Bruno Dutailly

Facial soft tissue depths in French adults: Variability, specificity and estimation

Facial soft tissue depths (FSTD) are used in facial approximation to render the shape of the face, and are traditionally published specifically to population, corpulence, and sex amongst other factors. This paper investigates the variability of FSTD collected at 37 landmarks on 500 CT (computed tomography) scans of French living individuals. The specificity of the sample is evaluated by comparing values with six published datasets of various populations and recording techniques. Apart from a significant influence of the corpulence, FSTD show negligible variations with age and sex. The differences between the French sample and other datasets contradict the hypothesis of major influence of population, and underline sample specificity linked with technique and methodology of data measurement. Regression equations were computed to estimate FSTD using age, sex, facial build, and craniometrics, leading to more accurate results if such factors are known. Nevertheless, application of the pooled T-table (Tallied-Facial-Soft-Tissue-Depth-Data) has been validated according to the French sample.

Three-dimensional computer-assisted craniometrics: A comparison of the uncertainty in measurement induced by surface reconstruction performed by two computer programs

Digital investigation of anthropological material through computed tomography (CT) offers several new opportunities in morphometrics. However, an object measured with computer-assisted methods does not necessarily exactly match the original one. The scanning and surface reconstruction of the object induce some alterations, and data acquisition is prone to measurement uncertainty. The purpose of this research is to evaluate the intra- and inter-observers variations in medical CT scan measurements of a known-size phantom and two dry crania. Two software packages, AMIRA and Treatment and Increased Vision for Medical Imaging (TIVMI), which use different techniques of surface reconstructions, were compared. The mean difference between the measurements was lower for TIVMI, using an objective algorithm based on the half-maximum height (HMH) protocol in three dimensions (3D). AMIRA can induce up to a 4% error in known measurements and 5% uncertainty in dry skull measurements. This study emphasises the risk of object shape alteration in each step of its digitisation.

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.

Anatomical Placement of the Human Eyeball in the Orbit—Validation Using CT Scans of Living Adults and Prediction for Facial Approximation*

Abstract:  Accuracy of forensic facial approximation and superimposition techniques relies on the knowledge of anatomical correlations between soft and hard tissues. Recent studies by Stephan and collaborators (6,8,10) reviewed traditional guidelines leading to a wrong placement of the eyeball in the orbit. As those statements are based on a small cadaver sample, we propose a validation of these findings on a large database (n = 375) of living people. Computed tomography scans of known age and sex subjects were used to collect landmarks on three‐dimensional surfaces and DICOM with TIVMI. Results confirmed a more superior and lateral position of the eyeball relatively to the orbital rims. Orbital height and breadth were used to compute regression formulae and proportional placement using percentages to find the most probable position of the eyeball in the orbit. A size‐related sexual dimorphism was present but did not impact on the prediction accuracy.

3D surface reconstruction using HMH algorithm

3D surface reconstruction using the half maximum height (HMH) algorithm is a method to extract a surface of interest from a voxel data set. It is based on the original HMH method applied to each voxel of the segmented surface to reconstruct. From a 3D voxel grid, an initial segmentation is computed to extract a discrete surface of interest. For each of these voxels, HMH computes a segmentation and an orientation. The result of this step is then processed using a marching cube-like algorithm. The two major advantages of this method are the precision of the surface extraction and its non user-dependancy.

Validation and reliability of the sex estimation of the human os coxae using freely available DSP2 software for bioarchaeology and forensic anthropology

OBJECTIVES A new tool for skeletal sex estimation based on measurements of the human os coxae is presented using skeletons from a metapopulation of identified adult individuals from twelve independent population samples. For reliable sex estimation, a posterior probability greater than 0.95 was considered to be the classification threshold: below this value, estimates are considered indeterminate. By providing free software, we aim to develop an even more disseminated method for sex estimation. MATERIALS AND METHODS Ten metric variables collected from 2,040 ossa coxa of adult subjects of known sex were recorded between 1986 and 2002 (reference sample). To test both the validity and reliability, a target sample consisting of two series of adult ossa coxa of known sex (n = 623) was used. The DSP2 software (Diagnose Sexuelle Probabiliste v2) is based on Linear Discriminant Analysis, and the posterior probabilities are calculated using an R script. RESULTS For the reference sample, any combination of four dimensions provides a correct sex estimate in at least 99% of cases. The percentage of individuals for whom sex can be estimated depends on the number of dimensions; for all ten variables it is higher than 90%. Those results are confirmed in the target sample. DISCUSSION Our posterior probability threshold of 0.95 for sex estimate corresponds to the traditional sectioning point used in osteological studies. DSP2 software is replacing the former version that should not be used anymore. DSP2 is a robust and reliable technique for sexing adult os coxae, and is also user friendly.

