Changes in aortic shape and diameters after death: comparison of early postmortem computed tomography with antemortem computed tomography

Abstract

Purpose: The purpose of this study is to evaluate the postmortem deformation of the aorta on postmortem computed tomography (CT) by comparison with the antemortem CT in the same patient.

Materials and methods: A total of 58 non-traumatic patients without hemorrhagic events who underwent torso CT before and shortly after death were enrolled. Antemortem chest and abdominal CT were obtained in 44 cases and in 57 cases, respectively. The lengths of the major and minor axes of the ascending and descending thoracic aorta and the abdominal aorta were measured on both antemortem and postmortem CT in the same patient. To evaluate the shape of the aorta, the major axis-minor axis ratio (Ma-MiR) was calculated. Mean values of the diameters of the aorta and Ma-MiRs on postmortem CT were compared with those on antemortem CT using the Wilcoxon signed-rank test. We also evaluated the major and minor axes and Ma-MiRs on both antemortem and postmortem CT in two age groups: 65 years and under (n=13) and over 65 years (n=45).

Results: At each level tested, the aorta significantly shrank after death (p<0.001) (ascending thoracic aorta, descending thoracic aorta, and abdominal aorta: 38.5 mm × 33.5 mm, 28.0 mm × 25.9 mm, and 24.4 mm × 21.8 mm on antemortem CT, 30.0 mm × 26.2 mm, 24.4 mm × 20.7 mm, and 21.5 mm × 14.5 mm on postmortem CT, respectively). The postmortem Ma-MiRs significantly increased at the descending thoracic aorta and the abdominal aorta (p<0.001). The diameters of the aorta are longer in older cases at all levels on both antemortem and postmortem CT. The reduction rates were larger in younger cases than older cases at all levels.

Conclusions: After death, the aorta shrunk at all levels, and became oval in shape in descending thoracic and abdominal aorta. The contraction was greater in younger cases than older cases. Investigators who interpret postmortem imaging should be aware of the postmortem deformation of the aorta.