Virtual anthropology:a preliminary test of macroscopic observation versus 3D surface scans and computed tomography(CT)scans

Virtual anthropology(VA)is based on applying anthropological methods currently used to analyse bones to 3D models of human remains.While great advances have been made in this endeavour in the past decade,several interrogations concerning how reliable these models are and what their proper use should be remain unanswered.In this research,a fundamental assumption of VA has been investigated:if the way we perceive and apply an anthropological method is truly similar when looking at bones macroscopically and through various 3D media.In order to answer,10 skulls of known age and sex were scanned using a computed tomography(CT)scanner and a 3D surface scanner.Two observers separately applied a defined staging method to eight suture sites on these skulls,first looking at the bone macroscopically,then at the 3D surface scan,and finally on the CT scan.Two rounds of observation were carried out by each observer.Intra-and inter-observer error were evaluated,and two sample t-tests used to evaluate if the different types of medium used yielded significantly different observations.The results show a high degree of inter-observer error,and that data obtained from 3D surface scans differ from macroscopic observation(confidence level 95%,P≤0.05).CT scans,in these settings,yielded results comparable to those obtained through macroscopic observations.These results offer many possibilities for future research,including indications on the kind of anthropological methods and anatomical landmarks that might be reliably transferable to the virtual environment.All current methods used in traditional anthropology should be tested,and if they prove unreliable,new techniques to analyse bones from virtual models should be developed.

A fatal case of oxygen embolism in a hospital

This case reports on a 68-year-old man who was found dead in hospital next to his bed.Before this,he had been treated with intravenous antibiotics for pneumonia.The body was found with a peripheral venous catheter connected to a nasal cannula delivering oxygen(O_(2))from the wall.Extensive medico-legal examinations were performed,including post-mortem computed tomography(CT),complete conventional autopsy,histological and immunohistochemistry analysis,toxicological analysis and post-mortem chemistry.Additionally,CT-guided gas sampling was performed at multiple sites to collect samples for gas analysis.During the external examination,massive subcutaneous emphysema was visible over the entire surface of the body.The CT scan revealed the presence of gas throughout the vascular system,and in the subcutaneous and muscular tissues.The autopsy confirmed the presence of lobar pneumonia and multiple gas bubbles in the vascular system.The gas analysis results showed a subnormal concentration of oxygen,confirming the suspected pure O_(2) embolism.Moreover,the carbon dioxide(CO_(2))concentration in the gas sample from the heart was elevated to a level similar to those found in scuba diving fatalities.This could come from degassing of dissolved CO_(2) that accumulated and was trapped in the cardiac cavity.Based on the results of the different exams performed,and especially the gas analysis results,it was concluded that the cause of death was O_(2) embolism.

Sex estimation in a Turkish population using Purkait’s triangle:a virtual approach by 3-dimensional computed tomography(3D-CT)

Sex estimation is considered one of the first steps in the forensic identification process.Morphological and morphometrical differences between males and females have been used as means for morphoscopic and metric methods on both cranial and postcranial skeletal elements.When dry skeletal elements are not available,virtual data can be used as a substitute.The present research explores 3-dimensional(3D)scans from a Turkish population to test a sex estimation method developed by Purkait(2005).Overall,296 individuals were used in this study(158 males and 138 females).Purkait’s triangle parameters were measured on computed tomography(CT)scans obtained from both right and left femora of each patient at the Bakirkoy Dr.Sadi Konuk Training Research Hospital(Istanbul,Turkey).Intra-and inter-observer errors were assessed for all variables through technical error of measurements analysis.Bilateral asymmetry and sex differences were evaluated using parametric and non-parametric statistical approaches.Univariate and multivariate discriminant function analyses were then conducted.Observer errors demonstrated an overall agreement within and between experts,as indicated by technical error of measurement(TEM)results.No bilateral asymmetries were reported,and all parameters demonstrated a statistically significant difference between males and females.Fourteen discriminant models were generated by applying single and combined parameters,producing a total correct sex classification ranging from 78.4%to 92.6%.In addition,over 67%of the total sample was accurately classified,with 95%or greater posterior probabilities.Our study demonstrates the feasibility of 3D sex estimation using Purkait’s triangle on a Turkish population,with accuracy rates comparable to those reported in other populations.This is the first attempt to apply this method on virtual data and although further validation and standardisation are recommended for its application on dry bone,this research constitutes a significant contribution to the development of population-specific standards when only virtual data are available.