【作者】 秦少华；

【导师】 黎元； 冯晓源； 刘含秋； 何慧瑾； 姚振威； 梁宗辉；

【作者基本信息】 复旦大学 ， 影像医学与核医学， 2009， 硕士

【摘要】 第一部分高渗盐对急性氨中毒大鼠脑效应的MR弥散成像研究目的:研究急性氨中毒情况下大鼠脑MR弥散成像的表观弥散系数(ADC)的变化,以及高渗盐对此变化的影响。材料和方法:12只雄性SD大鼠随机分为二组,生理盐水对照组和高渗盐组,每组6只。12只大鼠分别腹腔注射醋酸铵5mmol/kg,浓度调整到每只注射量为3ml/kg:于用氨前,用氨后5min各自进行MR弥散成像,用于急性氨中毒况下大鼠脑的表观弥散系数(ADC)的变化研究。然后6只急性氨中毒大鼠通过股静脉滴注23.4%高渗盐溶液,6ml/kg,15min滴完;另6只急性氨中毒大鼠通过股静脉滴注生理盐水作为对照;之后马上进行MR弥散成像。原始图象运用GE Functiontool软件处理,分别选定双侧尾壳核、运动皮层、感觉皮层、丘脑及小脑实质为兴趣区(ROI),获得兴趣区(ROI)的表观弥散系数(ADC)平均值。结果:在所选10个兴趣区中,用氨前后双侧尾壳核ADC值降低达到统计学有意义;滴注23.4%高渗盐溶液后所有选定兴趣区的ADC值均较对照组高,然而并未达到统计学有意义。结论:急性氨中毒导致双侧尾壳核细胞毒性水肿;高渗盐溶液引起几乎所有ROI的ADC值升高,但均未达到统计学意义,是否与测量时点过早有关,尚需进一步研究。第二部分急性氨中毒大鼠脑MR灌注成像研究目的:研究急性氨中毒情况下大鼠脑的MR灌注成像的NEI(negative enhancedintegral,负性增强积分),MSD(maximum slope of decrease,最大下降斜率)和MTT(mean transit time,平均通过时间)值的变化,探讨急性氨中毒大鼠脑的灌注变化规律。材料和方法:12只大鼠随机(数字表法)分为空白对照组和氨中毒组,每组6只。氨中毒组6只大鼠均以腹腔注射醋酸铵的方法造成急性氨中毒。大鼠模型制备后5min行MR扫描。原始图像传送至工作站(AdvantageWorkstation AW4.0-05,GE公司),采用Functiontool灌注软件处理,分别获得NEI、MSD和MTT参数图,选择尾壳核(CPu)、运动皮层(MCx),感觉皮层(SCx),丘脑(Tha)及小脑(Cb)实质为兴趣区(ROI);分别测量上述部位的NEI、MSD和MTT值,然后取双侧小脑(Cb)实质均值并分别计算上述左侧或右侧兴趣区(ROI)与之的比值,得到相对NEI、MSD和MTT(rNEI、rMSD及rMTT),两组进行比较。结果:氨中毒后所选各个脑区rMTT值均较对照组缩短,并且达到统计学意义;rNEI及rMSD与对照组相比没有明显差异。结论:急性氨中毒导致大鼠脑灌注血流增加,提示可能存在充血改变。磁共振灌注成像可以反映急性氨中毒大鼠脑微循环的变化。第三部分高渗盐对急性氨中毒大鼠脑效应的MR灌注成像研究目的:研究高渗盐对急性氨中毒情况下大鼠脑的MR灌注成像的NEI(negative enhanced integral,负性增强积分),MSD(maximum slope ofdecrease,最大下降斜率)和MTT(mean transit time,平均通过时间)值的影响,进而揭示高渗盐对急性氨中毒大鼠脑灌注的影响。材料和方法:24只大鼠随机(数字表法)分为生理盐水组、高渗盐组、氨+生理盐水组、氨+高渗盐组,每组6只。其中氨+生理盐水组、氨+高渗盐组的12只大鼠均以腹腔注射醋酸铵造成急性氨中毒;然后按照预先分组6只急性氨中毒大鼠通过股静脉滴注23.4%高渗盐溶液;另6只急性氨中毒大鼠通过股静脉滴注相同剂量生理盐水作为对照。另两组生理盐水组、高渗盐组只通过股静脉滴注23.4%高渗盐溶液或生理盐水,15min滴完,作为对照:之后马上进行MR成像。原始图像传送至工作站(Advantage Workstation AW4.0-05,GE公司),采用Functiontool灌注软件处理,分别获得NEI、MSD(maximum slode of decrease,最大下降斜率,相当于局部血流流入速度)和MTT参数图,选取尾壳核(CPu)、运动皮层(MCx),感觉皮层(SCx),丘脑(Tha)及小脑(Cb)实质为兴趣区(ROI),分别测得双侧上述ROI的NEI、MSD、MTT值,然后取双侧小脑(Cb)实质均值并分别计算上述左侧或右侧兴趣区(ROI)与之的比值,得到相对NEI、MSD和MTT(rNEI、rMSD及rMTT),然后四组进行比较。结果:左侧尾壳核区的rNEI值氨+高渗盐组及高渗盐组低于氨+生理盐水组,具有统计学意义;右侧尾壳核区的rNEI值氨+生理盐水组较其他三组均高,且具有统计学意义;而其他各脑区rNEI值比较没有明显差异。各组rMTT及rMSD值比较均无明显差异。结论:大鼠急性氨中毒尾壳核区存在充血变化,高渗盐溶液输注后可引起尾壳核区的rNEI值降低,表明高渗盐溶液可缓解大鼠急性氨中毒后尾壳核区高灌注状态,所以高渗盐可以缓解急性氨中毒大鼠脑高灌注,有利于脑水肿缓解。更多还原

