The Difficult Task of Diagnosing Prostate Cancer Metastases on Dry Bone

Sexual Dimorphism of Cranial Morphological Traits in an Italian Sample: A Population-Specific Logistic Regression Model for Predicting Sex

Simple Summary

Despite the fact that sex estimation methods from crania are very popular in forensic anthropology, few validation studies have verified their accuracy and reliability in different populations. Different from craniometrics, for which validation studies have remarkably increased lately, the methods based on cranial morphology still need to be thoroughly investigated, even if a large consensus exists on the effects of population variability on sexual cranial dimorphism. When dealing with forensic contexts, appropriately-validated methods should be applied for building accurate biological profiles. Since the possible sexual dimorphism variation of cranial morphological traits needs to be evaluated properly in various populations, in this study, we analyzed the accuracy of existing regression models for predicting sex from cranial morphological traits in an Italian contemporary/modern population. In addition, we propose new logistic regression models that are more accurate and specific for our sample. The results also update the reference standards for populations of this geographical area and provide an additional important warning on sexual dimorphism to anthropologists working in forensic contexts.

Abstract

Although not without subjectivity, the cranial trait scoring method is an easy visual method routinely used by forensic anthropologists in sex estimation. The revision presented by Walker in 2008 has introduced predictive models with good accuracies in the original populations. However, such models may lead to unsatisfactory performances when applied to populations that are different from the original. Therefore, this study aimed to test the sex predictive equations reported by Walker on a contemporary Italian population (177 individuals) in order to evaluate the reliability of the method and to identify potential sexual dimorphic differences between American and Italian individuals. In order to provide new reference data to be used by forensic experts dealing with human remains of modern/contemporary individuals from this geographical area, we designed logistic regression models specific to our population, whose accuracy was evaluated on a validation sample from the same population. In particular, we fitted logistic regression models for all possible combinations of the five cranial morphological traits (i.e., nuchal crest, mastoid process, orbital margin, glabella, and mental eminence). This approach provided a comprehensive set of population-specific equations that can be used in forensic contexts where crania might be retrieved with severe taphonomic damages, thus limiting the application of the method only to a few morphological features. The results proved once again that the effects of secular changes and biogeographic ancestry on sexual dimorphism of cranial morphological traits are remarkable, as highlighted by the low accuracy (from 56% to 78%) of the six Walker’s equations when applied to our female sample. Among our fitted models, the one including the glabella and mastoid process was the most accurate since these features are more sexually dimorphic in our population. Finally, our models proved to have high predictive performances in both training and validation samples, with accuracy percentages up to 91.7% for Italian females, which represents a significant success in minimizing the potential misclassifications in real forensic scenarios.

An osteometric and 3D analysis of the atlanto-occipital joint: An initial screening method to exclude crania and atlases in commingled remains

OBJECTIVES

The anatomical features of the atlanto-occipital joint can be potentially useful in re-associating or excluding crania to atlases in commingled remains. This study investigated whether linear measurements and the 3-dimensional (3D) surface of occipital condyles and articular facets of atlases can represent valid insights for this purpose.

METHODS

The variations among eight corresponding linear distances were analyzed in a sample of 150 individuals through six supervised machine learning techniques attempting to develop classifiers able to identify elements belonging to the same individual. Furthermore, a 3D analysis was conducted on the articular surfaces through superimpositions of 3D models of corresponding and non-corresponding crania and atlases obtained by using respectively stereophotogrammetry and laser scanning. This analysis investigated differences in terms of point-to-point distances (Root Mean Square, RMS) of superimposed 3D surfaces.

RESULTS

None of the six machine learning techniques were able to correctly detect a satisfying percentage of correspondent pairs in the overall sample by using the linear variables. The 3D analysis of the articular surfaces found RMS values over 0.53 mm only for superimposed non-corresponding surfaces, which sets a threshold value to identify 32% of incorrect pairs.

DISCUSSION

The re-association of cranium to atlas proved to be challenging and hardly possible when considering only metric variables. However, the 3D geometry of the articular surfaces represents a valid variable for this purpose and 3D analyses pave the way for an initial exclusion of incorrect re-associations, thus should not be considered as a re-association method per se, but as an exclusionary screening technique.

