Nesta tese, buscou-se avaliar se a tomografia computadorizada de duplaenergia pós-contraste (TCDE) é capaz de detectar diferenças regionais da perfusão pulmonar em um modelo animal suíno incluindo variações de decúbito, lesão alveolar e oclusão da artéria pulmonar com balão, comparando estes resultados com os obtidos pela perfusão de primeira passagem com a tomografia computadorizada dinâmica (TCD). Dez suínos landrace foram divididos em Grupos A (N = 5, controle) e B (N = 5). Animais do Grupo B foram submetidos ao protocolo de lesão alveolar induzida por ventilação mecânica (LPIV). O volume sanguíneo perfundido e o fluxo sanguíneo pulmonar foram, respectivamente, estimados pela TCDE (%VSPTCDE) e pela TCD (FSPTCD), em diversas condições experimentais: posição supina versus prona, presença versus ausência de LPIV, presença ou ausência de oclusão da artéria pulmonar. A correlação entre %VSPTCDE e FSPTCD foi moderada (R = 0,60) com ampla variabilidade (intervalo 0,35-0,91) entre animais. %VSPTCDE e FSPTCD demonstraram padrões similares de heterogeneidade da perfusão pulmonar nas diferentes condições experimentais. Entretanto, reduções do %VSPTCDE causadas pela oclusão com balão foram em média -29,32 %, enquanto reduções do FSPTCD foram em média -86,78 % (p < 0,001). Estimativas quantitativas do VSPTCDE tiveram um erro médio de +4.3 ml/100g em comparação com o FSPTCD, com limites de concordância de 95 % entre -16,6 ml/100g e 25,1 ml/100g. A TCDE póscontraste é capaz de prover estimativas semiquantitativas que refletem a heterogeneidade regional da perfusão pulmonar causada por mudanças de decúbito, lesão alveolar e oclusão da artéria pulmonar com balão, apresentando moderada correlação com a perfusão de primeira passagem pela TCD / We aimed to evaluate whether contrast-enhanced dual-energy CT (DECT) detects regional pulmonary perfusion changes in a swine model of acute lung injury, with variations in decubitus and transient occlusion of the pulmonary artery, comparing these results with those obtained with dynamic CT perfusion (DynCT). Ten landrace swine were assigned to Groups A (N = 5, control) and B (N = 5). Group B was subjected to ventilator-induced lung injury (VILI). Perfused blood volume and pulmonary blood flow were quantified by DECT (PBVDECT) and DynCT (PBFDynCT), respectively, under different settings: supine versus prone, and with/without balloon occlusion of a pulmonary artery (PA) branch. Correlation of regional PBVDECT versus PBFDynCT was moderate (R = 0.60) with high variability (range 0.35-0.91) among the animals. Regional pulmonary perfusion changes assessed by %PBVDECT agreed with PBFDynCT in response to decubitus changes, lung injury and balloon occlusion in the multivariate analysis. However, reductions in %PBVDECT caused by balloon occlusion were in average -29.32 %, whereas reductions in PBFDynCT were in average -86.78 % (p < 0.001). Quantitative estimates of PBVDECT had a mean bias of +4.3 ml/100g in comparison with PBVDynCT, with 95 % confidence intervals between -16.6 ml/100g and 25.1 ml/100g. Semiquantitative contrastenhanced DECT reflects regional changes in perfusion caused decubitus changes, acute lung injury, and balloon occlusion of the PA, with moderate correlation in comparison with DynCT

