死后角膜褶皱变化与死后经过时间关系的实验性研究

An experimental study on the association between postmortem corneal fold change and postmortem interval

摘要:

目的：探讨应用数字图像分析技术研究死后角膜褶皱时序性变化规律并筛选合适量化指标。方法：兔缢死后随机分为睁眼组和闭眼组，每组20只，置于20 ℃暗室内。于死后72 h内每隔1 h，使用数码相机采集兔角膜图像，应用MATLAB软件分割出角膜瞳孔区域图像，并提取反映死后角膜皱褶变化的4项图像纹理特征参数值（CON、COR、ASM、HOM）。比较死后睁、闭眼对各参数值随死后经过时间（postmortem interval，PMI）的变化趋势影响，分析各特征参数（y）与PMI（x）的相关性。结果：不论死后睁眼或闭眼，CON随PMI呈上升趋势，COR呈下降趋势，但睁眼组CON、COR值较闭眼组变化迅速且幅度大；CON、COR值与PMI相关性较好（P<0.05），回归方程分别为y=0.002 4x2-0.026 8x+0.467 3（R2=0.978，睁眼组）、y=0.000 4x2-0.010 6x+0.304 4（R2=0.904，闭眼组），y=-0.000 4x2+0.014 2x+3.893 8（R2=0.938，睁眼组）、y=-3E-05x2+0.001 2x+3.980 8（R2=0.852，闭眼组）；ASM、HOM值与PMI关系无统计学意义（P>0.05）。结论：个体死后角膜褶皱发生时序性变化，纹理特征CON、COR与死后经过时间相关性较好。

Abstract:

Objective：To investigate the temporal variation of corneal folds after death using the digital image analysis technique，and to screen out appropriate quantitative indicators. Methods：Rabbits were randomly divided into open-eye group and closed-eye group after hanging，with 20 rabbits in each group，and then they were placed in a dark room at a temperature of 20 ℃. A digital camera was used to capture rabbit corneal images at a one-hour interval within 72 hours after death. MATLAB software was used to obtain the im－ages of the pupil region of the cornea，and the four parameters of image texture features（CON，COR，ASM，and HOM） which reflected the postmortem change of corneal folds were extracted dynamically. The two groups were compared in terms of the variation trend of each parameter with postmortem interval（PMI），and the correlation between each parameter（y） and postmortem interval（x） was ana－lyzed. Results：CON increased with PMI and COR decreased with PMI in both groups，but compared with the closed-eye group，the open-eye group had significantly faster and greater changes. CON and COR were significantly correlated with PMI（P<0.05），and the regression equations were y=0.002 4x2-0.026 8x+0.467 3（CON，R2=0.978 in the open-eye group），y=0.000 4x2-0.010 6x+0.304 4（CON，R2=0.904 in the closed-eye group），y=-0.000 4x2+0.014 2x+3.893 8（COR，R2=0.938 in the open-eye group），and y=-3E-05x2+0.001 2x+3.980 8（COR，R2=0.852 in the closed-eye group）. ASM and HOM had no significant correlation with PMI（P>0.05）. Conclusion：The temporal variation of corneal folds is observed after death，and the texture features of CON and COR are well corre－lated with PMI.