Résumé : Imager la vascularisation cérébrale de la manière la plus exacte, précise et rapide possible représente un enjeu important pour plusieurs domaines de recherche. En plus d’aider à mieux comprendre le fonctionnement normal du cerveau, cela peut servir à caractériser diverses pathologies ou à développer de nouveaux traitements. Dans un premier temps, ce mémoire présente l’optimisation d’une technique d’angiographie cérébrale in vivo chez un modèle animal fréquemment utilisé, la souris. La technique emploie une séquence d’imagerie par résonance magnétique (IRM) 3D pondérée en susceptibilité ainsi qu’un agent de contraste, le Resovist. Les paramètres d’acquisition à l’IRM ont été optimisés à l’aide d’images acquises avant l’injection du Resovist. Ces paramètres permettent d’imager le cerveau entier en 41 minutes avec une résolution de 78 × 78 × 104 μm3. L’emploi d’une pondération en susceptibilité offre une excellente sensibilité aux petits vaisseaux (diamètre ≃ 40μm). L’analyse des images permet d’extraire des informations sur la morphologie vasculaire. Dans un second temps, la méthode de l’acquisition compressée (AcqC) a été implémentée dans le but d’accélérer l’acquisition des images angiographiques. La méthode de l’AcqC utilise des hypothèses de compressibilité des images pour diminuer la quantité de données acquise. L’AcqC a jusqu’à présent principalement été développée pour des images réelles (au sens des nombres complexes). Or, les images angiographiques obtenues présentent d’importantes variations de phase en raison de la pondération en susceptibilité. La présence de ces variations diminue d’une part la force des hypothèses de compressibilité habituelles et rend d’autre part l’espace-k moins propice au sous-échantillonnage requis par l’AcqC. En raison de ces deux facteurs, l’AcqC standard s’avère inefficace pour accélérer l’acquisition des images angiographiques acquises. Leur mise en lumière suggère cependant différentes pistes pour améliorer l’AcqC appliquée aux images comportant d’importantes variations de phase. / Abstract : Imaging neurovasculature with highest exactitude, precision and speed is of critical importance for several research fields. Beside providing an insight on normal brain activity, it can help characterize numerous pathologies or develop novel treatments. This thesis presents in its first part the optimization of a cerebral angiographic in vivo technique in a frequently used animal model, the mouse. The technique uses both a 3D magnetic resonance imaging (MRI) susceptibility weighted sequence and a strongly paramagnetic contrast agent, Resovist. MRI acquisition parameters were optimized using images acquired before contrast agent injection. Those parameters allow whole brain vascular imaging of the mouse brain in 41 minutes with a 78 × 78 × 104 μm3 resolution. Susceptibility weighting offers an excellent detection sensitivity for small vessels (diameter ≃ 40μm). Image treatment and analysis allow the extraction of vascular morphological information such as vessel size and vessel density. In the second part of this thesis, an attempt to accelerate angiographic images acquisition using the compressed sensing (CS) method is presented. CS method aims at reducing the acquired data by using compressibility hypothesis on images. Presently, CS is mainly developped for real images (within the meaning of complex numbers). However, the previously obtained angiographic images contain important phase variations due to the susceptibility weighting. First, those variations reduce the strength of the compressibility hypothesis normally used in CS. Second, those same variations make information distribution in k-space less appropriate for the undersampling required by CS. For those reasons, standard CS does not allow significant acceleration of the acquisition process for the presented angiographic technique. Studying those reasons however suggests new ways to increase CS efficiency when applied to images with important phase variations.

