MEPROCS framework for Craniofacial Superimposition: Validation study

Automatic landmark annotation in 3D surface scans of skulls: Methodological proposal and reliability study

BACKGROUND AND OBJECTIVES

Craniometric landmarks are essential in many biomedical applications, such as morphometric analysis or forensic identification. The process of locating landmarks is usually a manual and slow task, highly influenced by fatigue, skills and the experience of the practitioner. Localization errors are propagated and magnified in subsequent steps, which can result in incorrect measurements or assumptions. Thereby, standardization, reliability and reproducibility lay the foundations for the necessary accuracy in subsequent measurements or anatomical analysis. In this paper, we present an automatic method to annotate 3D surface skull models taking into account anatomical and geometrical features.

METHODS

The proposed method follows a hybrid structure where a deformable template is used to initialize the landmark positions. Then, a refinement stage is applied using prior anatomical knowledge to ensure a correct placement. Our proposal is validated over thirty 3D skull scans of male Caucasians, acquired by hand-held surface scanning, and a set of 58 craniometric landmarks. A statistical analysis was carried out to analyze the inter- and intra-observer variability of manual annotations and the automatic results, along with a visual assessment of the final results.

RESULTS

Inter-observer errors show significant differences, which are reflected in the expert consensus used as reference. The average localization error was 2.19±1.5 mm when comparing the automatic landmarks to the reference location. The subsequent visual analysis confirmed the reliability of the refinement method for most landmarks.

CONCLUSIONS

Repeated manual annotations show a high variability depending on both skills and expertise of the observer, and landmarks' location and characteristics. In contrast, the automatic method provides an accurate, robust and reproducible alternative to the tedious and error-prone task of manual landmarking.

Twenty-five years of unidentified bodies: an account from Milano, Italy

The identification of decedents has always been a central issue in forensic pathology, for ethical, criminal, and administrative reasons, but today, it needs more attention due to issues related not only to migration but also to the weakening of family ties. This article presents a descriptive study discussing the Italian regulatory situation developed in the last decade to face the many identification issues, with all its improvements and flaws. Hence, data gathered in 25 years of at the Institute of Legal Medicine of Milan and the epidemiology of unidentified decedents are illustrated. Briefly, from 1995 to 2019, the number of unidentified human remains with no identity or requesting verification of identity amounts to 726, i.e., 3% circa of all autopsies performed at the Institute, with an average of 29 individuals per year. In total, 528 (72.7%) individuals were successfully identified, 100 (13.8%) remained without an identity, and 98 (13.5%) individuals remained with suspected yet unconfirmed identities. Percentages for each identification technique are displayed, with insight into the role of forensic anthropology and odontology compared to genetics, and into the misuse of non-scientific methods allowed by Public Prosecutors. All the data is compared, as much as possible, with the very few recent studies concerning the problem worldwide. Finally, the article aims to show the Italian experience in dealing with unidentified bodies, in order to provide food for thought for other countries toward a discussion regarding a global issue which is sometimes taken for granted and underestimated.

Craniofacial photographic superimposition: New developments

Craniofacial superimposition is a technique used in the field of forensic anthropology to assist in the analysis of an unknown skull. The process involves superimposing an image of the recovered skull over an ante mortem image of the suspected individual. In the past two decades, there has been a decline in the application due to the development of molecular analysis as a more precise and accurate identification technique. Despite its decrease in use, there has been significant development in superimposition techniques in the past five years, specifically to standardize procedures. One project, MEPROCS (The New Methodologies and Protocols of Forensic Identification by Craniofacial Superimposition), has attempted to establish a framework for solving the problems of past superimposition techniques. Future researchers should consider integrating information gleaned from clinical practices with the statistical and technical advances of craniofacial superimposition for better facilitating its use in forensic anthropology.