大鼠颅脑损伤动态CT灌注成像及相关病理生理学基础的初步研究

Dynamic CT perfusion imaging in rats with traumatic brain injury and its relating pathophysiological basis： preliminary study

目的探讨大鼠创伤性颅脑损伤后64排CT动态灌注成像的变化规律及其相关的病理生理学基础。方法将80只成年雄性SD大鼠按照随机数字表法分为正常对照组、假致伤组以及致伤组，致伤组又分为2，6，12，24，48，72，120，168h时相点组。致伤后各组分别进行CT灌注成像、脑含水量、血脑屏障通透性的测定，并观察病理改变，计算损伤区域CT灌注参数与病理生理学变化的相关性。结果伤后2h损伤区域血流灌注骤降达最小值，2～12h内，相对脑血流量（rCBF）和相对脑血容量（rCBV）仍处于低灌注状态，但有所升高。相对平均通过时间（rMYr）延长，表面通透性（PS）增大。随着时间的延长，rCBF、rCBV逐渐升高，直至伤后24h开始逆转，伤侧呈高灌注状态，PS值达最大。48h为高灌注的顶峰期，后逐渐趋于正常。脑含水量于伤后2h开始升高，48h达到高峰期。伤后2h血脑屏障通透性即开始增加，24h达最大值。rCBF和rCBV与脑水肿的变化关系均呈正相关，PS与血脑屏障通透性的变化呈正相关。结论CT灌注成像间接反映血脑屏障和水肿的演变过程，可以作为一种预测活体脑组织灌注和水肿程度的无创性影像学评价手段。

Objective To observe the variation of dynamic 64-slice CT perfusion imaging of rats with traumatic brain injury and discuss the relating pathophysiological basis. Methods A total of 80 adult male SD rats were randomly divided into three groups according to random number table, ie, normal control group, sham injury group and injury group. The injury group was divided into eight subgroups at time points of 2, 6, 12, 24, 48, 72, 120 and 168 hours. The detection of CT perfusion imaging, water content and blood-brain barrier permeability was done in the injured rats at all time points. The pathological changes were also observed to calculate their correlation with CT perfusion parameters of the injured region. Results The relative value of the blood perfusion was decreased significantly to the mimimum within 24 hours after injury. Within 2-12 hours, relative cerebral fluid （rCBF） and relative cerebral blood volume （rCBV） remained in a low perfusion state, with just a little increase. Relative mean transit time （rMTT） was prolonged and permeability surface （PS） increased, rCBF and rCBV were increased gradually with time, which was reversed till at 24 hours after injury and the injured side was in a high perfusion state, with the highest value of PS. The perfusion reached peak at 48 hours after injury and then became normal gradually. The water content was increased at 2 hours after injury and reached its peak at 48 hours. The permeability of blood-brain barrier （BBB） began to increase at 2 hours after injury and reached the peak at 24 hours, rCBF and rCBV were positively correlated with change of brain edema and PS was positively correlated with BBB permeability. Conclusion The dynamic 64-slice spiral CT perfusion imaging reflects the variation of BBB and edema and can be used as noninvasive imaging method for predicting the degree of brain perfusion and edema.