High-Resolution 3-Tesla-MRI of the Carotid Arteries in the Evaluation of Cryptogenic Stroke

大约70%的缺血性中风是由心源性栓塞、小血管疾病或大动脉粥样硬化引起的。尽管进行了广泛的检查，但仍有高达25%的病例病因不明（隐源性卒中）。然而，颈动脉血管中的动脉粥样硬化斑块仅在存在显著狭窄（例如>50%; TOAST分类系统）时被认为是病因。从病理生理学的观点来看，这种分类似乎值得怀疑。然而，常规应用的成像方法的技术局限性限制了对血管壁的非狭窄性动脉粥样硬化变化的详细分析和易损斑块（VP）的识别。颈动脉血管的高分辨率MRI是一种相对新颖的非侵入性方法，可以识别与组织病理学具有良好相关性的VP。基于我们研究小组先前的工作，即VP和缺血性卒中之间存在实质性相关性，启动了前瞻性、多中心急性卒中颈动脉斑块成像（CAPIAS）研究。本研究的目的是检查VP在隐源性卒中患者中的患病率，以及VP的存在是否对临床表现或无症状性卒中的复发率以及血管壁动脉粥样硬化变化的进展有影响。中风对侧的血管和一组已知中风病因的患者作为对照。本提案旨在提供研究补助金，以支持/实现对CAPIAS研究期间（基线和12个月随访时）已经和仍在采集的颈动脉和脑颅MRI数据进行有效分析。颈动脉的图像数据将使用专用软件算法进行评估。根据AHA分类系统表征动脉粥样硬化病变，并获得血管壁和单个斑块成分（例如斑块内出血、富脂/坏死核心、钙化）的定量参数。基于这些数据，评价了VP与隐源性卒中、VP与卒中复发之间的相关性，以及VP对动脉粥样硬化进展的影响。此外，专业数据库的建立将确保评估的表型数据的长期有效可用性。

Approximately 70% of ischemic strokes are caused by cardioembolism, small vessel disease or large artery atherosclerosis. Despite extensive workup the etiology remains unknown in up to 25% of cases (cryptogenic stroke). However, atherosclerotic plaques in the carotid vessels are only considered as causative if significant stenosis is present (e.g. >50%; TOAST-classification system). From a pathophysiological viewpoint this classification may seem questionable. Technical limitations of routinely applied imaging methods however limit the elaborate analysis of non-stenosing atherosclerotic changes of the vessel wall and the identification of vulnerable plaque (VP). High-resolution MRI of the carotid vessels is a relatively novel non-invasive approach, allowing for identification of VP with good correlation to histopathology. Based on previous work of our study group which suggests a substantial correlation between VP and ischemic stroke, the prospective, multicenter Carotid Plaque Imaging in Acute Stroke (CAPIAS)-study was initiated. Objectives of the study are to examine the prevalence of VP in patients with cryptogenic stroke and whether the presence of VP has influence on the recurrence rate of clinical manifest or silent stroke as well as on the progression of atherosclerotic changes in the vessel wall. Vessels contralateral to stroke and a group of patients with known stroke etiologies serve as controls. This Proposal is aimed at a research grant to support/enable an efficient analysis of MRI data of the carotid arteries as well as of the neurocranium which has already been and is still being acquired during the CAPIAS-study (at baseline and 12 month follow-up). Image data of the carotids is going to be evaluated using dedicated software algorithms. Atherosclerotic lesions are characterized according to the AHA-classification system and quantitative parameters of the vessel wall and singular plaque components (e.g. intraplaque hemorrhage, lipid-rich/necrotic core, calcifications) are obtained. Based on this data correlations between presence of VP and cryptogenic stroke, VP and stroke recurrence, and the effect of VP on progression of atherosclerosis are evaluated. Furthermore the establishment of a professional data base is going to ensure the long-term and effective availability of the assessed phenotypical data.