摘要
目的:利用大鼠弥漫性轴索损伤(DAI)模型,研究DAI发生后脑干部位磁共振弥散张量成像(DTI)的影像特点,对照病理形态学表现以及免疫组化检查,探讨DAI大鼠脑干部表观弥散系数(ADC)值、FA值与AQP4表达的相关性。方法:将48只SD大鼠随机分成6组,每组8只,其中1组为对照组,不进行头部重物打击,5组为实验组,采用Marmarou自由落体致伤模型造成弥漫性轴索损伤,分别于致伤后3h,6h,12h,24h,72h行MRI扫描,随后立即处死行病理学检查。6组均行常规MRI检查、弥散张量成像、HE染色、嗜银染色及AQP4免疫组化染色。比较DTI结果与病理学检查结果。结果:病理检查显示DAI后大鼠脑干部水肿、轴索肿胀、轴索收缩球出现。DAI后AQP4表达上调,于24h达到高峰,随后下降。ADC值先升高后降低,12h达到顶峰,各向异性FA值持续下降。AQP4表达与ADC值在12h内具有显著相关性(P<0.01),在12～24h内未有相关性,24～72h具有显著相关性(P<0.01)。AQP4表达与FA值在72h内具有显著相关性(P<0.01)。结论:DTI可以在活体水平无创的观察DAI后脑水肿变化情况及轴索的病理改变。DAI后AQP4的表达随时间变化,提示DAI后脑水肿变化情况。大鼠DAI后脑干ADC值与AQP4表达具有相关性,联合AQP4表达及ADC值能够为DAI后的血管源性脑水肿和细胞毒性脑水肿的类型鉴别、发生机理及演变提供理论依据。
Objective： To investigate the changes of magnetic resonance diffusion tensor image（DTI） after diffuse axonal injury（DAI） in rats brainstem.At various stages,diffusion tensor image was used to measure apparent diffusion coefficient（ADC） and fractional anisotropy（FA）,with immunostaining being used to determine Aquaporin 4（AQP4）.Methods： Forty-eight rats were randomly divided into 6 groups.Five separate groups with eight rats in each group were injured and imaged at 3h,6h,12h,24h,72h post-injury by a weight drop trauma model.One group as contral.Rats in DAI group were sacrificed for histology immediately after the scan.The control group of 8 rats was imaged and sacrificed for histology but not injured.Each group was studied by conventional MR imaging,diffusion tensor imaging and histologically examination including HE,silver staining,and immunohistochemistry of AQP4.The results of conventional MRI and DTI were compared with the changes of histopathology.Results： Histological examination showed axonal damage and brain edema in rats of DAI groups.AQP4 expression increased,reached the peak values at 24h and decreased gradually afterwards.ADC value increased and reached the peak values at 12h,and also decreased afterwards.FA value decreased consecutively.There was significant correlation of ADC value and AQP4 expression in brainstem between DAI group and control subjects within 12h and between 24 to 72h（P〈0.01） respectively.There was no significant correlation between 12h to 24h（P0.05）.AQP4 expression was strongly correlated with FA value（P〈0.01） within 72h.Conclusion： The expression of AQP4 protein after DAI is time-dependent and possibly implicated in the formation and resolution of DAI-induced cerebral edema.ADC measurements in brainstem were correlated with AQP4 after DAI.Combining AQP4 expression and ADC value is helpful for reflecting the classification between vasogenic brain edema and cytotoxic brain edema.
出处
《中国临床医学影像杂志》
CAS
北大核心
2011年第6期394-398,409,共6页
Journal of China Clinic Medical Imaging
基金
广东省自然科学基金项目(07008199)
广东省科学计划项目(2010B031600129)
关键词
弥漫性轴索损伤
磁共振成像
弥散
Diffuse axonal injury
Diffusion magnetic resonance imaging
