CT灌注扫描评价微栓子栓塞兔脑缺血模型

Evaluation of Rabbit Cerebral Mini-embolic Ischemia Model with CT Perfusion

目的:探索通过16层CT灌注扫描评价利用微小SiO_2颗粒建立兔脑微栓子栓塞模型的可行性,同时描述其CT灌注表现。材料和方法:22只成年新西兰兔,平均体重2.5kg。经颈外动脉主干向颈内动脉推注含SiO_2颗粒(～0.5mm大小不等)的生理盐水混悬液约2ml。30min后行16层CT灌注扫描,原始图像转入工作站进行灌注后处理。结果:22只家兔中3只由于操作不当实验失败,其余19只均成功完成了微栓子的注入。在这19只新西兰兔中,有1只灌注扫描失败,其余均获得了良好的灌注成像CBF、CBV、MTT图,并可进行病灶区分析。18只兔脑微栓子栓塞后30min行CT灌注扫描15只获得阳性结果;3只CT灌注未见异常,24h复查仍未见异常。阳性结果表现为以下5种类型:①右侧颞、额叶大片状低灌注;②右侧颞叶散在小片状低灌注;③右侧颞叶片状低灌注合并基底节区局灶低灌注;①双侧额、颞叶散在小片状低灌注;⑤大脑、小脑、脑干多区域低灌注。灌注表现异常的共计35个病灶(大片低灌注算1个病灶区)中:35个表现为MTT延长,32个有CBF下降,15个有CBV下降。结论:通过颈外动脉向颈内动脉注入微小SiO_2颗粒可成功建立兔脑微栓子栓塞缺血模型。CT灌注扫描可适时反映模型建立的情况,并可显示模型建立的类型,为研究颈动脉粥样硬化微小栓子引起的早期脑缺血和脑梗死提供有价值的方法。

Purpose- To explore the possibility of establishing rabbit cerebral miniembolic ischemia model through small SiO2 grains and evaluating it with 16 row CT perfusion, and describe its CT perfusion appearance. Materials and Methods： Twenty - two New Zealand white adult rabbits, average weight 2.5kg, were selected. Their right cervical vessels were separated and about 2 ml saline with SiO2 grains （ - 0.5mm） were injected into internal carotid artery （ICA） through external carotid artery（ECA） .30 minutes later, CT perfusion on 16 row CT scanner was performed, the raw data were transfer to workstation for perfusion imaging. Results： Three rabbits were died during the experiment. CT perfusion examination failed in one rabbit. We got fine CBF, CBV, and MTT pictures on eighteen rabbits, and their ischemia lesions could be analyzed. Among them, fifteen rabbits were abnormal on CT perfusion maps except 3 normal which were still normal on 24 hour follow - up. 5 types of abnormal perfusion were observed including： （1）Broad low perfusion on right frontal and temporal lobes; （2）Disseminate focal low perfusion in right temporal lobe; （3）Broad low perfusion in right temporal lobes and focal low perfusion in right basal ganglia; （4）Local low perfusion in both side of frontal and temporal lobes; （5）Broad low perfusion in right frontal and temporal lobes, basal ganglia and cerebral stem. 35 lesions of abnormal perfusion appeared： 35 MTT increased, 32 CBF decreased and 15 CBV decreased. Conclusion： Cerebral ischemia model in rabbits can be established through injecting small SiO2 grains from ECA into ICA. CT perfusion can be used to survey the model in time and illustrated the type of ischemia model, these will provide vaiuable method for exploring early stage cerebral ischemia and infarction from embolus of cervical artery.