Computed tomographic age estimation from the pubic symphysis using the Suchey-Brooks method: A Systematic Review and Meta-analysis

Mandibular torus thickness associated with age: Postmortem computed tomographic analysis

Age estimation is an essential step in identifying human corpses. Several mandibular landmarks have been highlighted as skeletal sites for age estimation since aging causes morphological changes. Reports suggest that mandibular torus size may be associated with aging; however, thorough investigation has not been performed owing to the difficulty in measuring it. Therefore, this study aimed to determine the association between age and mandibular torus thickness using postmortem computed tomography data from Japanese corpses. This study included 2,792 corpses with mean (standard deviation) age of 58.0 (22.4) years (range, 0-101 years) and 67.6 % males. Further, 2,662 (95.3 %), 14 (0.5 %), 59 (2.1 %), and 57 (2.0 %) corpses were in the permanent, mixed, primary, and predental dentition periods, respectively. Multivariable analysis was performed to quantify the impact of age on mandibular torus thickness, adjusting for sex, height, weight, and occlusal contact status. The model also included an interaction term between age and occlusal status because of the potential effect modification by occlusion. Results of the multivariable regression analysis showed that mandibular torus thickness increased with age (the regression coefficients (95 % confidence interval) were 0.6 (0.2-1.0), 0.7 (0.3-1.0), 1.0 (0.6-1.4), 1.3 (0.9-1.7), 1.3 (0.8-1.8), and 1.1 (0.4-1.7) for age groups 30-39, 40-49, 50-59, 60-69, 70-79, and 80-89 years, respectively), especially in males with occlusal contact. A significant association between mandibular torus thickness and age, modified by occlusal status and sex, was identified. Therefore, data regarding the thickness of the mandibular torus and occlusal status may be useful for age estimation in human corpses.

Development of a deep-learning algorithm for age estimation on CT images of the vertebral column

PURPOSE

The accurate age estimation of cadavers is essential for their identification. However, conventional methods fail to yield adequate age estimation especially in elderly cadavers. We developed a deep learning algorithm for age estimation on CT images of the vertebral column and checked its accuracy.

METHOD

For the development of our deep learning algorithm, we included 1,120 CT data of the vertebral column of 140 patients for each of 8 age decades. The deep learning model of regression analysis based on Visual Geometry Group-16 (VGG16) was improved in its estimation accuracy by bagging. To verify its accuracy, we applied our deep learning algorithm to estimate the age of 219 cadavers who had undergone postmortem CT (PMCT). The mean difference and the mean absolute error (MAE), the standard error of the estimate (SEE) between the known- and the estimated age, were calculated. Correlation analysis using the intraclass correlation coefficient (ICC) and Bland-Altman analysis were performed to assess differences between the known- and the estimated age.

RESULTS

For the 219 cadavers, the mean difference between the known- and the estimated age was 0.30 years; it was 4.36 years for the MAE, and 5.48 years for the SEE. The ICC (2,1) was 0.96 (95 % confidence interval: 0.95-0.97, p < 0.001). Bland-Altman analysis showed that there were no proportional or fixed errors (p = 0.08 and 0.41).

CONCLUSIONS

Our deep learning algorithm for estimating the age of 219 cadavers on CT images of the vertebral column was more accurate than conventional methods and highly useful.

Adult age estimation from the sternum using maximum intensity projection images of CT and data mining in a Chinese population

This study aimed to explore and develop data mining models for adult age estimation based on CT reconstruction images from the sternum. Maximum intensity projection (MIP) images of chest CT were retrospectively collected from a modern Chinese population, and data from 2700 patients (1349 males and 1351 females) aged 20 to 70 years were obtained. A staging technique within four indicators was applied. Several data mining models were established, and mean absolute error (MAE) was the primary comparison parameter. The intraobserver and interobserver agreement levels were good. Within internal validation, the optimal data mining model obtained the lowest MAE of 9.08 in males and 10.41 in females. For the external validation (N = 200), MAEs were 7.09 in males and 7.15 in females. In conclusion, the accuracy of our model for adult age estimation was among similar studies. MIP images of the sternum could be a potential age indicator. However, it should be combined with other indicators since the accuracy level is still unsatisfactory.

