AbstractThere has been a global rise in migration due to factors including conflict, famine, economic deprivation, health inequalities and more. This has resulted in an increase in the necessity for age assessments to be conducted. This requires methodologies that are both scientifically robust and ethical. Clinical imaging is generally the approach of choice and Magnetic Resonance Imaging (MRI) is of increasing value as it permits visualisation of osteological maturation which is strongly correlated with chronological age and it meets necessary health and safety requirements. However, limitations exist in the reproducibility and comparison of studies based on MRIs.
To identify accurate and appropriate age estimation methodologies this research project aimed to chart maturation of the distal end of the femur using T1 weighted MRIs, relate the changes to chronological age and develop an age estimation method that could be used to predict the age with accuracy and repeatability.
A data set of 321 (164 males,157 females) T1 weighted MRIs were collected from a Scottish medical sample aged between 10 and 20 years at the time of image acquisition.
An eight-stage classification system was developed and maturational maps of the femoral growth plate were created for each MRI and for each 1-year age cohort. To facilitate comparison of the maturational maps, 8 areas within the created maps were identified and tested to establish whether significant differences existed between them. To relate maturational stage to chronological age, age ranges for each of the 8 stages within the classification system were obtained. Twelve machine learning random forest and random forest with hyperparameter grid regression models (6 for male, 6 for females) for age prediction using 6 different combinations of feature factors were developed. The models were then tested on 40 MRIs as proof of concept.
From the results it was observed that the growth plate starts to fuse in the central area and fusion progresses centrifugally. The results showed that when utilising MRIs as the imaging modality the first bone bridges were present in females by 11 years 1 month (133 months) and in males by 12 years 4 months (147 months). The growth plate was mature by 15 years 4 months (184 months) in females, and 16 years 9 months (201 months) in males. Complete fusion of the growth plate at the distal end of the femur can be of assistance in determining the minimum age of 16 years in males, and 14 years in female individuals. It was not possible to assess the minimum age of 18 years in neither sex. A series of stages along with their location within the growth plate that can be useful for age prediction were also identified, specifically for the age thresholds of 12, 14, 16 and 18 years. From the analysis of the age prediction models, the random forest with hyperparameter grid gave the best results. For females the best model results gave a mean absolute error (MAE) of 12.73 months, R2 0.79, while for males a MAE of 9.20 months, R2 0.88. When considering location of the stages within the growth plate when predicting age, the age assessment did not improve, and when using only selected areas of the growth plate the MAE in months increased, suggesting that the whole growth plate should be used when predicting age, instead of selected images or areas.
In conclusion, maturation of the distal end of the femur was described for an age cohort of 10-20 years of age, providing final recommendations to assess age from MRIs of the distal end of the femur for relevant age thresholds.
|Date of Award||2021|
|Supervisor||Lucina Hackman (Supervisor) & Sue Black (Supervisor)|
- Age estimation in the living
- Forensic anthropology
- age estimation
- distal end of femur
- bone development
- growth plate