The patients enrolled into the research will have detailed clinical evaluation and their imaging studies (MRI and Doppler) will be reviewed. After informed consent, subjects will be examined in the stroke Ward /TIA clinic upon recruitment, and later at less than 48 hours of recruitment (blood extraction and urine samples) and for follow up visits at 1 month+/-7 days (clinical evaluation and to extract blood and urine samples), at 3 months (telephonic conversation only) and at 1 year (clinical and repeat MRI brain).