Objective To study the changes of cerebral hemodynamics revealed by CT perfusion imaging (CTPI) in rabbit models of cerebral microembolism. Methods Thirty normal New Zealand rabbits were randomly divided into two groups:Group A (n =5) underwent sham operation, group B (n =25) underwent an operation of microembolism. About ten SiO₂ grains (D=0.5 mm) were injected into the internal carotid artery from external carotid artery. CTPI was performed continuously at 30 minutes, 3,6, 12, and 24 hours after embolization. At 24 hours after embolism, the rabbits were sacrificed and the brain was removed and prepared for histopathology with HE staining. According to the results of HE staining, the rabbits were divided into cerebral ischemia and cerebral infarction subgroups. The serial changes in cerebral blood flow (CBF), cerebral blood volume (CBV) and mean transit time (MTT) were discussed respectively. ResultsNo abnormality was seen on both CTPI and HE staining pathology in the group A. In the group B, three rabbits died during the experiment, CTPI was failed in one rabbit because of the failure of femoral vein puncture, and CTPI was succeeded in twenty-one rabbits, including abnormal perfusion in eighteen rabbits and normal perfusion in three rabbits. By HE staining, among the rabbits of abnormal perfusion, ten rabbits were of cerebral infarction, seven rabbits were of cerebral ischemia and one rabbit was normal. At 30 minutes after embolization, the ischemic brain had low perfusion to a different degree, reduced CBF, prolonged MTT and almost normal CBV. During 3 to 6 after embolization, the descended perfusion was further aggravated, the value of CBV was slightly descended. During 12 to 24 hours, the low perfusion was lightened. The cerebral infarction had evidently low perfusion in 30 minutes which showed remarkably descended CBF and CBV, and significantly prolonged MTT. Three rabbits had lightened low perfusion at 3 hours, 6 hours and 12 hours, respectively, but in the subsequent time, the perfusion was descended rapidly again and further aggravated along with time. Another seven rabbits had evidently low perfusion and the degree was aggravated gradually or fluctuated slightly at a certain level. ConclusionsThe cerebral ischemia has most evidently low perfusion during 3 to 6 hours and the low perfusion is lightened during 12 to 24 hours, while the cerebral infarction show that the low perfusion is gradually aggravated along with the time or descended rapidly again after lightened to a different degree. The cerebral ischemia is characterized by mismatch in CBF and CBV values which show a significantly reduced CBF but almost normal CBV, whereas the cerebral infarction shows a matched significant decrease in both CBF and CBV values.