Three-dimensional imaging of past skeletal TB: From lesion to process

3D imaging has become an essential tool in the field of biological anthropology, notably for human evolution purposes. High resolution virtual 3D reconstructions of original specimens contribute to their preservation and broaden the ability for research, teaching and exchanges. Paleopathology can get substantial benefit from these methods, among others for reconstructing infectious pathological processes on ancient bones. Tuberculosis is frequently diagnosed on ancient human remains; however, some osseous expressions are difficult to interpret using classical methods. We illustrate here the interest of 3D methods for reconstructing processes involved in pathological bone changes due to Mycobacterium tuberculosis infection. Four paleopathological specimens attributed to this infection, dating from different time periods and concerning diverse parts of the skeleton have been analyzed using a specific 3D digital chain we have previously developed. These 3D analyses allow to virtually reconstruct the initial location and aspect of the infectious process, its extension as well as its possible diffusion to the surrounding soft tissues. This possible virtual follow-up of the disease leads to the concept of processual paleopathology that we would like to introduce in the field. The 3D methodology can help to improve our knowledge of natural history and evolution of ancient human infections such as tuberculosis.

Nouvelles données sur l'édification des molaires et l'estimation de l'âge dentaire des enfants par imagerie médicale et 3D : apports et perspectives

RésuméLes méthodes d’estimation de l’âge des enfants se fondent sur des référentiels pouvant être biaisés. L’évolution technologique aidant, l’imagerie médicale et 3D peuvent être utilisées pour améliorer ou développer des méthodes moins subjectives. Ces nouvelles approches conduisent également à identifier de nouveaux critères d’estimation de l’âge au décès. Aussi, pour en proposer, il est essentiel de s’appuyer sur un échantillon de référence, dont il faut connaître les caractéristiques et qui offre un aperçu de la variabilité populationnelle. Cette variabilité, comparée à celle des taxons fossiles, permet d’apporter de nouvelles informations sur le développement dentaire de ces derniers et d’approfondir la réflexion sur l’estimation de l’âge des sujets immatures en général et des fossiles en particulier. En effet, à travers cette étude, nous nous proposons de fournir des améliorations méthodologiques aux méthodes de Moorrees et al. 1963a, b et de proposer de nouvelles pistes dans l’estimation de l’âge des enfants grâce à l’imagerie médicale et 3D à travers les volumes dentaires. Une première application de ces propositions à l’enfant néanderthalien Châteauneuf 2 a été effectuée. Elle rend compte de l’importance des critères sélectionnés pour l’estimation de l’âge, produisant des écarts plus importants que pour des enfants modernes. De plus, elle met en avant le développement différentiel des premières molaires permanentes entre les deux arcades dentaires.AbstractAge estimation methods vary considerably and are based on reference frameworks that may be biased. New technologies, including medical and 3D imaging, are contributing to the development of improved and less subjective methods, and can identify new characteristics to support estimations of age at death. The use of a reference sample with known characteristics (origin, age, sex, etc.) is essential to develop new standards for age estimation. Comparing variability within a well characterized sample with the variability of fossil specimens provides new information on dental maturation and further insights for juvenile age estimation. Here, we propose an improvement to the juvenile age estimation methods of Moorrees et al. based on dental volumes derived from medical and 3D imaging. Its initial application to the Châteauneuf 2 Neanderthal child demonstrated the importance of the criteria selected for age estimation, which produced larger differences than in modern children, and brought out differences between the two arches in the rate of maturation of the first permanent molars.

