In some specific indications, contrast enhancement can be obtained through the use of ultrasound contrast agents, which mainly consist of encapsulated air bubbles. Power Doppler color-codes the strength of the Doppler signals and is particularly well-adapted for the examination of small vessels and low-velocity flows due to its increased sensitivity. Color-DUS adds color-coded flow patterns that indicate flow direction and velocity in real time. However, several technological improvements have been made available to vascular practitioners. According to these guidelines, DUS, which allows the flow velocity to be measured by combining pulsed-wave Doppler and ultrasonography (US), remains the gold standard for the first-line diagnosis and quantification of CAS. The degree of stenosis should be confirmed by computed tomography (CT) or magnetic resonance (MR) angiography, especially when a surgical intervention is foreseen. The take-home message of these guidelines is that stenosis should be considered hemodynamically significant when the ICA PSV >125 cm/s and CR >2.0. This quantification relies on Duplex ultrasonography (DUS) determination of the peak systolic velocity (PSV) of both the ICA and common carotid artery (CCA), from which the ICA-to-CCA ratio of the PSV, namely the carotid ratio (CR), can be calculated. In recent guidelines, the European Society of Cardiology (ESC) recommended quantifying the percentage of ICA stenosis by a combination of the observations made in two major studies: the European Carotid Surgery Trial and the North American Symptomatic Carotid Endarterectomy Trial. ), even if asymptomatic, is an indication for surgical intervention either by endarterectomy or stenting. Therefore, severe ICA stenosis (>70% of the artery lumen as determined following the recommendations of Sprynger et al. Although most cases of moderate CAS remain asymptomatic and require only regular follow-up and preventive medication, severe stenosis of the internal carotid artery (ICA) can have dramatic consequences, ranging from ischemic stroke or transient ischemic attack to fatal stroke. With the global aging of the population and the subsequent increase in the number of cardiovascular events, the frequency of carotid artery stenosis (CAS) is steadily rising, with an estimated overall prevalence ranging from 1.7% to 12.5% depending on sex, age, and CAS severity.
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