Pierre Guyomarc'h

Discrimination of Falls and Blows in Blunt Head Trauma: A Multi‐Criteria Approach

Abstract:  In the discrimination of falls versus blows, the hat brim line (HBL) rule is mentioned in several textbooks as the most useful single criterion. Recent studies, however, have found that the HBL rule is only moderately valid and that its use on its own is not recommended. The purpose of this 6‐year retrospective study was to find additional individually useful criteria in the distinction of falls from blows. Overall, the following criteria were found to point toward blows: more than three lacerations, laceration length of 7 cm or more, comminuted or depressed calvarial fractures, lacerations or fractures located above the HBL, left‐side lateralization of lacerations or fractures, more than four facial contusions or lacerations, presence of ear lacerations, presence of facial fractures, and presence of postcranial osseous and/or visceral trauma. Based on the most discriminating criteria, a decision tree was constructed to be potentially applicable to future cases.

Morphometric Comparison of Clavicle Outlines from 3D Bone Scans and 2D Chest Radiographs: A Shortlisting Tool to Assist Radiographic Identification of Human Skeletons†

This paper describes a computerized clavicle identification system primarily designed to resolve the identities of unaccounted‐for U.S. soldiers who fought in the Korean War. Elliptical Fourier analysis is used to quantify the clavicle outline shape from skeletons and postero‐anterior antemortem chest radiographs to rank individuals in terms of metric distance. Similar to leading fingerprint identification systems, shortlists of the top matching candidates are extracted for subsequent human visual assessment. Two independent tests of the computerized system using 17 field‐recovered skeletons and 409 chest radiographs demonstrate that true‐positive matches are captured within the top 5% of the sample 75% of the time. These results are outstanding given the eroded state of some field‐recovered skeletons and the faintness of the 1950s photofluorographs. These methods enhance the capability to resolve several hundred cold cases for which little circumstantial information exists and current DNA and dental record technologies cannot be applied.

Anthropological facial approximation in three dimensions (AFA3D): Computer-assisted estimation of the facial morphology using geometric morphometrics

This study presents Anthropological Facial Approximation in Three Dimensions (AFA3D), a new computerized method for estimating face shape based on computed tomography (CT) scans of 500 French individuals. Facial soft tissue depths are estimated based on age, sex, corpulence, and craniometrics, and projected using reference planes to obtain the global facial appearance. Position and shape of the eyes, nose, mouth, and ears are inferred from cranial landmarks through geometric morphometrics. The 100 estimated cutaneous landmarks are then used to warp a generic face to the target facial approximation. A validation by re‐sampling on a subsample demonstrated an average accuracy of c. 4 mm for the overall face. The resulting approximation is an objective probable facial shape, but is also synthetic (i.e., without texture), and therefore needs to be enhanced artistically prior to its use in forensic cases. AFA3D, integrated in the TIVMI software, is available freely for further testing.

Quantification of perspective-induced shape change of clavicles at radiography and 3D scanning to assist human identification.

Change in perspective between antemortem and postmortem imaging sessions (radiograph to radiograph and surface scan to radiograph) may cause different 2D renderings of the same osseous element complicating comparisons for identification. In this study, clavicle shape changes due to radiographic positioning and 3D laser scanning were examined in 20 right‐side specimens, as pertinent to chest radiograph comparisons. Results indicate substantial changes in clavicle form with short source‐to‐image receptor distance, elevation of the element from the image receptor, and movement of the element away from the center beam (10% mean square for shape). Although quantitative shape differences were small when the clavicle was in close opposition to the image receptor (3% mean square), important qualitative differences remained with large distances from the center beam (e.g., conoid tubercle presence/absence). The significance of these results for image superimposition and computer‐automated‐shape‐based searches of radiographic libraries to find matching candidates is discussed.

Human Identification via Lateral Patella Radiographs: A Validation Study.

This research examines the utility of patella outline shape for matching 3D scans of patellae to knee radiographs using elliptical Fourier analysis and subjective methods of human visual comparison of patellae across radiographs for identification purposes. Repeat radiographs were captured of cadavers knees for visual comparison before patellae were extracted and skeletonized for quantitative comparisons. Quantitative methods provided significant narrowing down of the candidate pool to just a few potential matches (<5% of original sample), while the human analysts showed high capacity for correctly matching radiographs, irrespective of educational level (positive predictive value = 99.8%). The successful computerized matching based on a single quantified patella trait (outline shape) helps explain the potency achieved by subjective visual examination. This work adds to a growing body of studies demonstrating the value of single isolated infracranial bones for human identification via radiographic comparison.