Nouvelles données sur l'édification des molaires et l'estimation de l'âge dentaire des enfants par imagerie médicale et 3D : apports et perspectives = New data on the development and age estimations of molars in children, using medical and 3D imaging

RésuméLes méthodes d’estimation de l’âge des enfants se fondent sur des référentiels pouvant être biaisés. L’évolution technologique aidant, l’imagerie médicale et 3D peuvent être utilisées pour améliorer ou développer des méthodes moins subjectives. Ces nouvelles approches conduisent également à identifier de nouveaux critères d’estimation de l’âge au décès. Aussi, pour en proposer, il est essentiel de s’appuyer sur un échantillon de référence, dont il faut connaître les caractéristiques et qui offre un aperçu de la variabilité populationnelle. Cette variabilité, comparée à celle des taxons fossiles, permet d’apporter de nouvelles informations sur le développement dentaire de ces derniers et d’approfondir la réflexion sur l’estimation de l’âge des sujets immatures en général et des fossiles en particulier. En effet, à travers cette étude, nous nous proposons de fournir des améliorations méthodologiques aux méthodes de Moorrees et al. 1963a, b et de proposer de nouvelles pistes dans l’estimation de l’âge des enfants grâce à l’imagerie médicale et 3D à travers les volumes dentaires. Une première application de ces propositions à l’enfant néanderthalien Châteauneuf 2 a été effectuée. Elle rend compte de l’importance des critères sélectionnés pour l’estimation de l’âge, produisant des écarts plus importants que pour des enfants modernes. De plus, elle met en avant le développement différentiel des premières molaires permanentes entre les deux arcades dentaires.AbstractAge estimation methods vary considerably and are based on reference frameworks that may be biased. New technologies, including medical and 3D imaging, are contributing to the development of improved and less subjective methods, and can identify new characteristics to support estimations of age at death. The use of a reference sample with known characteristics (origin, age, sex, etc.) is essential to develop new standards for age estimation. Comparing variability within a well characterized sample with the variability of fossil specimens provides new information on dental maturation and further insights for juvenile age estimation. Here, we propose an improvement to the juvenile age estimation methods of Moorrees et al. based on dental volumes derived from medical and 3D imaging. Its initial application to the Châteauneuf 2 Neanderthal child demonstrated the importance of the criteria selected for age estimation, which produced larger differences than in modern children, and brought out differences between the two arches in the rate of maturation of the first permanent molars.

Nouvelles données sur l'édification des molaires et l'estimation de l'âge dentaire des enfants par imagerie médicale et 3D : apports et perspectives New data on the development and age estimations of molars in children, using medical and 3D imaging: contributions and perspectives

RésuméLes méthodes d’estimation de l’âge des enfants se fondent sur des référentiels pouvant être biaisés. L’évolution technologique aidant, l’imagerie médicale et 3D peuvent être utilisées pour améliorer ou développer des méthodes moins subjectives. Ces nouvelles approches conduisent également à identifier de nouveaux critères d’estimation de l’âge au décès. Aussi, pour en proposer, il est essentiel de s’appuyer sur un échantillon de référence, dont il faut connaître les caractéristiques et qui offre un aperçu de la variabilité populationnelle. Cette variabilité, comparée à celle des taxons fossiles, permet d’apporter de nouvelles informations sur le développement dentaire de ces derniers et d’approfondir la réflexion sur l’estimation de l’âge des sujets immatures en général et des fossiles en particulier. En effet, à travers cette étude, nous nous proposons de fournir des améliorations méthodologiques aux méthodes de Moorrees et al. 1963a, b et de proposer de nouvelles pistes dans l’estimation de l’âge des enfants grâce à l’imagerie médicale et 3D à travers les volumes dentaires. Une première application de ces propositions à l’enfant néanderthalien Châteauneuf 2 a été effectuée. Elle rend compte de l’importance des critères sélectionnés pour l’estimation de l’âge, produisant des écarts plus importants que pour des enfants modernes. De plus, elle met en avant le développement différentiel des premières molaires permanentes entre les deux arcades dentaires.AbstractAge estimation methods vary considerably and are based on reference frameworks that may be biased. New technologies, including medical and 3D imaging, are contributing to the development of improved and less subjective methods, and can identify new characteristics to support estimations of age at death. The use of a reference sample with known characteristics (origin, age, sex, etc.) is essential to develop new standards for age estimation. Comparing variability within a well characterized sample with the variability of fossil specimens provides new information on dental maturation and further insights for juvenile age estimation. Here, we propose an improvement to the juvenile age estimation methods of Moorrees et al. based on dental volumes derived from medical and 3D imaging. Its initial application to the Châteauneuf 2 Neanderthal child demonstrated the importance of the criteria selected for age estimation, which produced larger differences than in modern children, and brought out differences between the two arches in the rate of maturation of the first permanent molars.