ASIA study flow chart. The diagram shows baseline procedures and follow-up in ASIA study. Subjects with asymptomatic intracranial atherostenoses (ASIA) in basal ultrasound study will undergo a Magnetic Resonance Angiograph (MRA) and will be followed annually in our centre. Two years after inclusion a new duplex and NPS (neuropsychological) study will be performed. Subjects without ASIA will be followed in PERART study.