Getting into shape: a comparison of three methods used to characterize personal uniqueness of the frontal sinuses using computed tomography (CT) data

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Richer, Sarah M.
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Identification of unknown individuals is important in forensic cases to notify next of kin and to execute legal matters. Several areas in the skeleton have been proposed to aid in identification. The frontal sinuses have long been considered unique to each individual because of the high degree of observed morphological variation. Due to their location inside the skull, visualisation of the frontal sinuses is achieved through radiographic imaging, typically X-Ray or computed tomography (CT). Visual comparison and superimposition of an antemortem image over a postmortem image to identify a match is the most basic method for identifying if two frontal sinuses come from the same individual. This simple approach has given way to several quantification methods. These methods can broadly be grouped into three categories: measurement, coding and outline methods. Recently, owing to the Daubert ruling, an increased emphasis has been placed on quantification and testing to develop accurate and replicable methods within forensic anthropology. In line with this ruling, it is crucial to test and validate all personal identification methods on independent samples. This dissertation compares three methods for quantifying the personal uniqueness present in the frontal sinuses on an independent sample. The three methods tested here are a measurement method (Ribeiro, 2000), a coding method (Reichs and Dorion, 1992) and an outline method (Cox et al., 2009). The sample used in this study is a postmortem CT collection of 130 individuals from the University of Copenhagen. The protocols are described, including the adaptations made to the Ribeiro (2000) and Cox et al. (2009) methods which were originally designed to be used with X-ray image data rather than CT data. The three methodologies are evaluated and compared for their abilities to characterize individuality and produce unique matches in this sample. The results show that the weakest method is the coding system, while the strongest are the outline and measurement techniques. Recommendations for forensic anthropologists to increase standardization are made. Future directions, including the potential application of three dimensional renderings of the frontal sinuses for morphological comparison, are considered.
Forensic anthropology, Frontal sinuses, Computed tomography, CT, personal identification