Non-invasive imaging techniques, such as micro-CT or optical imaging, provide valuable information about tumour microstructure, size, volume and growth dynamics. Although histology is an approach capable of describing several of these characteristics, the invasiveness of this analysis remains a disadvantage. The main aim of this work is the methodological development of non-invasive imaging of the dynamics of tumour growth and progression. The preparation of a dual-reporter lentiviral vector enables non-invasive study of tumour growth and dissemination of metastasis. The same dual reporter will also be a part of a second vector designed as a construct for targeting mouse embryonic stem cells with aim to produce corresponding transgenic reporter mouse line. This reporter mouse line can be beneficial for future projects by providing a novel approach for studying the dynamics of tumour growth under various genetic conditions. In addition to optical imaging, this project will also include the use of micro-CT technology which, as a non-invasive approach, has the potential to provide information about the microstructure of tumour tissue in 3D that histology is not able to report.

The aim of this thesis was to investigate some methods for quantitative analysis of bone structure, particularly techniques which might ultimately be applied post-operatively following orthopaedic reconstruction operations. Initially it was decided to explore the efficacy of MRI in quantifying the bone structure at high resolution by comparing high resolution MRI against 'gold standards' such as Scanning Electron Microscopy (SEM) and optical histology. This basic study provided a measure of the distortions in the morphological bone parameters derived from MR images due to susceptibility artefacts and partial volume effects. The study of bone architecture was then extended to a model of advanced renal osteodystrophy in a growing rat. For this study, high-resolution micro computed tomography (microCT) was used and as a result of the high resolution images obtained, three new bone morphological parameters were introduced to characterise the bone structure. The desire to study bone architecture post-operatively in hip replacements led to a preliminary study on ex-vivo sheep acetabulae following total hip replacement, to determine the extent that the bone architecture could be investigated around the acetabulum. The motivation for studying the acetabulum was based on the high occurrence of debonding at the bone / prosthesis interface. This study demonstrated the superior nature of 3D MRI over conventional x-ray radiographs in early quantitation of fibrous membranes located between the host bone and the non-metallic implant and/or the bone cement. The presence of such fibrous membranes is strongly indicative of failure of the prosthesis. When using clinical MRI to image post-operative hip replacement, the image quality is severely affected by the presence of the metallic implant. The head of the prosthesis is shaped like a metal sphere and is located in the acetabular cup. This problem was investigated by performing simulations of MR images in the presence of the field perturbation induced by the presence of a metal sphere, with the effects of slice excitation and frequency encoding incorporated into the simulations. The simulations were compared with experimental data obtained by imaging a phantom comprising a stainless steel ball bearing immersed in agarose gel. The simulations were used to predict the effects of changing imaging parameters that influence artefact size and also to show how current metal artefact reduction techniques such as view angle tilting (VAT) work and to identify their limitations. It was shown that 2D SE and VAT imaging techniques should not be used when metallic prosthesis are present due to extreme slice distortion, whereas 3D MRI provided a method that has no slice distortion, although the effects of using a frequency encoding gradient still remain.