【Abstract】 PartⅠ:Effect of hypertonic saline on rats with acute ammonia intoxication:a study utilizing diffusion-weighted magnetic resonance imagingPurpose:To investigate the value of Apparent diffusion coefficient in rats with acute ammonia intoxication before and after using hypertonic saline.Materials and Methods:twelve male SD rats were randomly divided into two groups.12 rats were performed MR diffusion-weighted imaging before and after they were injected intraperitoneally with ammonium acetate;and then 6 rats were injected by femoral vein with hypertonic saline and the other 6 control rats were injected by femoral vein with saline.After 15min MR imaging were performed.Apparent diffusion coefficient(ADC)topographical maps were archived by the Workstation(AW4.0-05,GE).The values of ADC of the right or left sensory cortex,caudate-putamen,thalamus, cerebellar hemisphere and the motor cortex were measured.Results:We measured ADC in 10 brain regions,ADC decrease only in bilaeral caudate-putamen.The using hypertonic saline dose not influence the values of ADC in 15min.Conclusion:The values of ADC decrease in bilaeral caudate-putamen suggested ammonia induced cytotoxic edema in rats with acute ammonia intoxication.Hypertonic saline dose not influence the values of ADC in short time period.PartⅡ:Study of rats with acute ammonia intoxication with magnetic resonance perfusion imagingPurpose:To investigate the change of the value of NEI (negative enhanced integral),MSD(maximum slope of decrease) and MTT (mean transit time) in rats with acute ammonia intoxication.Materials and Methods:twelve male SD rats were randomly divided into twogroups.6 rats were performed MR perfusion-weighted imaging after they were injected intraperitoneally with ammonium acetate;and then the other 6 control rats were performed MR perfusion-weighted imaging.NEI、MSD and MTT topographical maps were archived by the Workstation(AW4.0-05,GE). The values of NEI、MSD and MTT of the right or left sensory cortex, caudate-putamen,thalamus,cerehellar hemisphere and the motor cortex were measured.Then take mean NEI,MSD and MTT of two-sides of cerebellar hemisphere ROIs in every rat,the relative NEI,MSD and MTT(rNEI、rMTT and rMSD) were calculated as ratios to the averged left and right cerebellar values.Take the ratios of two groups into statistical analysis.Results:relative MTT prolonged in everv ROIs after poisoning, had statistical significance(P＜0.05),which compared with pre-poisoning;relative NEI and MSD of poisoned rats compared with pre-poisoning have no significant differences.Conclusion:Rats with acute ammonia intoxication can be obvered cerebral hyperemia in all ROIs. MR perfusion weighted imaging can reflect changes of the microcirculation of the poisoned rats’ brain,which suggest that brain microcirculation severe disturbance is possibly one of the causes which aggravate brain injury and induce delayed encephalopathy.PartⅢ:Effect of hypertonic saline on rats with acute ammonia intoxication:a study utilizing perfusion - weighted magnetic resonance imagingPurpose:To apply MR perfusion weighted imaging to reflect the changes of the perfusion of rat in acute ammonia poisoning before and after using hypertonic saline.Materials and Methods:24 male SD rats were randomly divided into four groups,ammonia plus hypertonic saline,ammonia plus saline,saline and hypertonic saline.12 rats were injected intraperitoneally with ammonium acetate;and then 6 rats were injected by femoral vein with hypertonie saline and the other 6 control rats were injected by femoral vein with saline,after 15min MR perfusion-weighted imaging were performed.the other group were injected by femoral vein with hypertonic saline and saline,after 15min MR perfusion-weighted imaging were performed too.NEI、MSD and MTT topographical maps were archived by the Workstation(AW4.0-05,GE).The values of NEI、MSD and MTT of the right or left sensory cortex, caudate-putamen,thalamus,cerebellar hemisphere and the motor cortex were measured.Then take mean NEI,MSD and MTT of two-sides of cerebellar hemisphere ROIs in every rat,the relative NEI,MSD and MTT(rNEI、rMTT and rMSD) were calculated as ratios to the averged left and right cerebellar values.Take the ratios of four groups into statistical analysis.Results:Relative MTT and MSD had no remarkable changes in four groups.Relative NEI(rNEI) decreased in group of ammonia plus hypertonic saline in the caudate-putamen ROIs,which compared with that of ammonia plus saline;had statistical significance(P＜0.05). The values of relative NEI(rNEI) in groups of saline and hypertonic saline are low than that of in group of ammonia plus hypertonic saline in the caudate-putamen ROIs,had statistical significance(P＜0.05).Conclusion:The values of relative NEI decrease in group of ammonia plus hypertonic saline in eaudate-putamen suggested perfusion cut down.So hypertonic saline can relieve brain hyperemia in rats with acute ammonia intoxication.更多还原