CT灌注成像对大鼠急性脑梗死缺血半暗带的判定

目的：探讨CT灌注成像对脑梗死缺血半暗带参数阈值的判定。方法：取54只Wistar大鼠，随机分为三组。缺血组于梗死后相应的时间点（3h、4h、6h、8h），再灌注组于各个时间点灌注前后分别行CT灌注成像的检查，确定半暗带。取大鼠的脑组织进行病理观察。结果：随着缺血时间的延长缺血范围逐渐扩大。在缺血4h之前，即使该区域的rCBF低至0．146，仍可逆；6h之后，只有rCBF〉0．212时，该区域才有挽救的意义。病理结果显示在缺血6h后，光镜和电镜发现有坏死神经细胞。结论：CT灌注成像能够判断半暗带的阈值。

Penumbra assessment of acute cerebral ischemic in rats by CT perfusion

Objective To investigate viability thresholds of penumbra by CT perfusion in acute cerebral ischemia. Methods Acute cerebral ischemic models were presented in 54 Wistar rats by obstructing the unilateral middle cerebral artery. Dynamic scans with venous bolus injection of contrast media were performed at 3, 4, 6, 8 h respectively after operation in ischemic group with SIEMENS Somatom Sensation 16-slice CT. In reperfusion group, dynamic scans with venous bolus injection of contrast media were performed at 3, 4, 6, 8 h respectively before and after reperfusion. The relative cerebral blood flow (rCBF) of region of interest was measured and calculated. After every intervals of CT scan, cerebral tissues were observed by photomicroscope and electron microscope. Results The techniques of CT perfusion, not only located the ischemic focus during the acute phase, but also quantitatively evaluated the abnormal hemodynamics in the pre-infarction periods and differentiate cerebral infarction from ischemia. If cerebral ischemic models after operation were in 4 h, there were still penumbra areas even if that of rCBF was 0.146, viability threshold of penumbra after 6 h was 0.212. After ischemic 6 h, infracted areas and cell karyopycnosis could be found by photomicroscope and electron microscope. Conclusion CT perfusion imaging could assess the viability thresholds of penumbra in acute cerebral ischemia.