Background　and　Objectives:　Clinical　diagnosis　of　ischemic　stroke　commonly　relies　on　examining　cerebral　perfusion　changes　by　using　computed　tomography　perfusion　(CTP)　techniques.　However,　the　radiation　dose　in　CTP　is　quite　higher　in　comparison　to　computed　tomography　angiography　(CTA),　with　associated　costs　and　time.　Methods:　Hence,　this　study　established　a　lumped-parameter　model　(LPM)　of　brain　tissue　microcirculation　(BTM)　based　on　CTA,　aiming　to　achieve　real-time　calculation　of　cerebral　perfusion.　After　validation　of　calculated　flow　results　with　clinical　data,　the　BTM-LPM　model　was　used　to　examine　the　changes　in　cerebral　perfusion　following　ischemic　stroke,　in　which　the　effects　of　nine　anatomical　structures　of　the　Circle　of　Willis　(CoW)　together　with　various　distribution　patterns　of　stenosis　in　the　feeding　arteries　were　considered.　Results:　When　compared　the　calculated　flow　results　from　BTM-LPM　with　the　clinically　measured　data　of　literature,　the　mean　squared　error　(MSE)　value　for　the　feeding　arteries　was　3.9　%　and　its　total　value　for　microcirculatory　flow　in　each　region　was　0.1　%.　Notably,　the　calculation　time　was　35.6　s.　In　the　case　of　the　CoW　missing　the　left　and　right　posterior　communicating　artery,　a　60　%　stenosis　of　the　basilar　artery　is　likely　to　cause　ischemic　damage　to　some　temporal　and　occipital　lobes　of　the　right　and　left　hemispheres.　While　in　the　case　of　the　CoW　missing　the　anterior　communicating　artery　and　the　left　posterior　communicating　artery,　ischemic　damage　to　the　entire　frontal　lobe　and　parts　of　the　temporal　and　parietal　lobes　of　the　left　hemisphere　was　found　when　80　%　stenosis　occurred　in　the　left　internal　carotid　artery.　Conclusions:　The　BTM-LPM　proposed　in　this　study　could　accurately　calculate　cerebral　perfusion　in　real　time　and　demonstrated　the　importance　of　CoW　anatomy　in　different　ischemic　injuries　to　cerebral　tissue.　The　calculated　cerebral　perfusion　would　be　a　reference　value　for　early　diagnosis　and　preoperative　planning　of　different　ischemic　injuries　to　cerebral　tissue,　thereby　the　BTM-LPM　holds　great　promising　for　replacing　CTP　examination.　©　2023