单体素~1H-MRS推断死亡时间的初步研究

目的检测脑内N-乙酰天门冬氨酸、胆碱复合物及磷酸肌酸和肌酸的变化规律,并探讨其与死亡时间的关系。方法选取12只白兔,利用单体素氢质子磁共振波谱测定死后0.5、1、2、4、6、8、12、16、24h脑内N-乙酰天门冬氨酸、胆碱复合物及磷酸肌酸和肌酸峰下面积;分析其在上述时间点的变化规律,建立与死亡时间相关的回归方程。结果在死后24h内N-乙酰天门冬氨酸、磷酸肌酸和肌酸峰下面积随死亡时间的延长而降低(各时间点比较P<0.05),胆碱复合物在死后24h内无明显变化(各时间点比较P>0.05)。回归方程为:Naa:y=0.7425x2-27.282x+299.984(R2=0.962);Cr:y=0.3234x2-12.007x+210.503(R2=0.986)。结论死后24h内兔脑N-乙酰天门冬氨酸、磷酸肌酸和肌酸呈现出一定的变化规律,其与死亡时间相关程度较高,可用于对一定条件下死亡时间的推断。

A preliminary study on estimation of time since death by single-voxel proton 1H-MR spectroscopy

Objective To investigate the time-dependent relationship among postmortem intervals and postmortem levels of nacetylaspartate(Naa),total choline(Cho) and creatine(Cr) in rabbit's brain by single-voxel proton MR spectroscopy(1H-MRS).Methods Naa,Cho and Cr were determined in 12 rabbits' brains by 1H-MRS.The metabolite peak areas of Naa,Cho and Cr were calculated at 0.5,1,2,4,6,8,12,16 and 24h after death with regression equations established.Results Decrease in the metabolite peak areas of Naa and total Cr was noted with the extension of post-mortem interval within 24 hours after death.No variation was found in total Cr.The regression equations were deduced as: y=0.7425x2-27.282x 299.984(R2=0.962) for Naa,and y=0.3234x2-12.007x 210.503(R2=0.986) for total Cr.Conclusion Nacetylaspartate and total creatine level varies time-dependently in the rabbit brain with the extention of postmortem interval,which may be used as parameters for estimating time since death.