Carotid plaque assessment using Pulse Wave Imaging

中风是第五大致死原因，也是可预防残疾的主要原因。 根据美国心脏协会(Mozaffari Et Et)的最新统计数据 艾尔2016)。每年，约有795,000人继续经历新的或复发的 卒中。平均每40秒，美国就有一个人中风， 大约每4分钟就有一人死于此病。识别高危患者， 因此，无症状的颈动脉斑块仍然是预防中风的一个难以捉摸但必不可少的步骤。 一个这样的标准是斑块硬度。脂斑块已经被证明有明显的僵硬。 是钙化斑块造成的。据报道，中风患者的动脉僵硬也有所增加。 然而，临床上的医学成像设备都不能提供这样的信息。 因此，当前的标准与血管管腔属性有关，而不是直接与颈动脉壁本身相关 上面有牌匾，证实了手头的挑战。一个标准可以可靠地确定 不稳定的斑块将确保通过颈动脉内膜切除术(CEA)及时清除， 尤其是无症状的患者或有低度管腔狭窄的患者，其中风风险为 目前评估很差。为此，我们团队开创了非侵入性超声波- 基于脉搏波成像(PWI)的描述脉搏波传播的技术 沿着脉管壁，并映射下面的脉冲波引起的壁位移 使用高帧速率、高精度运动估计与 相应的声像图。PWI已被证明能够表征斑块的特征 在本研究中，我们的目标是描述颈动脉斑块的特征。 以便及时预测缺血性卒中的预后。我们假设PWI可以显著增强 常规血管超声的预后能力。组建的团队高度多元化-- 学科涵盖所有研究领域，如超声波、生物力学、临床 放射学、血管病理学、血管外科和生物统计学。因此，具体目标是： 1)在实验模体中优化和评估PWI的基本性能；2)评估 PWI表征活体猪斑块僵硬的能力；3)验证PWI在 患者体内的颈动脉斑块。在拟议的优化和验证研究之后， 这种高度平移的技术可以很容易地集成到临床超声扫描仪中，以 颈动脉斑块稳定性评估和卒中预防。PWI可以与 标准的血管超声扫描和顺应性地图可以覆盖在标准上 B超识别斑块的机械属性，从而确定整体稳定性。

Stroke is the fifth leading cause of death and the primary cause of preventable disability in the U.S according to the most recent statistics by the American Heart Association (Mozaffarian et al. 2016). Each year, approximately 795,000 people continue to experience a new or recurrent stroke. On average, every 40 seconds, someone in the United States has a stroke, and someone dies of one approximately every 4 minutes. Identification of patients with high-risk, asymptomatic carotid plaques remains thus an elusive but essential step in stroke prevention. One such criterion is plaque stiffness. Lipid plaques have been shown to have distinct stiffness from calcified plaques. Increased arterial stiffness has also been reported in stroke patients. However, none of the medical imaging modalities in the clinic can provide such information. Current criteria thus relate to the vessel lumen properties but not directly to the carotid wall itself that bears the plaque, confirming the challenge at hand. A criterion that would reliably identify unstable plaques would ensure timely removal through carotid endarterectomy (CEA), especially in asymptomatic patients or those with low endoluminal stenosis whose stroke risk is currently poorly assessed. To that end, our group has pioneered the noninvasive, ultrasound- based technique of Pulse Wave Imaging (PWI) that depicts the intrinsic pulse wave propagation along the vessel wall and maps the underlying pulse-wave induced wall displacement and compliance using high-frame-rate, high-precision motion estimation seamlessly integrated with the corresponding sonogram. PWI has been shown capable of characterizing plaques based on their distinct underlying stiffness In this study, we aim at the characterization of carotid plaques for timely prognosis of ischemic stroke. We hypothesize that PWI can significantly reinforce the prognostic capability of a conventional vascular ultrasound. The team assembled is highly multi- disciplinary encompassing all research fields such as ultrasound, biomechanics, clinical radiology, vascular pathology, vascular surgery and biostatistics. The specific aims are thus to: 1) Optimize and assess fundamental performance of PWI in experimental phantoms; 2) Assess capability of PWI to characterize plaque stiffness in pigs in vivo; 3) Validate PWI findings in carotid plaques of patients in vivo. Following the proposed optimization and validation studies, this highly translational technology could be readily integrated in clinical ultrasound scanners for carotid plaque stability assessment and stroke prevention. PWI can be used in conjunction with a standard vascular ultrasound scan and the compliance map can be overlaid onto a standard B-mode to identify the plaque mechanical properties and thus overall stability.