BioAlder: a tool for assessing chronological age based on two radiological methods

A probability model for estimating age in young individuals relative to key legal thresholds: 15, 18 or 21-year

Age estimations are relevant for pre-trial detention, sentencing in criminal cases and as part of the evaluation in asylum processes to protect the rights and privileges of minors. No current method can determine an exact chronological age due to individual variations in biological development. This study seeks to develop a validated statistical model for estimating an age relative to key legal thresholds (15, 18, and 21 years) based on a skeletal (CT-clavicle, radiography-hand/wrist or MR-knee) and tooth (radiography-third molar) developmental stages. The whole model is based on 34 scientific studies, divided into examinations of the hand/wrist (15 studies), clavicle (5 studies), distal femur (4 studies), and third molars (10 studies). In total, data from approximately 27,000 individuals have been incorporated and the model has subsequently been validated with data from 5,000 individuals. The core framework of the model is built upon transition analysis and is further developed by a combination of a type of parametric bootstrapping and Bayesian theory. Validation of the model includes testing the models on independent datasets of individuals with known ages and shows a high precision with separate populations aligning closely with the model's predictions. The practical use of the complex statistical model requires a user-friendly tool to provide probabilities together with the margin of error. The assessment based on the model forms the medical component for the overall evaluation of an individual's age.

A machine learning approach for age prediction based on trigeminal landmarks

OBJECTIVE

The aim of this study was to estimate the chronological age (CA) of a growing individual using a new machine learning approach on Cone Beam Computed Tomography (CBCT).

MATERIALS AND METHODS

The dataset included 48 CBCT and hand-wrist radiographs of growing individuals. 12 landmarks related to trigeminal trajectories were plotted on each CBCT and principal component analysis was applied for dimensionality reduction. The estimated CA was obtained using a decision tree. Finally, a genetic algorithm was implemented to select the best set of landmarks that would optimize the estimation. The age was also assessed following Greulich and Pyle's (GP) method on hand-wrist radiographs. The results (GP and Machine Learning) were then compared to the true CA.

RESULTS

Among the 12 landmarks, the genetic algorithm selected 7 optimal features, and 12 principal components out of 36. The best results for age prediction were obtained by a combination of genetic algorithm, principal component analysis, and regression tree where the Mean Squared Error (MSE) and Mean Absolute Error (MAE) were respectively 1.29 and 0.92. These outcomes showed improved accuracy compared to those of the hand-wrist method (MSE = 2.038 and MAE = 1.775).

CONCLUSIONS

A numerical application on a dataset of CBCT showed that the proposed machine learning method achieved an improved accuracy compared to conventional methods and had satisfying performance in assessing age for forensic purposes. Validation of the presented method on a larger and more diverse sample would pave the way for future applications in forensic science as a tool for age prediction.

Age prediction in sub-adults based on MRI segmentation of 3rd molar tissue volumes

PURPOSE

Our aim was to investigate tissue volumes measured by MRI segmentation of the entire 3rd molar for prediction of a sub-adult being older than 18 years.

MATERIAL AND METHOD

We used a 1.5-T MR scanner with a customized high-resolution single T2 sequence acquisition with 0.37 mm iso-voxels. Two dental cotton rolls drawn with water stabilized the bite and delineated teeth from oral air. Segmentation of the different tooth tissue volumes was performed using SliceOmatic (Tomovision^©). Linear regression was used to analyze the association between mathematical transformation outcomes of the tissue volumes, age, and sex. Performance of different transformation outcomes and tooth combinations were assessed based on the p value of the age variable, combined or separated for each sex depending on the selected model. The predictive probability of being older than 18 years was obtained by a Bayesian approach.

RESULTS

We included 67 volunteers (F/M: 45/22), range 14-24 years, median age 18 years. The transformation outcome (pulp + predentine)/total volume for upper 3rd molars had the strongest association with age (p = 3.4 × 10^-9).

CONCLUSION

MRI segmentation of tooth tissue volumes might prove useful in the prediction of age older than 18 years in sub-adults.

Mathematically optimal decisions in forensic age assessment

Forensic age estimation generally involves considerable amounts of uncertainty. Forensic age indicators such as teeth or skeleton images predict age only approximately, and this is likely to remain true even for future forensic age indicators. Thus, forensic age assessment should aim to make the best possible decisions under uncertainty. In this paper, we apply mathematical theory to make statistically optimal decisions to age assessment. Such an application is fairly straightforward assuming there is a standardized procedure for obtaining age indicator information from individuals, assuming we have data from the application of this procedure to a group of persons with known ages, and assuming the starting point for each individual is a probability distribution describing prior knowledge about the persons age. The main problem is then to obtain such a prior. Our analysis indicates that individual priors rather than a common prior for all persons may be necessary. We suggest that caseworkers, based on individual case information, may select a prior from a menu of priors. We show how information may then be collected over time to gradually increase the robustness of the decision procedure. We also show how replacing individual prior distributions for age with individual prior odds for being above an age limit cannot be recommended as a general method. Our theoretical framework is applied to data where the maturity of the distal femur and the third molar is observed using MRI. As part of this analysis we observe a weak positive conditional correlation between maturity of the two body parts.

