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

The four-minute approach revisited : accelerating MRI-based multi-factorial age estimation

Objectives: This feasibility study aimed to investigate the reliability of multi-factorial age estimation based on MR data of the hand, wisdom teeth and the clavicles with reduced acquisition time. Methods: The raw MR data of 34 volunteers-acquired on a 3T system and using acquisition times (TA) of 3:46 min (hand), 5:29 min (clavicles) and 10:46 min (teeth)-were retrospectively undersampled applying the commercially available CAIPIRINHA technique. Automatic and radiological age estimation methods were applied to the original image data as well as undersampled data to investigate the reliability of age estimates with decreasing acquisition time. Reliability was investigated determining standard deviation (SSD) and mean (MSD) of signed differences, intra-class correlation (ICC) and by performing Bland-Altman analysis. Results: Automatic age estimation generally showed very high reliability (SSD < 0.90 years) even for very short acquisition times (SSD ≈ 0.20 years for a total TA of 4 min). Radiological age estimation provided highly reliable results for images of the hand (ICC ≥ 0.96) and the teeth (ICC ≥ 0.79) for short acquisition times (TA = 16 s for the hand, TA = 2:21 min for the teeth), imaging data of the clavicles allowed for moderate acceleration (TA = 1:25 min, ICC ≥ 0.71). Conclusions: The results demonstrate that reliable multi-factorial age estimation based on MRI of the hand, wisdom teeth and the clavicles can be performed using images acquired with a total acquisition time of 4 min

Forensic age estimation in males by MRI based on the medial epiphysis of the clavicle

Increasing cross-border migration has brought forensic age assessment into focus in recent decades. Forensic age estimation is based on the three pillars: physical and medical constitution, bone age, and tooth age. Part of the bone age examination includes the assessment of the medial end of the clavicles when the hand bones are already fully developed and a minority must be excluded. Recent research has brought MRI to the forefront as a radiation-free alternative for age assessment. However, there exits only a few studies with large sample size regarding the clavicles and with controversies about staging, motion artifacts, and exclusion based on anatomic norm variants. In the current prospective study, 338 central European male individuals between 13 and 24 years of age underwent MRI examination of the sternoclavicular region. Development was assessed by three blinded raters according to the staging system described by Schmeling et al. and Kellinghaus et al. and related to age by descriptive statistics and transition analyses with a cumulative probit model. In addition, reliability calculations were performed. No statistically significant developmental difference was found between the left and right clavicles. Inter-rater agreement was only moderate, but intra-rater agreement, on the other hand, was good. Stage 3c had a minimum age of 19.36 years and appears to be a good indicator of proof of majority. The minimum age of stage 4 was lower compared with other studies, 20.18 years, and therefore seems not to be an indicator of age of 21 years. In conclusion, we confirmed the value of clavicular MRI in the age estimation process. The transition analysis model is a good approach to circumvent the problems of age mimicry and samples that are not fully equilibrated. Given the moderate agreement between raters, a consensus reading is recommended

Magnetic resonance imaging for multi-factorial age estimation using a Bayesian approach : a validation study in two independent samples

Background: The use of medical imaging for forensic age estimation remains a controversial subject and is often labeled as unethical and imprecise. To prevent exposure of an individual to ionizing radiation, MRI has been proposed as a suitable imaging modality to visualize developing anatomical structures.1-3 Moreover, to increase the accuracy of the point prediction of age, to reduce its uncertainty, and to decrease the chance of an ethically unacceptable error, MFA is preferred.1 Indeed, two research groups independently demonstrated that age estimation around the age of 18 years should combine data of the third molars, left hand/wrist, and both clavicles.3,4 One of these research groups developed MFA models based on Bayes’ rule combining MRI data of the third molars, left hand/wrist, and/or both clavicles but reported only on internal cross-validation.4 In males, combining all three anatomical sites rendered a mean absolute error equal to 1.36 years, a mean width of the 95% prediction intervals equal to 5.49 years, 94% correctly categorized adults, and 90% correctly categorized minors. In females, the corresponding results were 1.41 years, 5.91 years, 93%, and 91%, respectively. However, external validation is essential before the approach could be used in practice. Purpose: To externally validate MFA models based on MRI in two independent samples.4 This study hypothesized that the original models perform equally well in the external validation samples as reported for internal cross-validation. Materials and Methods: The relevant anatomical structures were studied in two samples, independent of the sample used in the De Tobel study.4 Note that the validity of the models can be studied only if the MRI protocol applied in the validation sample is equal to (or at least very similar to) the MRI protocol applied in the original sample. In a first validation sample, which will be referred to as the Ghent sample, MRI of the left wrist and both clavicles was prospectively conducted in 108 healthy Belgian Caucasian volunteers (52 males, 56 females), with ages between 16 and 21 years.5 In a second validation sample, which will be referred to as the Graz sample, MRI of the third molars, left hand/wrist, and both clavicles was prospectively conducted in 337 healthy Austrian Caucasian males, with ages between 13 and 25 years. Development was staged and age estimation performance was tested, calculating mean absolute errors, 95% prediction intervals and their coverage, and percentages of correctly identified minors and adults.4, 6-8 Results: Because this is ongoing research, no results that confirmed or rejected the hypothesis were available at the time of this submission