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No. of bitstreams: 1 fernandes_ra_me_araca_int.pdf: 2718642 bytes, checksum: 4dea3e0dc607519bbdbdb41a172e9277 (MD5) Previous issue date: 2019-01-18 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo desse estudo foi inferir a Densidade Mineral óssea (DMO) a partir da imagem radiográfica (Raios-X) usando como referência a DMO de uma escada de alumínio mensurada por Absorciometria por de Duas-Energias (DXA). Para isso foram utilizadas 30 amostras de tecido ósseo cortical e 30 amostras de tecido ósseo trabecular de osso bovino “in vitro”. Foram mensurados neste estudo a Densidade Mineral Óssea (DMO), o Conteúdo Mineral Ósseo (CMO) ambos obtidos pelo densitômetro LUNAR®–DPX ALPHA; a Quantidade Mineral Óssea (QMO) massa das cinzas após a calcinação das amostras; a densidade real das amostras (dReal=massa/volume). Foram feitas 10 tomadas de RX com as 60 amostras, entremeadas pela escada de alumínio (referencial densitométrico). A correlação entre as técnicas (DR-tons de cinza e DXA g/cm2) gerou equações de regressão para cada uma das dez radiografias e permitiu inferir a densidade mineral óssea (DMODR), obtida através da conversão dos tons de cinza em densidade radiográfica pelo software ImageJ® para cada uma das 10 tomadas radiográficas; calculou-se então a média da densidade mineral óssea calculada pela densitometria radiográfica (XDMODR) de todas as dez radiografias. Foi observado que a média da densidade real das amostras foi de 2,2±0,23g/cm2 e 1,05±0,09g/cm2 enquanto que a média da densidade mensurada pelo DXA foi de 0,73±0,11g/cm2 e 0,22±0,11g/cm2, observou que a media da DMODR ficou em 0,93±0,11g/cm2 e 0,34±0,14 g/cm2 para o osso cortical e trabecular respectivamente. A média da CMO foi de 0,19±0,9g e 0,08±0,02g e a media da QMO 0,14±0,04g e 0,05±0,03g para o osso cortical e trabecular respectivamente. Foi possível obter bons coeficientes de determinação entre todas as variáveis estudadas: CMO e QMO, R2 =0,747; DMO e dReal com R2 = 0,765; dReal e DMODR; DMO e XDMODR, respectivamente 0,764 e 0,856. Para as correlações foram usadas amostras de dois tecidos ósseos cortical e trabecular, o que sugere distinção entre as amostras com as metodologias utilizadas / The aim of this study was to infer the bone mineral density (BMD) from the radiographic image (X-X) with reference to the BMD of an aluminum step wedge measured by absorptiometry Dual-energy (DXA). For this we used 30 samples of cortical bone 30 and cancellous bone tissue samples of bovine bone "in vitro". Were measured in this study Bone Mineral Density (BMD), bone mineral content (BMC) both obtained by densitometer LUNAR® DPX-ALPHA; Volume Bone Mineral (QMO) mass of ash after calcination of the samples; the real density of the samples (dReal = mass / volume). 10 taken RX were made with the samples 60, interspersed by aluminum step wedge (densitometric reference). The correlation between the techniques (gray DR-tones and DXA g / cm 2) generated regression equations for each of the ten X-rays and allowed to infer bone mineral density (DMODR) obtained by converting grayscale radiographic density by ImageJ® for each of the 10 radiographic taken. It was then calculated average bone mineral density calculated by X-ray densitometry (XDMODR) radiographs of all ten. Was observed that the average true density of the samples was 2.2±0.23g/cm2 and 1.05±0.09g/cm2 while the average density measured by DXA was 0.73±0.11g/cm2 and 0.22±0.11g/cm2 interesting that the average DMODR was 0.93±0.11g/cm2 and 0.34±0.14g/cm2 for cortical and cancellous bone respectively. The average of the BMC was 0.19±0.08g and 0.9±0.02g, and the average QMO 0.14±0.04g and 0.05±0 03g for cortical and cancellous bone respectively. It was possible to obtain good determination coefficients between all variables: BMC and QMO, R2 = 0.747; BMD and dReal with R2 = 0.765; dReal and DMODR; BMD and XDMODR respectively 0.764 and 0.856. For correlations were used two samples of cortical and cancellous bone tissues, suggesting a difference between the samples with the methodologies used.

