WFUMB Ultrasound Open (Dec 2023)
The updated roles of new ultrasound imaging techniques in assessing carotid vulnerable plaques
Abstract
Carotid atherosclerosis, a subtype of large artery atherosclerosis, is a significant contributor to ischemic stroke events. Considering the pivotal role of ultrasound in assessing carotid artery pathology, this review emphasizes its application in visualizing carotid atherosclerosis, with a particular interest in distinguishing stable from vulnerable carotid plaques. Recent advancements have improved our understanding of the relationship between plaque stability and ischemic stroke. This has motivated a comparative analysis of cutting-edge ultrasound techniques to evaluate extracranial carotid plaque, particularly focusing on areas of intraplaque vulnerability. The B-Mode remains the standard first-line imaging modality for both detecting carotid plaques and their morphology. However, its diagnostic potential is typically realized during the intermediate to advanced stages of atherosclerosis. In contrast, the latest innovations in ultrasound imaging techniques, such as contrast-enhanced ultrasound (CEUS), shear wave elastography (SWE), grayscale median (GSM), and the refined Doppler method (superb microvascular imaging, SMI), offer a detailed quantitative approach to categorize carotid plaques into “stable” or “vulnerable” categories. Their application, however, is not widespread in outpatient settings due to factors such as exorbitant costs, extended imaging duration, and a prevalent lack of technical knowledge among healthcare providers. Beyond conventional echogenicity markers, both CEUS and SMI imaging possess the capability to evaluate intraplaque neovascularization, illuminating deep and microvessels within hypoechoic plaques. This aids in identifying high-risk plaque attributes, such as morphological irregularities and ulcerations, which are paramount for risk stratification and monitoring therapeutic responses. SWE offers insights into tissue rigidity and carotid plaque constituents, such as the fibrous cap and lipid core by gauging shear wave velocity and quantifying shear deformation with a specificity of 66.7 % which is higher than that of CEUS (58.3 %). Therefore, a multiparametric ultrasound approach offers a viable strategy for a holistic evaluation of carotid plaques. The timely identification of susceptible plaques can tailor therapeutic interventions, potentially averting cerebrovascular incidents, including acute ischemic strokes (AIS) and transient ischemic attacks (TIA).