A prática assistencial na área da saúde implica situações de risco, os quais podem ser maximizados, minimizados ou projetados no julgamento à luz da fundamentação científica. O reprocessamento de materiais de uso único é uma prática que, a cada dia, tem exigido esforços dos profissionais de saúde no sentido de buscar e produzir evidências que auxiliem no processo de tomada de decisão em relação à não-realização ou sob que condições podem ser executadas. O objetivo geral deste estudo foi avaliar a aplicação de diferentes processos de limpeza e a esterilização em óxido de etileno a 100% nos cateteres de angiografia cardiovascular com vista à determinação da capacidade de redução da carga microbiana e do resíduo orgânico neles antes e após a utilização pelo paciente, assim como em situações de simulação com testes desafio. Trata-se de pesquisa experimental, aplicada, comparativa e controlada realizado no Research Centre do Saint Boniface General Hospital filiado à University of Manitoba, localizada em Winnipeg no Canadá. Os cateteres foram utilizados uma única vez por pacientes submetidos a angiografia coronariana e à análise de resíduos orgânicos (hemoglobina, carboidrato, proteína e endotoxina) por meio de testes bioquímicos diretos e indiretos utilizando a técnica de espectrofotometria. A carga microbiana foi avaliada por meio da realização de cultura microbiológica por método indireto. Esses experimentos foram realizados em quatro etapas, sendo a primeira imediatamente após o uso dos cateteres para determinação da sujidade basal; a segunda, após o uso pelo paciente e limpeza do cateter por diferentes métodos; a terceira, após o uso pelo paciente, de inoculação de sujidade artificial e limpeza por diferentes métodos e a quarta, após o uso pelo paciente, teste desafio, limpeza e esterilização simulando-se cinco reusos. Foram utilizadas técnicas de estatística descritiva e analítica por meio de testes estatísticos paramétricos (análise de variância) e, quando necessário, testes não paramétricos (Kruskall-Wallis). Em todas as análises estatísticas, foram considerados testes bilaterais com um nível de significância estatística de 5% ou 0,05 e o intervalo de confiança estabelecido foi de 95%. O resultado positivo em qualquer um dos testes de detecção de resíduo orgânico e microbiológico foi indicativo de ineficácia do método de limpeza testado. As unidades amostrais foram submetidas aos seguintes métodos de limpeza: limpeza manual com detergente enzimático com enxágüe em água de torneira ou água tratada com osmose reversa e esterilizada; limpeza manual com detergente contendo peróxido de hidrogênio com enxágüe com água tratada com osmose reversa e esterilizada; limpeza automatizada com detergente enzimático sem enxágüe ou com enxágüe em água tratada com osmose reversa e esterilizada; limpeza sob pressão contínua com detergente contendo peróxido de hidrogênio com enxágüe em água de torneira ou água tratada com osmose reversa e esterilizada. Os resultados obtidos neste estudo apontam para a manutenção da carga microbiana antes e após a limpeza dos cateteres. Antes da execução de qualquer método de limpeza dos cateteres, a freqüência de culturas positivas foi de 8,2%, com uma carga microbiana média de 500UFC/unidade. Após a limpeza dos cateteres a freqüência de culturas positivas foi de 8,3% e a carga microbiana média foi de 250UFC/unidade. Os resíduos orgânicos basais detectados nos cateteres apresentavam-se nas seguintes concentrações: 146,3 µg/unidade de hemoglobina, 628,5 µg/unidade de proteína e 7,0 µg/unidade de carboidrato e 38,0 UE/unidade de endotoxina. Após a realização de cinco simulações, a concentração de hemoglobina indireta foi abaixo do limite de detecção do teste, proteína indireta =107,7 µg/unidade, carboidrato indireto= 340,1µg/unidade e endotoxina=5,4UE/unidade. A análise da concentração dos resíduos orgânicos de acordo com os métodos de limpeza demonstrou diferentes níveis de redução. Os métodos de limpeza que utilizaram o detergente contendo peróxido de hidrogênio apresentaram melhor desempenho em relação aos que utilizaram detergentes enzimáticos, sendo que o do método de limpeza sob pressão contínua foi superior aos demais métodos. Os resultados dos resíduos orgânicos dos cateteres que foram submetidos a cinco simulações de reuso mostraram-se inferiores aos valores médios absolutos de uma única simulação, com exceção da concentração média de carboidrato. / The healthy assistance implies in risk, which can be maximized, minimized or projected based on the scientific data. The reprocessing of single used devices is a practice that each day has demanded efforts of the healthcare professionals in order to search and to produce scientific evidences to help them make decision in relation to not reuse or reuse under safety conditions. The objective of this study was to evaluate different cleaning processes and sterilization in ethylene oxide 100% of the angiographic catheters in order to determine the capacity in reducing of the bioburden and the organic residual before and after patient use, as well as in simulated use with soil test. It is an experimental research, comparative and controlled permed in the Research Centre of the Saint