Nos últimos anos, o corpo de evidência científica a respeito da relação entre as doenças periodontais e desordens metabólicas - como a obesidade e a síndrome metabólica - vem aumentando consideravelmente. Entretanto, estudos avaliando os mecanismos biológicos que permeiam esta associação ainda são escassos. A presente tese teve como objetivo principal avaliar, em ratos Wistar, o efeito da obesidade e da síndrome metabólica (MetS) sobre a patogênese da perda óssea alveolar. Nesse sentido, foram produzidos 4 artigos científicos, sendo 2 revisões de literatura e 2 estudos experimentais. A primeira revisão de literatura buscou avaliar a literatura disponível acerca da relação MetS e doença periodontal. Pode-se observar que poucos estudos foram localizados e, dentre aqueles avaliados, a maioria tratouse de estudos de natureza epidemiológica transversal. Não foram localizados estudos de natureza longitudinal e apenas um estudo de intervenção piloto foi avaliado. A análise desta evidência permitiu concluir que o tópico é de interesse, porém ainda não foi explorado na perspectiva dos fatores de risco. Para o segundo e terceiro artigos, foi utilizado um modelo animal que reproduz as características de obesidade (artigo 2) e MetS (artigo 3). Para o segundo artigo, foram utilizados 28 ratos Wistar machos divididos em 2 grupos experimentais. O grupo controle recebeu ração padrão e água e o grupo teste além da ração padrão/água foi exposto a uma dieta de cafeteria (CAF) para indução de obesidade. Foi definido um ponto de corte para ocorrência de doença periodontal, sendo essa considerada positiva quando da presença de perda óssea alveolar ≥0.51mm em fotografias padronizadas. Diferenças significativas para o peso e índice de Lee foram observadas no grupo exposto a dieta CAF indicando presença de obesidade neste grupo. Observou-se que os animais obesos apresentaram significativamente mais sítios positivos para doença periodontal. Portanto, pode se concluir que a obesidade aumenta a perda óssea alveolar espontânea em ratos Wistar. Para o terceiro artigo, 60 ratos Wistar foram divididos em 4 grupos: Controle (ração padrão e água), Doença Periodontal (DP) (ração padrão e ligadura no semana 12), MetS (dieta CAF por 17 semanas) e MetS+DP (ligadura na semana 12 e dieta CAF por 17 semanas). Dois animais foram perdidos ao longo do período experimental por razões não relacionadas ao protocolo do estudo. Diferenças significativas foram observadas para o peso, índice de Lee colesterol total e triglicerídeos, indicando presença de MetS. Foram realizadas análises do percentual de perda óssea alveolar através de micro-tomografias e os níveis séricos de IL1- e TNF- foram avaliados por ELISA. Observou-se que os animais portadores de MetS exibiram maiores percentuais de perda óssea alveolar induzida e espontânea. Não foram observadas diferenças significativas para os níveis séricos das citocinas avaliadas. Nesse sentido, pode ser concluído que a presença de MetS modula a resposta do hospedeiro, provavelmente pela quebra da homeostase do periodonto. O artigo 4 tratou-se de uma revisão de literatura com caráter informativo alertando aos profissionais da odontologia a responsabilidade da transcender as abordagens odontológicas tradicionais colocando a profissão como parte importante e integrantes da equipe de saúde. A partir dos resultados obtidos nos artigos constituintes da presente tese e frente às reflexões realizadas, pode-se concluir que a doença periodontal é influenciada por desordens metabólicas. Recomenda-se, portanto, a inclusão de questionamentos e análises dessas condições e suas potenciais inter-relações pelos profissionais da saúde / between periodontal diseases and metabolic disorders – like obesity and metabolic syndrome – has considerably increased. However, studies evaluating the biological mechanisms related to this association are still scarce. The present thesis had as main objective to evaluate, in Wistar rats, the effect of obesity and metabolic syndrome (MetS) on the pathogenesis of alveolar bone loss. In this respect, 4 scientific articles were written, being 2 literature reviews and 2 experimental studies. The first literature review evaluated the available literature relating MetS and periodontal disease. It can be observed that few studies were retrieved and, among thos evaluated, the majority were of cross-sectional epidemiological nature. Longitudinal studies were not found and only one pilot intervention study was evaluated. The analysis of this evidence lead to the conclusion that the topic is of interest, however still has not been explored in the perspective of risk factors. For the second and third articles, an animal model was used, that mimics obesity (article 2 and MetS (article 3). For the second article, 28 male Wistar rats were divided in 2 experimental groups. The control group received chow and water and the test group, besides the standard chow/water was exposed to cafeteria diet (CAF) in order to induce obesity. A cut-off point was defined for the occurrence of periodontal disease, being this considered positive when alveolar bone loss ≥0.51mm was present in standardized pictures. Significant differences for body weight and Lee Index were observed in the group exposed to CAF diet, indicating obesity. Obese animals presented significantly more sites positive for periodontal disease. Thus, it may be concluded that obesity increases spontaneous alveolar bone loss in Wistar rats. For the third article, 60 male Wistar rats were divided in 4 groups: Control (standard chow and water), Periodontal disease (PD) (standard rat chow and ligature on week 12, MetS (CAF diet for 17 weeks and MetS+PD (ligature on week 12 and CAF diet for 17 weeks). Two animals were lost during the experimental period for reasons not related to the study protocol. Significant differences were observed in body weight, Lee Index, total cholesterol and triglycerides, indicating the presence of MetS. Analyses of percent alveolar bone loss were performed by microcomputer tomography and the serum levels of IL1- and TNF- were performed by ELISA. Animals with MetS exhibited higher percentage of spontaneous and induced alveolar bone loss. No significant differences were observed for the serum levels of the evaluated cytokines. Thus, it may be concluded that the presence of MetS modulates the host response, probably breaking the periodontium homeostasis. Article 4 is a literature review with informative characteristics alerting the dental professionals about the responsibility of going beyond the traditional dental practices, making the profession an important component of the health team. Taking into consideration the obtained results in the articles in this thesis, and the thoughts coming from them, it may be concluded that periodontal disease is influenced by metabolic disorders. It is recommended that questions and analyzes are made about these conditions and their potential interrelationships by the health personnel.

