A revised method for the preparation of dry bone samples used in histological examination: Five simple steps

Automatic Segmentation of Osteonal Microstructure in Human Cortical Bone Using Deep Learning: A Proof of Concept

Cortical bone microstructure assessment in biological and forensic anthropology can assist with the estimation of age-at-death and animal-human differentiation, for example. Osteonal structures within cortical bone are the key feature under analysis, with osteon frequency and metric parameters providing crucial information for the assessment. Currently, the histomorphological assessment consists of a time-consuming manual process for which specific training is required. Our work investigates the feasibility of automatic analysis of human bone microstructure images through the application of deep learning. In this paper, we use a U-Net architecture to address the semantic segmentation of such images into three classes: intact osteons, fragmentary osteons, and background. Data augmentation was used to avoid overfitting. We evaluated our fully automatic approach using a sample of 99 microphotographs. The contours of intact and fragmentary osteons were traced manually to provide ground truth. The Dice coefficients were 0.73 for intact osteons, 0.38 for fragmented osteons, and 0.81 for background, giving an average of 0.64. The Dice coefficient of the binary classification osteon-background was 0.82. Although further refinement of the initial model and tests with larger datasets are needed, this study provides, to the best of our knowledge, the first proof of concept for the use of computer vision and deep learning for differentiating both intact and fragmentary osteons in human cortical bone. This approach has the potential to widen and facilitate the use of histomorphological assessment in the biological and forensic anthropology communities.

Estimation of Age-at-Death Using Cortical Bone Histomorphometry of the Rib and Femur: A Validation Study on a British Population

Histomorphometry constitutes a valuable tool for age estimation. Histological interpopulation variability has been shown to affect the accuracy of age estimation techniques and therefore validation studies are required to test the accuracy of the pre-existing methodologies. The present research constitutes a validation study of widely known histological methods on the sixth rib and the femoral midshaft of a 19th century British population originating from Blackburn, England. An evaluation of the histomorphometric features of eleven ribs and five femora was performed and used to test the accuracy of selected methods. Results indicated that osteon area and circularity were the only histomorphometric variables that presented significant interpopulation variability. Cho et al.’s method for the ribs and the average value produced using Kerley and Ubelaker’s method for intact osteon and percentage of lamellar bone equations for femur were considered the only reliable markers for estimating the age on the Blackburn sample. In the case of old individuals, Goliath et al.’s method provided more satisfactory results. Overall, the present study provides evidence on the applicability of the aging histomorphometric methods on a British sample and highlights the limitations of applying histomorphometric methods developed on different reference populations than the one under investigation.

Age estimation for two Mediterranean populations: rib histomorphometry applied to forensic identification and bone remodelling research

Numerous intrinsic and extrinsic factors influence bone remodelling rates and have shown to affect the accuracy of histological aging methods. The present study investigates the rib cortex from two Mediterranean skeletal collections exploring the development of population-specific standards for histomorphometric age-at-death estimation. Eighty-eight standard ribs from two samples, Cretans and Greek-Cypriots, were processed histologically. Thirteen raw and composite histomorphometric parameters were assessed and observer error tested. The correlation between age and the parameters and the differences between sex and population subsamples were explored through group comparisons and analysis of covariance. General linear models assessed through data fit indicators and cross-validation were generated from the total dataset, and by sex and population subsamples. Most of the histological variables showed a statistically significant correlation with age with some differences observed by sex and by sample. From the twelve models generated, the optimal model for the whole sample included osteon population density (OPD), osteon perimeter, and osteon circularity producing an error of 10.71 years. When sex and samples were separated, the best model selected included OPD and osteon perimeter producing an error of 8.07 years for Greek-Cypriots. This research demonstrates the feasibility of quantitative bone histology to estimate age, obtaining errors rates in accordance with macroscopic ageing techniques. Sex and sample population differences need further investigation and inter-population variation in remodelling rates is suggested. Moreover, this study contributes to the creation of population-specific standards for Cretans and Greek-Cypriots.