Boniface General Hospital affiliated to the University of Manitoba located in Winnipeg, Canada. The catheters had been used only one time for coronariographic exam and submitted to the analysis of organic residues (hemoglobin, carbohydrate, protein and endotoxin) by in situ and destructive test reading by spectrophotometer. The bioburden was evaluated by microbial culture. These experiments had been performed in four phases, being the first immediately after patient use to determine the basaline soil; the second after patient use and cleaning of the catheter by different methods; the third after patient use, soil test inoculation and cleaning by different methods. The fourth phase was performed after patient use and simulated reuse. Descriptive and analytical statistic analysis by parametric statistical tests (variance analysis) or no parametric tests (Kruskall-Wallis) were performed. Had been considered bilateral tests with a significance level < 0,05 and the confidence interval was 95%. It was considered clening failure of the cleaning process any positive results of the detention of organic and microbiological residue. The catheters were submitted to the following cleaning methods: manual washing with enzymatic detergent with tap water or reverse osmosis sterile rinsing; manual washing with hydrogen peroxide detergent rinsing in reverse osmosis sterile water, automated washing with no rinse or reverse osmose sterile water; hydrogen peroxide detergent pumping with tap water or reverse osmosis sterile rinsing . The results gotten in our study showed the maintenance of the bioburden before and after the cleaning of the catheters. In the baseline phase 8,2% of the cultures were positive cultures and the microbial load was 500CFU/device. After cleaning it was 8,3% and the average microbial load was 250 CFU/device. The baseline organic residues data were hemoglobin 146,3µg/device, protein 628,5 µg/device, carbohydrate 7,0µg/device and endotoxin 38,0EU/device. After five simulated use, the indirect hemoglobin concentration was lower of the test limit of detention, protein = 107,7 µg/device, carbohydrate = 340,1µg/device and endotoxin=5,4EU/device. The organic residual analysis according the cleaning methods found different levels of reduction. The cleaning methods that had used a hydrogen peroxide detergent showed better performance relating the enzymatic detergents methods, as well as hydrogen peroxide detergent pumping with reverse osmosis sterile rinsing was the best method. After simulated use phase the organic residue showed lower concentration, excepted the carbohydrate level.

A prática assistencial na área da saúde implica situações de risco, os quais podem ser maximizados, minimizados ou projetados no julgamento à luz da fundamentação científica. O reprocessamento de materiais de uso único é uma prática que, a cada dia, tem exigido esforços dos profissionais de saúde no sentido de buscar e produzir evidências que auxiliem no processo de tomada de decisão em relação à não-realização ou sob que condições podem ser executadas. O objetivo geral deste estudo foi avaliar a aplicação de diferentes processos de limpeza e a esterilização em óxido de etileno a 100% nos cateteres de angiografia cardiovascular com vista à determinação da capacidade de redução da carga microbiana e do resíduo orgânico neles antes e após a utilização pelo paciente, assim como em situações de simulação com testes desafio. Trata-se de pesquisa experimental, aplicada, comparativa e controlada realizado no Research Centre do Saint Boniface General Hospital filiado à University of Manitoba, localizada em Winnipeg no Canadá. Os cateteres foram utilizados uma única vez por pacientes submetidos a angiografia coronariana e à análise de resíduos orgânicos (hemoglobina, carboidrato, proteína e endotoxina) por meio de testes bioquímicos diretos e indiretos utilizando a técnica de espectrofotometria. A carga microbiana foi avaliada por meio da realização de cultura microbiológica por método indireto. Esses experimentos foram realizados em quatro etapas, sendo a primeira imediatamente após o uso dos cateteres para determinação da sujidade basal; a segunda, após o uso pelo paciente e limpeza do cateter por diferentes métodos; a terceira, após o uso pelo paciente, de inoculação de sujidade artificial e limpeza por diferentes métodos e a quarta, após o uso pelo paciente, teste desafio, limpeza e esterilização simulando-se cinco reusos. Foram utilizadas técnicas de estatística descritiva e analítica por meio de testes estatísticos paramétricos (análise de variância) e, quando necessário, testes não paramétricos (Kruskall-Wallis). Em todas as análises estatísticas, foram considerados testes bilaterais com um nível de significância estatística de 5% ou 0,05 e o intervalo de confiança estabelecido foi de 95%. O resultado positivo em qualquer um dos testes de detecção de resíduo orgânico e microbiológico foi indicativo de ineficácia do método de limpeza testado. As unidades amostrais foram submetidas aos seguintes métodos de limpeza: limpeza manual com detergente enzimático com enxágüe em água de torneira ou água tratada com osmose reversa e esterilizada; limpeza manual com detergente contendo