Ultrasound (US) phenotypes of carotid atherosclerosis include intima-media thickness (IMT), total plaque area (TPA), total plaque volume (TPV), and Doppler ultrasound-based measurements of stenosis Doppler US is a well established screening tool in the assessment of stenosis severity However, Doppler flow-velocity-based measurements do not provide information on plaque morphology, plaque vulnerability, or composition The measurement of IMT from B-mode US images is a widely used US phenotype of atherosclerosis and has been regarded as a surrogate measurement of atherosclerosis as it correlates with vascular outcomes Although the measurement of IMT has been validated in many studies, it is clear that many distinct biological pathways and mechanisms may be reflected by the measurement More recently, TPA and TPV have emerged as useful US phenotypes of carotid atherosclerosis that measure plaque burden in 2D and 3D, respectively Total plaque area has been shown to be a stronger predictor of coronary events than IMT [Spence et al Stroke 33 2916-2922 2002, Johnsen et al, Stroke 38(11) 2873-2880,2007]In order to overcome some limitations and accelerate the translation of 3D US measurements of carotid atherosclerosis to clinical research and clinical practice, semiautomated methods of measurement and measurements that are derived from biological components of carotid disease with readily distinguishable US boundaries (enabling multiple observers to be trained in shorter time periods and with decreased interobserver variability) are required This has stimulated the development and validation of a new 3D US measurement of carotid atherosclerosis vessel wall volume (VWV), which is a measurement of vessel wall thickness and plaque within the common carotid artery, the Internal and external carotid branches This measurement can be more easily semi-automated, and observers can be trained to measure VWV in shorter durations and with greater reliabilityOur objective is to demonstrate that 3D US is a viable technique for quantifying the progression and regression of carotid atherosclerosis

Objective. We compared the intraobserver and interscan variability of carotid atherosclerosis measured using B-mode ultrasound for quantifying intima media thickness (IMT), 3-dimensional ultrasound (3DUS) for quantifying vessel wall volume (VWV) and total plaque volume (TPV), and magnetic resonance imaging (MRI) for measuring VWV. We also evaluated the associations of these measurements and sample sizes required to detect specific changes in patients with moderate atherosclerosis. Methods. Ten patients were evaluated with B-mode ultrasound, MRI, and 3DUS twice within 14 2 days. Measurements of IMT, MRI VWV, 3DUS VWV, and 3DUS TPV were performed by single observers using manual (VWV and TPV) and semiautomated (IMT) segmentation, Results. Intraobserver coefficients of variation were 3.4% (IMT), 4.7% (3DUS VWV), 6.5% (MRI VWV), and 23.9% (3DUS TPV). Interscan coefficients of variation were 8.1 % (MRI VWV), 8.9% (IMT), 13.5% (3DUS VWV), and 46.6% (3DUS TPV). Scan-rescan linear regressions were significant for 3DUS TPV (R-2 = 0.57), 3DUS VWV (R-2 = 0.59), and IMT (R-2 = 0.75) and significantly different (P < .05) for MRI VWV (R-2 = 0.87). Conclusions. B-mode ultrasound-derived IMT provided the highest intraobserver and interscan reproducibility. Three-dimensional measurements of VWV derived from 3DUS and MRI provided both high sensitivity and high intraobserver and interscan reliability.

Quantitative measurements of the progression (or regression) of carotid plaque burden are important in monitoring patients and evaluating new treatment options. 3D ultrasound (US) has been used to monitor the progression of carotid artery plaques in symptomatic and asymptomatic patients, and different methods of measuring various ultrasound phenotypes of atherosclerosis have been developed. We have developed a quantitative metric used to analyze changes in carotid plaque morphology from 3D US. This method matched the vertices on the carotid arterial wall surface with those on the luminal surface. Vessel–wall-plus-plaque thickness (VWT) was obtained by computing the distance between each corresponding pair, which was then superimposed on the arterial wall to produce the VWT map. Since the progression of plaque thickness is important in monitoring patients who are at risk for stroke, we also computed the change of VWT by comparing the VWT maps obtained for a patient at two different time points. In this paper, we propose a technique to flatten the 3D VWT and VWT-Change maps in an area-preserving manner, in order to facilitate the visualization and interpretation of these maps.

