Assessment of Carotid Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk

Publication Date: July 1, 2020
Last Updated: March 14, 2022

Recommendations

DEFINITION OF PLAQUE

We recommend that carotid arterial plaque visualized by ultrasound (with or without use of an ultrasound enhancing agent [UEA]) be defined in one of the following 2 ways:
1) any focal thickening thought to be atherosclerotic in origin and encroaching into the lumen of any segment of the carotid artery (protuberant-type plaque) or
2) in the case of diffuse vessel wall atherosclerosis, when carotid intima-media thickness (CIMT) measures ≥1.5 mm in any segment of the carotid artery (diffuse-type plaque).
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We recommend the evaluation of both protuberant and diffuse types of carotid arterial plaque for cardiovascular risk stratification and the serial assessment of atherosclerosis.
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We recommend that first, the carotid arterial wall be visually scanned for the presence of protuberant plaque, and if absent, then carotid intima-media thickness (CIMT) measurement be performed to identify the presence of diffuse plaque (defined as CIMT ≥1.5 mm). If performed, CIMT should be measured as described in the ASE Consensus Statement on the Use of Carotid Ultrasound to Identify Subclinical Vascular Disease and Evaluate Cardiovascular Risk.
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CLINICALLY SIGNIFICANT CAROTID ARTERIAL PLAQUE OR CIMT

We recommend against serial carotid intimamedia thickness (CIMT) measurements in an asymptomatic patient. Repeat measurements are not recommended unless the Grade and (CIMT) meets criteria for diffuse-type plaque (Grades II or III, and CIMT ≥1.5 mm) in which case it is a plaque equivalent.
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QUANTIFICATION METHODS

We recommend that plaque thickness (also known as height) be measured as the initial 2-dimensional approach* for quantification of carotid ultrasound plaque.
* Though plaque height is often measured from 2D images, it can be obtained from a 3D image acquisition when available, to overcome the out-ofplane limitations of 2D imaging.
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The maximal plaque height should be measured from the side in which a plaque is detected (unilateral) or from both the right and left carotid arterial segments (bilateral) using a caliper placed at the adventitial plane,** and extending into the center of the lumen at right angles to the vessel wall. For the purposes of standardization, this measurement should be taken from any segment of the long and short axis of the carotid artery (bulb, ICA, CCA) and the view and segment reported accordingly.
** This measurement begins at the same plane as where the carotid intima-media thickness (CIMT) measurement begins in order to be consistent with defining plaque beyond the CIMT threshold of >1.5 mm.
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We recommend the quantification of plaque volume for an individual plaque lesion when required (e.g., morphologic assessment, serial assessment, or pre-operative consideration), using either the stacked-contour method or specialized semi-automated tools.
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We recommend the quantification of right and/or left carotid arterial plaque volume using 3-dimensional ultrasound for cardiovascular risk stratification.
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We recommend the single-plaque or singleregion protocol where the 3-dimensional volume acquisition is centered over the identified plaque or the right and left carotid arterial bulb, allowing for quantification of total plaque volume in the distal common carotid artery (CCA), bulb, and bifurcation, as well as in the portion of the internal carotid artery (ICA) that can be visualized.
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We recommend the consideration of a fullvessel protocol provided the following criteria are met: time, expertise, equipment, and analytic software are available for accurate registration of multiple 3-dimensional volume acquisitions. In this latter protocol, total carotid arterial plaque is calculated by summing the volume of plaque seen in all major segments of the right and left carotid arteries
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Recommendation Grading

Overview

Title

Assessment of Carotid Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk

Authoring Organization

Publication Month/Year

July 1, 2020

Last Updated Month/Year

February 6, 2024

Supplemental Implementation Tools

Document Type

Guideline

External Publication Status

Published

Country of Publication

US

Inclusion Criteria

Female, Male, Adult, Older adult

Health Care Settings

Ambulatory

Intended Users

Physician, nurse, nurse practitioner, physician assistant

Scope

Management

Diseases/Conditions (MeSH)

D050197 - Atherosclerosis, D058226 - Plaque, Atherosclerotic

Keywords

atherosclerosis, risk stratification, Cardiovascular Risk, Carotid Arterial Plaque