Physical activity is critical to bone health. However, not all physical activity has optimum effect on bone health and metabolism. The purpose of this study was to determine the effects of a short term progressive jumping protocol on bone mineral density in college age Asian females. Sixteen participants aged18-28 years enrolled in the study. Participants were assigned to exercise (n=9) and control (n=8) groups. The exercise group completed a two-legged depth jump from an approximate 20cm stepbench followed immediately by a maximum vertical jump using arm swings for five days per week for two weeks. Each depth jump and vertical jump was performed ten times during each session. The exercise intervention progressed from one session per day to three sessions per day in ten days. The bone mineral density (BMD) by dualenergy x-ray absorptiometry (DXA), ground reaction force (GRF), bone specific physical activity questionnaire (BPAQ), and dietary log were administered to the participants pre- and post-intervention. The data were analysed using a dependent t-test and one-way repeated measures. There were no significant changes noted in BMD value in the study. The past BPAQ showed significant correlation to BMD change of left hip (p<0.01) in exercise group. The vertical GRF showed significant increase (p<0.05) in exercise group. It can be concluded from the study that intensity of the progressive jumping was intense enough to stimulate some changes in the bone metabolism.

No description available.

The thesis reports on 6 studies (2 of which were part of a multi-centre trial) examining hydration and fluid balance. The first study described in this thesis investigated the impact of hydration status on Dual energy x-ray absorptiometry (DXA) and other methods that are popular tools to determine body composition in athletes. We observed that it is important to ensure a euhydration when assessing body composition, particularly when considering changes associated with nutritional or exercise interventions. The second and third studies reported identified beverages that promote longer term fluid retention and maintenance of fluid balance in adults. We investigated the effects of 13 different commonly consumed drinks on urine output and fluid balance when ingested in a euhydrated state, with a view to establishing a beverage hydration index (BHI), i.e., the volume of urine produced after drinking expressed relative to a standard treatment (still water) for each beverage. The beverages with the highest BHI were oral rehydration solution, full fat milk and skimmed milk. BHI may be a useful measure to identify the short term hydration potential of different beverages when ingested in a euhydrated state. The fourth study aimed to systematically examine the influence of carbohydrate, sodium and caffeine content of beverages on the BHI. The BHI was greater in beverages with higher carbohydrate or higher sodium content, but not influenced by caffeine. The carbohydrate content of beverages has no effect on BHI at concentration up to 10% carbohydrate. Sodium content of beverages in concentrations of 27mmol/L and higher can improve the hydration potential of beverages. Caffeine doses in beverages up to 400mg/L do not have an impact upon diuresis when ingested in a euhydrated state. The fifth study compared net fluid balance (NFB) responses to the ingestion of commonly consumed drinks in young and older men. We observed that in young adults milk helps to maintain positive net fluid balance for longer than other drinks. In older adults this effect of milk is not observed despite similar net electrolyte balance responses. Future work should more fully explore these potential differences in fluid balance responses to drink ingestion between young and older adults. The final study investigated the hydration habits of Scottish young and older adults (+50 years old), identifying their fluid choices, volume, and preferences in relation to time of day. The results showed that 26.1% of the young females, 30.3% of the young males, 25.8% of the older females and 50.4% of the older males did not meet the European (EU) Food Safety Authority (EFSA) fluid intake recommendations. We also observed that the difference between those who met and those who did not meet the EFSA adequate intake could be attributed to differences in water ingestion, mainly during the mid-morning (after breakfast until 11 am) and during the early-afternoon (after lunch time up to 5 pm). It was concluded that these moments might be key when implementing interventions to improve hydration status especially in the older population.

