CT Perfusion Imaging Study of Acute Cerebral Microembolic Model in Rabbits

Purpose:To establish a stable microembolic model of brain in rabbits,and to evaluate the value of computed tomography perfusion imaging(CTPI) in acute ischemic cerebrovascular disease. Methods:Thirty New Zealand white rabbits were randomly divided into two groups:Group A(n = 5) underwent a sham operation;group B(n = 25) underwent an operation of microembolic brain injury. Right cervical vessels were separated,and about ten SiO2 grains(D = 0.5mm) were injected into internal carotid artery by external carotid artery in group B.After 30 minutes,CTPI was performed and the values of CBF,CBV,and MTT were measured in the lesions and the normal contralateral regions.After 24 hours,the brain was extracted and HE stain was performed.The analysis of receiver operating characteristic (ROC) curves of CBF,CBV and MTT were performed by SPSS 11.0 statistic software,and the accuracy of CTPI in diagnosing acute cerebral ischemia was evaluated.Results:No abnormity was seen both on CTPI and HE stain in group A.In group B,three rabbits were died during the experiment,CTPI was defeated in one rabbit because of the failure of puncture of femoral vein,and CTPI was succeeded in twenty - one rabbits,including abnormal perfusion in eighteen rabbits and normal perfusion in three rabbits.By HE stain,among the rabbits with abnormal perfusion,ten rabbits were with cerebral infarct, seven rabbits were with cerebral ischemia and one rabbit was normal.While among the rabbits with normal perfusion,one rabbit was with slightly ischemic and two rabbits were normal.Reduced CBF, prolonged MTT and slightly low or high CBV were found on CT perfusion maps.There was low perfusion in right frontal and temporal lobes in five rabbits,low perfusion in right frontal and temporal lobes,basal ganglia and cerebellum in four rabbits,local low perfusion in right temporal lobe in seven rabbits and local low perfusion in both side of frontal and temporal lobes in two rabbits.There were significant differences between abnormal side and normal side for CBF and MTT,but for CBV,there was no significant difference.By ROC analysis,when the value of CBF was set less than 67.06ml/(min·100g),the sensitivity and specificity were all 84.6%in diagnosing cerebral ischemia.If the value of CBV was set less than 3.08 ml/100g,the sensitivity and specificity were all 74.4%.And if the value of MTT was set more than 4.58s,the sensitivity and specificity were all 87.2%.Conclusion:CBF and MTT have high accuracy in diagnosing acute cerebral ischemia and CTPI can be used as an accurate and non - invasive method in evaluating the acute ischemic cerebrovascular disease.