Cervicothoracic junction in disaster victim identification: Idiosyncrasies and relevance of body position for advanced chest radiograph comparisons.

Standard plain film medical radiographs often form a valuable line of evidence to identify individuals in large-scale fatality events. While commonly available, chest radiographs present a challenge that their analysis is somewhat more involved and complex than radiographic records of other body regions. For example, chest radiographs concern subtler morphological varieties of smaller anatomical features across a larger number of skeletal elements in contrast to frontal sinus comparisons that concern a large, (often) single, highly variable void within one bone. This does not detract from or discount chest radiographs as useful identification aids, but it does demand additional prerequisite skills in radiographic interpretation to ensure valid conclusions are attained. When subjects deviate from standardized antemortem (AM) radiographic positions and/or the image quality decreases, the complexity of a chest radiograph comparison is elevated. Generally, the current body of forensic radiographic comparison literature infrequently addresses these more complex circumstances. In this paper, we use real-world radiographic comparison reference images from a military DVI repatriation context to illustrate these factors and outline some procedures that enable these complexities to be easily recognized and appropriately addressed at case examination. A report for an exemplar case that concurrently highlights multiple factors is presented. For novices learning radiographic comparison methods, this case review saliently demonstrates: (1) why the AM reference radiograph(s) drive(s) the radiographic comparison procedure; (2) why care should be taken for correct positioning of the cervicothoracic junction in postmortem radiography of chest elements.

An overview of the latest developments in facial imaging.

Facial imaging is a term used to describe methods that use facial images to assist or facilitate human identification. This pertains to two craniofacial identification procedures that use skulls and faces-facial approximation and photographic superimposition-as well as face-only methods for age progression/regression, the construction of facial graphics from eyewitness memory (including composites and artistic sketches), facial depiction, face mapping and newly emerging methods of molecular photofitting. Given the breadth of these facial imaging techniques, it is not surprising that a broad array of subject-matter experts participate in and/or contribute to the formulation and implementation of these methods (including forensic odontologists, forensic artists, police officers, electrical engineers, anatomists, geneticists, medical image specialists, psychologists, computer graphic programmers and software developers). As they are concerned with the physical characteristics of humans, each of these facial imaging areas also falls in the domain of physical anthropology, although not all of them have been traditionally regarded as such. This too offers useful opportunities to adapt established methods in one domain to others more traditionally held to be disciplines within physical anthropology (e.g. facial approximation, craniofacial superimposition and face photo-comparison). It is important to note that most facial imaging methods are not currently used for identification but serve to assist authorities in narrowing or directing investigations such that other, more potent, methods of identification can be used (e.g. DNA). Few, if any, facial imaging approaches can be considered honed end-stage scientific methods, with major opportunities for physical anthropologists to make meaningful contributions. Some facial imaging methods have considerably stronger scientific underpinnings than others (e.g. facial approximation versus face mapping), some currently lie entirely within the artistic sphere (facial depiction), and yet others are so aspirational that realistic capacity to obtain their aims has strongly been questioned despite highly advanced technical approaches (molecular photofitting). All this makes for a broad-ranging, dynamic and energetic field that is in a constant state of flux. This manuscript provides a theoretical snapshot of the purposes of these methods, the state of science as it pertains to them, and their latest research developments.

The utility of elliptical Fourier analysis for estimating ancestry and sex from lateral skull photographs.

Current quantitative methods for estimating ancestry and sex from skulls typically require substantial manual data collection and specialized recording equipment, which can limit analysis to the laboratory. This limitation could be addressed by establishing a faster, more user-friendly, and automatic data protocol as investigated in the current study using elliptical Fourier analysis (EFA). Ancestry and sex were estimated using outlines acquired from standardized photographs of the skull in norma lateralis (left side). In this investigation, training samples comprised anatomical specimens from five collections: the Hamann-Todd Human Osteological Collection, WM Bass Donated Skeletal Collection, Robert J. Terry Anatomical Skeletal Collection, Khon Kaen Osteological Collection, and Chiba Bone Collection. Groups were defined as Black American female (n=87), Black American male (n=109), Japanese male (n=59), Thai female (n=39), Thai male (n=47), White American female (n=97), and White American male (n=134). EFA was conducted on partial Procrustes-aligned skull outline coordinates, before extracting principal components and using linear discriminant analysis for group assignment. Classification accuracy was determined using the 5-fold cross-validation protocol. Ancestry and sex were classified correctly 73% of the time when all seven reference samples were used. When only Black and White Americans were retained in the reference sample with sex pooled, they were correctly classified 94% of the time. Accuracy of out-of-group ancestry and sex estimation was evaluated using nine White American males from the Defense POW/MIA Accounting Agency Laboratory. A seven-way comparison with all reference samples for estimating both ancestry and sex achieved 89% (8/9) correct classifications, with one misclassification as White American female. These out-of-group results, along with initial training group accuracies, indicate that lateral skull outlines can be used to successfully estimate ancestry and sex with similar accuracy to other methods, and set the basis for future cross-validation testing. Further, the reliance on a single easy-to-take photograph and user-friendly open-source R script facilitates easy application and field use. The protocol is freely available from CRANIOFACIALidentification.com as the SkullProfiler script.

