以数学模型分析脑缺血-再灌注大鼠缺血半暗带的磁共振成像数据信息

MRI imaging of the ischemic penumbra in rat models of acute cerebral ischemia/reperfusion: An analysis based on mathematical model

背景：多数学者认为广义的缺血半暗带位于严重缺血区周围的低灌注区,处于动态变化过程,能否成功挽救半暗带成为正常灌注区,是治疗过程中的关键。磁共振能够观察脑缺血的面积,但其数据不能直观地反映缺血时间和脑梗死面积之间的变化规律。目的：观察数学模型在大鼠脑缺血-再灌注模型缺血半暗带磁共振成像中的应用效果。方法：制作大鼠大脑中动脉闭塞缺血模型,分为永久缺血组和神经保护剂组,神经保护剂组于造模成功后经鼠尾静脉注射临床常规神经保护剂灯盏花素注射液。在0.5~48h内行弥散加权成像检查,测定缺血灶不同部位的表观弥散系数,计算病侧与对侧正常组织的相对值,即相对表观弥散系数。应用最小二乘法进行数据处理,得出缺血时间和梗死面积的函数关系式,并进行线性分析。结果与结论：大鼠脑缺血-再灌注模型即相对表观弥散系数在永久缺血组9~21h时段3,4点时间（X）和相对表观弥散系数值（Y）呈负相关,且两者线性关系显著,回归方程分别为y=1.458153-0.042770333x,y=1.510346-0.037141333x。在1~6h时间段均有r〉0,P〈0.05,故变量X与Y呈正相关,且线性关系显著。从24~48h,1,2,3,4点的相对表观弥散系数值均随时间增加而增加。提示1~6h时间段是缺血再灌注鼠脑模型神经保护的关键时期。

BACKGROUND: Most scholars believe that generalized ischemic penumbra (IP) was located in the hypoperfusion area next to severe ischemic region, and is a dynamic state. It is a key point for therapy to successfully remedy IP. MRI can observe area of brain ischemia, but the data cannot directly reflect changing rules between ischemia duration and infarct area. OBJECTIVE: To observe the effect of mathematical model in MRI imaging of rat models with acute cerebral ischemia/reperfusion. METHODS: The model of ischemia was established by obstructing middle cerebral artery occlusion. The model rats were divided into ischemia and neuroprotective agent groups (breviscapine injection following ischemia). DWI was performed in 0.5-48 hours. Apparent diffusion coefficient (ADC) in different areas of ischemic focus was measured and relative magnitude of ischemic areas and opposite side areas were calculated. Data processing was performed by using least square method, and the results of functional relation formula between ischemic time and infarct size was concluded, followed by linear analysis. RESULTS AND CONCLUSION: Ischemic time (X) was negatively correlated with relative ADC (Y) during 9-21 hours in points 3 and 4 in rat models of acute cerebral ischemia/reperfusion, and there was significant linear correlation. Those regression equations were following as: y=1.458 153-0.042 770 333x, y=1.510 346-0.037 141 333x. There was significant linear correlation during 1-6 hours in all points of neuroprotective agent group (r > 0, P < 0.05). From 24 to 48 hours, the rADC of all points was increased with time. Results showed that 1-6 hours is an important period for neuroprotection in rat models of acute cerebral ischemia/reperfusion.