Experimental study on changes of postmortem temperature distribution field of skeletal muscle blunt contusion before death in rabbits

Abstract:

Objective：To investigate the thermal imaging change of skeletal muscle blunt contusion in the early postmortem stage by using infrared thermal imaging technology，so as to obtain the regularity of its change with the time of death via objective and quanti－tative analysis. Methods：Rabbit models with blunt contusion were established and killed by air embolization after 6 h. the skeletal muscle blunt injury model was prepared. Infrared thermal imaging and histopathology examination of injured and healthy limbs were performed by infrared thermal imager immediately after injury，immediately after death，6 h after death，24 h after death，3 d after death and 6d after death. Average temperature（Tmean） and maximum temperature（Tmax） were extracted and the reason of image change was analyzed. Results：Immediately after the injury，the yellow region of central blunt contusion was increased，with visible outline. Immediately after death，the infrared thermal image of the damaged area turned into dark red. Damage contour at 6h after death was circular and distinguishable. The contour of damaged area was not recognizable during 24 h-6 d. There were significant differences in infrared thermal data values at different time points among groups（FTmean=1 162.040，PTmean=0.000；FTmax=1 217.042，PTmax=0.000）. Tmean and Tmax in the injured limb group were lower than those in the healthy limb group，and there were significant differences（FTmean=51.440，PTmean=0.000；FTmax=69.808，PTmax=0.000）. There was an interaction of detection time among groups（FTmean=19.040，PTmean=0.000；FTmax=15.769，PTmax=0.000）. Tmean and Tmax value in the injured limb were reached the peak at about 6 h after death，then gradually decreased，and gradually stabilized at 24 h，3 d and 6 d after death. Conclusion：Changes of infrared thermal imaging and temperature value parameter of skeletal muscle blunt contusion in different time after death have certain time regularity，which provides a nondestructive objective and quantitative testing method for predicting the time of skeletal muscle blunt contusion of individual after death.