Applicability of the Suchey-Brooks method for age estimation in an Indian population: A computed tomography-based exploration using Bayesian analysis and machine learning

Age estimation occupies a prominent niche in the identification process. In cases where skeletal remains present for examination, age is often estimated from markers distributed throughout the skeletal framework. Within the pelvis, the pubic symphysis constitutes one of the more commonly utilized skeletal markers for age estimation, with the Suchey-Brooks method comprising one of the more commonly employed methods for pubic symphyseal age estimation. The present study was targeted towards assessing the applicability of the Suchey-Brooks method for pubic symphyseal age estimation, an aspect largely unreported for an Indian population. In order to do so, clinically undertaken pelvic computed tomography scans of individuals were evaluated using the Suchey-Brooks method, and the error associated with the method was established using Bayesian analysis and different machine learning regression models. Amongst different supervised machine learning models, support vector regression and random forest furnished lowest error computations in both sexes. Using both Bayesian analysis and machine learning, lower error computations were observed in females, suggesting that the method demonstrates greater applicability for this sex. Inaccuracy and root mean square error obtained with Bayesian analysis and machine learning illustrates that both statistical modalities furnish comparable error computations for pubic symphyseal age estimation using the Suchey-Brooks method. However, given the numerous advantages associated with machine learning, it is recommended to use the same within medicolegal settings. Error computations obtained with the Suchey-Brooks method, regardless of the statistical modality utilized, indicate that the method should be used in amalgamation with additional markers to garner accurate estimates of age.

Technical note: Interest of focused fields in post-mortem computed tomography using photorealistic images for age at death estimation from the pubic symphysis

INTRODUCTION

The morphological assessment of the pubic symphysis using the Suchey-Brooks method is considered a reliable age at death indicator. Age at death estimation methods can be adapted to the images obtained from post-mortem computed tomography (PMCT). The aim of this study is to evaluate the utility of pubic symphysis photorealistic images obtained through Global illumination rendering (GIR) for age at death estimation from whole-body PMCT and from focused PMCT on the pubic bone.

MATERIALS AND METHODS

We performed virtual age at death estimation using the Suchey Brooks method from both the whole-body field of view (Large Field of View: LFOV) and the pubis-focused field of view (Small and Field of View: SFOV) of 100 PMCT. The 3D photorealistic images were evaluated by three forensic anthropologists and the results were statistically evaluated for accuracy of the two applied PMCT methods and the intra- and inter-observer errors.

RESULTS

When comparing the two acquisitions of PMCT, the accuracy rate reaches 98.5% when using a pubic-focused window (SFOV) compared to 86% with a whole-body window (LFOV). Additionally, the intra- and inter-observer variability has demonstrated that the focused window provides better repeatability and reproducibility.

CONCLUSION

Adding a pubic-focused field of view to standard PMCT and processing it with GIR appears to be an applicable technique that increases the accuracy rate for age at death estimation from the pubic symphysis.

Age estimation by modified Suchey-Brooks method using three-dimensional reconstructed CT images of Chinese Han population

The method proposed by Suchey-Brooks for adult age estimation based on the surface morphology of the pubic symphysis has been widely accepted. The applicability of the method varies considerably in different populations. The present study established a virtual reference sample and aimed to develop population-specific criteria that can be used for age estimation in different skeletal samples. First, The dry bone specimens from 100 individuals were compared with their corresponding three-dimensional (3D) reconstruction model and showed high inter-method agreement (k = 0.743-0.811), suggesting that the virtual bone model and physical bone specimens have comparable performances in describing the surface morphology of the pubic symphysis. We retrospectively collected clinical computed tomography (CT) data from 895 Chinese patients to create a virtual reference sample of the pubic symphysis. Based on the original Suchey-Brooks method, each of the 895 reference samples was assigned a phase, for each sex and phase, data on the mean age, standard deviation, and 95% age range of the corresponding sample were obtained, which was then used as the "method modified for Chinese" (modified method) and compared to the "SB method". Compared to the SB method, modified method had a lower inaccuracy in dry bones for males over 35 years and females over 45 years, in dry bone CT test sample for males over 55 years and females over 45 years, and in postmortem CT test sample for males over 35 years and females over 55 years. The modified method can improve the accuracy of age estimation for older samples over 40 years. It has shown considerable reliability when applied as a population-specific criterion, but its accuracy is still not sufficient, and caution is needed when using it.

Computed Tomographic Evaluation of Cranial Suture Obliteration for Age Estimation in an Indian Population

BACKGROUND

Age estimation is a critical aspect of human identification. Age is assessed using cranial suture obliteration, pelvic morphological changes, epiphyseal fusion of long bones, dental maturation, and other standard methods.

METHODS

The present study investigated three-dimensional (3D) computed tomography (CT) scans of 263 individuals (183 males and 80 females) to assess the extent of ectocranial suture closure. The assessment of obliteration was done using a three-stage scoring method. Spearman's correlation coefficient (p < 0.05) was calculated to assess the relationship between cranial suture closure and chronological age. Simple and multiple linear regression models were developed using the cranial suture obliteration scores to estimate age.

RESULTS

The standard errors of the estimate using multiple linear regression models developed for estimating age using obliteration scores of sagittal, coronal, and lambdoid sutures were 15.08 years in males, 13.27 years in females, and 14.74 years in the total study population.

