques. The selection of patients for endarterectomy in current clinical practice is primarily based on the degree of carotid artery stenosis and clinical symptoms. However, the content of the plaque is known to be more important for stroke risk. Intraplaque neovascularization (IPN) has recently emerged as a possible surrogate marker for plaque instability. Neo-microvessels from the adventitial vasa vasorum grow into the full thickness of the vessel wall in an adaptive response to hypoxia, causing subsequent intraplaque haemorrhage and plaque rupture. Conventional ultrasound cannot detect IPN. Contrast-enhanced ultrasound and Superb Microvascular Imaging (SMI), have, however, shown promise in IPN assessment. Recent research using Shear Wave Elastography (SWE) has also reported reduced tissue stiffness in the artery wall (reduced mean Young's modulus) in unstable compared to stable plaques. The purpose of this study is to identify unstable carotid artery plaques at risk of rupture and future ischemic stroke risk using multimodal assessments. Methods: Forty five symptomatic and 45 asymptomatic patients > 18 years, with > 50% carotid stenosis referred to Oslo University Hospital ultrasound lab will be included in this ongoing project. Patients will undergo contrast enhanced ultrasound, SMI, carotid-MRI and PET-(18 F-FDG). Contrast enhanced ultrasound will be analyzed semiquantitatively (5-levels visual classification) and quantitatively by plotting time-intensity curve analyses to obtain plaque peak contrast enhancement intensity. Plaques removed at carotid endarterectomy will be assessed histologically and the number of microvessels, areas of inflammation, granulation, calcification, lipid and fibrosis will be measured. Discussion: This multimodality study will primarily provide information on the clinical value of advanced ultrasound methods (SMI, SWE) for the detection of unstable carotid artery plaque in comparison with other methods including contrast-enhanced ultrasound, carotid-MRI and PET-(18 F-FDG) using histology as the gold standard. Secondly, findings from the methods mentioned above will be related to cerebrovascular symptoms, blood tests (leukocytes, CRP, ESR, lipoproteins and inflammatory markers) and cardiovascular risk factors at inclusion and at 1year follow-up. The overall aim is to optimize detection of plaque instability which can lead to better preventive decisions and reduced stroke rate.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.