Estimation of postmortem time based on aorta narrowing in CT imaging.

Computed tomography (CT) in forensic medicine is commonly used in determination of cause of death. Here, we show that the information provided by CT may also be of value for estimation of time after death. The relationship between abdominal aorta narrowing just below the diaphragm and time after death was examined in 140 cases. Aorta narrowing was defined using a flatness ratio, which was calculated by dividing the shorter axis of the aorta by the longer axis. Time after death was classified into 6 time periods. The flatness ratio gradually and significantly decreased with increased postmortem time, showing increased aorta narrowing with increased time after death. A further examination of aorta narrowing in 15 autopsy cases in which CT images were taken at two postmortem times gave similar findings. The results of the study suggest that aorta narrowing in postmortem CT imaging may be used to estimate time after death.