摘要
目的 :采用自体血栓栓塞模型研究CT灌注成像各参数在脑缺血 12h内的动态变化以及计算各参数的半暗带阈值。方法 :5只新西兰大白兔行自体血栓栓塞制成局灶性脑缺血模型。采用GELightspeed 16MSCT ,在基础灌注后于栓塞后 2 0min扫描一次 ,1～ 6h内每隔 1h扫描一次 ,6～ 12h内每隔 2h扫描一次。CT灌注软件可以给出每个时间点的各参数图。在完成缺血后 12hCT灌注扫描后 ,断头取脑 ,进行TTC染色 ,并根据CT灌注各参数图和TTC的染色结果将梗塞侧分为中心梗塞区 ,半暗带区和相对正常区三部分。结果 :所有参数的动态变化可分为三个阶段 :①梗塞后 2h内 :CBV在中心梗塞区明显下降 ,在半暗带区轻度下降或正常 ,在相对正常区轻度上升 ,CBF在三个区域均明显下降 ,MTT和TTP均明显延长 ;②梗塞后 2～ 5h :所有参数均在一定水平上轻度波动 ;③梗塞后 5～ 12h :在中心梗塞区和半暗带区CBV和CBF下降 ,MTT和TTP延长和轻度缩短 ,而在相对正常区CBV和CBF明显上升 ,MTT和TTP明显缩短。在缺血 2 0min时 ,若CBV % <6 6 .5 7% ,CBF % <39.2 2 % ,MTT % >2 .6 3或TTP % >1.97,缺血组织就发生不可逆损伤。结论 :实验证明CT灌注成像能够准确地显示脑缺血的部位和范围 ,也能在一定程度上反映脑缺血的病理生理改变。
Objective:To study the dynamic changes of CT perfusion parameters during the first 12 hours in the embolic cerebral ischemia models and calculate the threshold values of the penumbra.Methods:Five New Zealand white rabbits underwent surgery to establish a cerebral ischemia model by an autologous blood clot. All the CT scans were performed with a general electric medical system lightspeed 16 MSCT. Following the baseline scans, further CT scan were performed at the same location at 20 min, 1h, every an hour up to 6 hours and then scan at 2 hours interval up to 12 hours after the embolus was delivered. All parameters' maps were obtained by CT perfusion software (GEMS) at each time points. The brains were taken immediately after the 12～hour scan and stained by TTC. According to the CT perfusion images and the TTC results, the infarcted side could be divided into three regions: core, penumbra and the relatively normal region.Results:The changes of all parameters could be divided into three stages: the first two hours, in which the CBV descended more remarkably in the core than in the penumbra but ascended slightly in the relatively normal region while the CBF descended and MTT,TTP prolongated in all regions with different degrees. 2～5hours, in which all the parameters fluctuated slightly at a certain level. 5～12hours, in which the CBV and CBF descended, MTT and TTP prolongated or shortened slightly in the core and penumbra though much notably in the former while the CBV, CBF ascended and MTT, TTP shortened remarkably in the relatively normal region. The ischemic tissue was unsalvageable if CBV%<66.57%, CBF%<39.22%, MTT%>63 or TTP%>97 at the twenty minutes after ischemia.Conclusion:We have experimentally demonstrated that the location and extent of cerebral ischemia could be accurately assessed by CT perfusion images. The pathophysiology of the ischemia could be reflected by the CT perfusion at certain extent. CT perfusion maps could guide the selection of the thrombolytic therapy.
出处
《医学影像学杂志》
2004年第11期928-931,共4页
Journal of Medical Imaging
