Carotid Plaque Imaging in Acute Stroke

Even with extensive diagnostic workup the underlying etiology remains unidentified in about 25% of patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA). Non-invasive high-resolution magnetic resonance imaging (HR-MRI) of the carotid artery allows detecting vulnerable plaques (VP) and quantifying single plaque components. The hypotheses behind this study are that i) a substantial proportion of cases of AIS and TIA within the anterior circulation and no identified cause (cryptogenic AIS or TIA) are caused by VP in the carotid artery; ii) that these patients are at a high risk of developing a recurrent stroke, TIA, or clinically silent lesions detectable by brain MRI; and iii) that VP in the carotid artery are associated with specific infarct patterns as detected by diffusion-weighted MR imaging. Finally, the investigators will search for biomarkers associated with vulnerable carotid artery plaques. Motivating this study are the following considerations: i) data on the frequency and characteristics of VP in patients with cryptogenic AIS or TIA will provide valuable insights into stroke mechanisms; ii) depending on the results this study may have implications for diagnostic decision making and provide the basis for the planning of targeted interventional studies.

Inclusion criteria

• Age > 49 years old
• Acute ischemic stroke or transient ischemic attack (TIA)
• Neurological symptoms compatible with a stroke or TIA in the anterior circulation (territory of the internal carotid artery)
• Onset of symptoms within the last 7 days
• 1 or more acute ischemic lesion(s) visible on MR diffusion-weighted imaging (DWI) in the territory of a single internal carotid artery
• Presence of carotid artery plaques in the ipsilateral or contralateral carotid artery as defined by ultrasound (criteria: plaque thickness at least 2mm; located within 1cm proximal or distal to the carotid bifurcation)
• Written informed consent

Exclusion criteria

• Primary referral to an outside hospital (to avoid recruitment bias)
• DWI positive lesions outside the territory of a single internal carotid artery
• Carotid artery stenosis > 69% (North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria) ipsilateral to the stroke or TIA as defined by ultrasound (systolic peak flow velocity ≥ 300 cm/s)
• Standard contra-indications for MRI
• Documented allergy to MRI contrast media
• History of radiation to the neck area
• Renal clearance < 30 ml/minute
• Creatinine levels > 2 times the upper limit of the standard range of the respective laboratory within the last 30 days prior to MRI
• Surgical procedure within 24 hours preceding the MRI