Virtual anthropology and forensic identification using multidetector CT

Abstract

Virtual anthropology is made possible by modern cross-sectional imaging. Multislice CT (MSCT) can be used for comparative bone and dental identification, reconstructive identification and lesion identification. Comparative identification, the comparison of ante-and post-mortem imaging data, can be performed on both teeth and bones. Reconstructive identification, a considerable challenge for the radiologist, identifies the deceased by determining sex, geographical origin, stature and age at death. Lesion identification combines virtual autopsy and virtual anthropology. MSCT can be useful in palaeopathology, seeking arthropathy, infection, oral pathology, trauma, tumours, haematological disorders, stress indicators or occupational stress in bones and teeth. We examine some of the possibilities offered by this new radiological subspeciality that adds a new dimension to the work of the forensic radiologist. A multidisciplinary approach is crucial and involves communication and data exchange between radiologists, forensic pathologists, anthropologists and radiographers.Virtual autopsies are currently becoming increasingly common worldwide in forensic medicine.1 Use of multislice CT (MSCT) or multidetector CT (MDCT) before classic medicolegal autopsy gives the forensic pathologist considerable information on injuries and cause of death.2 A recent advance in forensic imaging is post-mortem CT angiography, which yields further information on soft tissues and visceral and vascular injuries. Modern cross-sectional imaging can be used in virtual anthropological studies as well as in virtual autopsy. 4 In biological anthropology, it can be applied to compare bone or dental criteria between species. An important application is forensic anthropology, to obtain positive identification of an unknown decedent. The introduction of imaging in anthropology is of course not new, and many radiographic applications have been already described and published.In virtual anthropology, teeth and bones can be studied by MRI or by MSCT. MRI has numerous applications, 5,6 and it will certainly become an important tool in forensic study of the living, particularly for age assessment. This technique presents many advantages compared with MSCT, and, like ultrasound, it is X-ray free. However, access to MRI in thanatology is currently difficult, mainly because of limited time availability of the machine.The wide range of possibilities offered by MSCT may seem bewildering to a non-radiologist! If an MSCT examination is to give optimal results, many technical conditions must be adhered to in terms of image quality, spatial resolution and contrast. If not, the final images may even be unusable, in particular, for analysis of fine trabecular bone lesions (Figure 1). The initial CTmust be performed with appropriate voltage, amperage, field of view and slice thickness. After acquisition, reconstruction time is critical. Choice of thickness and interval and choice of filters influence voxel size and the possibility of radiological interpretation...

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