单光子放射型计算机断层显像评估猪脑缺血的可逆性时相窗

背景:单光子放射型计算机断层显像检查能够准确发现脑的超早期循环障碍程度、确定时间窗及缺血后不同时间恢复脑功能的可逆程度.目的:制作猪缺血性脑卒中模型,观察其可逆时相窗,并了解单光子发射型计算机断层脑缺血灌注显像在超早期时相窗评估中的价值.设计:随机对照验证性实验.单位:一所市级医院的神经内科.材料:实验于2002-01/08在青岛市市立医院动物实验基地完成,选择4月龄普通家猪12头,雌雄不拘,体质量8～10 kg,按常规普通喂养.干预:将12头猪随机分为阻断组和再灌注组,每组6头,均用动脉夹夹断单侧颈总动脉.阻断组动物在第2,4,5,6,8,10小时处死,再灌注组在相应时间去除颈总动脉夹形成再灌注脑缺血模型,24 h后处死.所有动物在处死前分别行单光子放射型计算机断层显像检查,局部脑血流量测定,并行CT扫描.处死后取两侧大脑各叶组织1 mm3数块,用苏木精-伊红染色后采用光镜和电镜观察脑组织学变化.主要观察指标:单光子放射型计算机断层显像和脑CT检查观察阻断不同时间动物脑组织细胞学变化.结果:12头猪全部进入结果分析.光镜、电镜显示阻断5 h阻断侧神经元略有肿胀,出现线粒体肿胀,线粒体脊变少,胞质减少,少数出现核固缩等病理性改变,并随阻断时间延长而逐渐加重,而阻断4 h以内去除动脉夹者,脑组织结构基本恢复.结论:单光子放射型计算机断层显像可在脑缺血损伤即刻发现脑损伤表现,并经组织学验证脑缺血5 h后神经元即就进入不可逆的状态.

Time window of reversible cerebral ischemia in pigs by single photon emission computed tomography

BACKGROUND:Single photon emission computed tomography (SPECT)measurement is capable of detecting very early cerebral circulatory disorders accurately and assessing the time-window and the possibility of reversible brain function after reperfusion at various post-ischemia time points.OBJECTIVE: To establish the swine model of ischemic stroke, to assess the time-window of reversible ischemia and to evaluate the significance of SPECT cerebral ischemia-perfusion imaging on predicting very early time window.DESIGN: Randomized, controlled and experimental study.SETTING: Neurological department of a municipal hospital.MATERIALS: From January to August 2002, it was completed at the Laboratory Animal Research Center of Qingdao Municipal Hospital. Twelve 4 months old domestic swine (Sus scrofa), males and females and weighing 8-10 kg, were selected and fed with conventional method.INTERVENTIONS: Twelve swine pigs were divided into block group and reperfusion group, 6 in each group. In all the pigs, common carotid artery in one lateral was blocked by a clamp. Animals in block group sacrificed at 2, 4, 5, 6, 8 and 10 hour respectively. In perfusion group, clamps were removed at 2, 4, 5, 6, 8 and 10 hour respectively, and then the animals were killed 24 hours later. Before sacrifice, all the animals underwent SPECT examination, regional cerebral blood flow (rCBF) measurement and CT scan. After sacrifice, 1 mm3 brain tissues were taken from each lobe and were stained by HE staining. Then light microscope and electron microscope were used to study the histological changes.MAIN OUTCOME MEASURES: SPECT and brain CT scan were used to investigate the cytological changes in brain tissues after various length of ischemiaRESULTS: Twelve swine pigs entered the statistical analysis procedure.By using light microscope and electron microscope, it was found that at 5 hour after operation, neurons in operational side were a little swelled, with swelled mitochondria, a mitochondria crests loss and a progressive plasma loss in a few neurons. While in those with clamps removed within 4 hours after turn off, brain tissue structures were mainly restored.CONCLUSION: SPECT is capable of detecting ischemic brain injury immediately. It is proved by histological evidence that a more-than-5-hour ischemia will cause irreversible changes in neurons.