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Characterization of distensibility, plaque burden, and composition of the atherosclerotic carotid artery using magnetic resonance imaging.

ABSTRACT: Arterial distensibility is a marker that can measure vessel wall functional and structural changes resulting from atherosclerosis with applications including estimation of mechanical properties of the wall. We sought to assess the feasibility of using magnetic resonance imaging (MRI) to include wall distensibility in the characterization of atherosclerotic carotid arteries and to analyze the relationship between distensibility and morphological and compositional plaque features.Five healthy volunteers were imaged with a multiple-slice CINE MR sequence twice, within 24 h, to determine the interscan reproducibility of distensibility measurements. Twenty-one subjects with >15% carotid stenosis and the five healthy volunteers were imaged using a multicontrast carotid MRI protocol to characterize arterial wall morphology and composition. Normalized wall index (wall area∕total vessel area), maximum wall thickness and, if present, percentages of wall area occupied by calcification and lipid-rich necrotic core were determined. A multiple-slice CINE MR sequence was added to the multicontrast protocol to measure the distensibility coefficient (DC) at several locations spanning the bifurcation. The intraclass correlation coefficient (ICC) and the coefficient of variation were used to assess the reproducibility of DC measurements made on the healthy subjects. The DC was compared between arterial segments and between the healthy and diseased groups. Furthermore, within the diseased group, DC was correlated to plaque morphology and composition at each location as well as that averaged over the plaque.Distensibility measurements were highly reproducible: ICC (95% confidence interval) was 0.998 (0.96-1.0) for the common carotid segment and 0.990 (0.92-1.0) for the internal carotid segment. In healthy volunteers, we found significantly higher distensibility in the common segment of the carotid artery compared to the internal carotid segment (mean ± SD = 4.56 ± 1.02 versus 3.56 ± 1.32 × 10(-5)∕Pa; p < 0.05). However, no segmental differences were seen in the diseased group (3.25 ± 1.84 versus 3.26 ± 1.60 × 10(-5)∕Pa; p = 0.607). Location-to-location changes in DC were not found to correlate to changes in the local plaque morphology or composition nor were average DC found to be associated with aggregate plaque features.These results demonstrate the feasibility of MRI to measure distensibility in the carotid artery and to presumably detect changes in distensibility due to age and∕or disease. The results suggest that the effect of atherosclerosis on local distensibility may not strongly depend upon the specific underlying plaque features in mild to moderate stenotic carotid lesions though more diffuse or nonlocal changes in arterial distensibility could not be ruled out.

SUBMITTER: Canton G

PROVIDER: S-EPMC3470611 | biostudies-other | 2012 Oct

REPOSITORIES: biostudies-other

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Project description:ImportanceIt remains unknown whether in an asymptomatic community-based cohort magnetic resonance imaging (MRI) measures of plaque characteristics are independently associated with incident cardiovascular disease (CVD) events when adjusted for carotid artery (CA) wall thickness, a measure of plaque burden.ObjectiveTo assess associations of CA MRI plaque characteristics with incident CVD events.Design, setting, and participantsThe Atherosclerosis Risk in Communities (ARIC) study is a prospective epidemiologic study of the incidence of CVD in 15 792 adults of which 2066 women and men were enrolled in the ARIC Carotid MRI substudy. ARIC participants were enrolled from 1987 to 1989, and the substudy was conducted between January 2004 and December 2005. Analysis began January 2017 and ended August 2020.ExposuresIncident CVD events during a median (interquartile range [IQR]) follow-up time of 10.5 (8.1-10.9) years were assessed.Main outcomes and measuresProportional hazards Cox analyses were performed to ascertain associations between MRI variables of CA plaque burden and plaque characteristics.ResultsOf 15 792 ARIC participants, 2066 were enrolled in the substudy, of whom 1256 (701 women [55.8%]) had complete data and were eligible for incident CVD analyses. Carotid artery plaques in participants with incident CVD events (172 [13.7%]) compared with those without (1084 [86.3%]) had a higher normalized wall index (median [IQR], 0.48 [0.36-0.62] vs 0.43 [0.34-0.55]; P = .001), maximum CA wall thickness (median [IQR], 2.22 [1.37-3.52] mm vs 1.96 [1.29-2.85] mm; P = .01), maximum CA stenosis (median [IQR], 5% [0%-22%] vs 0% [0%-13%]; P < .001), and when present, a larger lipid core volume (median [IQR], 0.05 [0.02-0.11] mL vs 0.03 [0.01-0.07] mL; P = .03), respectively. The presence of a lipid core was independently associated with incident CVD events when adjusted for traditional CVD risk factors and maximum CA wall thickness (hazard ratio, 2.48 [95% CI, 1.36-4.51]; P = .003), whereas the presence of calcification was not. The frequency of intraplaque hemorrhage presence in this population of individuals free of CVD at baseline who were not recruited for carotid stenosis was too small to draw any meaningful conclusions (intraplaque hemorrhage presence: 68 of 1256 participants [5.4%]). Carotid artery lumen area and maximum stenosis, which were overall low, were independently associated with incident CVD events when adjusted for traditional CVD risk factors, as anticipated.Conclusions and relevanceThe presence of a CA lipid core on MRI is associated with incident CVD events independent of maximum CA wall thickness in asymptomatic participants.

