Table 2.

An overview on CIMT and carotid plaque definitions and acquisition techniques.

Study	CIMT Assessment	Carotid Plaque
	Definition, Acquisition Technique	Acquisition Technique, Definition
Mannheim IMT Consensus, 2012 [59]	Definition: CIMT is a double-line pattern visualized by ultrasound on both walls of the CCA in a longitudinal image, which consist of the leading edges of two anatomical boundaries: the lumen-intima and media-adventitia interfaces (Figure 1). Acquisition: High-resolution B-mode system with linear transducers at frequencies > 7 MHz, log gain compensation of app. 60 dB. Gain settings adjusted to obtain a symmetrical brightness on the near and far wall to eliminate artifacts in a longitudinal view lateral position. A long 10 mm length of a straight arterial segment is required for reproducible serial measurements. CIMT measurement within a region free of plaque with a clearly identified double-line pattern, preferably on the far wall of the CCA at least 5 mm below its end. CIMT can be measured at the CB or ICA in a region free of plaque, on a shorter length, taking caution of the large interindividual variability. These values must be recorded separately. CIMT measurements options include the mean, maximum, composite measures from both sides, and different arterial sites. Mean CIMT values averaged across the entire distance are less susceptible to outliers. The maximal CIMT may reflect more advanced stages with focal thickening or plaque formation.	Definition: Plaques are focal structures encroaching into the arterial lumen of at least 0.5 mm or 50% of the surrounding CIMT, or demonstrating a thickness of >1.5 mm as measured from the intima-lumen interface to the media-adventitia interface (Figure 1). Acquisition technique: Plaque location, thickness, area, and number scanned in longitudinal and cross-sections must be recorded. For plaque, a maximal thickness requires demonstration from 2 different angles of insonation, in longitudinal and cross-sectional views. The incremental value of recording texture (density, echogenicity, shadow) remains uncertain pending more research.
American Society of Echocardiography, 2008 [54] and 2020 [8]	Definition: not given Acquisition technique: B-mode imaging preferred over M-mode. Ultrasound system with a linear-array transducer at frequencies > 7 MHz. CIMT imaging (3–5 beat cine-loop and optimized R-wave gated still frames at each angle).Distal 1 cm of each CCA. Use of a semiautomated border detection program with validated accuracy. Scanning protocols from observational studies with published nomograms may be used if they are more germane to the age, sex, and race/ethnicity of the clinical population being investigated; however, the clinical laboratory must have sufficient expertise to perform them accurately and reproducibly. Use of values from clinically referred populations are discouraged, because of the high likelihood of referral bias and inaccurate risk estimates. Limiting CIMT measurements to the far wall of the CCA is the preferred strategy. Interpretation of carotid ultrasound studies for CVD risk assessment: Mean CIMT values from the far wall of the right and left CCAs (mean-mean) should be reported. Use of additional segments or maximum values is an alternative if there is local expertise and normative values with published associations to CVD risk are reported. Mean-mean values are more reproducible because multiple points along the traced segment are averaged, but are less sensitive to change. Mean-maximum values are more sensitive to change, but less reproducible. Evaluating for the presence or absence of plaque in conjunction with measuring CIMT-CCA offers a better representation of subclinical vascular disease and CVD risk than only measuring CIMT.	Definition: Carotid arterial plaque visualized with or without use of an ultrasound enhancing agent is defined as: (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 CIMT measures ≥ 1.5 mm in any segment of the carotid artery (diffuse-type plaque). Carotid plaque grading: Grade 0: no carotid plaque; Grade I: focal protuberant thickening of vessel wall < 1.5 mm; Grade II: focal protuberant plaque between 1.5 and 2.4 mm height, or diffuse thickening of the vessel wall between 1.5 and 2.4 mm; Grade III: either protuberant or diffuse thickening above 2.4 mm. 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.
		Acquisition technique: 2D techniques for quantifying plaque as initial approach with giving maximum plaque thickness. It should be measured from the side in which a plaque lesion 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 standardization, this measurement should be taken from segments of the long and short axis. 2D plaque area: the measurement should begin from medial-adventitial plane for the purposes of standardization. The quantification of plaque volume for an individual plaque lesion is recommended when required (e.g., morphologic assessment, serial assessment, or pre-operative consideration), using either the stacked-contour method or specialized semi-automated tools. 3D plaque volume: the quantification of right and/or left carotid plaque volume using 3D ultrasound for cardiovascular risk stratification with a single-plaque or single-region report, or a full-vessel protocol report.

2D, 2-dimentional; 3D, 3-dimensional.