Linking To And Excerpting From The American Society Of Echocardiography’s “Recommendations for the Assessment of Carotid Arterial Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk: From the American Society of Echocardiography”

Posted on December 4, 2025 by Tom Wade MD

Today, I review, link to, and excerpt from The American Society Of Echocardiography‘s Recommendations for the Assessment of Carotid Arterial Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk: From the American Society of Echocardiography. [PubMed Abstract] [Full-Text HTML] [Full-Text PDF]. J Am Soc Echocardiogr. 2020 Aug;33(8):917-933. doi: 10.1016/j.echo.2020.04.021. Epub 2020 Jun 27.

Comment in

There are 97 similar articles in PubMed.

The above article has been cited by 123 articles in PubMed.

All that follows is from the above resource.

Abstract

Atherosclerotic plaque detection by carotid ultrasound provides cardiovascular disease risk stratification. The advantages and disadvantages of two-dimensional (2D) and three-dimensional (3D) ultrasound methods for carotid arterial plaque quantification are reviewed. Advanced and emerging methods of carotid arterial plaque activity and composition analysis by ultrasound are considered. Recommendations for the standardization of focused 2D and 3D carotid arterial plaque ultrasound image acquisition and measurement for the purpose of cardiovascular disease stratification are formulated. Potential clinical application towards cardiovascular risk stratification of recommended focused carotid arterial plaque quantification approaches are summarized.

Keywords: Atherosclerosis; Carotid plaque; Risk stratification.

PubMed Disclaimer

Abbreviations and Acronyms

2D (two-dimensional)

3D (three-dimensional)

ASE (American Society of Echocardiography)

CCA (common carotid artery)

CIMT (carotid intima-media thickness)

CT (computed tomography)

CVD (cardiovascular disease)

FDG (fluorodeoxyglucose)

GSM (grayscale median)

ICA (internal carotid artery)

IPN (intra-plaque neovascularization)

MACE (major adverse cardiovascular events)

MRI (magnetic resonance imaging)

PDA (pixel distribution analysis)

PET (positron emission tomography)

UEA (ultrasound enhancing agent)

VWV (vessel wall volume)

Background

Atherosclerotic cardiovascular disease (CVD) remains the leading global cause of morbidity and mortality. Ultrasound imaging of the carotid artery has the ability to provide a unique “window” into the identification of a patient’s underlying cardiovascular risk. The presence and degree of atherosclerosis, as defined by plaque presence detected in the carotid arterial system, has been used to estimate and classify or reclassify an individual’s cardiovascular risk. Beyond overall risk stratification, carotid atherosclerosis is also a known predictor of other CVD events, such as stroke resulting from luminal vessel stenosis and plaque rupture.,
It is now recognized that CIMT may represent more than one distinct morphologic process while plaque primarily reflects atherosclerosis. CIMT may predominantly reflect the presence of cardiovascular risk factors (such as hypertension), whereas carotid plaque, a sub-intimal process, may be more reflective of atherosclerosis, as it correlates with overall atherosclerotic burden in the coronary vascular bed., The high prevalence of carotid atherosclerosis in subjects with an otherwise low Framingham risk score has potential implications for screening of subclinical atherosclerosis. Thus, quantification of carotid arterial plaque has emerged as an important tool for CVD risk stratification beyond what is offered by CIMT. This document focuses on the methods to quantify carotid arterial plaque, when present, for the purpose of risk stratification.
CIMT can still provide useful information even if no plaque is present. Currently, CIMT assessment is well described in “The ASE Consensus Statement on the Use of Carotid Ultrasound to Identify Subclinical Vascular Disease and Evaluate Cardiovascular Risk”. The CIMT related recommendations from this consensus continue to be endorsed by this writing panel. Henceforth, recommendations under the following headings from the previous consensus will not be revisited in the current document: 1) Rationale for Carotid Ultrasound to Identify Subclinical Vascular Disease, 2) Instrumentation, Display and Scanning Technique, 3) Reporting of Carotid Ultrasound Study Results, and 4) Training and Certification of Sonographers and Readers. The current document complements the previous consensus in its provision of a standardized approach to defining and quantifying carotid arterial plaque by ultrasound beyond the technical approach to CIMT measurement. Specifically the previous consensus did not provide a standardized approach to plaque quantification. Since the publication of the previous consensus in 2008, carotid ultrasound technology has advanced tremendously, first from the widespread availability of a dedicated three-dimensional vascular ultrasound probe, and now more recently, following the release of a 3D matrix array probe for carotid ultrasound with concomitant analysis software. The current document is the first to provide systematic recommendations for standardization of the quantification of carotid arterial plaque for the purposes of CVD risk stratification.

