Evaluation of a personal identification method using the fusion function of CT images and dental radiographs

Usefulness of virtual reassembly of the skull and spine in cases of fragmentation due to high-energy trauma: A feasibility study

With the widespread use of postmortem computed tomography (PMCT) beside forensic autopsies for investigation of causes of death, three-dimensional (3D) reconstruction and fusion imaging using PMCT data are now becoming common. In the present study, the applicability of virtual reassembly from PMCT data was investigated in three cases involving fragmentation of the skull or spine due to high-energy trauma, as in such cases it is sometimes difficult to obtain detailed information on fractures using macroscopic observation alone. In the first case, virtual reassembly of the skull provided more information about the fractures than conventional reconstruction with adhesive. In the second case, although the skull was severely fractured and could not be examined macroscopically, virtual reassembly allowed detailed visualization of the fractures. In the last case, virtual reassembly of the spine helped to clarify that the 6th-8th thoracic vertebrae had been run over by a vehicle at the scene. Thus, virtual reassembly was shown to be useful for assessment of injury patterns, and event reconstruction.

Implementation of a personal identification system using alveolar bone images

OBJECTIVE

In recent years, personal identification has been performed using antemortem panoramic X-ray images and postmortem-CT images. Using these, we have developed a personal identification method that focuses on the alveolar bone. This study examined the effectiveness of this method and aimed to implement a reproducible system.

MATERIALS AND METHODS

For personal identification, a total of 633 CT images and panoramic X-ray images belonging to three groups with different conditions were used.　These images were 160 sets in the same person group and 96,820 in the other groups. The similarity of alveolar bone images was calculated using the landmark method of Procrustes analysis. The processes were system implemented and the methodology was validated.

RESULTS

The ability to identify between the same person group and other person groups showed 0.9769 as the area under the curve (AUC: ROC curve). At the cutoff value of 4.978, there was no false rejection rate, but false acceptance rate was slightly higher.

CONCLUSION

This method was useful as a screening method for personal identification. In addition, system implementation was efficient and reduced human error. In the future, we aim to realize a more efficient personal identification method using distortion-corrected images and including auto-detective landmarks using deep learning.

New Method of Dental Personal Identification of Disaster Victims Using Oral Scanner

Dentistry plays an important role in the identification of victims in large-scale disasters. The current poor status of and problems with victim identification work were highlighted in the aftermath of the Great East Japan Earthquake of March 11, 2011, in which some 10,000 people lost their lives. The techniques of dental identification therefore need to be improved if they are to cope with the problems associated with identification that will accompany the predicted Tokai earthquake and other unexpected large-scale disasters in the future. The purpose of this study was to determine the effectiveness of applying a digital impression-taking device employed in regular dental care to dental personal identification. The Trophy 3DI pro (Yoshida Dental) was applied to a total of 150 dental models. The diagnosis was accurate in 2,096 teeth from a sample of 2,100 comprising 1,240 non-treated teeth, 670 treated teeth, and 190 missing teeth, yielding a 99.8% level of statistical precision. These results suggest that the level of accuracy offered by this impression-taking device indicates that it would be a useful tool in establishing personal identification in disaster victims.

Forensic imaging: a powerful tool in modern forensic investigation

Forensic imaging is a non-invasive examination process during the forensic investigation. It is mainly used in forensic pathology as an adjunct to the traditional autopsy. In the past two decades, forensic imaging has been vigorously developed by forensic experts from computed tomography (CT) to multiple augmented techniques through CT and magnetic resonance imaging (MRI). The application field of forensic imaging has also been broadened as its advantages are recognised by more forensic practitioners. In addition to the forensic pathology, this technique has been used in other forensic disciplines, including forensic anthropology, forensic odontology, forensic ballistics and wildlife forensics, etc. This article reviews the development of forensic imaging as the practice and research development in different forensic disciplines based on the relevant literature analysis.

Dignified Management of the Dead from Humanitarian Forensic Odontology Perspective: A Need for the National and State Level Scientific Disaster Victim Identification Teams in India

Disasters are always unpredictable irrespective of their origin. The loss of human lives is a common outcome of disasters. Along with the physical and emotional trauma sustained by the victims, there is the additional responsibility of handling the deceased. Though there is an exclusive component with the management of the dead in place the specific issue about identifying them is still a complex process. Humanitarian forensics especially involves handling, identifying and disposing the dead bodies. It requires the application of the principles of forensic sciences in a multidisciplinary way. The role of forensic odontologists and anthropologists is not only restricted to the scientific collection of dental data from the dead body but also the proper utilization of the antemortem dental data to successfully establish the identity of the deceased, either alone or combined with secondary characteristics. Elaborate and comprehensive information with justification on the role of dental data and forensic odontologists in the dignified management of the dead need to be highlighted to the Disaster Management authorities. Several International organizations have pointed out the importance of odontology features in human identification. Moreover, forensic odontologists and general dentists are also involved in the international disaster victim identification teams. The present article provides basic knowledge on disaster risk management and the institutional framework in Disaster Management and also highlights the role of forensic odontology in disaster victim identification. It calls for national and state disaster victim identification teams with the involvement of forensic odontologists.