Made available in DSpace on 2016-06-02T20:18:20Z (GMT). No. of bitstreams: 1 4970.pdf: 2137632 bytes, checksum: 24df6302ff25ccdf968d2ef39fc8b67f (MD5) Previous issue date: 2013-03-22 / The thesis consisted of two studies described below. The study I, entitled: "The influence of body composition measured by dual-energy absorptiometry functional capacity in patients with chronic obstructive pulmonary disease", aimed to analyze the influence of body composition assessed by dual-energy x-ray absorptiometry on functional capacity in patients with chronic obstructive pulmonary disease (COPD). We Eleven male patients with COPD (COPDG), 7 presenting moderate obstruction and 4 severe, and 11 sedentary male subjects (CG) were evaluated by dual-energy x-ray absorptiometry to assess their body composition, all subjects have also performed the 6 minute walk test (6MWT) and step test (6MST) to assess their functional capacity. No significant differences were found between groups for anthropometric data such as age, weight, height and body mass index (BMI). However, the COPDG presented forced vital capacity (FVC), forced expiratory volume in one second (FEV1), FEV1/FVC ratio, maximal voluntary ventilation (MVV),walked distance (WD) and number of steps (NS) significantly lower than the CG (p<0,05; Student s t test). The body bone mass (BBM), BBM%, Lean Mass (LM), LM%, and right lower limb (RLL) and left lower limb (LLL) were significantly lower in the COPDG when compared with the CG, presenting statistically significant positive correlations with 6MWT on WD and 6MST on NS (p<0,05, Pearson s test). We conclude that body composition is an important prognostic factor for patients with COPD, which reinforces the importance of assessing body composition by dual-energy absorptiometry since it has demonstrated with satisfactory accuracy in clinical practice. Moreover, it is a parameter useful evaluation and reassessment in pulmonary rehabilitation programs. Following the II study entitled: "Effects of training of high and low intensity in musculature inspiratory in individuals with severe COPD and malnourished," which aimed to verify and analyze the effects of training in high and low intensity inspiratory muscles in patients with severe COPD and malnourished. We evaluated 32 men with severe COPD and malnourished, divided into two groups (G1 and G2). Assessments of the degree of dyspnea, pulmonary function test, MIP, WD, SGRQ and DM were performed at pre-training and after 12 weeks of training. We found that G1 got significant increase in MVV, MIP, WD and DM, and significant decreases in the percentages MRCm and SGRQ at 12 weeks of training, which remained after 12 weeks without training. Group 2 showed the same behavior when compared with the G1 at 12 weeks of training, but values returned to the initial MVV, MRCm, DM and MIP and WD had values below the baseline, and the percentage increased significantly SGRQ after 12 weeks without training. In the intergroup analysis (12-12 weeks) G1 showed higher values in MVV, MIP, WD and DM values and smaller percentages in the SGRQ compared with G2. Comparing the 24-24 weeks, G2 showed lower values in MVV, MIP, WD and DM and significant increases in the percentages MRCm and SGRQ compared with G1. The TMI high and low intensity promoted benefits to individuals with severe COPD and malnourished, which were maintained after 12 weeks of high intensity training. / A tese constou de dois estudos descritos a seguir. O estudo I, intitulado: A influência da composição corporal avaliada pela absorciometria duo-energética na capacidade funcional em portadores de doença pulmonar obstrutiva crônica , teve como objetivo analisar a influência da composição corporal avaliada pela absorciometria duo-energética na capacidade funcional em portadores de DPOC. Foram avaliados 11 indivíduos do sexo masculino portadores de DPOC, sendo 7 com obstrução moderada e 4 grave (Grupo DPOC - GDPOC) e 11 indivíduos sedentários do sexo masculino (Grupo Controle - GC), por meio da absorciometria duo-energética para avaliar a composição corporal, bem como pelo teste de caminhada de seis minutos (TC6) e teste do degrau (TD6) para avaliar a capacidade funcional. Não houve diferenças significantes intergrupos na idade, peso, altura e índice de massa corporal (IMC). No entanto, o GDPOC apresentou Capacidade Vital Forçada (CVF), Volume Expiratório Forçado no primeiro segundo (VEF1), relação VEF1/CVF, Ventilação Voluntária Máxima (VVM), Distância Percorrida (DP) e Número de Degraus (ND) significantemente menores que o GC (p&#61603;0,05, teste t Student). A Massa Óssea Corporal (MOC), % MOC, Massa Magra (MM), % MM e MM do Membro Inferior Direito (MID) e Membro Inferior Esquerdo (MIE) no GDPOC foram significantemente menores que no GC obtendo correlações positivas estatisticamente significantes com a DP no TC6 e ND no TD6 (p&#61603;0,05; correlação de Pearson). Concluímos que a composição corporal é um importante fator de prognóstico para pacientes com DPOC, o que reforça a importância da avaliação da composição corporal pela absorciometria duo-energética uma vez que tem demonstrado precisão satisfatória na prática clínica. Além disso, é um parâmetro de avaliação e reavaliação útil em