Scope

This consensus statement provides recommendations for the 2- and 3-dimensional quantification of carotid arterial plaque by ultrasound for the basis of CVD risk stratification. Emerging techniques, including the role of ultrasound enhancing agents (UEA) for assessment of intraplaque neovascularization and composition analysis, are also discussed.

Definition of Plaque – Protuberant and Diffuse Types

Carotid arterial atherosclerosis is thought to develop beneath the intimal layer in the sub-intima. In contrast, the medial layer is subject to non-atherosclerotic medial hypertrophy commonly induced by aging and hypertension. Since the largest portion of CIMT (∼99% in healthy individuals and ∼80% when diseased) consists of the medial layer, CIMT has not been shown to consistently add to CVD risk prediction. Carotid plaque, on the other hand, represents the atherosclerotic process itself, and starts in the intimal layer and has thus been shown to predict CVD events better than CIMT., Despite this difference in carotid arterial phenotypes, which have been used to describe associations with CVD events and risks,, it can be difficult to discern medial thickening from diffuse atherosclerotic plaque. Though some atherosclerotic plaques are discrete lesions that can be easily distinguished from the surrounding wall, plaque can also be eccentric and spread over the surface of the wall, appearing indistinct from the media. In such cases it is difficult to determine whether there is simply medial thickening present or eccentric, diffuse plaque. Thus, arbitrary definitions to define the presence of diffuse plaque beyond a certain CIMT threshold have been proposed. Adding to this complexity is the debate as to whether the transition from increased CIMT to plaque formation is a continuous process, or if CIMT and plaque are truly separate phenotypes.
A commonly reported threshold value to define diffuse plaque is a CIMT value greater than 1.5 mm or a focal intimal medial thickening of greater than 50% of the surrounding area., However, confusion occurs because ultrasound resolution now allows for the visualization of distinct protuberant plaque lesions that could be smaller than this threshold value. Furthermore, even the threshold CIMT value signifying plaque varies among studies. For example, in one study, plaque was defined as a focal thickening of the intima-media greater than 1 mm, protruding into the lumen, that was at least twice as thick as the surrounding normal CIMT, thus providing varying definitions of plaque ranging from 0.5 mm to >1.5 mm. In comparison, another study defined plaque as CIMT >1.2 mm. In contrast, the European Mannheim consensus defined plaque as a focal thickening that encroaches into the lumen by 0.5 mm or by 50% of the surrounding intimal-medial thickness or where CIMT is >1.5 mm.
Our writing panel selected a CIMT threshold value signifying plaque that is slightly more conservative than the Mannheim consensus, by recommending ≥1.5 mm (vs >1.5 mm) as the cut-off CIMT threshold value for the presence of diffuse plaque. This newly established Plaque Grading Consensus, described in detail below, now allows for the identification and characterization of protuberant plaque lesions smaller than the CIMT threshold value for identifying diffuse plaque. In other words, we recognize that plaque lesions smaller than 1.5 mm can be highly resolved with today’s technology. Advances in ultrasound now allow for identification of such small lesions in exquisite detail, allowing for both quantification and even potential analysis of composition. Thus this modern grading system sets a framework for continued outcomes-based research across the spectrum of plaque lesion shapes, sizes, and types.
Recommendation #1: 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).
Recommendation #2: We recommend the evaluation of both protuberant and diffuse types of carotid arterial plaque for cardiovascular risk stratification and the serial assessment of atherosclerosis.
Recommendation #3: 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.

