磁共振波谱技术推测不同温度下的死亡时间

目的利用单体素质子磁共振波谱技术推断不同温度下的死亡时间(postmortem interval,PMI),探讨不受外界环境温度影响下推断PMI的可行性。方法选取24只白兔,分为A组(10℃)、B组(30℃),利用磁共振单体素波谱测定死后0.5、1、2、4、6、8、12、16和24h脑内N-乙酰天冬氨酸(N-acetyl-aspartate,Naa)、胆碱复合物(Choline,Cho)、磷酸肌酸和肌酸(phosphocreatine and creatine,Cr)峰下面积(相对含量)及各代谢物之间相对含量的比值。结果在死后24h内Naa和Cr峰下面积随PMI的延长而减少,Naa/Cr、Cho/Cr随PMI的延长而降低。回归分析:自变量为Naa/Cr的二次多项式方程为:y=0.0019x2-0.803x 1.4498(R2=0.962);自变量为Cho/Cr的二次多项式方程为:y=-0.0024x2 0.926x 1.1777(R2=0.986)。用Naa/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为2.10～37.90min,用Cho/Cr的方程推测PMI,当PMI<24h时,平均偏离时间为1.69～40.87min。结论Naa/Cr、Cho/Cr的死后变化与时间呈强相关性且受环境温度影响不大,可用于不同温度下PMI推断。

Estimation of postmortem interval with single-voxel proton 1H-MR spectroscopy at different temperature

Objective To find an objective method for estimation of postmortem interval(PMI) with single-voxel proton MR spectroscopy at different temperature.Methods Changes of metabolite peak area and peak area ratio of the Nacetylaspartateand(Naa),choline(Cho) and total creatine(Cr) in the brain of 24 rabbit models were measured by 1H-MR spectroscopy(1H-MRS) at 0.5,1,2,4,6,8,12,16 and 24 h,respectively after death.Results Naa and Cr decreased continuously with the extension of PMI,and the ratios of Naa/Cr and Cho/Cr also decreased continuously with the extension of PMI within 24 h.The quadratic polynomial regression equation is y=0.001 9 x2-0.803 x 1.449 8(R2=0.962)(Equation 1) with the Naa/Cr used as an independent variable,while the quadratic polynomial regression equation is y=-0.0024x2 0.926x 1.177 7(R2=0.986)(Equation 2) with the Cho/Cr used as an independent variable.The average deviations were about 2.10-37.90 min and 1.69-40.87 min,respectively if the PMI was estimated by Equation 1 and Equation 2,respectively.Conclusion Our study indicates that there is a strong correlation between Naa/Cr,Cho/Cr and PMI,which may be used for estimation of PMI at different temperature.