Rib histomorphometry: A reliability and validation study with a critical review of histological techniques for forensic age estimation

Fragmented human remains present a challenge for forensic experts as they attempt to identify individuals using standard forensic methods. Several histological age estimation techniques have been developed during the last fifty years to aid in this process. However, very few validation studies have been conducted in order to test their accuracy and bias, and thus, validation assessment is required as we employ them while testifying in court. Histological variables are assessed from rib thin sections from two Mediterranean samples; Cretans (N = 41) and Greek-Cypriots (N = 47). Intra and inter-observer errors are assessed through TEM analysis and Intra-class Correlation Coefficient by testing observers with different levels of experience as they collected data on osteon counts and area measurements. The relation between the variables and age is determined using correlation coefficients. Histomorphometric data are applied to four widely used age estimation formulas assessing the performance of the methods for the entire sample. Inaccuracy and bias are calculated with age estimations and known age tested for significance and proportional bias assessed. Overall, histological parameters presented acceptable intra- and inter-observer errors. All variables exhibited statistically significant correlation with age (P < 0.01). For three of the techniques, data showed a systematic underestimation of age with an increase in inaccuracy in older individuals. One of the age estimation formulas produced overestimation of young individuals yet, it more accurately estimated the age of older individuals. This validation study explores inter-population variation in bone remodeling dynamics and presents a critical evaluation on methodological issues that can affect the performance of existing histological techniques.

Bone histomorphometry of the clavicle in a forensic sample from Albania

Forensic assessment of skeletal material includes age estimation of unknown individuals. When dealing with extremely fragmented human remains that lack macro-features used in age estimation, histological assessment of the skeletal elements can be employed. Historically, microscopic methods for age assessment used by forensic anthropologists have been available since 1965. Several skeletal elements have been used for this purpose. Among them, the clavicle has garnered very little attention. The purpose of this study is to explore the validity of clavicular histomorphometry as an age marker in a modern Balkan sample. This study examined a modern clavicular autopsy sample from Albania. The sample consisted of 33 individuals of known age and cause of death. Data were collected for micro-anatomical features including osteon population density (OPD) and cortical area. Intra- and inter-observer errors were assessed through technical error of measurement (TEM) and R coefficient. A validation study was performed in order to test the accuracy of existing histological formulae. Regression analysis was run to developed age prediction models with the best models tested through cross-validation and the comparison between OPD for the Albanian sample and a European-American sample examined. Intra- and inter-observer error TEM results demonstrated values falling within the limits of acceptance. The existing histological methods did not perform accurately on the sample under study. Regression equations for Albanians produced age estimations deviating 8 and 11 years from known age. Cross-validation on the most accurate regression formula which includes OPD as a single variable demonstrated similar mean errors. Statistically significant differences were observed between the Albanian and the European-American population when the two samples were compared. The research presented is the fifth article published and the fifth population explored on clavicular microstructure. The potential of histology to estimate age on the Albanian population is shown here; however, population effect, diet and health status might be considered. Further inclusion of individuals will corroborate our preliminary findings.

Margin Analysis in Head and Neck Cancer: State of the Art and Future Directions

BACKGROUND

The status of surgical margins is the most important prognosticator for patients undergoing surgical resection of head and neck squamous cell carcinoma (HNSCC). Despite this, analysis of surgical margins is fraught with inconsistencies, including the ways in which margins are sampled and interpreted. Fundamentally, even the definition what constitutes a "clear" (or negative) margin may vary between institutions, surgeons, and pathologists.

METHODS

The PubMed database was queried for articles relevant to the topic, and experts in the field were consulted regarding key articles for inclusion. Abstracts were reviewed and the full text was accessed for articles of particular interest.

RESULTS

Data regarding various approaches to traditional margin analysis have been published without consensus. Several next-generation technologies have emerged in recent years that hold promise.

CONCLUSION

An overview and appraisal of traditional margin analysis techniques are provided. Additionally, we explore novel technologies that may assist in more accurate margin assessment, guide the extent of surgical resections intraoperatively, and inform decisions regarding adjuvant treatment postoperatively.