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Background: Deep learning is a promising technique to improve radiological age assessment. However, expensive manual annotation by experts poses a bottleneck for creating large datasets to appropriately train deep neural networks. We propose an object detection approach to automatically annotate the medial clavicular epiphyseal cartilages in computed tomography (CT) scans., Methods: The sternoclavicular joints were selected as structure-of-interest (SOI) in chest CT scans and served as an easy-to-identify proxy for the actual medial clavicular epiphyseal cartilages. CT slices containing the SOI were manually annotated with bounding boxes around the SOI. All slices in the training set were used to train the object detection network RetinaNet. Afterwards, the network was applied individually to all slices of the test scans for SOI detection. Bounding box and slice position of the detection with the highest classification score were used as the location estimate for the medial clavicular epiphyseal cartilages inside the CT scan., Results: From 100 CT scans of 82 patients, 29,656 slices were used for training and 30,846 slices from 110 CT scans of 110 different patients for testing the object detection network. The location estimate from the deep learning approach for the SOI was in a correct slice in 97/110 (88%), misplaced by one slice in 5/110 (5%), and missing in 8/110 (7%) test scans. No estimate was misplaced by more than one slice., Conclusions: We demonstrated a robust automated approach for annotating the medial clavicular epiphyseal cartilages. This enables training and testing of deep neural networks for age assessment., (© 2023. The Author(s).)

Age estimation of living individuals is a regular activity in medico-legal practice. Among the available tools for determining skeletal age, some authors have stated that the disappearance of epiphyseal scars could be a useful marker. The aim of the present study was to assess whether the presence of an epiphyseal scar on the knee, as seen on a plain X-ray, was linked to biological age. A total of 988 frontal X-rays of individuals (509 females and 479 males) aged between 15 and 40 years were analyzed to see whether a scar was visible or not on each of the three epiphyses of the knee. A scar was visible for 96% of the females and 98% of the males. For each sex, scars were visible at each year of age, from 15 to 40 years. In younger females, there were 15 individuals with no scar visible on the fibula, 16 on the tibia, and 20 on the femur. For males, the ages were respectively 16, 17, and 18 years. On a frontal X-ray, the persistence of epiphyseal scars was not a marker of a recent fusion. All individuals with fully ossified knee that had no scar on the femur were older than 18 years. Further studies focusing on epiphyseal scars on MR and CT scans could be useful, as these techniques allow the more precise analysis of the epiphysis.

Estimation of chronological age from skeletal material is dependent upon estimation of maturational stage observed. Following completion of epiphyseal fusion, a transverse radio-opaque line, termed "epiphyseal scar", may be observed in the region of the former growth plate. According to the literature, this line is likely to become obliterated shortly after completion of epiphyseal fusion. Consequently, presence of an epiphyseal scar has been interpreted as an indication of recent epiphyseal fusion; however, this has not been validated by quantitative research. A study was undertaken to determine persistence of the epiphyseal scars in a cross-sectional population of adults between 20 and 50 years of age. This study examined 1,216 radiographs of proximal and distal tibiae from both sexes and sides of the body. This study suggested that 98.05% of females and 97.74% of males retained some remnant of the epiphyseal scar at the proximal tibia whilst 92.72% of females and 92.95% of males retained some remnant of the epiphyseal scar at the distal tibia. General linear model (GLM) analysis determined that chronological age accounted for 2.7% and 7.6% of variation in persistence of the epiphyseal scar at the proximal and distal tibiae, respectively. This study suggests that obliteration of the epiphyseal scar is not as dependent on chronological age as previously thought. It is, therefore, recommended that this feature not be used as an indicator of chronological age during forensic age assessment.

Radiological analysis of the epiphyses of the knee joint provides new valuable information, which may be used in combination with these well-established techniques in order to maximise the accuracy in the assessment of age of 18 years. A total of 215 antero-posterior radiographs of the knee was reviewed retrospectively in patients aged between 14 and 24 years old (99 boys, 116 girls). Fusion was scored as stage 1, epiphysis not fused; stage 2, epiphysis is fully ossified and epiphyseal scar is visible; and stage 3, epiphysis is fully ossified and epiphyseal scar is not visible. Scores of 0, 1 and 2 were assigned to stages 1, 2 and 3, respectively. Lastly, the score related to epiphyseal fusion at the knee joint was obtained by adding the three scores of the distal femur, proximal tibia and proximal fibula. Age distribution gradually increased with each score, for both genders. The mean age (±standard error) in each score category varied between genders, but the differences were not significant (p > 0.11). Five tests were performed to discriminate between individuals who were or were not at age 18 years or more, according to the receiver operating curve. For boys, the highest value of accuracy was obtained with score 3, with high sensitivity (Se = 93.33 %) and specificity (Sp = 89.29 %). For girls, it was obtained with score 4, with high accuracy (Acc = 85.86 %). These results indicate that radiographic analysis of the knee is a valuable alternative as a non-invasive method of estimation of 18 years of age.