Quantitative measurements of the progression (or regression) of carotid plaque burden are important in monitoring patients and evaluating new treatment options. 3D ultrasound (US) has been used to monitor the progression of carotid artery plaques in symptomatic and asymptomatic patients. Different methods of measuring various ultrasound phenotypes of atherosclerosis have been developed. In this work, we extended concepts used in intima-media thickness (IMT) measurements based on 2D images and introduced a metric called 3D vessel-wall-plus-plaque thickness (3D VWT), which was obtained by computing the distance between the carotid wall and lumen surfaces on a point-by-point basis in a 3D image of the carotid arteries. The VWT measurements were then superimposed on the arterial wall to produce the VWT map. Since the progression of plaque thickness is important in monitoring patients who are at risk for stroke, we also computed the change of VWT by comparing the VWT maps obtained for a patient at two different time points. In order to facilitate the visualization and interpretation of the 3D VWT and VWT-Change maps, we proposed a technique to flatten these maps in an area-preserving manner.

Background Quantitative measurements of carotid plaque burden are used to monitor patients and evaluate established interventions as well as new treatment options.Purpose Three-dimensional ultrasound (3D US) techniques were developed to noninvasively monitor the progression of carotid artery disease in both symptomatic and asymptomatic patients.Methods Three-dimensional carotid US images were acquired and reconstructed, and methods for quantitative assessment were developed. The measurement of intimamedia thickness (IMT) based on two-dimensional ultrasound (2D US) images was extended to a 3D vessel-wall-plus-plaque thickness (VWT), obtained by computing the distance between the carotid wall and lumen surfaces on a point-by-point basis. VWT measurements were superimposed on the arterial wall to produce 3D VWT maps. VWT changes were determined by comparing the 3D VWT maps obtained at two different time points. To facilitate the visualization and interpretation of the VWT and VWT-Change maps, a technique to flatten these maps was developed.Results Carotid remodeling involving changes in both arterial wall and plaque thickness was assessed with VWT maps obtained from in vivo 3D ultrasound images.Conclusion 3D carotid ultrasound image evaluation with VWT mapping provides a feasible means for the analysis of plaque burden volumes and changes.

Quantitative measurements of carotid plaque burden progression or regression are important in monitoring patients and in evaluation of new treatment options. 3D ultrasound (US) has been used to monitor the progression or regression of carotid artery plaques. This paper reports on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US. The technique used is evaluated using manual segmentations of the arterial wall and lumen from 3D US images acquired in two imaging sessions. To reduce the effect of segmentation variability, segmentation was performed five times each for the wall and lumen. The mean wall and lumen surfaces, computed from this set of five segmentations, were matched on a point-by-point basis, and the distance between each pair of corresponding points served as an estimate of the combined thickness of the plaque, intima, and media (vessel-wall-plus-plaque thickness or VWT). The VWT maps associated with the first and the second US images were compared and the differences of VWT were obtained at each vertex. The 3D VWT and VWT-Change maps may provide important information for evaluating the location of plaque progression in relation to the localized disturbances of flow pattern, such as oscillatory shear, and regression in response to medical treatments.

