Due to slowing or even inhibition of postmortem processes, freezing may make an estimation of the time-since-death very difficult. This is also true in previously frozen and subsequently thawed bodies. Knowledge of prior freezing is important, as it may lead to a different assessment of the time since death. Twelve pig heads were frozen at −20 °C, and 6 heads were either kept at room temperature (approximately 20 °C) or in a cooling cell (approximately 5 °C). The frozen brains and cadavers were thawed at either room temperature or in a cooling cell. All specimens underwent repeated CT and MRI scanning until the brains were sampled for histological examination. Two radiologists assessed the images and two pathologists reviewed the histological slides with regard to thawing artifacts and putrefaction. All raters were blinded regarding whether the samples had been frozen, for how long and how they had been thawed. Imaging revealed distinct, tiny bubble-like artifacts only in previously frozen specimens. Histology also revealed artifacts only seen in such cases, namely very distinct, columnar bubbles in the cerebral cortex. All raters successfully identified previously unfrozen brains (100% specificity) and nearly all previously frozen brains. Our results suggest that initial post-mortem imaging can be of enormous importance in everyday forensic practice by identifying possible cases of previous freezing – cases that would therefore warrant closer scrutiny and thus raise caution regarding the time of death.
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The authors would like to thank the late Emma Louise Kessler, MD, whose legacy supported this study financially. We are grateful to the Zurich Veterinary Hospital and the Zurich abattoir for of the pig heads. We are also indebted to Sandra Baumann, Markus Enders and Valeria Hofer from the Institute of Forensic Medicine, University of Zurich, for extraction of the pig brains.
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Conflict of Interest
Levy AD, Harcke HT, Mallak CT. Postmortem imaging: MDCT features of postmortem change and decomposition. Am J Forensic Med Pathol. 2010;31:12–7.CrossRefPubMedGoogle Scholar
Schäfer AT, Kaufmann JD. What happens in freezing bodies? Experimental study of histological tissue change caused by freezing injuries. Forensic Sci Int. 1999;102:149–58.CrossRefPubMedGoogle Scholar
Panjabi MM, Krag M, Summers D, Videman T. Biomechanical time-tolerance of fresh cadaveric human spine specimens. J Orthop Res. 1985;3:292–300.CrossRefPubMedGoogle Scholar
Woo SL, Orlando CA, Camp JF, Ajeson WH. Effects of post-mortem storage by freezing on ligament tensile behavior. J Biomech. 1986;19:399–404.CrossRefPubMedGoogle Scholar
Linde F, Sorensen HCF. The effect of different storage methods on the mechanical properties of trabecular bone. J Biomech. 1993;26:1249–52.CrossRefPubMedGoogle Scholar
Hirpara KM, Sullivan PJ, O’Sullivan ME. The effects of freezing on the tensile properties of repaired porcine flexor tendon. J Hand Surg Am. 2008;33:353–8.CrossRefPubMedGoogle Scholar
Lee GH, Kumar A, Berkson E, Verma N, Bach BR Jr, Hallab N. A biomechanical analysis of bone-patellar tendon-bone grafts after repeat freeze-thaw cycles in a cyclic loading model. J Knee Surg. 2009;22:111–3.CrossRefPubMedGoogle Scholar
Lee W, Jasiuk T. Effects of freeze-thaw and micro-computed tomography irradiation on structure-property relations of porcine trabecular bone. J Biomech. 2014;47:1495–8.CrossRefPubMedGoogle Scholar
Maiden NR, Byard RW. Unpredictable tensile strength biomechanics may limit thawed cadaver use for simulant research. Aust J Forensic Sci. 2016;48:54–8.CrossRefGoogle Scholar
Klop AC, Vester MEM, Colman KL, Ruiter JM, Van Rijn RR, Oostra RJ. The effect of repeated freeze-thaw cycles on human tissue visualized by post-mortem computed tomography (PMCT). Clin Anat. 2017;30:799–804.CrossRefPubMedGoogle Scholar
Sugimoto M, Hyodoh H, Rokukawa M, Kanazawa A, Murakami R. Shimizu Jet al. Freezing effect on brain density in postmortem CT. Leg Med (Tokyo). 2016;18:62–5.CrossRefGoogle Scholar
O'Donnell C, Bedford P, Burke M. Massive hemoperitoneum due to ruptured ectopic gestation: Postmortem CT findings in a deeply frozen deceased person. Leg Med (Tokyo). 2011;13:245–9.CrossRefGoogle Scholar