Nos últimos anos, o corpo de evidência científica a respeito da relação entre as doenças periodontais e desordens metabólicas - como a obesidade e a síndrome metabólica - vem aumentando consideravelmente. Entretanto, estudos avaliando os mecanismos biológicos que permeiam esta associação ainda são escassos. A presente tese teve como objetivo principal avaliar, em ratos Wistar, o efeito da obesidade e da síndrome metabólica (MetS) sobre a patogênese da perda óssea alveolar. Nesse sentido, foram produzidos 4 artigos científicos, sendo 2 revisões de literatura e 2 estudos experimentais. A primeira revisão de literatura buscou avaliar a literatura disponível acerca da relação MetS e doença periodontal. Pode-se observar que poucos estudos foram localizados e, dentre aqueles avaliados, a maioria tratouse de estudos de natureza epidemiológica transversal. Não foram localizados estudos de natureza longitudinal e apenas um estudo de intervenção piloto foi avaliado. A análise desta evidência permitiu concluir que o tópico é de interesse, porém ainda não foi explorado na perspectiva dos fatores de risco. Para o segundo e terceiro artigos, foi utilizado um modelo animal que reproduz as características de obesidade (artigo 2) e MetS (artigo 3). Para o segundo artigo, foram utilizados 28 ratos Wistar machos divididos em 2 grupos experimentais. O grupo controle recebeu ração padrão e água e o grupo teste além da ração padrão/água foi exposto a uma dieta de cafeteria (CAF) para indução de obesidade. Foi definido um ponto de corte para ocorrência de doença periodontal, sendo essa considerada positiva quando da presença de perda óssea alveolar ≥0.51mm em fotografias padronizadas. Diferenças significativas para o peso e índice de Lee foram observadas no grupo exposto a dieta CAF indicando presença de obesidade neste grupo. Observou-se que os animais obesos apresentaram significativamente mais sítios positivos para doença periodontal. Portanto, pode se concluir que a obesidade aumenta a perda óssea alveolar espontânea em ratos Wistar. Para o terceiro artigo, 60 ratos Wistar foram divididos em 4 grupos: Controle (ração padrão e água), Doença Periodontal (DP) (ração padrão e ligadura no semana 12), MetS (dieta CAF por 17 semanas) e MetS+DP (ligadura na semana 12 e dieta CAF por 17 semanas). Dois animais foram perdidos ao longo do período experimental por razões não relacionadas ao protocolo do estudo. Diferenças significativas foram observadas para o peso, índice de Lee colesterol total e triglicerídeos, indicando presença de MetS. Foram realizadas análises do percentual de perda óssea alveolar através de micro-tomografias e os níveis séricos de IL1- e TNF- foram avaliados por ELISA. Observou-se que os animais portadores de MetS exibiram maiores percentuais de perda óssea alveolar induzida e espontânea. Não foram observadas diferenças significativas para os níveis séricos das citocinas avaliadas. Nesse sentido, pode ser concluído que a presença de MetS modula a resposta do hospedeiro, provavelmente pela quebra da homeostase do periodonto. O artigo 4 tratou-se de uma revisão de literatura com caráter informativo alertando aos profissionais da odontologia a responsabilidade da transcender as abordagens odontológicas tradicionais colocando a profissão como parte importante e integrantes da equipe de saúde. A partir dos resultados obtidos nos artigos constituintes da presente tese e frente às reflexões realizadas, pode-se concluir que a doença periodontal é influenciada por desordens metabólicas. Recomenda-se, portanto, a inclusão de questionamentos e análises dessas condições e suas potenciais inter-relações pelos profissionais da saúde / between periodontal diseases and metabolic disorders – like obesity and metabolic syndrome – has considerably increased. However, studies evaluating the biological mechanisms related to this association are still scarce. The present thesis had as main objective to evaluate, in Wistar rats, the effect of obesity and metabolic syndrome (MetS) on the pathogenesis of alveolar bone loss. In this respect, 4 scientific articles were written, being 2 literature reviews and 2 experimental studies. The first literature review evaluated the available literature relating MetS and periodontal disease. It can be observed that few studies were retrieved and, among thos evaluated, the majority were of cross-sectional epidemiological nature. Longitudinal studies were not found and only one pilot intervention study was evaluated. The analysis of this evidence lead to the conclusion that the topic is of interest, however still has not been explored in the perspective of risk factors. For the second and third articles, an animal model was used, that mimics obesity (article 2 and MetS (article 3). For the second article, 28 male Wistar rats were divided in 2 experimental groups. The control group received chow and water and the test group, besides the standard chow/water was exposed to cafeteria diet (CAF) in order to induce obesity. A cut-off point was defined for the occurrence of periodontal disease, being this considered positive when alveolar bone loss ≥0.51mm was present in standardized pictures. Significant differences for body weight and Lee Index were observed in the group exposed to CAF diet, indicating obesity. Obese animals presented significantly more sites positive for periodontal disease. Thus, it may be concluded that obesity increases spontaneous alveolar bone loss in Wistar rats. For the third article, 60 male Wistar rats were divided in 4 groups: Control (standard chow and water), Periodontal disease (PD) (standard rat chow and ligature on week 12, MetS (CAF diet for 17 weeks and MetS+PD (ligature on week 12 and CAF diet for 17 weeks). Two animals were lost during the experimental period for reasons not related to the study protocol. Significant differences were observed in body weight, Lee Index, total cholesterol and triglycerides, indicating the presence of MetS. Analyses of percent alveolar bone loss were performed by microcomputer tomography and the serum levels of IL1- and TNF- were performed by ELISA. Animals with MetS exhibited higher percentage of spontaneous and induced alveolar bone loss. No significant differences were observed for the serum levels of the evaluated cytokines. Thus, it may be concluded that the presence of MetS modulates the host response, probably breaking the periodontium homeostasis. Article 4 is a literature review with informative characteristics alerting the dental professionals about the responsibility of going beyond the traditional dental practices, making the profession an important component of the health team. Taking into consideration the obtained results in the articles in this thesis, and the thoughts coming from them, it may be concluded that periodontal disease is influenced by metabolic disorders. It is recommended that questions and analyzes are made about these conditions and their potential interrelationships by the health personnel.