Clinically Significant Carotid Arterial Plaque or CIMT

It is recognized that in some centers, repeat evaluation of CIMT in the absence of plaque is considered if CIMT is >75th percentile for age, race, and gender. Despite the lack of evidence surrounding the frequency of repeat testing, an interval for repeat testing of 2-5 years has been utilized in population studies, although published evidence suggests that more frequent CIMT measurements could increase the precision of the assessment of CIMT progression. Methodological limitations of this study notwithstanding, our expert panel recommends against serial CIMT measurements for CVD risk stratification especially when not meeting the threshold for diffuse plaque (≥1.5 mm). We recognized that based on limited or anecdotal evidence, there may be value in serial CIMT measurements in the hands of some experts for research,,, monitoring of progression or regression in specific cases ,, and as a potential tool to alter patient behavior. Additionally, it is possible that over time, an individual patient may have a CIMT value that has increased to ≥1.5 mm, signifying the development of diffuse atherosclerotic plaque by our definition; however the clinical utility of such long term CIMT monitoring is not yet established.
We have suggested that a CIMT ≥1.5 mm be considered a clinically significant lesion for patients less than 65 years of age. The thickness (also known as height in the long axis view) of a carotid arterial plaque lesion, whether it is protuberant or diffuse, was chosen as the initial measure to define plaque because of its widespread availability and because this variable can be measured in both protuberant or diffuse types of plaque lesions (Figure 1). Additional quantification techniques such as area and volume apply mostly to protuberant-type plaque lesions, and are difficult to define in atherosclerotic lesions that are diffusely layered along the intimal wall. Such lesions may be focal or diffuse wall calcification layered in a concentric or eccentric manner and may represent atherosclerotic or non-atherosclerotic processes. Accordingly, our panel suggests the grading system for both protuberant and diffuse plaque lesions as described in Figure 1.
Figure 1 Plaque Grading Consensus: carotid medial thickening and intimal plaque. Carotid intimal-medial thickening is thought to involve thickening of the medial layer whereas plaque is thought to be an intimal process as suggested in this schematic. However, diffuse intimal thickening may also occur that is difficult to distinguish from a medial process, and though not protuberant, eccentric or concentric thickening of 1.5 mm or greater is suggested to be a plaque equivalent by this system.
The grading system does not reflect the degree of vessel
occlusion but attempts to standardize the size of an individual plaque lesion for the purpose of comparison across studies. It is important to note that Grade I characterization applies only to small protuberant types of plaque lesions. This is because, though ultrasound can now resolve such small protuberant lesions, if the plaque is non-protuberant (diffuse or eccentric) and less than 1.5 mm in thickness, it is currently not possible to distinguish whether this is entirely due to medial thickening or is intimal. However at a CIMT value of 1.5 mm or greater (Grades II and III), this framework attributes the thickness to be due to diffuse atherosclerotic plaque (mostly intimal rather than medial) and is thus considered a plaque equivalent. The Grades II and III measurements are applied to obviously protuberant plaque in the same manner for simplicity (Figure 1).
Recommendation #4: We recommend against serial carotid intima-media 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.

Quantification Methods

Start here

Posted in American Society of Echocardiography, American Society Of Echocardiography Guidelines, Ultrasound Assessment Of Carotid Arterial Plaque | Comments Off on Linking To And Excerpting From The American Society Of Echocardiography’s “Recommendations for the Assessment of Carotid Arterial Plaque by Ultrasound for the Characterization of Atherosclerosis and Evaluation of Cardiovascular Risk: From the American Society of Echocardiography”