Specific oral and maxillofacial identifiers in panoramic radiographs used for human identification

Radiographically assisted dental identification is an important means for individual identification. Specific identifiers help to quickly filter some of the possible corresponding AM and PM images at the beginning. The study seeks specific oral and maxillofacial identifiers in panoramic radiographs. A total of 920 panoramic radiographs from 460 live patients were used. The most recent radiograph served as the surrogate post-mortem (PM) record of an unidentified person, and the earliest radiograph served as the ante-mortem (AM) record of the same person. We evaluated the following four groups of identifiers of the images: (1) dental morphology, tooth number, and position; (2) dental treatment and pathology; (3) morphological identifiers of the jaw; and (4) pathological identifiers of the jaw. The ratio of each identifier being identified simultaneously in the AM and PM databases was determined. Specific identifiers were defined as those that appeared at low frequency (ratio: 0%-0.250%). A total of 18 specific oral and maxillofacial identifiers were determined. The specific identifiers were a retained deciduous tooth (0.011%), S-shaped deflection of a tooth root (0.012%), distal deflection of tooth root (0.017%), inverted impaction (0.018%), malposition (0.038%), supernumerary teeth (0.061%), mesial deflection of tooth root (0.092%), microdontia (0.136%), buccal/lingual impaction (0.188%), cementoma (0.002%), hypercementosis (0.002%), continuous crown (0.004%), pulp calcification (0.023%), attrition (0.030%), residual root (0.106%), root resorption (0.137%), implant (0.156%), and osteomyelitis (0.002%). Identifiers of the teeth and jaw can be used for human identification, and dental identifiers are more specific than identifiers of jaw.

Superimposed CT imaging using fusion function to visualize the relationship between the knife and the wound path in a stabbing victim

With the increasing use of postmortem computed tomography (PMCT) in medicolegal autopsies, three-dimensional (3D) models of injured areas can now be generated from multislice computed tomography images. However, since PMCT has low sensitivity for detecting injuries in solid organs in the absence of contrast administration, it has been difficult to demonstrate the tracks of stab wounds leading to solid organ injury using 3D reconstruction. Here, we report one homicide case with two stab wounds. On the skin surface, the stab wounds were located on the neck and anterior chest wall. A medicolegal autopsy revealed that one stab wound in the neck had penetrated the wall of the right pleural cavity and the upper portion of the right lung whereas the other stab wound in the anterior chest wall had penetrated the right diaphragm and the heart. To illustrate the tracks of the stab wounds, superimposed CT images of the body, the excised organ, and a knife model were constructed to obtain a 3D model. This allowed clear and concise visualization of the complex relationship of the knife to the heart incision and the stab wound on the chest surface.

Post-mortem computed tomography as part of dental identification - a proposed guideline

PURPOSE

This paper presents a proposed guideline for the use of post-mortem computed tomography (PMCT) during forensic dental identification. Currently, whole-body PMCT is widely used prior to autopsies for the diagnosis of fractures, organ changes, hemorrhages, and for the localization of foreign bodies, but it may also facilitate the odontological identification process in single cases and in cases involving multiple fatalities. Several studies have described the use of PMCT in forensic odontological work, but we have not found any comprehensive set of guidelines on how to perform a forensic odontological examination using PMCT. The aim was to develop guidelines for creating post-mortem dental charts during forensic odontological identification examinations using the standard functions of PMCT.

METHODS

A proposed guideline was developed from 15 selected cases examined at the Section of Forensic Pathology, Department of Forensic Medicine at the University of Copenhagen in Denmark from October 2011 to May 2012. Using the functionalities and three-dimensional (3D) reconstructions of OsiriX DICOM-viewer software (Pixmeo Sarl, Bernex, Geneva, Switzerland) we adjusted the contrast and brightness settings and developed a proposed guideline for creating PMCT-based dental charts. A four-step guideline was produced.

CONCLUSION

In our casework, we are currently using the guidelines proposed herein. The use of PMCT has allowed us to target our clinical examinations, greatly improving their efficiency. Furthermore, PMCT allows the storage of data for later documentation and research. Further research is needed to validate the proposed guideline.

Quantification of odontological differences of the upper first and second molar by 3D-3D superimposition: a novel method to assess anatomical matches

PURPOSE

The introduction of modern 3D image acquisition systems has enabled researchers to develop novel procedures for personal identification. The present study aimed to assess differences between dental scans belonging to the same or different subjects, through an innovative 3D-3D superimposition and registration method.

METHODS

Twelve subjects (6 males and 6 females) with pre- and post-orthodontic treatment dental casts were recruited. A 3D scan from each cast was obtained through a laser scanner and the 3D model of the upper first and second molar on the post-treatment cast was superimposed on the pre-treatment scan, for a total of 12 matches and 100 mismatches. Point-to-point RMS (root mean square) distance was then calculated. Student's t test verified possible statistically significant differences according to group (matches/mismatches; p < 0.05).

RESULTS

In case of matches, on average the point-to-point distance RMS was 0.29 mm (SD: 0.08 mm), while it was 0.94 mm (SD: 0.30 mm) for mismatches, with a statistically significant difference (p < 0.001).

CONCLUSIONS

Results show that the novel procedure was able to distinguish matches from mismatches through an RMS threshold (0.50 mm): a possible method for personal identification is described, which needs to be verified through the application to a larger sample of casts.