高渗盐对急性氨中毒大鼠脑效应的MR灌注成像研究

Effect of hypertonic saline on rats with acute ammonia intoxication:a study utilizing perfusion-weighted magnetic resonance imaging

目的研究高渗盐对急性氨中毒情况下大鼠脑MR灌注成像的NEI,MSD和MTT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。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(AdvantageWorkstationAW4.0-05,GE公司),采用Functiontool灌注软件处理,分别获得NEI、MSD和MTT参数图,选取尾壳核、运动皮层,感觉皮层,丘脑及小脑实质为兴趣区(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值及各组rMTT及rMSD值比较均无明显差异。结论急性氨中毒大鼠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。

Objective To apply MR perfusion weighted imaging to reflect the changes of the perfusion of rat with acute ammonia poisoning before and after using hypertonic saline. 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 in- jected intraperitoneally with ammonium acetate; then 6 rats were injected by femoral vein with hypertonic saline and the other 6 control rats were injected by femoral vein with saline.The other groups were only injected by femoral vein with hypertonic saline and saline, after 15min MR perfusion-weighted imaging were performed. NEI, MSD and MTT topographical maps were achieved by the Workstation（AW4.0-05, GE）. The values ofNEI, MSD and MTT of the right or left sensory cortex, caudate-putamen, thalamus, cerebellar hemisphere and the motor cortex were measured. Then took means NEI, MSD and MTT of two-sides of cerebellar hemisphere ROIs in each rat. the relative NEI, MSD and MTT（rNEI, rMTT and rMSD） were calculated as ratios to the averged left and right cerebellar values.Took 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-puta- men 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 were lower than that of ammonia plus 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 caudateutamen than that of ammonia plus saline suggested perfusion cut down .So hypertonic saline can relieve brain hyperemia in rats with acute ammonia intoxication.