Dental and Skeletal Imaging in Forensic Age Estimation: Disparities in Current Approaches and the Continuing Search for Optimization

Medical imaging for forensic age estimation in living adolescents and young adults continues to be controversial and a subject of discussion. Because age estimation based on medical imaging is well studied, it is the current gold standard. However, large disparities exist between the centers conducting age estimation, both between and within countries. This review provides an overview of the most common approaches applied in Europe, with case examples illustrating the differences in imaging modalities, in staging of development, and in statistical processing of the age data. Additionally, the review looks toward the future because several European research groups have intensified studies on age estimation, exploring four strategies for optimization: (1) increasing sample sizes of the reference populations, (2) combining single-site information into multifactorial information, (3) avoiding ionizing radiation, and (4) conducting a fully automated analysis.

Die Aussagekraft sozialpädagogischer Altersschätzungen im Vergleich zur forensischen Altersdiagnostik

In der vorliegenden Studie sollte die Aussagekraft sozialpädagogischer Altersschätzungen im Vergleich zu forensischen Altersbegutachtungen, die entsprechend den Empfehlungen der Arbeitsgemeinschaft für Forensische Altersdiagnostik durchgeführt worden waren, analysiert werden. Hierfür wurden 47 Fälle ausgewertet, bei denen sowohl sozialpädagogische Altersschätzungen von in Jugendhilfeeinrichtungen betreuten unbegleiteten minderjährigen Flüchtlingen als auch forensische Altersgutachten zur Verfügung standen. In 44 Fällen, in denen die Einrichtungen von Minderjährigkeit ausgingen, bescheinigten die forensischen Altersgutachten in 12 Fällen zweifelsfreie Volljährigkeit und in 24 weiteren Fällen wahrscheinliche Volljährigkeit. In 2 Fällen, in denen die Einrichtungen die Minderjährigkeit anzweifelten, wurden im Ergebnis der forensischen Altersbegutachtung in dem einen Fall zweifelsfreie Volljährigkeit und in dem anderen Fall wahrscheinliche Volljährigkeit festgestellt. In einem Fall, in dem die Einrichtung von Volljährigkeit ausging, wurde auf der Grundlage der forensischen Altersbegutachtung wahrscheinliche Volljährigkeit mit noch möglicher Minderjährigkeit attestiert. Objektivierbare psychosoziale Kriterien, mit denen Volljährigkeit zweifelsfrei festgestellt werden kann, ließen sich nicht erkennen. Es ist davon auszugehen, dass der Anteil falsch-positiver Minderjährigkeitsfeststellungen bei sozialpädagogischen Altersschätzungen deutlich höher als bei forensischen Altersbegutachtungen ist. Ebenso scheint ein relevantes Risiko falsch-positiver Volljährigkeitsfeststellungen bei sozialpädagogischen Altersschätzungen zu bestehen. Es wurde geschlussfolgert, dass sozialpädagogische Altersschätzungen keine überzeugende Alternative zu forensischen Altersbegutachtungen darstellen.

Juristische Aspekte der forensischen Altersdiagnostik auf der Grundlage des § 42f SGB VIII

Seit Inkrafttreten des § 42f SGB VIII am 01.11.2015 ist das Verfahren zur Altersfeststellung von unbegleiteten und fraglich minderjährigen Ausländern durch Jugendämter in Deutschland gesetzlich geregelt. Hiernach hat das Jugendamt die Minderjährigkeit zunächst durch Einsichtnahme in die Ausweispapiere des jungen Menschen zu prüfen. Fehlen gültige Ausweispapiere, oder sind die in ihnen enthaltenen Geburtsdaten zweifelhaft, haben Jugendamtsmitarbeiter die Minderjährigkeit mittels einer qualifizierten Inaugenscheinnahme zu beurteilen. Lässt sich auch dadurch eine Minderjährigkeit nicht zweifelsfrei ausschließen, hat das Jugendamt eine ärztliche Untersuchung zur Altersfeststellung zu veranlassen. Eine Analyse der einschlägigen Rechtsprechung sowie der juristischen Fachliteratur ergab, dass Röntgenuntersuchungen zur forensischen Altersdiagnostik auf der Grundlage des § 42f SGB VIII nicht nur zulässig sind, sondern diese auch ausdrücklich eingefordert werden. Die Rechtsprechung erkennt zudem die medizinischen Untersuchungen nach den Empfehlungen der Arbeitsgemeinschaft für Forensische Altersdiagnostik (AGFAD) zur Altersdiagnostik unbegleiteter minderjähriger Ausländer als rechtlich zulässige, valide und zumutbare Methode an. Der von der Zentralen Ethikkommission (ZEKO) bei der Bundesärztekammer vertretenen Auffassung, dass die von der AGFAD empfohlenen Methoden nicht geeignet seien, Volljährigkeit hinreichend zuverlässig nachzuweisen, wird von der Rechtsprechung nicht gefolgt. Vielmehr wird darauf verwiesen, dass durch die Anwendung des Mindestalterkonzepts die von der ZEKO geäußerten Bedenken hinsichtlich der Schwankungsbreiten medizinischer Untersuchungen ausgeräumt werden.