The cone-beam flat panel micro-CT is a high definition imaging system. It acquires projections of an object or animal to reconstruct a 3D image of its internal structure. The device is basically composed by a radiation tube and a detector panel, which are fixed to a gantry that rotates all around the test subject. The micro-CT system is affected by several imperfections and problems, that might lead to serious artifacts that deteriorate the quality of the reconstructed image. In particular, two issues have been discussed in the present work: the source-panel geometric misalignment and the detector lag effect. The first problem concerns the consequences of systems where the different elements are not perfectly aligned to each other. The second issue regards the residual signal, left in the detector's sensor after a projection acquisition, which affects the following frames with ghost images. Both these arguments have been investigated to describe their characteristics and behaviour in a typical acquisition protocol. Then two correction methods have been presented and tested on a real micro-CT device to verify their effectiveness in the artifacts compensation. In the end, a comparison between images before and after the corrections is provided and future prospects are discussed.

No description available.

No description available.

The primary objective was to predict the relative storage capacity of carbonate rocks relevant for carbon dioxide sequestration. To achieve this, a detailed pore scale characterization of model carbonate rocks, Indiana Limestone and Pink Dolomite, was conducted utilizing micro-computed tomography (microCT) data using pore network modeling and invasion percolation simulations. For the first time in literature, Pink Dolomite’s pore space characteristics were analyzed. A secondary objective was to compare thresholding techniques as applied to carbonates which exhibit dual porosity (porosity at multiple length scales). The analysis showed the sensitivity of existing methods to the thresholding technique, imaging method and material. Overall, the contributions of this work provide an assessment of two carbonates relevant for carbon capture and storage at the pore scale; and a preliminary assessment into thresholding dual porosity carbonates.

The primary objective was to predict the relative storage capacity of carbonate rocks relevant for carbon dioxide sequestration. To achieve this, a detailed pore scale characterization of model carbonate rocks, Indiana Limestone and Pink Dolomite, was conducted utilizing micro-computed tomography (microCT) data using pore network modeling and invasion percolation simulations. For the first time in literature, Pink Dolomite’s pore space characteristics were analyzed. A secondary objective was to compare thresholding techniques as applied to carbonates which exhibit dual porosity (porosity at multiple length scales). The analysis showed the sensitivity of existing methods to the thresholding technique, imaging method and material. Overall, the contributions of this work provide an assessment of two carbonates relevant for carbon capture and storage at the pore scale; and a preliminary assessment into thresholding dual porosity carbonates.

No description available.