Carotid endarterectomy (CEA) is a common surgical method for patients with significant carotid stenosis. The evaluation of perioperative cerebral perfusion is extremely important to evaluate the efficacy of CEA. It can provide information of both the etiology of stroke due to carotid stenosis and cerebral hemodynamic changes after CEA. Arterial spin labeling (ASL) is a magnetic resonance imaging (MRI) technique that uses the protons of arterial blood water molecules as endogenous tracers to evaluate cerebral blood flow (CBF) noninvasively and repeatedly. Territorial ASL (t-ASL), a modified ASL technique, allows independently labeling a single brain-feeding artery to visualize its cerebral blood perfusion territory.  Therefore, we supposed that ASL techniques have ability to provide more information for the evaluation of cerebral perfusion changes pre- and post- CEA.