programas de reabilitação pulmonar. Na sequência, o estudo II intitulado Efeitos do treinamento de alta e baixa intensidade na musculatura inspiratória em indivíduos com DPOC grave e desnutridos , que objetivou verificar e analisar os efeitos do treinamento de alta e baixa intensidade na musculatura inspiratória em indivíduos com DPOC grave e desnutridos. Foram avaliados 32 homens com DPOC grave e desnutridos, divididos em dois grupos (G1 e G2). As avaliações do grau de dispneia, prova de função pulmonar, PImáx, DP, SGRQ e MD foram realizadas no pré-treinamento e após 12 semanas de treinamento. Observou-se que o G1 obteve aumento significante da VVM, PImáx, DP e MD, e diminuições significantes na MRCm e das porcentagens do SGRQ em 12 semanas de treinamento, os quais se mantiveram após 12 semanas sem treinamento. O G2 apresentou o mesmo comportamento quando comparado com o G1 em 12 semanas de treinamento, porém os valores voltaram aos iniciais na VVM, MRCm, MD e as variáveis PImáx e DP apresentaram valores abaixo da avaliação inicial, e as porcentagens do SGRQ aumentaram significantemente após 12 semanas sem treinamento. Na análise intergrupo (12-12 semanas) o G1 apresentou valores maiores na VVM, PImáx, DP e MD e valores menores nas porcentagens do SGRQ quando comparado com o G2. Na comparação das 24-24 semanas, o G2 apresentou valores menores na VVM, PImáx, DP e MD e aumentos significantes na MRCm e nas porcentagens do SGRQ quando comparados com G1. O TMI de alta e baixa intensidade proporcionou efeitos benéficos aos indivíduos com DPOC grave e desnutridos, os quais se mantiveram após 12 semanas do treinamento de alta intensidade.

A Tomografia Computadorizada de Energia Dupla (DECT em inglês) é um dos campos das imagens tomográficas que mais evoluiu nos últimos anos. O DECT usa dois espectros para irradiar pacientes e é capaz de diferenciar tecidos com base na sua composição elementar. Apesar de serem semelhantes aos dispositivos padrão de tomografia, para essa modalidade é necessário o desenvolvimento de ferramentas específicas que permitam o estudo de suas propriedades de imagem. O objetivo deste trabalho era construir um sistema simulado de Tomografia Computadorizada (TC) com a capacidade de produzir imagens semelhantes às obtidas em dispositivos DECT reais. O TC simulado também permitiria explorar as propriedades das imagens de materiais de teste antes de sua construção física. Este trabalho presenta a simulação do processo de aquisição de imagens de um dispositivo DECT que funciona a partir da troca rápida de kV, o GE Discovery CT 750 HD. A geometria simulada foi baseada num dispositivo atualmente disponível no InRad (Instituto de Radiologia da Faculdade de Medicina da Universidade de São Paulo). As simulações foram realizadas usando o código Monte Carlo PENELOPE/penEasy para simular o transporte de radiação através dos materiais e detectores. Também é apresentada uma comparação entre as imagens obtidas no dispositivo real e nas simulações. Para isso, foi preparado um objeto simulador cilíndrico contendo concentrações de materiais equivalentes a iodo e cálcio. As imagens de tal objeto simulador foram adquiridas no equipamento GE Discovery CT 750 HD. Um objeto simulador equivalente foi modelado e as suas imagens foram simuladas com o código PENELOPE/penEasy. As imagens foram adquiridas e reconstruídas de acordo com as possibilidades do equipamento clínico de tomografia. Imagens de concentração de material e imagens monoenergéticas foram obtidas a partir do dispositivo CT clínico e das simulações. O algoritmo BMD (Basis Material Decomposition em Inglês) baseado nas projeções foi implementado usando os coeficientes de atenuação mássicos da água e do iodo. Consequentemente, imagens de concentração dos materiais água e iodo foram obtidas. A concentração medida nos cilindros de iodo foi equivalente às esperadas tanto no dispositivo real quanto nas imagens simuladas. Foram observados artefatos de endurecimento de feixe nas imagens de concentração de material. Imagens monoenergéticas foram obtidas para diferentes energias. Tais imagens foram obtidas a partir da superposição das imagens de concentração de água e iodo, que foram ponderadas pelos seus respectivos coeficientes de atenuação mássicos. Verificou-se que para as imagens monoenergéticas simuladas e reais em altas energias a imagem de concentração da água é a componente dominante, produzindo imagens que apresentaram as cavidades de iodo como menos atenuantes do que a água. Por outro lado, para energias baixas, a componente dominante nas imagens monoenergéticas foi a imagem de concentração do iodo. O CNR foi analisado nas imagens monoenergéticas como função da energia. As curvas do CNR dos dispositivos simulado e real exibiram semelhanças em sua forma, mas com escala diferente devido à diferença no ruído. Foi possível concluir que o modelo DECT simulado apresenta resultados qualitativos semelhantes aos obtidos no dispositivo real. O sistema de TC simulado permite explorar as características das imagens com diferentes materiais e composições. Ele também pode ser usado como uma ferramenta didática para melhorar a compreensão da diferenciação de materiais em tomografia espectral e DECT. / Dual Energy (DE) Computed