Abstract: Cerebral collateral circulation is important in the treatment of acute ischemic stroke. Collateral circulation is a major aspect that physicians would consider to decide the treatment of acute ischemic stroke and a good indicator of patient prognosis. Thus， it is important to accurately evaluate collateral circulation of acute ischemic stroke patients. This paper will review the techniques and clinical applications of CT in collateral circulation assessment， including singlephase CT angiography， multiphase CTA， and CT perfusion.

Key words: cerebrovascular disorders, collateral circulation, tomography,  , Xray computed