peróxido de hidrogênio com enxágüe com água tratada com osmose reversa e esterilizada; limpeza automatizada com detergente enzimático sem enxágüe ou com enxágüe em água tratada com osmose reversa e esterilizada; limpeza sob pressão contínua com detergente contendo peróxido de hidrogênio com enxágüe em água de torneira ou água tratada com osmose reversa e esterilizada. Os resultados obtidos neste estudo apontam para a manutenção da carga microbiana antes e após a limpeza dos cateteres. Antes da execução de qualquer método de limpeza dos cateteres, a freqüência de culturas positivas foi de 8,2%, com uma carga microbiana média de 500UFC/unidade. Após a limpeza dos cateteres a freqüência de culturas positivas foi de 8,3% e a carga microbiana média foi de 250UFC/unidade. Os resíduos orgânicos basais detectados nos cateteres apresentavam-se nas seguintes concentrações: 146,3 µg/unidade de hemoglobina, 628,5 µg/unidade de proteína e 7,0 µg/unidade de carboidrato e 38,0 UE/unidade de endotoxina. Após a realização de cinco simulações, a concentração de hemoglobina indireta foi abaixo do limite de detecção do teste, proteína indireta =107,7 µg/unidade, carboidrato indireto= 340,1µg/unidade e endotoxina=5,4UE/unidade. A análise da concentração dos resíduos orgânicos de acordo com os métodos de limpeza demonstrou diferentes níveis de redução. Os métodos de limpeza que utilizaram o detergente contendo peróxido de hidrogênio apresentaram melhor desempenho em relação aos que utilizaram detergentes enzimáticos, sendo que o do método de limpeza sob pressão contínua foi superior aos demais métodos. Os resultados dos resíduos orgânicos dos cateteres que foram submetidos a cinco simulações de reuso mostraram-se inferiores aos valores médios absolutos de uma única simulação, com exceção da concentração média de carboidrato. / The healthy assistance implies in risk, which can be maximized, minimized or projected based on the scientific data. The reprocessing of single used devices is a practice that each day has demanded efforts of the healthcare professionals in order to search and to produce scientific evidences to help them make decision in relation to not reuse or reuse under safety conditions. The objective of this study was to evaluate different cleaning processes and sterilization in ethylene oxide 100% of the angiographic catheters in order to determine the capacity in reducing of the bioburden and the organic residual before and after patient use, as well as in simulated use with soil test. It is an experimental research, comparative and controlled permed in the Research Centre of the Saint Boniface General Hospital affiliated to the University of Manitoba located in Winnipeg, Canada. The catheters had been used only one time for coronariographic exam and submitted to the analysis of organic residues (hemoglobin, carbohydrate, protein and endotoxin) by in situ and destructive test reading by spectrophotometer. The bioburden was evaluated by microbial culture. These experiments had been performed in four phases, being the first immediately after patient use to determine the basaline soil; the second after patient use and cleaning of the catheter by different methods; the third after patient use, soil test inoculation and cleaning by different methods. The fourth phase was performed after patient use and simulated reuse. Descriptive and analytical statistic analysis by parametric statistical tests (variance analysis) or no parametric tests (Kruskall-Wallis) were performed. Had been considered bilateral tests with a significance level < 0,05 and the confidence interval was 95%. It was considered clening failure of the cleaning process any positive results of the detention of organic and microbiological residue. The catheters were submitted to the following cleaning methods: manual washing with enzymatic detergent with tap water or reverse osmosis sterile rinsing; manual washing with hydrogen peroxide detergent rinsing in reverse osmosis sterile water, automated washing with no rinse or reverse osmose sterile water; hydrogen peroxide detergent pumping with tap water or reverse osmosis sterile rinsing . The results gotten in our study showed the maintenance of the bioburden before and after the cleaning of the catheters. In the baseline phase 8,2% of the cultures were positive cultures and the microbial load was 500CFU/device. After cleaning it was 8,3% and the average microbial load was 250 CFU/device. The baseline organic residues data were hemoglobin 146,3µg/device, protein 628,5 µg/device, carbohydrate 7,0µg/device and endotoxin 38,0EU/device. After five simulated use, the indirect hemoglobin concentration was lower of the test limit of detention, protein = 107,7 µg/device, carbohydrate = 340,1µg/device and endotoxin=5,4EU/device. The organic residual analysis according the cleaning methods found different levels of reduction. The cleaning methods that had used a hydrogen peroxide detergent showed better performance relating the enzymatic detergents methods, as well as hydrogen peroxide detergent pumping with reverse osmosis sterile rinsing was the best method. After simulated use phase the organic residue showed lower concentration, excepted the carbohydrate level.