This study was designed to evaluate changes in carotid atherosclerosis using plaque and wall thickness maps derived from three-dimensional ultrasound (3DUS) images. Five subjects with carotid stenosis were scanned at baseline and 3 mo as part of a placebo-controlled intensive statin treatment study and three subjects with moderate atherosclerosis were scanned at baseline and again within 14 +/- 2 d. 3DUS-derived vessel wall volume (VWV) was measured using manual segmentation to provide segmentation contours that were used to generate scan and rescan carotid atherosclerosis thickness maps and thickness difference maps. There was no significant difference in VWV between scan and rescan for the three subjects scanned twice in 2 wk or the single subject treated with placebo. There was a significant difference between scan and rescan VWV for carotid stenosis subjects treated with atorvastatin (p < 0.001). Carotid atherosclerosis thickness difference maps showed visual qualitative evidence of thickness changes in vessel wall and plaque thickness in the common carotid artery for all statin-treated subjects and no change in a placebo-treated subject and subjects scanned twice in 2 wk. Carotid atherosclerosis thickness difference maps generated from 3DUS images provide evidence of vessel wall and plaque thickness changes for all subjects assessed.

Carotid atherosclerotic lesions are a major cause of stroke and the identification and quantification of such lesions in patients is important for the development of a better understanding of atherogenesis in high risk populations and for the design of studies to assess treatment efficacy. Our objective was to develop and validate a new three-dimensional ultrasound (3DUS) measurement or phenotype of carotid atherosclerosis, vessel wall volume (VWV), which is a three-dimensional measurement of vessel wall thickness and plaque within the carotid arteries measured in 3DUS images. To assess both intraobserver and interscan variability, 3DUS images were acquired from the right and left carotid arteries of ten subjects with carotid atherosclerosis scanned twice within a period of 2 wk. For both VWV and total plaque volume (TPV), an expert observer performed five measurement trials of all images acquired at baseline scan and 2-wk rescan with a 5-d period between measurement trials for images. Images were re-randomized for each measurement trial and both TPV and VWV were measured by observers who were blinded to subject identification for each time-point measurement. Coefficients of variation (COV) and intraclass correlation coefficients (ICC), for VWV measurements indicated higher intraobserver (scan COV = 4.6% ICC = 0.95, rescan COV = 3.4%, ICC = 0.96) and interscan reproducibility (COV = 5.7%, ICC = 0.85) than TPV measurements (intraobserver variability scan COV = 22.7% ICC = 0.85, rescan COV = 21.1% ICC = 0.88 and interscan variability, COV = 31.1%, ICC = 0.83), although absolute variances for both phenotypes were very similar (VWV = 90 mm3, TPV = 80 mm3).

Atherosclerosis is an inflammatory process similar to scar formation in the inner wall of the artery. It is the underlying cause of heart attacks and some strokes. Atherosclerotic lesions in the artery wall are called plaques. 3D ultrasound (US) has been used to monitor the progression of carotid vessel plaques in symptomatic and asymptomatic patients. Different ways of measuring various ultrasound phenotypes of atherosclerosis have been developed. Here, we report on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US. In an effort to extend our previous work in plaque thickness analysis, we developed a procedure that facilitates the visualization and comparison of the distribution of plaque thickness by mapping the 3D arterial structure into a 2D plane.

Atherosclerosis is characterized by the development of plaques in the arterial wall, which ultimately leads to heart attacks and stroke. 3D ultrasound (US) has been used to screen patients' carotid arteries. Plaque measurements obtained from these images may aid in the management and monitoring of patients, and in evaluating the effect of new treatment options. Different types of measures for ultrasound phenotypes of atherosclerosis have been proposed. Here, we report on the development and application of a method used to analyze changes in carotid plaque morphology from 3D US images obtained at two different time points. We evaluated our technique using manual segmentations of the wall and lumen of the carotid artery from images acquired in two US scanning sessions. To incorporate the effect of intraobserver variability in our evaluation, manual segmentation was performed five times each for the arterial wall and lumen. From this set of five segmentations, the mean wall and lumen surfaces were reconstructed, with the standard deviation at each point mapped onto the surfaces. A correspondence map between the mean wall and lumen surfaces was then established, and the thickness of the atherosclerotic plaque at each point in the vessel was estimated to be the distance between each correspondence pairs. The two-sample Student's t-test was used to judge whether the difference between the thickness values at each pair corresponding points of the arteries in the two 3D US images was statistically significant.