Stroke is the first and the fourth leading cause of death in the United States and China, respectively. Disruption of cerebrovascular vulnerable atherosclerotic plaque is the major etiology of ischemic stroke. Therefore, early detection and treatment of vulnerable plaques occurring at the feeding arteries to brain (cerebral arteries) will be helpful for prevention of stroke.

Atherosclerosis is a systemic disease that usually affects multiple vascular beds. Previous studies have shown that these high risk lesions in different segments of cerebral arteries (intracranial and extracranial arteries) might be racially specific. It is reported that, in stroke patients, intracranial vulnerable plaques are prevalent in Asian populations whereas atherosclerosis more frequently involves extracranial carotid arteries in American subjects. However, these findings are based on angiographic imaging approaches via measuring arterial luminal stenosis. Because the atherosclerotic plaque often appears as outward expansion, namely positive remodeling during progression, measuring luminal stenosis will underestimate the disease severity. Hence, directly viewing the plaque in the vessel wall is strongly suggested in order to objectively evaluate the cerebrovascular vulnerable plaque.

High resolution, black-blood magnetic resonance (MR) imaging has been widely used to accurately characterize carotid vulnerable plaque in the last two decades. The aim of using MR black-blood techniques is to suppress the blood signal (black) to enhance the signal contrast between the vessel wall and blood in the arterial lumen. Excellent agreement has been achieved between MR imaging and histology in identification of plaque components, such as intraplaque hemorrhage and lipid core. For assessing carotid plaque, MR imaging is superior to computed tomography and ultrasound imaging techniques due to its advantages including noninvasive imaging, lack of ionizing radiation, excellent soft tissue resolution, and multi-parametric image acquisition.

The Investigators hypothesize that there are specific characteristics in carotid vulnerable plaques in Chinese patients with ischemic cerebrovascular events such as ischemic stroke and transient ischemic attack (TIA). This study seeks to investigate the characteristics of vulnerable plaque in carotid arteries using high resolution, black-blood MR imaging in patients with recent TIA or ischemic stroke.

This is a cross-sectional, multicenter study. A total of 1000 patients will be recruited from more than 10 different hospitals across China within 3 years. All patients will undergo MR imaging for brain and carotid arteries within two weeks after symptom onset. The prevalence of carotid vulnerable plaque and its correlations with brain ischemic lesions, traditional risk factors, and regional distribution of China will be determined.

Inclusion Criteria:

• Patients with recent TIA of ischemic stroke (2 weeks) and carotid plaque determined by ultrasound will be included in this study.

Exclusion Criteria:

• Patients with contraindications to MR scan
• Patients with hemorrhagic stroke
• Patients with evidence of cardiogenic stroke
• Patients with brain tumors
• Patients underwent carotid revascularization therapy, such as stenting and endarterectomy

In this study, we plan to recruit patients with recent TIA of ischemic stroke (within 2 weeks) and carotid atherosclerotic plaque determined by ultrasound. The patients will be recruited from more than 10 hospitals in different areas of China.