No description available.

El presente plan de negocio tuvo como objetivo demostrar la viabilidad técnica y económica de la implementación del servicio de diagnóstico y tratamiento de enfermedades vasculares para el rescate del pie diabético mediante procedimientos angiográficos ambulatorios en el Centro de Especialidades Médicas Intervencionistas – CEMI ubicado en la ciudad de Lima. Al respecto, existe una demanda no satisfecha y una oportunidad de negocio, que será atendida por medio de una estrategia de liderazgo en costos. La propuesta de valor es un servicio oportuno, de calidad, alta tecnología y médicos reconocidos. El mercado potencial, con 48 IAFAS, es de un total de 4 196 asegurados con pie diabético. El modelo de negocios se basará en convenios y contratos con dichas IAFAS. También se espera, como parte de los objetivos estratégicos no financieros, fidelizar al 95% de los clientes, usar la capacidad instalada a más del 75% y mantener nexos con los diferentes profesionales de la salud asociados a la subespecialidad en diabetes y la comunidad. Según el análisis económico y financiero, se requiere una inversión inicial de S/ 4 831 045,70, 40% financiada a 5 años y 60% asumida por los socios. A los 10 años este proyecto creará un Valor Presente Neto Económico (VPNE) de 28 015 047,31 y una Tasa Interna de Retorno (TIR) de 60%. Financieramente, generará un Valor Presente Neto Incremental (VPNI) de 17 687 598,28 y una Tasa Interna de Retorno Incremental (TIRI) de 78%. Todo lo anterior indica que se trata de una buena inversión, con un modelo estable y riesgos controlables. / The aim of this business plan was to demonstrate the technical and economic feasibility in the implementation of the diagnosis and treatment service of vascular diseases for rescue of the diabetic foot through outpatient angiographic procedures at the Centro de Especialidades Médicas Intervencionistas - CEMI located in the city of Lima. In this regard, there is an unmet demand and a business opportunity, which will be met through a cost leadership strategy. The value proposition is a timely service, quality, high technology and recognized doctors. The potential market, with 48 IAFAS, is a total of 4 196 insured with diabetic foot. The business model will be based on agreements and contracts with these Health care financing sources. It is also expected, as part of the non-financial strategic objectives, to retain 95% of the clients, use the installed capacity over than 75% and maintain connection between different Health professional asocciated with diabetes specialization and, community. According to economic and financial analysis, an initial investment of S/ 4 831 045.70, 40% financed at 5 years and 60% assumed by the partners, is required. In ten years, this project will create an Economic Net Present Value (NPV) of 28,015,047.31 and an Internal Rate of Return (IRR) of 60%. Financially, it will generate an Increasing Net Present Value (NPV) of 17 687 598.28 and an Incremental Internal Return Rate (IRR) of 78%. All of the above indicates that it is a good investment, with a stable model and controllable risks. / Trabajo de investigación

Computed tomography (CT) is gaining popularity as a minimally invasive diagnostic modality in veterinary science. The use of contrast agents is well described and used with increasing frequency, having marked benefits over the invasive angiographic procedures used previously. Methods to perform CT angiographic (CTA) studies include bolus tracking, test bolus and empirical scan delay techniques. In human medicine, empirical scan delays have been extensively investigated but due to the marked patient variability encountered in veterinary medicine, this technique cannot, at this stage, be confidently used. This then poses the question that if both techniques can be used, is one significantly better than the other one when performing, in particular thoracic CTA? CTA studies were performed on 6 adult beagles, using the bolus tracking (BT) technique and the test bolus (TB) technique on two separate occasions, at least 2 weeks apart. Each beagle acted as its own control. The patients were placed under general anaesthesia. Two ml/kg of 