Forensic Anthropology Tomographic-cephalometric evaluation of the pars petrosa of temporal bone as sexing method L.N. Pezo-Lanfranco a, *, R.G. Haetinger b, c a Laboratório de Antropologia Biológica, Instituto de Biociências da Universidade de São Paulo, Rua do Matão 277, 05508-090, Cidade Universitária, São Paulo, SP, Brazil b Med Imagem–BP Medicina Diagnóstica, Hospital Beneficência Portuguesa de São Paulo, São Paulo, SP, Brazil c Departamento de Anatomia, Instituto de Ciências Biomédicas da Universidade de São Paulo, Av. Prof. Lineu Prestes 2415, 05508-900, Cidade Universitária, São Paulo, SP, Brazil A B S T R A C T This study assesses a common issue in Forensic Anthropology: sex determination in fragmented or incomplete human skeletal remains. Previous studies have reported a significant sexual dimorphism in adult individuals for the lateral angle and acoustic pore of the pars petrosa of temporal bone. Our aim is to test the usefulness of pars petrosa as method for estimating sex using standardized CT axial images and cephalometric techniques. We evaluate four cephalometric markers of the pars petrosa (lateral angle, acoustic pore diameter, the divergence of the medial- posterior and medial-anterior segments, and a proposed angle named “Cephalometric Angle of pars petrosa”) in 150 adult individuals of known sex and age treated in the Hospital Beneficência Portuguesa (São Paulo, Brazil). Discriminant analysis using these four parameters allows correct sex classification in 72 % of individuals, however, the Cephalometric Angle, individually, reaches 74 % of correct classifications. Our results suggest that tomographic- cephalometric evaluation of the pars petrosa of temporal bone can be employed as indicial method for differentiating sex in some contexts. A R T I C L E I N F O Keywords: Lateral angle Forensic anthropology Internal acoustic canal Sexual dimorphism Human identification 1. Introduction The determination of sex in skeletal human remains, based on the recognition of dimorphic anatomical traits of the pelvic bones and skull, is a standardized procedure of wide application in physical and forensic anthropology [1,2]. However, human bones are not always well- preserved and forensic-anthropologists are compelled to work with fragmented, cremated or taphonomically altered bones (i.e., environ- mental factors, burial conditions, mass disasters, time), which represents a serious problem in Forensic Anthropology when the identification of individuals is imperative. The search for alternative methods on sex determination in skeletonized individuals has guided the study of sexual dimorphism in various anatomical traits. The pars petrosa ossis temporalis, a compact structure that houses the internal organs of the auditory system, has been part of these attempts. Due to its density and robustness, pars petrosa is often the only bone that survives integrally to the effects of disasters, cremation, or long burial periods, so it has great informative potential from a forensic viewpoint [3–6]. Several anatomical features of the pars petrosa have reported significant sexual dimorphism [3,7–12]. Among them, the diameter of the acoustic pore [9] and the course of the meatus acusticus internus [10,8–12] have been tested as methods of sex discrimination. The “lateral angle” (LA) denotes, in cross-section, the inclination of the internal acoustic canal (which contains the vestibulocochlear and facial nerves) relative to the medial surface of the pars petrosa. The pioneering method of the LA measurement was developed by Wahl [10] in a forensic sample of 70 individuals using negative casts (replicas) of the meatus acusticus internus obtained using clay as impression material. Prior sectioning of the replica with a scalpel, he measures LA, the acute angle formed by the surface of the medial facies of the petrous bone and the anterior wall of the meatus acusticus internus, with an angle protractor. This research concluded that LA measurements equal to or greater than 45  were more frequent in females. Further research using silicone replicas in forensic samples of known sex [5,6,11–13] confirmed that mean values of LA differed in approxi- mately 10  between sexes (39.4  in males; 48.3  in females; p < 0.001 [11]). None of these studies accused significant side differences, so either side could be used for sexdiscrimination. These studies also showed that the number of correctly classified individuals varied between 63 % and 83.2 % [5,6,11–13]. Considering the relative technical difficulties of obtaining reliable measurements from silicone replicas [5,13,14], the use of multislice computed tomography (MSCT) in the evaluation of LA was introduced. * Corresponding author. E-mail address: luispezolanfranco@usp.br (L.N. Pezo-Lanfranco). http://doi.org/10.1016/j.fsir.2021.100174 Received 2 November 2020; Received in revised form 11 January 2021; Accepted 13 January 2021 Available online 19 January 2021 2665-9107/© 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Forensic Science International: Reports 3 (2021) 100174 Contents lists available at ScienceDirect Forensic Science International: Reports jo u r nal h o mep ag e: ww w.els evier .c om /lo cat e/fs ir