Norwegian Carotid Plaque Study

BACKGROUND: In 30-40% the cause of ischemic stroke remains undetermined. Most likely, this category hides an additional number of strokes caused by artery-to-artery embolisms due to unidentified atherosclerotic disease, or caused by cardioembolism. Both types are associated with a high risk of recurrent ischemic events and multiple cerebral infarctions. Large-artery atherosclerosis of the brain-supplying arteries is the assumed underlying cause in 10 to 15% of ischemic stroke, mostly deriving from the extracranial carotid artery. Carotid intima-media thickness (cIMT) measured by 2-dimensional (2D) B-mode ultrasonography and estimation of the overall atherosclerotic plaque burden aids future risk prediction. Arterial wall changes, artery caliber variations, degree of stenosis, local hemodynamic alterations and certain plaque characteristics are important for the evaluation of plaque vulnerability and vascular risk stratification. Transcranial Doppler monitoring (TCDM) is a non-invasive bedside examination eligible for detection of microemboli in the human cerebral circulation. HYPOTHESIS: Atherosclerotic stenosis and plaque characteristics can be more accurately assessed by the combination of routine 2D ultrasound, contrast enhanced ultrasound (CEUS), and 3-dimensional (3D) ultrasound. TCDM, CEUS and 3D visualization of the carotid plaque improve the differentiation of stroke etiology and quantification of plaque vulnerability, and aid the prediction of future risk for cerebrovascular events in the individual patient. AIMS: Assessment of prevalence and frequency of Microemboli signals (MES) in unselected patients with cerebral ischemia, the influence of antithrombotic drugs on MES, and the relationship between MES and recurrent stroke or Transient ischemic attack (TIA). Categorization of atherosclerotic carotid artery disease by use of routine and advanced neurosonographic techniques combined with anamnestic and clinical data. Development of a visualization solu