Computerized Tomography (CT) Updates and Challenges in Diagnosis of Bone Metastases During Prostate Cancer

Prostate cancer is one of the most common cancers in men. This cancer is often associated with indolent tumors with little or no lethal potential. Some of the patients with aggressive prostate cancer have increased morbidity and early deaths. A major complication in advanced prostate cancer is bone metastasis that mainly results in pain, pathological fractures, and compression of spinal nerves. These complications in turn cause severe pain radiating to the extremities and possibly sensory as well as motor disturbances. Further, in patients with a high risk of metastases, treatment is limited to palliative therapies. Therefore, accurate methods for the detection of bone metastases are essential. Technical advances such as single-photon emission computed tomography/ computed tomography (SPECT/CT) have emerged after the introduction of bone scans. These advanced methods allow tomographic image acquisition and help in attenuation correction with anatomical co-localization. The use of positron emission tomography/CT (PET/CT) scanners is also on the rise. These PET scanners are mainly utilized with 18F-sodium-fluoride (NaF), in order to visualize the skeleton and possible changes. Moreover, NaF PET/CT is associated with higher tracer uptake, increased target-to-background ratio and has a higher spatial resolution. However, these newer technologies have not been adopted in clinical guidelines due to lack of definite evidence in support of their use in bone metastases cases. The present review article is focused on current perspectives and challenges of computerized tomography (CT) applications in cases of bone metastases during prostate cancer.

Preliminary study on sexual dimorphism of metric traits of cranium and mandible in a modern Italian skeletal population and review of population literature

This study aims to assess the sexual dimorphism of skull in a modern skeletal collection through a direct anthropometric methodology by using a logistic regression analysis as statistical approach in order to provide specific regression formulae for the Italian population. Thirtyfour measurements (24 from cranium, 10 from mandible; 33 linear distances, one angle) were taken on 80 individuals (40 males, 40 females). A stepwise discriminant function analysis selected the combination of variables which best discriminated between sexes, and a cross-validation assessed the accuracy rate of the original sample. Most distances resulted longer in males than in females, but differences were statistically significant only for 12 and 6 out of respectively 24 cranium and 10 mandibular distances. Five combined cranium features returned a prediction accuracy of 88.6% (y = -81.01 + 0.14* Maximum cranial length + 0.16* Basion-bregma height -0.05* Cranial base length +0.20* Bizygomatic breadth +0.31* Nasal height; adjusted R2 = 47.0%). Nine mandibular features were required to reach 74.7% accuracy (y = -93.08 + 0.19* Bigonial width +0.14* Bicondylar breadth +0.11* Mandibular length +0.18* Height of the mandibular body at mental foramen +0.21* Chin height -0.09* Mandibular angle -0.06* Minimum ramus breadth -0.05* Maximum ramus height -0.01* Maximum ramus breadth; adjusted R2 = 23.92%). Current results and existing literature suggested that only few cranial measurements can be used for diagnosis of sex: the same variables showed similar accuracy in different ethnic contexts. In conclusion, some aspects of sexual dimorphism of skull seem to be independent from ancestry.

What's that big thing on your head? Diagnosis of a large frontoparietal lesion on an Eastern Zhou skull from Henan, China

We carried out a differential diagnosis of a large frontoparietal lesion on a human skull from a Late Bronze Age archaeological site located on the Central Plain of China, dating to between 771 and 476 BC. The head of this individual was covered in cinnabar, a mercury-based pigment that later was used for medicinal purposes in China. The lesion was well-circumscribed and involved the outer and inner tables of the skull, slight diploë thickening, and coarsening of bone trabeculae with expansion of intertrabecular spaces. We show that the observed changes are most consistent with cavernous hemangioma of the skull, a benign vascular malformation that preferentially affects older adults. Hemangiomas are often neglected in the paleopathological literature because of their benign nature - they tend to be asymptomatic and do not affect quality of life to a significant degree. Nevertheless, they produce characteristic lesions that can be confused with several other conditions with unrelated etiologies, including congenital hemoglabinopathies, traumas, malignant or benign neoplasms, and Paget's disease. We outline the diagnostic criteria that distinguish cavernous hemangioma from other conditions affecting the skull.

The synergy between radiographic and macroscopic observation of skeletal lesions on dry bone

The diagnosis of bone lesions is a fundamental part of the study of skeletal remains, both in the archeological and forensic context. On the one side, the literature proved the relevance of radiography for the detection of bone lesions; on the other side, the careful macroscopic observation of the morphology of bone lesions is often underestimated. For this study, we examined and performed plain radiography on 14 skeletons of the CAL Milano Cemetery Skeletal Collection diagnosed with rheumatoid arthritis, diabetes, multiple myeloma, metastatic cancer, and osteomalacia to compare the macroscopic morphology and radiographic visualization of bone lesions. At least 200 osteolytic lesions and 65 areas of proliferative bone reaction (either spongiosclerotic or periosteal) were studied. We realized "comparative sets" of macroscopic pictures and radiographic imaging of the same skeletal elements to allow comparisons of detection and recognition of bone lesions. As a result, while trabecular lesions may be lost through naked eye observation, many lesions can also be unperceived on radiographs due to contrast, including periosteal reactions, osteolytic lesions, and spongiosclerosis. The aim of this research was to investigate the strengths and pitfalls of digital radiography and macroscopic analysis and to demonstrate the synergy of a complementary approach between the two methods for lesion analysis in dry bone.