300mgI/ml iodinated contrast agent was injected through a 20 gauge catheter place in the cephalic vein for the BT technique. Scans were initiated when the contrast in the aorta reached 150 Hounsfield units (HU). For the TB technique, the dogs received a test dose of 15% of 2ml/kg of 300mgI/ml iodinated contrast agent injected manually into the cephalic catheter, followed by a series of low dose sequential scans. Time attenuation curves were generated using dynamic evaluation software programs (DYNAEVA®). The full dose of 2ml/kg of the 300mgI/ml iodinated contrast agent was then administered and the scans were conducted at optimal times as identified from the time attenuation curves. The full dose of contrast administration was administered using a pressure injector operated at 3ml/sec and was followed by a manual saline flush for all studies. Mean attenuation in HU was taken at three consecutive levels in the aorta (Ao), caudal vena cava (CVC) and right caudal pulmonary artery (rCPA) by placing a region of interest (ROI) in the vessel of interest. These observations were done for both arterial and venous phases using the BT and TB studies in five of the six dogs. Additional observations included the visualisation of the smaller thoracic vessels, in particular the arteries, the study duration, milliampere (mA), computed tomography dose index volume (CTDI(vol)), dose length product (DLP) and the pressure and the duration of the contrast injection. These observations were done in all six dogs. Statistical analysis included the comparison of the attenuation achieved in the major vessels (Ao, CVC and rCPA) for the two techniques. The test bolus technique was deemed to be the gold standard, as this is adapted for each individual patient. In one beagle the study was considered non diagnostic with a later time to peak enhancement noted in the Ao than the CVC. No statistical analysis was done on the dynamic and attenuation data obtained in this dog. In all the other studies, the attenuation achieved in the vessels evaluated was deemed to be of diagnostic quality except for the attenuation achieved in the CVC during the arterial phase. The attenuation in the Ao during the arterial phase for the BT technique was not significantly different (660.52 HU ± 138.49) than the TB technique (469.82 HU ± 199.52)(p = 0.13). The attenuation in the Ao during the venous phase for the BT and TB techniques was also not significantly different (BT = 190.6 HU ± 28.29 and TB = 188.8 HU ± 21.9, p = 0.92). The attenuation in the CVC during the arterial phase and venous phases for the BT techniques were not significantly different (arterial phase BT = 37.84 HU ± 20.8, arterial phase TB = 91.48 HU ± 66.54, p = 0.069; venous phase BT = 171.3 HU ± 32.36, venous phase TB = 191.08 HU ± 19.59, p = 0.087). The attenuation in the rCPA during the arterial phase was not statistically different between the two techniques (BT= 606.34 HU ± 143.37 and TB = 413.72 HU ± 174.99, p = 0.28), nor was the attenuation in the rCPA during the venous phase (BT = 174.34 HU ± 27.25 and TB = 164.46 HU ± 18.51, p = 0.51). The mean mA for the BT technique (3538.5 ± 171.27) was significantly lower than the TB technique (3929.6 ± 312.3) with p = 0.024. The mean CTDI(vol) for the BT technique (24.42 ± 11.89) was significantly lower than the TB CTDI(vol) (45.32 ± 0.94) with a p-value of 0.013. The mean DLP did not differ significantly between the two techniques (BT = 139.1 ± 7.65, TB = 162.8 ± 33.1) (p = 0.12). The BT technique resulted in a significantly shorter procedural duration and utilised less contrast material than the TB technique. The injection duration and injection pressures did not differ significantly between the two techniques (p = 0.23 and p = 0.62 respectively). This study identifies that there is no preference for either technique when evaluating the Ao, CVC or rCPA, however, the BT technique is shown to be shorter in procedural duration, utilises less contrast material and results in less radiation dose to the patient when compared to the TB technique. Copyright / Dissertation (MMedVet)--University of Pretoria, 2011. / Companion Animal Clinical Studies / unrestricted

No description available.

