Post-mortem radiological CT identification based on classical ante-mortem X-ray examinations

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Abstract

Radiological identification is important in forensic medicine. Identification using comparison of individualising structures with ante- and post-mortem conventional radiographs has been known for a long time. New radiological procedures such as computed tomography (CT) and magnetic resonance imaging (MRI) are being increasingly used for identification. In this paper, a new comparative approach using various radiological methods is described and its application demonstrated. This new approach is the comparison of ante-mortem conventional radiographs with projected images calculated from post-mortem CT data.

The identification procedure will be illustrated with reference to the frontal sinus and the pelvis.

Introduction

Radiological identification still has a very important place in forensic medicine, particularly in the absence of comparative DNA samples and fingerprints. It involves the comparison of ante-mortem radiographs, usually performed for clinical reasons, with post-mortem radiographs taken solely for the identification of specific, individualising structures. Until now, radiological images of the same type have been compared, i.e. ante- with post-mortem conventional radiographs [1], [2], [3], [4], computed tomography (CT) or magnetic resonance imaging (MRI) images [5], [6], [7], [8], [9].

In this study, which was originally performed as a medical dissertation [10], we show that identification is also possible using comparison of images of two different radiological methods: ante-mortem X-rays and post-mortem CTs.

Section snippets

Principle and steps of the proposed method

For computed tomography, parts of the body, or the entire corpse, are represented radiologically using continuous volume measurements in sections of approximately 1 mm thickness. Images of axial sections are primarily represented. By using such a thin section thickness, isotropic data are generated (isotropic imaging, i.e. geometric resolution is nearly identical in all three directions of space).

In an example of the head approximately 400 sequential sections of 1(–2) mm thickness offer

Anatomy skull (Fig. 2(1–5))

Fig. 2(1) shows a skull obtained from the Institute of Anatomy in Berne. The corresponding conventional radiographs a.p. (slightly rotated) and oblique from front right can be seen in Fig. 2(2 and 3). A frontal sinus configuration that is specific for an individual can immediately be recognised in Fig. 2(2): double-arched and large on the right side (yellow arrow), small on the left side (white arrow). It can be seen that this image is not taken exactly a.p., but is slightly rotated. The

Discussion

In forensic medicine, it is difficult to obtain a conventional post-mortem X-ray image that corresponds exactly to the viewing angle of any available ante-mortem radiograph [15]. The method described in this paper can solve this problem. Three-dimensional documentation of the volume with secondary preparation of projection images in any desired projection direction makes it possible to represent the data on the computer screen in such a way that it can be quickly decided whether the 2D

Acknowledgement

We are grateful to the Institute of Anatomy, University of Berne, for lending us the skulls.

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