Is bone analysis with μCT useful for short postmortem interval estimation?

Abstract

The evaluation of the postmortem interval (PMI) is an important consideration in forensic medicine. The time between death and the discovery thereof is extremely important, not only in terms of the legal process, but also for the course of the investigation. At the time of the discovery of human bones, the evaluation of the PMI is extremely difficult. To date, there is no really effective tool for this evaluation. The objective of our study is to characterize the architectural modifications of human bones using micro-tomography (μCT) in the postmortem period. Ten bone samples were extracted from a single fresh human cranial vault (no freezing, no embalming) from a body donation. The samples were conserved in a controlled environment (a laboratory hood at 20 °C with 60% humidity) for 10 weeks. Every 2 weeks after the death and the sample extraction from the vault, the samples were analyzed with μCT (resolution 10 μm, Bruker HR1172 ®). The 3D analysis focused on general 3D data related to the trabeculae: the total volume (TV), the bone volume (BV), and the bone surface (BS), as well as specific trabeculae data; namely: the number of trabeculae (TbN), trabecular thickness (TbTh), the average distance between the trabeculae (TbSp), and the trabecular pattern factor (TbPf). Each sample was observed separately and compared to itself over time; no comparisons among samples were made. We used a linear mixed model for repeated measures (an unstructured covariance pattern model) and post hoc comparisons between each consecutive time using linear contrast with an SAS software package, release 9.3 (SAS Institute, Cary, NC). We showed a statistical difference for BS/BV (p = 0.046) over time, with a significant decrease during the first 2 weeks (p = 0.003; mean decrease, - 0.99, 95% CI [- 1.61; - 0.36]), while TbSp (p< 0.0001) showed a significant increase during the first 2 weeks (p < 0.0001; mean increase, 0.022, 95% CI, [- 0.016; - 0.028]).Our study highlighted architectural trabecular modifications on postmortem bones using the μCT. These modifications occurred at an early stage, during the first 2 weeks of conservation. Complementary work will need to be performed to allow for better understanding of the biological phenomena observed and to create databases of osseous taphonomy, starting with various individuals, mediums of conservation, types of bone, and with varying techniques for analysis.

Evaluation of Parameters for Estimating the Postmortem Interval of Skeletal Remains Using Bovine Femurs: A Pilot Study

“…In particular, in cases of skeletal remains, the PMI becomes very difficult to estimate because soft tissues decrease substantially or completely. Many researchers have focused on the development of novel methods, including infrared (IR)/Raman microscopic imaging techniques [1,2], inductively coupled plasma optical emission spectroscopy (ICP-OES) [3], or microcomputed tomography (µCT) [4,5]. In addition, combinations of techniques have been reported, such as the combined use of different physicochemical methods [6], luminol and microscopic techniques to screen bones before the use of radiocarbon dating [7], ultraviolet (UV)-induced fluorescence and 490 nm induced fluorescence [8], and µCT, mid-infrared microscopic imaging, and energy-dispersive X-ray mapping [9].…”

Estimation of Late Postmortem Interval: Where Do We Stand? A Literature Review

“…Le Garff et al [ 76 ] conducted a study using bones with a short PMI. They analysed bone samples using micro-CT, observing trabecular modifications through three-dimensional reconstruction of images.…”

Forensic applications of micro-computed tomography: a systematic review

“…It emerged that after 1 month, bone samples extracted from a fresh human vault showed a decrease of mean bone volume, bone surface, and trabecular number, whereas the mean trabecular separation and trabecular thickness increased [58,59]. Moreover, during the first 2 weeks of post-mortem, a significant decrease of the ratio between bone surface and bone volume and of the average distance between the trabeculae was observed [60].…”