Hierarchical Micro-CT Top-Down Examination of Cranial Gunshot Injuries

Abstract

Micro-CT examination has been considered a valuable tool for investigating the bone microstructure in various contexts. To date, however, there has not been a sufficient body of work examining the employment of micro-CT modalities for assessment of skeletal wounds within the forensic context. The present study explores the potential of micro- CT examination in assessing selected qualitative and quantitative characteristics of gunshot injuries in the human skull. For this purpose, two cases bearing gunshot entrance wounds occurring under different conditions (in fresh or dry bone) were scanned at multiple hierarchical levels (ranging from 140 μm to 6 μm) using a micro-CT device. The aim was to find the best imagery (e.g., voxel size) relative to a measured volume and physical dimensions of the samples, and suitable for (micro)- trauma assessment of cranial cracks and microcracks. The best setting for recording trauma-related microcracks with respect to the display level, processing efficiency and necessary trade-off of the sample physical dimensions (several centimetres in this case) was associated with a voxel size of 12 μm. At this resolution, the size, the shape, the course, and the spatial arrangement of the observed microcracks of adequate captured extent of damage can be assessed with sufficient accuracy. This also permits evaluating and comparing various types of injuries (such as peri- and post-mortem) and conducting their differential diagnostics.