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PURPOSE: Imaging plaque morphology, in addition to luminal grading, may improve stroke risk-management by identifying structural atherosclerotic plaques alterations responsible for cerebrovascular events. The purpose of this study was to evaluate the agreement between our enhanced ultrasound (US) imaging method and high-resolution cross-sectional imaging modalities, such as multidetector-row computed tomography (CT) and magnetic resonance imaging (MRI), in the characterization of vulnerable plaques. METHODS: Sixty tissue-like phantoms were created to simulate various types of diseased plaque segments. We prospectively assessed each sample with US, CT, and MRI. Plaque characteristics considered included surface irregularity, ulceration, fissure, and presence of internal fluid core(s). We evaluated the agreement between and among the three modalities, as well as the accuracy of each compared with the true pathology. RESULTS: There was moderate to substantial agreement among the three modalities in the detection of morphologic characteristics. There was no significant difference in accuracy between US and CT in the presence of ulceration(s) (P = .23), lucency (P = .23), or fissures (P = .07); however, US was significantly more accurate than MRI for each of these characteristics (P = .0001, P = .0001, P = .02, respectively). None of the three modalities did display any significant difference in accuracy in the identification of irregular surface. There was substantial agreement among the three radiologists (intraclass correlation coefficient, 0.61; 95% confidence interval, 0.46-0.74) in their assessment of plaque subtype, ranging from 80%-85% accuracy in identifying the plaque subtypes for each classification. CONCLUSIONS: Enhanced plaque imaging can identify potentially significant plaque characteristics and provide insight into early causative conditions of carotid atherosclerosis. Our results suggest that the types of plaque pathologies derived from our US method showed good agreement with CT and surpass information gathered on MRI. This imaging protocol could potentially shift the paradigm in early carotid plaque imaging likely to predict the onset of vulnerable plaques, thus improving preventative management of atherosclerosis.
RESUMO
OBJECTIVES: Imaging carotid plaque morphology with the use of ultrasound (US) may improve stroke risk management by identifying alterations in atheroma at increased risk for cerebrovascular events. Limited reports on advanced US plaque imaging have identified the potential for evaluation and risk stratification of vulnerable carotid plaques. The purpose of this series was to evaluate the usefulness of integrating an advanced US plaque imaging method to characterize atheromas and to measure the agreement with multidetector row computed tomography (CT) and radiographic pathology. METHODS: Three patients with known high-grade symptomatic carotid artery disease confirmed on CT and scheduled for endarterectomy were recruited for this study. Before surgery, we prospectively assessed carotid arteries for high-risk morphological characteristics using our advanced US plaque imaging mechanism. The plaque characteristics considered included the presence of ulceration, internal lipid or hemorrhagic core(s), calcification(s), and/or thin/dense fibrous plaque caps. US plaque features were correlated with previous CT imaging and postendartertectomy histologic studies. RESULTS: There was substantial agreement in the detection of morphologic characteristics. Our advanced US method yielded 100% sensitivity, specificity, and accuracy in the identification of ulceration, lipid/hemorrhagic core(s) and calcification(s), leading over CT. In the identification of a thin/dense fibrous plaque cap, CT yielded 0% sensitivity versus 33% on US. CONCLUSIONS: Advanced US plaque imaging to further identify significant plaque abnormalities responsible for strokes can reliably identify vulnerable plaque characteristics on both two-dimensional and three-dimensional US. Our results suggest that the type of abnormality identified with our advanced US imaging method surpassed information gathered on CT. Our advanced imaging protocol shows potential for early noninvasive prediction of plaque vulnerability, thus improving preventive management of atherosclerosis.
RESUMO
Cerebrovascular (CVA) accidents are the second leading cause of death worldwide and their numbers are increasing. Strokes can arise from several causes, with extracranial carotid artery atherosclerosis (CAS) being one of the leading causes. CAS causes these strokes either by diminishing blood flow distal to the diseased stenotic segment of the artery or, as more recently discovered, by a thromboembolic event of material from the plaque site itself. The specific etiology of CAS is unknown, but causative factors in the formation of atherosclerotic plaque of the carotid arteries have been linked to specific morphological areas within the plaque that may be vulnerable to rupture, leading to thromboemboli into the cerebrovascular circulation. The current means for imaging and reporting CAS is through the measurement of the severity of luminal diameter stenosis caused by atherosclerotic disease. Recent developments in medical imaging techniques have expanded the role of early imaging and detection of CAS. Although current practice uses luminal narrowing as the surrogate marker to assess CAS, it has been recently discovered that plaque morphology and composition may help predict the clinical behavior of CAS and better determine the necessary medical intervention or risk of stroke. Although a single optimized imaging modality for standard CAS imaging has not been established or agreed on, various modalities can provide key elements to a successful exam. This review article will evaluate the most commonly used methods for CAS imaging along with the new and upcoming uses, advantages, and limitations for advanced CAS imaging.
