Abstract

Intracranial atherosclerotic disease (ICAD) is defined as atherosclerotic lesions affecting large intracranial arteries at the base of the brain, including the intracra-nial carotid artery (ICA), middle cerebral artery (MCA), and basilar artery, etc. ICAD was once known as one of the most common subtype of strokes worldwide, especially in Asians and Hispanics [1-3]. However, ICAD has received less attention due to a focus on the more accessible extracranial carotid artery occlusive disease in the West. A study that showed a strikingly high prevalence of both intracranial plaque and intracranial stenosis in 339 autopsies of patient with stroke suggested that the real prevalence of ICAD in whites may be underestimated [4]. The increasing prevalence of risk factors for ICAD, such as diabetes and metabolic syndrome, also contribute to the increase in the prevalence of ICAD. Only one or two decades ago, it was not easy to screen for ICAD in asymptomatic patients, because ICAD is not easily detected by physical examination or clinical history. However, with advances in CT and MR techniques making it easier to apply these modalities more widely, ICAD is being detected much more frequently. An increase in the diagnosis of ICAD has lead to an increase in new knowledge about stroke risk and the pathophysiology of ICAD. High-resolution magnetic resonance imaging (HR-