Tomography (CT) is one of the fields of tomographic images that has evolved rapidly during the last years. DECT uses two X-ray spectra to irradiate patients It is capable to differentiate materials based on its elementary composition. Despite being similar to standard CT devices, DECT devices require the development of specific tools that allow the study of their image properties. The objective of this work was to build a modelled CT system capable of producing images similar to those obtained in real DECT devices. The modelled CT would also allow exploring the image properties of test materials before their physical construction. This work presents the simulation of the acquisition process of a DECT device that works with rapid kV switching, the GE Discovery CT 750 HD. The simulated geometry was based on a device currently available at the InRad (Institute of Radiology of the Faculty of Medicine of the University of São Paulo). The simulations were carried out using the PENELOPE/penEasy Monte Carlo code, which simulates radiation transport through the materials and detectors. A comparison between the images obtained in the real device and from simulations is also presented. To do so, a real phantom was prepared to be imaged and an equivalent system was simulated. The phantom contained inserts with concentrations of iodine and calcium. The images were acquired and reconstructed according to the possibilities of the real CT device. Standard, material concentration and virtual monoenergetic images were acquired[L1] from both, the real CT device and simulations. The Projection-Based BMD method was implemented using the mass attenuation coefficients of water and iodine. Then, material concentration images of water and iodine were obtained. The iodine concentrations estimated from the images agreed with the expected values in both real device and simulated images. Beam hardening artefacts were observed in the simulated material concentration images. Monoenergetic images were obtained for different energies. Such images were obtained as a superposition of the concentration images of water and iodine, weighed by their respective mass attenuation coefficient. It was verified that in the simulated and real device images, at high energies, the water concentration image predominated in the monoenergetic images, producing images that presented the iodine cavities as less attenuating than water. In contrast, at low energies, the predominant component of the monoenergetic images was the iodine concentration image. Contrast Noise Ratio (CNR) was analysed in the monochromatic images as a function of energy. Simulated and real device CNR curves exhibited similarities in their shape but with a different scale due to their difference in noise. It was possible to conclude that the simulated DECT model presented qualitative results similar to the obtained in the real device. The modelled CT system permits exploring the image features with different materials and compositions. It could also be used as a didactic tool to improve the understanding of material differentiation in spectral or DECT.

Ce travail portant sur l’imagerie tomodensitométrique double énergie de la ventilation a permis d’établir les points suivants :• L’irradiation d’un examen thoracique acquis en double énergie peut être abaissée à celle d’un examen acquis en simple énergie, grâce à l’utilisation de la reconstruction itérative.• L’analyse qualitative du parenchyme pulmonaire en imagerie double énergie doit se faire sur les reconstructions monochromatiques 50-55keV.• L’atténuation théorique maximale du Krypton dosé à 80% est modérément inférieure à celle du Xénon dosé à 30%.• La décomposition des matériaux en tomodensitométrie double énergie simple source est possible sur le Xénon et le Krypton.• L’utilisation d’un produit de contraste gazeux n’a pas d’impact significatif sur le Workflow en routine clinique.• Le Krypton est cliniquement sûr à la dose de 80%.• La technique ne permet pas de détecter le Krypton au-delà de la carène de manière satisfaisante, probablement en raison d’une concentration en gaz atteinte insuffisante.• Le recalage élastique augmente les performances diagnostiques de détection de la bronchiolite oblitérante par rapport à une simple analyse visuelle. / This work on dual energy CT ventilation imaging has established the following:• The radiation dose of a dual energy chest CT can be reduced to that of a single energy examination through the use of iterative reconstruction.• The qualitative analysis of the lung parenchyma should be made on the 50-55keV monochromatic reconstructions.• The maximum theoretical attenuation obtained with 80% Krypton is moderately inferior to that of 30% Xenon.• Dual energy material decomposition of Xenon and Krypton is efficient with a single source technique.• The use of a gaseous contrast agent has no significant impact on the workflow in the clinical setting.• The Krypton is safe at 80% concentration.• The technique does not satisfactorily detect Krypton beyond the carina, probably due to insufficient gas concentration.• The elastic registration increases the diagnostic performance of bronchiolitis obliterans syndrome detection, compared to a simple visual analysis.

