Ultrasound shear-wave elastography applicability in estimation of post-mortem time

Introduction: Post-mortem rigidity of the tissues is one of the basic principles in forensic medicine to estimate the time of death. Qualitative methods to determine the stiffness of the corpse may have some limitations. Methods that provide quantitative values may be useful. We intended to evaluate the applicability of ultrasound shear-wave elastography of the tissues to estimate the post-mortem interval (PMI). Methods: For 80 corpses, shear-wave elastography of the liver, sartorius muscle, testis, thyroid and parotid was performed before autopsy. Based on the forensic reports as the reference method to define postmortem interval, the corpses were divided into four groups: group 0 (PMI <24 hours), group 1 (PMI >= 24 hours and <48 hours), group 2 (PMI >= 48 hours and <72 hours), and group 3 (PMI >= 72 hours). There were 24, 38, 13, and 5 corpses, respectively, in groups 0, 1, 2, and 3. Results: A significant rise in the elasticity values in comparison to elasticity of normal tissues in live adults was seen very early in the post-mortem period. Between-group comparisons showed that a significant difference in the liver elasticity was present among the groups. The mean (SD) liver elasticity was 10.29 (+/- 0.83) in group 0, 14.98 (+/- 1.56) in group 1, 12.49 (+/- 1.09) in group 2, and 15.64 (+/- 1.68) kilopascals (kPa) in group 3 (P 0.035). Nevertheless, elasticity measurements in other tissues were not helpful in distinguishing post-mortem interval groups. Conclusion: It is possible to use liver quantitative shear-wave elastography to estimate the time of death.