电磁脉冲照射前后大鼠心肌超声背向散射参数变化的研究

Variation of myocardial integrated backscatter before and after exposure to electromagnetic pulse in rats

目的探讨电磁脉冲照射前、后SD大鼠心肌组织超声背向散射参数变化特点。方法40只二级雄性SD大鼠,单盲法随机分为辐照组和对照组,辐照组给以相应参数的电磁脉冲(EMP)照射,对照组给以假照射。分别于照射前、照射后24 h采集大鼠胸骨旁左室短轴射频图像,并测量感兴趣区心肌背向散射积分(IBS)值、心腔内血池IBS值,计算出标准化心肌背向散射积分(IBS%),两时间点采集图像后每组各活杀10只大鼠,取心肌组织行透射电镜观察。结果EMP照射后大鼠心肌细胞水肿,细胞器改变。与对照组比较,辐照组照射24 h后左室前后壁IBS%均显著降低(P<0.01);后壁IBS值减低(P<0.05)。辐照组前、后壁IBS及IBS%均显著降低。结论SD大鼠EMP照射后心肌IBS%值较照射前降低,IBS值有不同程度改变,提示EMP照射后心肌组织的病理学改变。

AIM To explore the alternating pattern of myocardial ultrasonic integrated backscatter of SD rats before and after being exposed to electromagnetic pulse （EMP）. METHODS Forty SD rats were randomly divided into 2 groups and one group was exposed to EMP. Radio frequency images were acquired from short axis views of left ventricular at the time before and 24 hours after exposure to EMP. The radio frequency images of the normal group were acquired at the same time. Ten rats from each group were then killed and the tissue segments were excised and observed using transmission electron microscope. The values of ultrasonic integrated backscatter （IBS） were obtained with acoustic densitometry technique. RESULTS After exposure , the values of IBS% from either anterior wall or posterior wall decreased （ P 〈 0.05 ） and the values of IBS decreased by various degrees compared with those of normal control group or before exposure to EMP. Under transmission electron microscope, we saw intracellular edema and the alteration of cell organ. CONCLUSION The ultrasonic integrated backscatter values of the rats after exposure to EMP are significantly lower than those before exposure, suggesting some pathological alteration in rats＇ myocardial tissue after exposure to EMP.