实验性急性脑梗塞早期MRI表现与病理对照研究

Experimental study of acute cerebral infarction:early MRI appearances and pathologic findings.

目的 阻断狗大脑中动脉建立急性脑梗塞动物模型，观察早期 Ｍ Ｒ Ｉ表现及其病理改变。方法 将 １６ 只成年狗随机分为实验组（１０ 只）和对照组（６ 只）。经颞开颅阻断一侧大脑中动脉（ Ｍ Ｃ Ａ），造成 Ｍ Ｃ Ａ 供应区急性缺血性脑梗塞，术后 ４、６、８、１２ｈ 行 Ｍ Ｒ Ｉ薄层扫描；取出动物大脑观察病理改变，测定不同时相梗塞区 Ｔ２ 时间和组织水含量。结果 梗塞 ２ｈ Ｍ Ｒ Ｉ Ｔ２ 加权可见尾状核头部、豆状核信号增高；６ｈ Ｍ Ｒ Ｉ可见尾状核、豆状核形成明确梗塞，并出现占位征象。２ｈ 电镜下已有缺血水肿改变，４ｈ 光镜下出现脑缺血水肿改变，电镜下见到血脑屏障受损。相关分析表明：病灶区 Ｔ２ 时间变化与组织水含量变化在时序上有密切关系（ｒ＝ ０．９５３７， Ｐ＜ ０．０１）。结论 Ｍ Ｒ Ｉ可用于脑梗塞早期的诊断。急性脑梗塞早期 Ｍ Ｒ Ｉ表现的病理基础是脑水肿。

Objective To study early MRI appearances of acute cerebral infarction and its pathologic changes.Methods All the dogs underwent craniectomy through transtemporal and their middle cerebral artery (MCA) were occuluded.The thin slice MRI scan were examed at 2,4,6,8,10,12hours on the experimental group.The histopathological changes in different period were studied.Results The MRI intensity as 2 hours after ischemia increased signal intersity on T 2W imaging were observed at the head of caudate nucleus and the lentiform nucleus.At 6h after ischemia both MRI were found to indicate definite infarct foci in the caudate nucleus and the lentiform nucleus,mass effect was seen too.Histopathologic findings:At 2h after ischemia,electro microscope revealed the changes of ischemia and edema.At 4h after ischemia,the photomicroscope demonstrated the changes of ischemia edema and the electromicroscope indicated the damage to blood brain barrier.The correlation analysis demonstrated that the changes of T 2 time were closely relative to the alteration of water content(P<0.01).Conclusion The brain edema is the hispathological basis of early MRI appearances (in 12h) of acute cerebral infarction.MRI can be applied to early diagnosis of acute cerebral infarction.