Characterization of structural changes in spinal vertebrae based on perturbations to an adaptive model

Diffuse Idiopathic Skeletal Hyperostosis, or DISH, is a disease characterized by ossification of the entheses and the anterior longitudinal ligament. The diagnosis is made by visual analysis of an X-ray by a professional using the Resnick Criterion. The different experience among professionals and the fact that this criterion is only suitable in advanced stages of the disease make diagnosis difficult. Therefore, this work aims to contribute to the development of an auxiliary diagnostic tool for this disease. For this, a semi-automatic vertebral segmentation algorithm based on active morphological contours was proposed, comparing it with previous work and with segmentations made by experts on two radiographic images. Next, the corners of the vertebrae, where the disease manifests itself, were analyzed in order to characterize images with DISH. To accomplish this, it was assumed symmetry of the vertebrae and a Gaussian distribution of the histograms of those corners to analyze them and calculate two ratios: Left upper corner mean value / Right upper corner mean value (LS/RS) and Left lower corner mean value / Right lower corner mean value (LI/RI), in order to find a differentiating metric between vertebrae with pathology and those without. The results achieved by the algorithm were clearly superior to the previous work and similar to that of the experts. The analysis of pathologic vertebrae revealed a difference in the shift of the distributions of pathologic corners relative to non-pathologic ones, which is not seen in vertebrae without apparent pathology. Regarding the ratios, the LI/RI proved to be particularly effective in differentiating, being closer to 1 when pathology is not present.A Hiperostose Esquelética Idiopática Difusa, ou DISH, é uma doença caracterizada pela ossificação das entéses e do ligamento longitudinal anterior. O diagnóstico é realizado pela análise visual de um raio-X, por um profissional, utilizando o Critério de Resnick. A diferente experiência entre profissionais e o facto de este critério só ser adequado em fases avançadas da doença tornam o diagnóstico difícil. Por isso, este trabalho visa contribuir para o desenvolvimento de um instrumento auxiliar de diagnóstico desta doença. Para isso, foi proposto um algoritmo de segmentação de vertebras, semi-automático, baseado em contornos morfológicos ativos, comparando-o com o trabalho anterior e com as segmentações feitas por especialistas em duas imagens radiográficas. De seguida, foram analisadas as extremidades das vértebras, onde a doença se manifesta, com o objetivo de identificar imagens com DISH. Para tal, assumiu-se a simetria das vértebras e uma distribuição Gaussiana dos histogramas das extremidades para analisar as mesmas e calcular dois rácios: Valor médio do canto superior esquerdo / Valor médio do canto superior direito(LS/RS) e valor médio do canto inferior esquerdo /Valor médio do canto inferior direito(LI/RI), a fim de encontrar uma métrica diferenciadora das vértebras com patologia das não patológicas. Os resultados conseguidos pelo algoritmo foram claramente superiores ao do trabalho anterior e semelhantes ao dos peritos. A análise das vértebras patológicas revelou uma diferença na deslocação das distribuições dos cantos patológicos relativamente aos não patológicos, o que não se verifica em vértebras sem patologia aparente. Relativamente aos rácios, o LI/RI mostrou ser particularmente eficaz na diferenciação, estando mais próximo de 1 quando a patologia não está presente

Assessing disease activity and response to treatment in axial spondyloarthritis: The unmet clinical need and potential role for quantitative imaging

BACKGROUND: Objective assessments of disease activity and response to treatment in axial spondyloarthritis (axSpA) remain an area of unmet clinical need. Quantitative magnetic resonance imaging (qMRI) offers potential for more accurate measures of disease activity and therapeutic response. PURPOSE: To critically appraise current methods of disease activity in axSpA and determine the responsiveness and validity of quantitative imaging biomarkers (QIBs) in patients with axSpA undergoing biologic therapy. METHODS: An observational cohort study was carried out to assess the specificity of our current disease activity measure on patients with axSpA. A systematic literature review was performed to assess the use of MRI in the assessment of axSpA. A prospective cohort study was carried out on 30 patients with axSpA undergoing biologic therapy or switching biologic therapy. Conventional and qMRI scans, including diffusion-weighted imaging (DWI) and chemical shift-encoded imaging (CSI) were carried out at baseline and after 12-16 weeks of treatment. Apparent diffusion coefficient (ADC) and proton density fat fraction (PDFF) maps were analysed using the partially-automated Bone Edema and Adiposity Characterisation with Histograms (BEACH) tool, which derives a series of quantitative imaging biomarkers (QIBs) for both ADC and PDFF. Conventional MR images were assessed using established visual scoring methods. QIBs were assessed in terms of change after treatment and correlation with clinical and conventional MRI measures of disease activity. RESULTS: Current disease activity measures are not specific to axSpA and can be increased in a number of other spinal pathologies. ADC biomarkers are sensitive to changes in inflammation and show significant reductions following biologic therapy, while PDFF-based QIBs showed nonsignificant reductions. Responsiveness to therapy was moderate for ADC based biomarkers and small for conventional scoring systems. ADC and PDFF correlated well with conventional MRI scoring methods. CONCLUSION: Quantitative MRI offers promise for a more accurate assessment of disease activity in axSpA