Elliptical Fourier analysis: fundamentals, applications, and value for forensic anthropology.

The numerical description of skeletal morphology enables forensic anthropologists to conduct objective, reproducible, and structured tests, with the added capability of verifying morphoscopic-based analyses. One technique that permits comprehensive quantification of outline shape is elliptical Fourier analysis. This curve fitting technique allows a form's outline to be approximated via the sum of multiple sine and cosine waves, permitting the profile perimeter of an object to be described in a dense (continuous) manner at a user-defined level of precision. A large amount of shape information (the entire perimeter) can thereby be collected in contrast to other methods relying on sparsely located landmarks where information falling in between the landmarks fails to be acquired. First published in 1982, elliptical Fourier analysis employment in forensic anthropology from 2000 onwards reflects a slow uptake despite large computing power that makes its calculations easy to conduct. Without hurdles arising from calculation speed or quantity, the slow uptake may partly reside with the underlying mathematics that on first glance is extensive and potentially intimidating. In this paper, we aim to bridge this gap by pictorially illustrating how elliptical Fourier harmonics work in a simple step-by-step visual fashion to facilitate universal understanding and as geared towards increased use in forensic anthropology. We additionally provide a short review of the method's utility for osteology, a summary of past uses in forensic anthropology, and software options for calculations that largely save the user the trouble of coding customized routines.

Photo-Realistic Statistical Skull Morphotypes: New Exemplars for Ancestry and Sex Estimation in Forensic Anthropology.

Graphic exemplars of cranial sex and ancestry are essential to forensic anthropology for standardizing casework, training analysts, and communicating group trends. To date, graphic exemplars have comprised hand-drawn sketches, or photographs of individual specimens, which risks bias/subjectivity. Here, we performed quantitative analysis of photographic data to generate new photo-realistic and objective exemplars of skull form. Standardized anterior and left lateral photographs of skulls for each sex were analyzed in the computer graphics program Psychomorph for the following groups: South African Blacks, South African Whites, American Blacks, American Whites, and Japanese. The average cranial form was calculated for each photographic view, before the color information for every individual was warped to the average form and combined to produce statistical averages. These mathematically derived exemplars-and their statistical exaggerations or extremes-retain the high-resolution detail of the original photographic dataset, making them the ideal casework and training reference standards.

Effect of Head Position on Facial Soft Tissue Depth Measurements Obtained Using Computed Tomography.

Facial soft tissue depth (FSTD) studies employing clinical computed tomography (CT) data frequently rely on depth measurements from raw 2D orthoslices. However, the position of each patient's head was not standardized in this method, potentially decreasing measurement reliability and accuracy. This study measured FSTDs along the original orthoslice plane and compared these measurements to those standardized by the Frankfurt horizontal (FH). Subadult cranial CT scans (n = 115) were used to measure FSTDs at 18 landmarks. Significant differences were observed between the methods at eight of these landmarks (p < 0.05), demonstrating that high-quality data are not generated simply by employing modern imaging modalities such as CT. Proper technique is crucial to useful results, and maintaining control over head position during FSTD data collection is important. This is easily and most readily achieved in CT techniques by rotating the head to the FH plane after constructing a 3D rendering of the data.

A standardized nomenclature for craniofacial and facial anthropometry.

Standardized terms and methods have long been recognized as crucial to reduce measurement error and increase reliability in anthropometry. The successful prior use of craniometric landmarks makes extrapolation of these landmarks to the soft tissue context, as analogs, intuitive for forensic craniofacial analyses and facial photogrammetry. However, this extrapolation has not, so far, been systematic. Instead, varied nomenclature and definitions exist for facial landmarks, and photographic analyses are complicated by the generalization of 3D craniometric landmarks to the 2D face space where analogy is subsequently often lost, complicating anatomical assessments. For example, landmarks requiring palpation of the skull or the examination of the 3D surface typology are impossible to legitimately position; similar applies to median landmarks not visible in lateral photographs. To redress these issues without disposing of the craniometric framework that underpins many facial landmarks, we provide an updated and transparent nomenclature for facial description. This nomenclature maintains the original craniometric intent (and base abbreviations) but provides clear distinction of ill-defined (quasi) landmarks in photographic contexts, as produced when anatomical points are subjectively inferred from shape-from-shading information alone.

Facial soft tissue thicknesses: Noise, signal, and P.

Facial soft tissue thicknesses (FSTTs) hold an important role in craniofacial identification, forming the underlying quantitative basis of craniofacial superimposition and facial approximation methods. It is, therefore, important that patterns in FSTTs be correctly described and interpreted. In prior FSTT literature, small statistically significant differences have almost universally been overemphasized and misinterpreted to reflect sex and ancestry effects when they instead largely encode nuisance statistical noise. Here we examine FSTT data and give an overview of why P-values do not mean everything. Scientific inference, not mechanical evaluation of P, should be awarded higher priority and should form the basis of FSTT analysis. This hinges upon tempered consideration of many factors in addition to P, e.g., study design, sampling, measurement errors, repeatability, reproducibility, and effect size. While there are multiple lessons to be had, the underlying message is foundational: know enough statistics to avoid misinterpreting background noise for real biological effects.