A Magnetic Resonance Imaging Based Computational Analysis of Plaque Morphology and Hemodynamics in Patients with High Grade Asymptomatic Carotid Artery Stenosis

项目摘要/摘要 颈内动脉(ICA)狭窄是导致中风、长期残疾和死亡的主要原因。 目前对颈内动脉狭窄的评估是基于双功能超声(DUS)对狭窄百分比的评估。 或横断面血管造影术。里程碑式的研究表明，无症状的狭窄患者 颈动脉内膜切除术(CEA)应考虑60%的病变，但通常需要干预。 保留给80%狭窄病变和/或易损斑块的患者。仅%狭窄率就很差 作为斑块易损性的替代品，并不能识别中风的高危患者。此外， 狭窄严重程度不考虑斑块负荷、壁切应力(WSS)、 压力梯度和脑血流补偿是了解中风风险的关键。最优 颈动脉血运重建术的患者选择，特别是无症状患者，仍然是一个 重要的临床需求。 我们已经开发了一个基于患者特定CFD建模的工作流程， 并证明了使用DUS诊断出的类似程度狭窄(70%狭窄)的患者 和/或横断面血管造影术)在压力梯度和脑血流量方面存在差异。 这些结果再次表明，仅靠解剖和血流数据不能确定中风风险的标志 以及将从颈动脉血运重建中受益的患者。在本计划中，我们将利用核磁共振来 表征斑块成分和CFD建模以评估斑块上的血流动力学负荷 从而提供更好的脆弱性评估。我们假设有相似程度的患者 无症状的高度颈内动脉狭窄(根据DUS速度标准为70%的狭窄) 会有不同的斑块形态，斑块的血流动力学应力，以及 脑血流灌注与其DUS血流速度曲线和狭窄严重程度无关。至 验证这一假设，我们将追求以下目标：1)使用T1/T2确定斑块组成 磁共振成像、斑块上的血流动力学负载和脑血流使用MRI校准的CFD工作流在 无症状高度颈内动脉狭窄患者的队列，这些患者的血流速度曲线相似 杜斯。2)表征上述指标的可变性程度，从而测试以下指标的有效性 我们的假设。3)在被选为CEA的患者中，我们将调查 术前、术后血流动力学差异评价手术疗效 修理。

PROJECT SUMMARY/ABSTRACT Internal carotid artery (ICA) stenosis is a leading cause of stroke, long-term disability, and death. Current assessment of ICA stenosis is based on estimation of % stenosis via duplex ultrasound (DUS) or cross-sectional angiography. Landmark studies suggested that asymptomatic patients with stenotic lesions >60% should be considered for carotid endarterectomy (CEA), however intervention is often reserved to those with stenotic lesions >80% and/or vulnerable plaques. The % stenosis alone is a poor surrogate for plaque vulnerability and does not identify patients at high risk for stroke. Moreover, stenosis severity does not account for indices such as plaque burden, wall shear stress (WSS), pressure gradients, and cerebral flow compensation which are key to understand stroke risk. Optimal patient selection for carotid artery revascularization, particularly in asymptomatic patients, remains a significant clinical need. We have developed a workflow based on patient-specific CFD modeling informed by MRI data, and demonstrated that patients with similar degrees of stenosis (> 70% stenosis diagnosed using DUS and/or cross sectional angiography) have differences in pressure gradients and cerebral blood flow. These results suggest again that anatomic and flow data alone fail to identify markers for stroke risk and patients who would benefit from carotid revascularization. In this proposal, we will leverage MRI to characterize plaque composition and CFD modeling to assess hemodynamic loads on the plaque to thus provide a better assessment of vulnerability. We hypothesize that patients with similar degrees of asymptomatic high-grade (> 70% stenosis on DUS velocity criteria) extracranial ICA stenosis will have differences in plaque morphology, hemodynamics stresses on the plaque, and cerebral perfusion that are independent of their DUS velocity profiles and stenosis severity. To test this hypothesis, we will pursue the following Aims: 1) To determine plaque composition using T1/T2 MRI, hemodynamic loads on the plaque and cerebral flow using MRI-calibrated CFD workflows in a cohort of patients with asymptomatic high grade ICA stenosis who have similar velocity profiles on DUS. 2) To characterize the degree of variability in the above metrics, and therefore test the validity of our hypothesis. 3) In a subset of the patients who are chosen for CEA, we will investigate the differences in pre-operative and post-operative hemodynamic to assess the efficacy of the surgical repair.