Bolliger Stephan A, Tomasin Doris, Heimer Jakob, Richter Henning, Thali Michael J, Gascho Dominic
Zurich Institute of Forensic Medicine, Department of Forensic Medicine and Imaging, University of Zurich, Winterthurerstrasse 190/52, 8057, Zurich, Switzerland.
Vetsuisse Faculty, Diagnostic Imaging Research Unit (DIRU), Clinic for Diagnostic Imaging, Department of Clinical Diagnostics and Services, University of Zurich, Zurich, Switzerland.
Forensic Sci Med Pathol. 2018 Mar;14(1):85-94. doi: 10.1007/s12024-018-9955-0. Epub 2018 Feb 12.
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.
由于死后过程减缓甚至受到抑制，冷冻可能会使死亡时间的估计变得非常困难。在先前冷冻并随后解冻的尸体中也是如此。了解先前的冷冻情况很重要，因为这可能会导致对死亡时间的评估有所不同。将12个猪头在-20°C下冷冻，6个猪头则保存在室温（约20°C）或冷藏箱（约5°C）中。冷冻的大脑和尸体在室温或冷藏箱中解冻。所有标本都进行了多次CT和MRI扫描，直到对大脑进行组织学检查取样。两名放射科医生评估图像，两名病理学家查看组织学切片，以检查解冻伪像和腐败情况。所有评估人员对于样本是否被冷冻、冷冻了多长时间以及如何解冻均不知情。成像显示，只有在先前冷冻的标本中出现了明显的微小气泡状伪像。组织学检查也仅在这类病例中发现了伪像，即在大脑皮层中出现非常明显的柱状气泡。所有评估人员都成功识别出先前未冷冻的大脑（特异性为100%）以及几乎所有先前冷冻的大脑。我们的结果表明，在日常法医实践中，通过识别可能存在先前冷冻情况的案例，初始尸检成像可能具有极其重要的意义——这些案例因此需要更仔细的审查，从而在死亡时间方面引起警惕。
