Postmortem CT morphometry of great vessels with regard to the cause of death for investigating terminal circulatory status in forensic autopsy

Postmortem CT (PM-CT) is useful to investigate the viscera in situ before opening the body cavities at autopsy. The present study involved a virtual morphometric analysis of thoracic and abdominal great vessels with regard to the cause of death as a possible index of terminal circulatory status in forensic autopsy cases, using PM-CT data of forensic autopsy cases within 3 days postmortem (n = 93). Perimeters and cross-sectional areas of the aorta and vena cava depended on the age and/or gender of subjects; however, when the vessel flattening index (vFI) was calculated as the ratio of the cross-sectional area (a) to the estimated circle area having the same perimeter (l), using the formula vFI = 4πa/l², the vFI showed distinct differences among the causes of death without significant postmortem time dependence. The index was low for each vessel in fatal bleeding, while the vFI of the abdominal aorta and inferior vena cava was low in hyperthermia (heatstroke), but higher in drowning, hypothermia (cold exposure) and sudden cardiac death. These CT findings provide quantitative data as supplementary indicators to reinforce autopsy findings for interpreting terminal circulatory status.