Quantifying Palaeopathology Using Geometric Morphometrics

Palaeopathology is the study of disease and injury in archaeological bone. Traditional methods rely heavily on macroscopic description which can have a high degree of subjectivity and error, as well as limiting the types of research questions possible. Geometric morphometrics are a suite of shape analysis techniques and provide an opportunity to investigate possible relationships between skeletal morphological variation and disease. This thesis aims to demonstrate the potential of applying these methods in palaeopathological research and the results illustrate the benefits of using quantifiable and objective shape analysis methods in palaeopathology. The first half of the thesis discusses the use of geometric morphometrics to investigate skeletal variation to identify possible aetiological factors in the development of Schmorl's nodes and osteoarthritis. There was a strong association found between vertebral morphology and Schmorl's nodes in the lower spine. These findings have great implications for both bioarchaeological interpretation and clinical understanding of the aetiology and pathogenesis of Schmorl's nodes. Joint morphology of the proximal ulna and distal humerus was found to have no identifiable relationship with osteoarthritis, indicating that joint morphology is not a predisposing factor in elbow osteoarthritis, nor does osteoarthritis deform the joints in a systematic manner. A tentative relationship between eburnation and knee joint morphology was identified, although these results need to be verified with future research. If the association can be supported, shape analyses may provide a way for clinicians to monitor the progression of the disease. Geometric morphometrics were also shown to objectively record pathological shape deformation resulting from leprosy and residual rickets. The ability to objectively describe lesions with quantified data will greatly strengthen palaeopathology by decreasing the subjectivity and error inherent in macroscopic based methods. This thesis represents promising groundwork for the incorporation of geometric morphometrics into palaeopathological research

THE STRUCTURAL VIOLENCE OF MAYA SACRIFICE: A CASE STUDY OF RITUALIZED HUMAN SACRIFICE AT MIDNIGHT TERROR CAVE, BELIZE

The site of Midnight Terror Cave is located in the karstic Roaring Creek Valley near the village of Springfield in the Cayo District of Belize. The site was discovered in 2006 and fieldwork was conducted by the Western Belize Regional Cave Survey Project and California State University, Los Angeles, between 2008 and 2010. This dissertation focuses on the osteological analysis of the bones of 118 individuals recovered and recorded at the site. The osteological, contextual, and demographic evidence is framed within ritual and costly signaling theory of structural violence and viewed with the ethnohistoric and ethnographic literature of the ancient and modern Maya in mind. Analyses of the data indicate that the site’s remains constitute the largest assemblage of probably sacrificed individuals in the Southern Maya Lowlands, and that these sacrifices may have coincided with the Terminal Classic droughts. Demographic analysis indicates that the mortuary assemblage is significantly different from what would be expected for a “normal” cemetery assemblage of a horticultural society. The large quantities of older children and young adults apparently sacrificed in this cave suggest that these may have been petitions to the Maya rain deity. Isotopic data and paleopathology evidence suggest that geographical outsiders and possible social outcasts were at least sometimes chosen for sacrifice

Musculo-Skeletal Stress Markers in Bioarchaeology: Indicators of Activity Levels or Human Variation? A re-analysis and Interpretation.

Musculoskeletal stress markers (MSM) have been widely used by bio-archaeologists as indicators of physical activity. These markers occur at the sites of attachment of soft tissue to bone. They are anomalies of bone formation or destruction at these sites and often called enthesopathies in clinical literature. The aims of this research were firstly to determine the aetiology of these features; in particular, whether they can be used as indicators of physical activity. Secondly, to create a new digital and quantifiable recording method, that is both cheap and simple to use. To achieve the first aim, several literature reviews were undertaken: of the bio-archaeological literature; of the anatomy of the attachment sites; of the relationship between trauma and enthesopathy formation; and of the relationship between enthesopathy formation and disease. Many diseases, for example DISH and ankylosing spondylitis, were found to be associated with enthesopathy formation. Findings of these reviews indicated current bio-archaeological recording methods and interpretive practises are at odds with clinical literature. The second aim had to take these factors into account. Pilot studies were undertaken to develop a new recording method. The final method used visual recording and measurement of enthese along with digitalisation of the surface in two-dimensions using a profile gauge. The digital curves were then quantified using roughness parameters commonly used in materials science. These described the surfaces and could also be used to determine whether this method was applicable to differentiate between normal entheses and those with enthesopathies. Discriminant function analysis demonstrated that this was possible. Stringent diagnostic criteria were also set in place to remove any individuals with possible disease-related enthesopathies. Using the same method, it was found that these could (in some circumstances) also be differentiated from the normal samples.EThOS - Electronic Theses Online ServiceGBUnited Kingdo