Matthew Meredith

Evaluation of the Suchey-Brooks method of age estimation in an Australian subpopulation using computed tomography of the pubic symphyseal surface.

Despite the prominent use of the Suchey-Brooks (S-B) method of age estimation in forensic anthropological practice, it is subject to intrinsic limitations, with reports of differential interpopulation error rates between geographical locations. This study assessed the accuracy of the S-B method to a contemporary adult population in Queensland, Australia and provides robust age parameters calibrated for our population. Three-dimensional surface reconstructions were generated from computed tomography scans of the pubic symphysis of male and female Caucasian individuals aged 15-70 years (n = 195) in Amira and Rapidform. Error was analyzed on the basis of bias, inaccuracy and percentage correct classification for left and right symphyseal surfaces. Application of transition analysis and Chi-square statistics demonstrated 63.9 and 69.7% correct age classification associated with the left symphyseal surface of Australian males and females, respectively, using the S-B method. Using Bayesian statistics, probability density distributions for each S-B phase were calculated, providing refined age parameters for our population. Mean inaccuracies of 6.77 (±2.76) and 8.28 (±4.41) years were reported for the left surfaces of males and females, respectively; with positive biases for younger individuals (<55 years) and negative biases in older individuals. Significant sexual dimorphism in the application of the S-B method was observed; and asymmetry in phase classification of the pubic symphysis was a frequent phenomenon. These results recommend that the S-B method should be applied with caution in medico-legal death investigations of Queensland skeletal remains and warrant further investigation of reliable age estimation techniques.

Morphometric modelling of ageing in the human pubic symphysis: Sexual dimorphism in an Australian population

Despite the prominent use of the pubic symphysis for age estimation in forensic anthropology, little has been documented regarding the quantitative morphological and micro-architectural changes of this surface. Specifically, utilising post-mortem computed tomography data from a large, contemporary Australian adult population, this study aimed to evaluate sexual dimorphism in the morphology and bone composition of the symphyseal surface; and temporal characterisation of the pubic symphysis in individuals of advancing age. The sample consisted of multi-slice computed tomography (MSCT) scans of the pubic symphysis (slice thickness: 0.5mm, overlap: 0.1mm) of 200 individuals of Caucasian ancestry aged 15-70 years, obtained in 2011. Surface rendering reconstruction of the symphyseal surface was conducted in OsiriX(®) (v.4.1) and quantitative analyses in Rapidform XOS™ and Osteomeasure™. Morphometric variables including inter-pubic distance, surface area, circumference, maximum height and width of the symphyseal surface and micro-architectural assessment of cortical and trabecular bone compositions were quantified using novel automated engineering software capabilities. The major results of this study are correlated with the macroscopic ossification and degeneration pattern of the symphyseal surface, demonstrating significant age-related changes in the morphometric and bone tissue variables between 15 and 70 years. Regardless of sex, the overall dimensions of the symphyseal surface increased with age, coupled with a decrease in bone mass in the trabecular and cortical bone compartments. Significant differences between the ventral, dorsal and medial cortical surfaces were observed, which may be correlated to bone formation activity dependent on muscle activity and ligamentous attachments. Our study demonstrates significant sexual dimorphism at this site, with males exhibiting greater surface dimensions than females. These baseline results provide a detailed insight into the changes in the structure of the pubic symphysis with ageing and sexually dimorphic features associated with the cortical and trabecular bone profiles.

Standardized anthropological measurement of postcranial bones using three-dimensional models in CAD software

This study introduces a standardized protocol for conducting linear measurements of postcranial skeletal elements using three-dimensional (3D) models constructed from post-mortem computed tomography (PMCT) scans. Using femoral DICOM datasets, reference planes were generated and plane-to-plane measurements were conducted on 3D surface rendered models. Bicondylar length, epicondylar breadth, anterior-posterior (AP) diameter, medial-lateral (ML) diameter and cortical area at the midshaft were measured by four observers to test the measurement error variance and observer agreement of the protocol (n=6). Intra-observer error resulted in a mean relative technical error of measurement (%TEM) of 0.11 and an intraclass correlation coefficient (ICC) of 0.999 (CI=0.998-1.000); inter-observer error resulted in a mean %TEM of 0.54 and ICC of 0.996 (CI=0.979-1.000) for bicondylar length. Epicondylar breadth, AP diameter, ML diameter and cortical area also yielded minimal error. Precision testing demonstrated that the approach is highly repeatable and is recommended for implementation in anthropological investigation and research. This study exploits the benefits of virtual anthropology, introducing an innovative, standardized alternative to dry bone osteometric measurements.

Bayesian modeling predicts age and sex are not required for accurate stature estimation from femoral length

Despite the recognized flaws in applying traditional stature estimation equations such as those of Trotter and Gleser (1952) [5] to a contemporary population, there are currently no available alternatives for stature estimation in Australia that address these limitations. Post mortem computed tomography (PMCT) DICOM scans of the left and right femora were acquired from 76 Australian deceased individuals aged 17-76 years for metric analysis. Femoral bicondylar length, femoral epicondylar breadth and anterior-posterior (AP) diameter, medial-lateral (ML) diameter, circumference and cortical area at the femoral midshaft were measured on three-dimensional (3D) models to build statistical models for estimating stature. In addition, Australian individuals aged 16-63 years (n=111) were measured in standing and supine positions to aid in the adjustment of supine stature of deceased individuals utilized in this study to standing stature. The results of this preliminary evaluation strongly indicate that the optimal model for estimating stature includes bicondylar femoral length and epicondylar breadth, that the effect of sex as an independent variable is very low, and there is limited practical benefit in including age in the estimation of stature. Our study indicates that the Australian population sampled represents a small yet significant shift in stature from the original Trotter and Gleser sample. Additionally, in the case of fragmentary remains, it was found that epicondylar breadth and AP diameter had the highest probability of accurate stature estimation in the absence of bicondylar femoral length. As stature forms a significant component of a biological profile and therefore aids in the personal identification of human remains, it is important that forensic anthropologists utilize the most accurate methodologies available. Stature estimation of Australian individuals is therefore achieved with higher accuracy through utilizing the femoral equations proposed in this study.

Correlation between CT and postmortem findings in choking deaths

Introduction: Invariably, adult choking deaths are accidental and the bolus is food. Deaths are associated with neurological or psychiatric conditions, acute alcohol intoxication, or poor/missing dentition. Computed tomography (CT) is a useful tool for investigating these deaths. Four case studies are presented. Cases: Case 1 was a 45-year-old male with a history of alcohol abuse, who was found deceased on his kitchen floor. A foreign body in the upper airways was found on CT, and a meat bolus confirmed on autopsy. His blood alcohol level (BAL) was 0.24%. Case 2 was 62-year-old male with a history of Parkinsonism, found dead in bed. The upper airways were obstructed by a food bolus. Case 3 was a 52-year-old male with motor neurone disease, found dead in his kitchen. A foreign body in his hypopharynx was demonstrated on CT and a meat bolus confirmed on internal examination. His BAL was 0.053%. Case 4 was an 87-year-old woman with a history of dementia, found deceased in bed. CT showed extensive foreign material within her airways. External examination showed food material in her oropharynx. Conclusion: Four cases of unwitnessed upper airway obstruction by food are presented. All patients had conditions compromising their motor functioning. CT correlation is informative, and may guide the extent of adjuvant testing at autopsy.