Buerger disease is characterized by progressive distal extremity ischemia in persons with recent tobacco consumption. Typically, affected persons are young men. There have been case reports of Buerger disease in older men. Almost all of the reported cases were characterized with progressive, severe disease requiring amputation. We report a case of an older man with features of Buerger disease without significant proximal progression despite active smoking. Arteriographic and pathologic studies confirmed the diagnosis.

Doenças vasculares são um problema mundial, que representa 28% das mortes no mundo e 66% do total de doenças que acometem os brasileiros. Dessa forma, há um grande interesse em pesquisar formas de prevenção e tratamento dessas doenças. Algumas medidas são relevantes no auxílio de diagnóstico, tal como: tamanho médio dos ramos, diâmetro médio das seções transversais dos vasos e padrões de divisão de ramos. Calcular essas medidas de forma manual é uma tarefa demorada e trabalhosa. Assim, esta Tese tem como objetivo, propor um método computacional de rastreamento e extração de atributos em redes vasculares a partir de imagens 3D de angiografia por ressonância magnética e por tomografia computadorizada. Trata-se de uma abordagem de rastreamento e identificação de bifurcações que difere das técnicas anteriores, utilizando a Transformada de Hough para identificar o diâmetro do vaso em cortes transversais num dado ponto ao longo de um vaso sanguíneo. Mais detalhadamente, essa abordagem utiliza um campo vetorial advindo do cálculo de uma matriz formada por derivadas parciais de segunda ordem, obtida da intensidade luminosa da imagem, para identificar a direção de um ramo de vaso. Além disso, durante o processo de rastreamento de um ramo de vaso, são calculados vários descritores de forma com o objetivo de classificar regiões como pertencentes a uma bifurcação ou não. Em adição a estes descritores, desenvolvemos uma nova medida chamada de variância do raio que permite distinguir, bifurcações, não-bifurcações e segmentos de vaso com stents (aparelho metálico usado para aumentar o diâmetro dos vasos). Para a classificação de bifurcações, criamos a medida de bifurcação, que trata-se de uma combinação linear de todos os descritores de forma apresentados neste trabalho. Testes foram realizados para atestar a eficácia da abordagem proposta, utilizando tanto imagens sintéticas quantoimagens reais. Os resultados mostraram que o método é capaz de rastrear 91% de uma rede vascular sintética variando o ponto de inicialização e 76% variando o nível de ruído. Também foi observado por meio de testes que o método proposto consegue rastrear vasos e identificar bifurcações em imagens reais sem avaliação numérica. Essa abordagem permite a extração da relação hierárquica entre os ramos em uma rede vascular e a extração do padrão de divisão dos vasos, o que contribui sobremaneira para o estudo do comportamento do fenômeno da angiogênese e no auxílio no diagnóstico de anomalias vasculares. / Vascular diseases are a main health problem, representing 28% of deaths worldwide and 66% of all diseases affecting the Brazilian population. Thus, it is important that researches in prevention and treatment of this type of disease increase. Moreover, there are several demands, such as computational tools capable of analyzing and extracting attributes from non-invasive images. The scope of this work is the analysis and extraction of data from magnetic resonance angiography and computed tomography angiography images by highlighting blood vessels. In this context, this thesis aims the development of a novel computational tracking and feature extraction method for vascular networks from 3D images. Our approach presents the following steps: First, identify the vessel cross-sections along it using the Hough transform. Then, compute a matrix composed of second order partial derivatives of image intensity to identify the direction of the vessel. Perform a feature analysis of the vessel contour to classify the bifurcation point, and finally, identify the direction of the new branch in a bifurcation point. The main contribution of this Thesis is the two new measures developed, called radius ratio and bifurcation measure, the radius ratio is capable to distinguish between a region with bifurcation, stents or without both of them. The bifurcation measure is a linear combination that allows to classify a region as bifurcation or not. Tests were performed in order to verify the proposed approach effectiveness, using both synthetic images and real images. The results showed the method is capable to track 91% of synthetic vascular networks varying the seed point and 76% varying the level of noise. Also, we performed tests in real images and by visual evaluation, we could observed that the proposed method was able to track vessels and identify bifurcations from different parts of the body. This approach allows to calculate, in the future, the density of bifurcations in a vascular network, the distance between them, the stenosis and aneurysms grading and characterize specific vessels. In addition, the vascular networks extraction allows the study of the angiogenesis phenomena and vascular anomalies.

No description available.