不同时间兔短暂性局灶脑缺血MRI动态演变和病理组织学改变  

Ischemic lesions on Magnetic Resonance Imaging and histological outcomes after different transient periods of focal ischemia in rabbits

作　　者：王志红[1] 刘怀军[2] 黄渤源[2] 徐英进[2] 宋利宏[2] 贺丹[2] 王藏海[2] 

机构地区：[1]河北医科大学第二医院神经内科,石家庄050000 [2]河北医科大学第二医院影像科,石家庄050000

出　　处：《脑与神经疾病杂志》2009年第3期190-194,共5页Journal of Brain and Nervous Diseases

基　　金：河北省自然基金资助项目(c2006000927)

摘　　要：目的研究兔不同时间短暂局灶脑缺血后MRI(包括DWI、PWI和T2WI)缺血改变的时程,并且评价其组织病理学改变。为短暂性脑缺血发作患者的临床诊断和治疗提供依据。方法60只新西兰白兔分为7、10和30min短暂大脑中动脉阻塞模型和假手术组,各组15只。在阻塞前、阻塞中和再灌注后0.5h、2h、6h、12h、24h、48h、72h对实验动物MRI检查(包括DWI,PWI和T2WI),在MRI检查后于72h时间点进行组织病理学评价。结果在假手术组,无MRI和组织学异常。在7、10和30min组,在阻塞时的灌注不足和DWI高信号于再灌注后消失。此后,在7min组,DWI,PWI和T2WI保持正常,而在15和30min组,于6～12小时观察点出现继发的DWI高信号和T2WI异常。组织学检查显示在三组均有神经元坏死,但是,坏死神经元数目在15和30min组显著高于7min组(P<0.001)。结论于再灌注后DWI信号异常的短暂或持久消失依赖于缺血持续时间。DWI信号异常的短暂消失动物有广泛的神经元坏死;然而,DWI信号异常持久消失并不不表明缺血损伤的脑组织完全恢复。这些结果有助于解释在有些脑缺血后DWI正常的患者神经功能缺失的表现,以及有些经历过TIA的患者表现认知功能改变。Objective The purposes of this study were to investigate the time course of ischemic changes on Magnetic Resonance Imaging（including DWI, PWI and T2WI） after different brief periods of focal brain ischemia in rabbits and to evaluate the histopathological outcomes in the regions of DWI abnormalities. Methods Sixty rabbits were subjected to 7 minutes （n=15）; 15 minutes （n=15）; 30 minutes （n=15） of middle cerebral artery occlusion ; and sham operation （n=15）. Magnetic Resonance Imaging （including DWI, PWI and T2WI） were performed during before occlusion; 5min after occlusion and at 0.5, 2.0, 6.0, 12, 24, 48, and 72 hours after reperfusion. After the last MRI study at 72 hours after reperfusion, the brains were evaluated by histopathology. Results No MRI or histological abnormalities were observed in the sham-operated rabbits. In the 7-minute, 15-minute and 30-minute groups, the perfusion deficits and DWI hyperintensities that occurred during occlusion disappeared shortly after reperfusion. The DWI, PWI, and T2WI results remained normal thereafter in the 7-minute group, whereas secondary DWI hyperintensity and T2-WI abnormalities developed at the 612 hour observation point in the 15-minute and 30-minute groups. Histological examinations demonstrated neuronal necrosis in three groups, but the number of necrotic neurons was significantly higher in the 15-minute and 30-minute group than in the 7-minute group （P〈0.001）. Conclusion Transient or permanent resolution of initial DWI lesions after reperfusion depends on the duration of ischemia. Transient resolution of DWI lesions is associated with widespread neuronal necrosis; moreover, permanent resolution of DWI lesions does not necessarily indicate complete salvage of brain tissue from ischemic injury. These results may help to explain the of neurological deficits in some patients who have normal DWI results after cerebral ischemia and cognitive deficits in some patients who experience transient ischemic attacks.

关 键 词：兔 短暂性脑缺血 神经损害 磁共振成像 

分 类 号：R743.32[医药卫生—神经病学与精神病学]