In this study, both medial clavicular epiphyses of 77 men were evaluated by two researchers with a digital ultrasound system. The degree of ossification was classified in four stages according to Schulz et al. (Int J Legal Med 122:55-58, 17). Of the test persons over 21 years of age, stage 4 was found bilaterally in 25 (60%), while for five (12%) stage 4 was found on only one side; 12 (28%) further subjects did not show stage 4 on either side, although nine were exactly 21 years old. For the subjects under 21 years of age, stage 4 was found bilaterally in three cases (8.5%), and in three additional cases stage 4 was found on one side. Particularly, the three cases in which stage 4 was diagnosed bilaterally before completion of the 21st year of age limit the value of the used examinatory technique. For these cases it would be interesting to know if parts of the epiphyseal plate that might have been obstructed from the view of the ultrasound transducer would have been visible with CT.

Determination of the stage of ossification of the medial clavicular epiphysis is a crucial part of forensic age estimation when evaluating living subjects over 18 years of age. In the present study, we comparatively assessed conventional radiographs and computed tomography (CT) scans of sternoclavicular joints used to perform forensic age assessments in 57 individuals undergoing criminal proceedings. With CT, it was possible to determine the ossification stage of all clavicles studied. In the case of conventional radiography, reliable assessment of ossification stage was not possible in 15 out of 114 clavicles studied due to the superimposition of other structures. Regarding agreement between the methods, both radiography and CT produced identical staging results in 97 out of 99 clavicular epiphyses. In two cases, however, ossification was classified as stage 2 by CT and as stage 3 by conventional radiography. Regarding stages 4 and 5, both methods produced identical staging results in all cases. In forensic age estimation practice, it is necessary that conventional radiographic reference studies be used for ossification stage classification by conventional radiography and that CT reference studies be used for ossification stage classification by CT. Further studies in dead bodies of known age are required to issue a recommendation as to whether conventional radiography using obtained in three planes or CT is the method of choice for the assessment of clavicular ossification.

Radiological analysis of the hand skeleton is a key pillar of forensic age diagnostics in living subjects undergoing criminal proceedings. The present study investigated whether ossification stage classification of selected epiphyses of the hand could provide added value to hand radiograph analysis. Hand radiographs from 265 male and 164 female subjects aged 10-18years old who had been X-rayed due to traumatological indications were therefore assessed. Epiphyseal ossification of selected elements of the hand skeleton (ulna, radius and third metacarpal, basal phalanx, mesophalanx and telephalanx) was graded based on the criteria of the five-stage classification system of Schmeling et al. (Int J Legal Med, 118:5-8, 2004) for clavicular epiphyseal cartilage. Stage 5 (absence of the epiphyseal scar) does not occur in the radius of men before the age of 18. Stage 5 can therefore be regarded as a potential parameter for valid determination of a minimum age of 18 years for forensic age estimation in criminal proceedings.

Radiological assessment of the degree of ossification of the medial clavicular epiphyseal cartilage plays a vital part in forensic age diagnosis of living adolescents and young adults. A total of 873 plain chest radiographs requested by the staff medical officer for members of staff aged 16-30 at the University Hospital Charité were evaluated retrospectively. Of these X-rays 699 permitted an assessment of ossification of at least 1 side of the clavicle. In addition to the customary stages (1: non-ossified epiphysis, 2: discernible ossification centre, 3: partial fusion, 4: total fusion) a stage 5 was also defined, characterised by the disappearance of the epiphyseal scar following total fusion. The earliest age at which stage 3 was detected in either gender was 16 years. Stage 4 was first observed in women at 20 years and in men at 21 years. In both genders, the earliest observation of stage 5 was at 26 years. It was concluded that plain chest radiographs can essentially be used to assess clavicular ossification. In practice, if overlap in posterior-anterior views impedes evaluation, a lateral view should also be taken to facilitate age estimation. In forensic practice the reference values of the present paper should be applied.