Orientadores: Gil Guerra Júnior, Roberto Teixeira Mendes / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas / Made available in DSpace on 2018-08-27T03:51:40Z (GMT). No. of bitstreams: 1 Samur-SanMartin_JuanEduardo_D.pdf: 1683906 bytes, checksum: 919ec09c31bfe0bfe0e71a27f12c92e7 (MD5) Previous issue date: 2015 / Resumo: Estrutura da Tese: Estudo estruturado pelo "modelo Escandinavo", denominado de "modelo alternativo" no Programa de Pós-Graduação em Saúde da Criança e do Adolescente da Faculdade de Ciências Médicas da Universidade Estadual de Campinas (FCM ¿ Unicamp). Esta tese está composta por introdução geral, objetivos, capítulos (1 e 2) e conclusão geral. A introdução geral aborda: aspectos sobre a síndrome de Down (SD); da obesidade com temas direcionados à fisiopatologia, tipos, incidência e diagnóstico em crianças e adolescentes; da obesidade na SD; da associação da obesidade com a doença cardiovascular (DCV), como também a avaliação dos fatores de risco cardiovascular em indivíduos com e sem SD. Os capítulos 1 e 2 estão em formato de artigo. Na conclusão geral foram apresentadas as principais conclusões dos dois artigos. As referências bibliográficas foram apresentadas no final de cada capítulo e da tese. Objetivos: Os objetivos do presente estudo são: (1) estimar o ponto de corte do Índice de Massa Corporal (IMC) para o diagnóstico de obesidade em adolescentes com SD de acordo com diferentes referências para classificação do IMC em relação ao percentual de gordura corporal (%GC) avaliado pela absorciometria com raios-X de dupla energia (DXA) e (2) avaliar os fatores de risco cardiovascular em adolescentes com SD e compará-los em relação ao diagnóstico de obesidade estabelecido pelo escore z do IMC da World Health Organization (WHO). Casuística e Métodos: Participaram no primeiro artigo (capítulo 1) 34 adolescentes com SD e no segundo artigo (capítulo 2) 32, de ambos os sexos (idade: 10 e 17 anos). No capítulo 1, duas técnicas foram utilizadas para avaliar a composição corporal: IMC e DXA. O IMC foi avaliado de acordo com as referências da International Obesity Task Force (IOTF), da WHO para população geral, e de Myrelid et al. e Styles et al. para população com SD. O %GC foi avaliado pela DXA de corpo inteiro e classificado de acordo NHANES 2011. No capítulo 2, o IMC considerado como alterado foi ?2,00. Foram avaliados circunferência da cintura, pressão arterial, perfil lipídico, HOMA-IR e proteína C reativa (PCR). O colesterol total, o HDL, o LDL, os triglicérides, o HOMA-IR e a PCR foram considerados fatores de risco cardiovascular e analisados em relação ao escore z do IMC. Resultados: No capítulo 1, apenas os meninos apresentaram a altura significativamente maior que as meninas e estas %GC maior que os meninos. Todas as referências que usaram IMC para avaliar obesidade apresentaram associação positiva com o %GC avaliado pela DXA no diagnóstico de obesidade. Utilizando a curva ROC em relação ao %GC pela DXA, todas as referências apresentaram alta sensibilidade, porém, o escore z do IMC pela WHO apresentou melhor especificidade, com o valor da acurácia de 82% para o ponto de corte >2,14. No capítulo 2, seis adolescentes não apresentaram nenhum dos seis fatores de risco cardiovascular, 15 apresentaram um ou dois fatores de risco e 11 apresentaram três ou mais. O escore z do IMC com melhor sensibilidade (81,8%), especificidade (71,4%) e acurácia (72%) para identificar os grupos com menos de três ou três ou mais fatores de risco cardiovascular foi o 2,14. Conclusão: De todas as referências utilizadas para o diagnóstico de obesidade o ponto de corte do escore z >2,14 de IMC da WHO mostrou melhor especificidade. O ponto de corte do escore z >2,14 de IMC da WHO confirmou ser o melhor ponto de corte para diagnóstico de obesidade relacionada a risco de DCV entre adolescentes com SD / Abstract: Structure of the Thesis: This study is structured by "Scandinavian Model," called "Alternative