Multi-factorial forensic age estimation : combining magnetic resonance imaging of the third molars, the left wrist and both clavicles

Current age estimation methods rely on radiographs and/or computed tomography (CT) to visualise developing structures. However, these methods show major drawbacks. Firstly, they necessitate exposure to ionising radiation, without a medical diagnostic or therapeutic indication. Thus, in certain countries, their use is considered not to be ethically justifiable in civil and asylum procedures. Neither is their use ethically justifiable to verify age in sports. Secondly, superposition of anatomical structures can hamper the interpretation of radiographs, because the image is a projection. Conversely, superposition is eliminated when CT is used, since that imaging modality renders slices through the targeted structures. Thirdly, developmental information of different anatomical structures should be combined to increase the accuracy. However, large scale studies using ionising radiation to study development in healthy volunteers would not be ethically justifiable. Thus, to date, no uniform approach to combine the information of different anatomical structures has been proposed. Finally, no internationally accepted standardised approach is available to estimate age. This causes discrepancies between age estimation results from different institutions, whether in different countries, or even from within the same country. As a response to the drawbacks of the current approach, the use of magnetic resonance imaging (MRI) is investigated as an alternative to radiographs and CT. This imaging modality renders slices through the examined anatomical structures, without using ionising radiation. Consequently, it allows studying different anatomical structures of the same individual simultaneously in an ethically justifiable way. The current PhD project includes the joint efforts made in Belgium and the Netherlands to strive for an optimisation of age estimation. The project builds upon the foundations laid at Ghent University and the Catholic University of Leuven, reinforced by the Netherlands Forensic Institute. The study population included 335 healthy Belgian and Dutch Caucasian volunteers from 14 to 26 years old (with some exceptions from 6 to 30 years old). They underwent 3 Tesla MRI of all third molars, the left wrist and both clavicles, since it is recommended to combine those three sites for age estimation in adolescents and young adults. Combining the three anatomical sites yielded the best performance. Particularly around the age of 18, all three sites contributed significantly to the age estimation. Based on the current study population, the performance of the multi-factorial model was as follows: - In females, the MAE equalled 1.41 years; the mean width of 95% PI equalled 5.91 years; the proportion of correctly classified adults was 93%; and the proportion of correctly classified minors was 91%. - In males, the MAE equalled 1.36 years; the mean width of 95% PI equalled 5.49 years; the proportion of correctly classified adults was 94%; and the proportion of correctly classified minors was 90%. With the current PhD project, a statistically appropriate method was presented, ready to be enriched with data from other groups