Abstract: Objective To investigate the clinical value of dynamic 4D spiral CT for cerebral blood flow perfusion and vascular imaging in patients with acute cerebral infarction before and after thrombolysis with rt-PA. Methods The imaging data of dynamic 4D CT of 62 patients with acute cerebral infarction undergoing thrombolysis with rt-PA were retrospectively analyzed,and the regional cerebral blood flow(rCBF),regional cerebral blood volume(rCBV),peak time(TPP)and mean transit time(MTT)in the focal region of patients with acute cerebral infarction before and after the thrombolysis with rt-PA was compared. Results All 62 patients included 55 cases of local arterial branches decreased for and 7 cases without obvious abnormalities by cerebral angiography;after the thrombolysis with rt-PA,there were 60 cases of the local vascular branches increase,and 2 cases without obvious abnormalities by cerebral angiography.The levels of rCBF,rCBV,TPP and MTT before the thrombolysis were 20.73±5.44,1.21±0.30,19.37±3.70 and 6.52±0.77,respectively,and after thrombolysis were 37.66±8.10,1.96±0.41,18.98±4.25 and 6.55±0.81,respectively.Between the two groups,there were statistical significant difference in the levels of rCBF and rCBV(P<0.05),but not in the levels of TTP and MTT(P>0.05). Conclusion The perfect cerebral blood flow perfusion and vascular imaging in patients with acute cerebral infarction before and after thrombolysis with rt-PA can be shown by dynamic 4D CT and the scan will provide accurate bases for the evaluation of treatment.