CONCLUSION

This study concludes that in the absence of additional skeletal age markers, this method can be used alone or in conjunction with other well-established methods of age assessment.

McKern-Stewart method as a technique for analysing age related pubic symphyseal changes: A systematic review and meta-analysis

Age estimation is one of the essential criteria in the identification process. The method of age estimation employed depends on the availability of skeletal material brought for forensic examination. McKern and Stewart's method constitutes one of the principal approaches towards pubic symphyseal age estimation. The method entails evaluating morphological changes within the pubic symphysis and subsequently allotting a specific score corresponding to the observed changes. Based on the obtained scores, an age range is then assigned to the remains presenting for examination. The present systematic review was undertaken to ascertain the applicability of the McKern-Stewart method for age estimation. Studies pertaining to the use of the McKern-Stewart method for age estimation in skeletal remains were retrieved by keying in a combination of MeSH terms and other free terms from four databases. The retrieved articles were subjected to a stringent inclusion and exclusion criteria, following which the risk of bias was assessed and the overall quality of evidence was established. Once the final tally of relevant articles was obtained, data specific to the mean age corresponding to each score was extracted. Non-parametric tests and boxplots were employed to compare the mean ages reported across multiple studies. The present systematic review concludes that the McKern-Stewart method can be applied for the purpose of age estimation in skeletal remains. Broader age cohorts for higher scores, as well as, overlapping values for age ranges in relation to the cumulative scores, however, can be considered a limitation for its applicability in forensic case work.

Validity of age estimation methods and reproducibility of bone/dental maturity indices for chronological age estimation: a systematic review and meta-analysis of validation studies

Several approaches have been developed to estimate age, an important aspect of forensics and orthodontics, using different measures and radiological examinations. Here, through meta-analysis, we determined the validity of age estimation methods and reproducibility of bone/dental maturity indices used for age estimation. The PubMed and Google Scholar databases were searched to December 31, 2021 for human cross-sectional studies meeting pre-defined PICOS criteria that simultaneously assessed the reproducibility and validity. Meta-estimates of validity (mean error: estimated age-chronological age) and intra- and inter-observer reproducibility (Cohen's kappa, intraclass correlation coefficient) and their predictive intervals (PI) were calculated using mixed-effect models when heterogeneity was high (I2 > 50%). The literature search identified 433 studies, and 23 met the inclusion criteria. The mean error meta-estimate (mixed effects model) was 0.08 years (95% CI - 0.12; 0.29) in males and 0.09 (95% CI - 0.12; 0.30) in females. The PI of each method spanned zero; of nine reported estimation methods, Cameriere's had the smallest (- 0.82; 0.47) and Haavikko's the largest (- 7.24; 4.57) PI. The reproducibility meta-estimate (fixed effects model) was 0.98 (95% CI 0.97; 1.00) for intra- and 0.99 (95% CI 0.98; 1.00) for inter-observer agreement. All methods were valid but with different levels of precision. The intra- and inter-observer reproducibility was high and homogeneous across studies.

The accuracy and reliability of the Suchey-Brooks pubic symphysis age estimation method: Systematic review and meta-analysis

Suchey-Brooks method has been studied many times with varying reports of accuracy and reliability. A systematic review and meta-analyses were utilized to quantitatively determine the accuracy and reliability of the Suchey-Brooks (S-B) method. A systematic search of PubMed and EBSCO health and medical databases was performed. Meta-analyses were performed to quantify the relationship between actual known age at death and the S-B method using Spearman's Rho and Pearson's r for (1) combined males and females estimates, (2) male-only estimates, and (3) female-only estimates. Overall correlation coefficient using Cohen's kappa, Spearman's Rho, and Pearson's r was also calculated to determine the interrater and intrarater reliability using the S-B method. Eighteen studies classified as moderate-to-high methodological quality met the inclusion criteria. The sample sizes were different for the combined male and female (n = 2620), male-only (n = 2602), and female-only (n = 1431) meta-analyses. The effect size of the age at death meta-analyses was large and significant for combined males and females (Spearman's Rho = 0.62; Pearson's r = 0.65), male-only (Spearman's Rho = 0.77; Pearson's r = 0.75), and female-only (Spearman's Rho = 0.71; Pearson's r = 0.71). The overall correlation coefficients of the interrater (Kappa = 0.76; Spearman's Rho = 0.73; Pearson's r = 0.80) and intrarater (Kappa = 0.81; Spearman's Rho = 0.91; Pearson's r = 0.83) reliability meta-analyses were large and significant. A significant degree of heterogeneity was present in all meta-analyses, with minimal evidence of publication bias. The meta-analyses results suggest the S-B method is highly reliable with a moderate-to-high degree of accuracy. Our results also identified sample size and accuracy differences between male and female individuals.