Skull Fracture with Brain Expulsion in a One-Level Jumping-Fall

Abstract:  Here presented is the case of a one‐level jumping‐fall with extensive skull fractures and brain expulsion. The body was found on the basement floor at the foot of the stairs. At the autopsy, the skull was extensively fractured, with about half of the brain expulsed several feet away from the body. The cause of death was established as a craniocerebral trauma with brain expulsion. The circumstances and manner of death were still unclear at that time. A low fall seemed very unlikely considering the severity of the skull and brain damage. The police investigation clearly revealed that the man, in a paranoid psychotic state, attacked his wife with a knife and then was witnessed by his children to have hit his head several times with a hammer. Afterwards, they saw him running to the top of the basement stairs and jumping to the bottom of the stairs head first.

Facial soft tissue depth measurement: validation of the 75-shormax

The shorth and 75‐shormax were recently posited as an improved alternative to the arithmetic mean for describing facial soft tissue thicknesses in craniofacial identification. The shorth better estimates the data peak, while the 75‐shormax provides improved provisions for a long right tail. When first proposed, the 75‐shormax was subjectively gauged. Herein, shormax errors are calculated at every whole percentile to quantitatively determine zones of error minimization in two large samples: (a) CT data of French adults, n‐range = 211–469 individuals; and (b) all C‐Table data, n‐range = 60–1065 individuals [including part but not all of sample (a)]. The smallest residuals were found at the 79th percentile (mean of raw residuals) and the 74th percentile (mean of absolute residuals). The 75‐shormax is subsequently verified as good error minimizer since the absolute differences carry the greatest weight and the 74th percentile closely approximates the 75th percentile.

A Large-Sample Test of a Semi-Automated Clavicle Search Engine to Assist Skeletal Identification by Radiograph Comparison

In 2014, a morphometric capability to search chest radiograph databases by quantified clavicle shape was published to assist skeletal identification. Here, we extend the validation tests conducted by increasing the search universe 18‐fold, from 409 to 7361 individuals to determine whether there is any associated decrease in performance under these more challenging circumstances. The number of trials and analysts were also increased, respectively, from 17 to 30 skeletons, and two to four examiners. Elliptical Fourier analysis was conducted on clavicles from each skeleton by each analyst (shadowgrams trimmed from scratch in every instance) and compared to the search universe. Correctly matching individuals were found in shortlists of 10% of the sample 70% of the time. This rate is similar to, although slightly lower than, rates previously found for much smaller samples (80%). Accuracy and reliability are thereby maintained, even when the comparison system is challenged by much larger search universes.

Landmark Typology in Applied Morphometrics Studies: What's the Point?: Landmark Typology: What's the Point?

Landmarks are the hallmark of biological shape analysis as discrete anatomical points of correspondence. Various systems have been developed for their classification. In the most widely used system, developed by Bookstein in the 1990s, landmarks are divided into three distinct types based on their anatomical locations and biological significance. As Bookstein and others have argued that different landmark types possess different qualities, e.g., that Type 3 landmarks contain deficient information about shape variation and are less reliably measured, researchers began using landmark types as justification for selecting or avoiding particular landmarks for measurement or analysis. Here, we demonstrate considerable variation in landmark classifications among 17 studies using geometric morphometrics (GM), due to disagreement in the application of both Booksteins landmark typology and individual landmark definitions. A review of the literature furthermore shows little correlation between landmark type and measurement reproducibility, especially when factors such as differences in measurement tools (calipers, digitizer, or computer software) and data sources (dry crania, 3D models, or 2D images) are considered. Although landmark typology is valuable when teaching biological shape analysis, we find that employing it in research design introduces confusion without providing useful information. Instead, researchers should choose landmark configurations based on their ability to test specific research hypotheses, and research papers should include justifications of landmark choices along with landmark definitions, details on landmark collection methods, and appropriate interobserver and intraobserver analyses. Hence, while the landmarks themselves are crucial for GM, we argue that their typology is of little use in applied studies. Anat Rec, 302:1144–1153, 2019.