Forensic age assessment of living adolescents and young adults at the Institute of Legal Medicine, Münster, from 2009 to 2018

Due to high migration inflows to Europe, forensic age assessment of living persons has clearly gained importance. If there is a legal justification for X-ray examinations without a medical indication, the Study Group on Forensic Age Diagnostics (AGFAD) recommends the combination of a physical examination with anamnesis, an X-ray examination of the hand and a dental examination with evaluation of an orthopantomogram for age assessments of adolescents and young adults. If the development of the hand skeleton has been completed, an additional CT examination of the clavicles is to be performed. To demonstrate the outcome of forensic age assessments according to AGFAD recommendations with regard to migrants of doubtful minority declaration, this study analyzes the expert reports carried out at the Institute of Legal Medicine, Münster, from 2009 to 2018. A total of 597 age assessments were performed during the study period. A total of 227 age assessments were issued on behalf of youth welfare offices in the legal area of social law, 282 in family law proceedings, 76 in criminal proceedings, and 12 age assessments in immigration law proceedings. In 211 out of 597 cases, the stated age was compatible with the findings of the age assessment. In the remaining 386 cases, the average difference between the stated age and the minimum age was 1.9 years. The average difference between stated age and most probable age was 5.1 years. Of the 521 age assessments carried out outside criminal proceedings, 197 unaccompanied minors with questionable age minority (37.8%) have reached the age of majority beyond doubt. A total of 388 unaccompanied minors (74.5%) have most probably reached the age of majority. Forensic age assessments with the AGFAD methodology make an important contribution to legal certainty, the welfare of the child, and the fair distribution of resources.

Dental age estimation based on the radiographic visibility of the periodontal ligament in the lower third molars: application of a new stage classification

The purpose of the present study was to test whether a new stage classification based on radiographic visibility of the periodontal ligament in lower third molars in a Chinese population can be used for the 18- and 21-year thresholds. A total of 1300 orthopantomograms, including equal numbers of northern Chinese males and females evenly distributed between the ages of 15 and 40 years, were analyzed. The stages were defined according to the visibility of periodontal ligament for the outer parts of lower third molar roots because the visibility status of the periodontal ligament between the roots of lower third molars is none valuable in many Chinese individuals. Stage 0 was first achieved at the age of 17.05 years in males and 17.46 years in females. The earliest appearance of stage 1 was 17.47 years in males and 17.86 years in females. Stage 2 was first observed in males at the age of 21.43 years and in females at the age of 21.96 years. The onset of stage 3 was first observed at the age of 25.83 years in males and 23.14 years in females. Compared with the stage classification of Olze et al., which also considers the mesial parts of the roots, the number of assessable cases could be significantly increased. Therefore, our novel approach is effective for age estimation in the Chinese population.

Bone age for chronological age determination - statement of the European Society of Paediatric Radiology musculoskeletal task force group

Radiologists are sometimes requested to determine a person's age based on skeletal radiographs. Critical reviews demonstrate that this cannot be done with sufficient accuracy with existing methods.

Dental age estimation in Somali children and sub-adults combining permanent teeth and third molar development

Estimation of an individual’s age has important applications in forensics. In young individuals, it often relies on separate evaluations of permanent teeth (PT) and third molars (TM) development. Here, we analysed the age prediction performance of combined information from PT and TM in an unusual sample of healthy Somalis, born and living in Finland. PT development was staged according to Demirjian et al. (Hum Biol, 1973) and TM development according to Köhler et al. (Ann Anat, 1994), using panoramic radiographs from 803 subjects (397 males, 406 females) aged 3–23 years. A sex-specific Bayesian age-estimation model for the multivariate distribution of the stages conditional on age was fitted on PT, TM and PT and TM combined. The age-estimation performances were validated and quantified. The approach combining PT and TM only overestimated age with an ME of − 0.031 years in males and − 0.011 years in females, indicating the best age prediction performance.