Project description:BackgroundIt is unclear whether faster progression of atherosclerosis explains the higher risk of cardiovascular events in CKD. The objectives of this study were to 1. Characterize the associations of CKD with presence and morphology of atherosclerotic plaques on carotid magnetic resonance imaging (MRI) and 2. Examine the associations of baseline CKD and carotid atherosclerotic plaques with subsequent cardiovascular events.MethodsIn a subgroup (N = 465) of Systolic Blood Pressure Intervention Trial. (SPRINT) participants, we measured carotid plaque presence and morphology at baseline and after 30-months with MRI. We examined the associations of CKD (baseline eGFR < 60 ml/min/1.73m2) with progression of carotid plaques and the SPRINT cardiovascular endpoint.ResultsOne hundred and ninety six (42%) participants had CKD. Baseline eGFR in the non-CKD and CKD subgroups were 77 ± 14 and 49 ± 8 ml/min/1.73 m2, respectively. Lipid rich necrotic-core plaque was present in 137 (29.5%) participants. In 323 participants with both baseline and follow-up MRI measurements of maximum wall thickness, CKD was not associated with progression of maximum wall thickness (OR 0.62, 95% CI 0.36 to 1.07, p = 0.082). In 96 participants with necrotic core plaque at baseline and with a valid follow-up MRI, CKD was associated with lower odds of progression of necrotic core plaque (OR 0.41, 95% CI 0.17 to 0.95, p = 0.039). There were 28 cardiovascular events over 1764 person-years of follow-up. In separate Cox models, necrotic core plaque (HR 2.59, 95% CI 1.15 to 5.85) but not plaque defined by maximum wall thickness or presence of a plaque component (HR 1.79, 95% CI 0.73 to 4.43) was associated with cardiovascular events. Independent of necrotic core plaque, CKD (HR 3.35, 95% CI 1.40 to 7.99) was associated with cardiovascular events.ConclusionsPresence of necrotic core in carotid plaque rather than the presence of plaque per se was associated with increased risk of cardiovascular events. We did not find CKD to be associated with faster progression of necrotic core plaques, although both were independently associated with cardiovascular events. Thus, CKD may contribute to cardiovascular disease principally via mechanisms other than atherosclerosis such as arterial media calcification or stiffening.Trial registrationNCT01475747 , registered on November 21, 2011.

Project description:RationaleRemodeling of the vessel wall and the formation of vascular networks are dynamic processes that occur during mammalian embryonic development and in adulthood. Plaque development and excessive neointima formation are hallmarks of atherosclerosis and vascular injury. As our understanding of these complex processes evolves, there is a need to develop new imaging techniques to study underlying mechanisms.ObjectiveWe used tissue clearing and light-sheet microscopy for 3-dimensional (3D) profiling of the vascular response to carotid artery ligation and induction of atherosclerosis in mouse models.Methods and resultsAdipo-Clear and immunolabeling in combination with light-sheet microscopy were applied to image carotid arteries and brachiocephalic arteries, allowing for 3D reconstruction of vessel architecture. Entire 3D neointima formations with different geometries were observed within the carotid artery and scored by volumetric analysis. Additionally, we identified a CD31-positive adventitial plexus after ligation of the carotid artery that evolved and matured over time. We also used this method to characterize plaque extent and composition in the brachiocephalic arteries of ApoE-deficient mice on high-fat diet. The plaques exhibited inter-animal differences in terms of plaque volume, geometry, and ratio of acellular core to plaque volume. A 3D reconstruction of the endothelium overlying the plaque was also generated.ConclusionsWe present a novel approach to characterize vascular remodeling in adult mice using Adipo-Clear in combination with light-sheet microscopy. Our method reconstructs 3D neointima formation after arterial injury and allows for volumetric analysis of remodeling, in addition to revealing angiogenesis and maturation of a plexus surrounding the carotid artery. This method generates complete 3D reconstructions of atherosclerotic plaques and uncovers their volume, geometry, acellular component, surface, and spatial position within the brachiocephalic arteries. Our approach may be used in a number of mouse models of cardiovascular disease to assess vessel geometry and volume. Visual Overview: An online visual overview is available for this article.

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Characterization of distensibility, plaque burden, and composition of the atherosclerotic carotid artery using magnetic resonance imaging.

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