Model" in the Postgraduate Program in Child and Adolescent Health of the School of Medical Sciences, at State University of Campinas (FCM - Unicamp). This thesis is composed of general introduction, objectives, chapters (1 and 2) and general conclusion. The general introduction approach aspects of the history of Down syndrome (DS), prevalence, genetics, clinical features and demonstrations in DS; as well as dealing with obesity issues directed to the pathophysiology, types, prevalence and diagnosis in children and adolescents, diagnostic methods and obesity in DS; the association of obesity with cardiovascular disease (CVD), as well as the assessment of cardiovascular risk factors in children, adolescents and adults with and without DS. Chapters 1 and 2 are in article format. In general conclusion were presented the main conclusions of the two articles. References were presented at the end of each chapter and of the thesis. Objectives: The aims of this study are: (1) to estimate the cutoff point of the body mass index (BMI) for the diagnosis of obesity in adolescents with DS according to different references for BMI in relation to the percentage of body fat (%BF) measured by absorptiometry dual-energy X-ray absorptiometry (DXA) and (2) to assess the cardiovascular risk factors in adolescents with DS and compare them in relation to obesity diagnosis determined by z-score for BMI of the World Health Organization (WHO). Materials and Methods: In this study, participated in the first article (Chapter 1) 34 adolescents with DS and the second article (Chapter 2) 32 adolescents with DS, of both sexes (age: 10 to 17 years). In Chapter 1, two techniques were used to assess body composition: BMI and DXA. BMI was evaluated according to the references of the International Obesity Task Force (IOTF), the WHO for the general population, and Myrelid et al. and Styles et al. for people with DS. The %BF was assessed by whole body DXA and classified according to NHANES. In chapter 2, weight and height were measured and BMI calculated. BMI considered abnormal was >2.14. We evaluated waist circumference, blood pressure, lipid profile, HOMA-IR and C-reactive protein (CRP). Total cholesterol, HDL, LDL, triglycerides, HOMA-IR and CRP were considered cardiovascular risk factors and analyzed in relation to BMI z score. Results: In Chapter 1, all references who have used BMI to assess obesity was positively associated with %BF measured by DXA in the diagnosis of obesity. Using the ROC curve in relation to %BF by DXA, all references showed high sensitivity, but the z-score of BMI by WHO showed better specificity, with the value of the accuracy of 82% for the cutoff point above 2.14. In Chapter 2, six teenagers do not show any of the six cardiovascular risk factors, 15 had one or two risk factors and 11 had three or more. The z scores of BMI with better sensitivity (81.8%), specificity (71.4%) and accuracy (72%) to identify the groups with less than three or three or more cardiovascular risk factors was 2.14. Conclusion: All the references used for the diagnosis of obesity of the cutoff point of z-scores above 2.14 by WHO showed better specificity. WHO BMI z scores greater than 2.14 confirmed to be the best cutoff point for obesity diagnosis related to risk of the cardiovascular disease among adolescents with DS / Doutorado / Saude da Criança e do Adolescente / Doutor em Ciências

This diploma thesis deals with reduction of metal artifacts in CT data with submicron resolution. The first part of this thesis briefly describes x-ray computed tomography followed by the description of artifacts of tomographic images and existing approaches of the reduction of metal artifacts. In the second part proposed methods of reduction of metal artifacts and their implementation in Matlab programming environment are described. Finally functionality of algorithms is tested on a newly created database and the results are compared, evaluated and discussed.