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

A instabilidade patelar é uma patologia comum dentro da especialidade da cirurgia do joelho. O principal fator estabilizador dessa articulação é o ligamento patelofemoral medial, sendo esta a principal estrutura a ser reconstruída no tratamento cirúrgico da instabilidade patelar. Apesar de sua reconstrução apresentar excelentes resultados clínicos, não se sabe ao certo o real efeito in vivo desse procedimento no movimento da patela ao redor do fêmur. A avaliação da articulação patelofemoral tradicionalmente é feita através de exames de imagem estáticos. Com a evolução dos aparelhos de tomografia computadorizada, se tornou possível realizar esse exame durante movimento ativo, técnica ainda pouco utilizada para estudo de articulações como o joelho. O objetivo deste estudo foi padronizar o uso da tomografia de 320 fileiras de detectores para estudo dinâmico da articulação patelofemoral em pacientes com instabilidade patelar recidivante pré e pós-reconstrução do ligamento patelofemoral medial, analisando o efeito da cirurgia no trajeto da patela ao longo do arco de movimento. Foram selecionados 10 pacientes com instabilidade patelar e indicação de reconstrução do ligamento patelofemoral medial isolada, que foram submetidos à tomografia antes e após um mínimo de 6 meses da cirurgia. Os parâmetros anatômicos avaliados foram os ângulos de inclinação da patela e distância da patela ao eixo da tróclea através de um programa de computador desenvolvido especificamente para esse fim. Foram aplicados os escores clínicos de Kujala e Tegner e calculada a radiação dos exames. O protocolo escolhido para aquisição de imagens na tomografia foi: potencial do tubo de 80 kV, carga transportável de 50 mA, espessura de corte de 0,5 mm e tempo de aquisição de 10 segundos, o que gerou um DLP (dose length product) de 254 mGycm e uma dose efetiva estimada de radiação de 0,2032 mSv. O paciente realizava uma extensão ativa do joelho contra a gravidade. Os resultados não mostraram mudança do trajeto da patela após a reconstrução do ligamento patelofemoral medial, apesar de não ter havido nenhuma recidiva da instabilidade e os escores clínicos apresentarem melhora média de 22,33 pontos no Kujala (p=0,011) e de 2 níveis no Tegner (p=0,017) / Patellar instability is a common pathology in the practice of knee surgeons. The most important stabilizing structure in the patellofemoral joint is the medial patellofemoral ligament. This ligament is the main structure to be reconstructed during surgery for patellofemoral instability. Although clinical results for this procedure are excellent, the real in vivo effect of medial patellofemoral ligament reconstruction on patellar tracking is unknown. The study of this joint is usually made with static imaging. With the recent evolution of tomographers, it is now possible to analyze anatomical structures moving during active range of motion. This technique (dynamic computerized tomography) has not been routinely used to study joints as the knee. This study had the purpose of standardizing the use of 320-detector row computerized tomography for the patellofemoral joint, analyzing patients before and after surgical reconstruction of medial patellofemoral ligament. We selected 10 patients with patellofemoral instability referred to isolated medial patellofemoral ligament reconstruction surgery, and submitted them to a dynamic computerized tomography before and at a minimum of 6 months after surgery. Patellar tilt angles and shift distance were analyzed using a computer software specifically designed for this purpose. Kujala and Tegner scores were applied and the radiation of the exams was recorded. The protocol for imaging acquisition was: tube potential of 80 kV, 50 mA, slice thickness of 0.5 mm and 10 seconds of acquisition duration. This produced a DLP (dose length product) of 254 mGycm and a radiation effective estimated dose of 0.2032 mSv. There were no changes in patellar tracking after medial patellofemoral ligament reconstruction. There was no instability relapse. Clinical scores showed an average improvement of 22.33 points for Kujala (p=0.011) and of 2 levels for Tegner (p=0.017)

Die zerstörungsfreie Ultraschallprüfung von akustisch anisotropen Werkstoffen stellt auch heute noch eine Herausforderung dar. Die Gefügestruktur in solchen Materialien beeinflusst die Wellenausbreitung derart, dass es zum einen zu starken Streuungen durch die großflächigen Korngrenzen und zum anderen, aufgrund der akustischen Anisotropie, zu einer Richtungsabhängigkeit der Schallgeschwindigkeiten kommt. In den vergangenen Jahren wurden bereits Lösungsansätze zur mathematischen Modellierung der Schallausbreitung in anisotropen Materialien vorgestellt. Diese basieren in der Regel auf FEM- bzw. FIT- Algorithmen, die durch die Diskretisierung des gesamten Volumens einen hohen Rechenaufwand erfordern und in der täglichen Prüfpraxis aufgrund ihrer Komplexität bei der Parametrierung nur bedingt einsetzbar sind. Aus diesem Grund wird hier ein Ansatz zur Schallfeldberechnung gewählt, der auf die praktische Anwendung von Gruppenstrahler-Prüfköpfen zugeschnitten ist. Während sich andere Verfahren auf einzelne Wellenanteile und monofrequente Lösungen beschränken, um den Rechenaufwand zu reduzieren, können mit diesem Ansatz die reale Signalform des Prüfkopfes sowie alle auftretenden Wellenanteile in homogenen transversalisotropen Medien berücksichtigt werden. Durch entsprechende Optimierungen im Berechnungsalgorithmus lässt sich das gesamte vierdimensionale Schallfeld eines Gruppenstrahler-Prüfkopfes im Halbraum in kürzester Zeit berechnen. Die analytische Lösung der Wellengleichung für den Halbraum in Form einer Greenschen Funktion wird dabei in eine Gleichung umgeformt, die hier als vierdimensionale Punktrichtwirkung bezeichnet wird. Dieser Modellansatz ermöglicht es, die Parameter eines Gruppenstrahlersystems in der praktischen Anwendung zu überprüfen und durch iterative Rechnungen zu optimieren. Mit Hilfe einer einfach zu handhabenden Visualisierungstechnik ist es möglich diesen Modellansatz mit realen Schallfeldmessungen zu vergleichen. Dazu werden mit elektrodynamischen Sonden die einzelnen Komponenten des dreidimensionalen Vektors der Teilchenverschiebung an der Oberfläche von Festkörpern abgetastet. Die an den Messpunkten ermittelten Zeitfunktionen des Verschiebungsvektors werden dann dem berechneten Zeitverlauf der Wellenausbreitung gegenübergestellt. Die berechneten und gemessenen Schallfelder stimmen in der Phasenlage und im Amplitudenverlauf gut überein. Die Ergebnisse zeigen, dass mit dem verwendeten Rechenmodell alle in der Realität auftretenden Wellenanteile vollständig berücksichtigt werden und dreidimensionale Problemstellungen aus der Praxis mit diesem Modell korrekt berechnet werden können. / The non-destructive ultrasonic testing of acoustic anisotropic materials is an important challenge. The texture of these materials causes a strong scattering of the sound wave by the extensive grain boundaries and a direction dependent sound velocity by the acoustic anisotropy. Several approaches for the modelling of the sound propagation in anisotropic materials were presented in the last years. These approaches are normally based on FEM or FIT algorithms using a discretisation of the complete volume. Their calculation needs extensive time and a very complex parameterisation. Thus these algorithms are not suitable in practice of ultrasonic testing. In this work an approach is presented that is optimised for the application of phased array transducers. The new approach considers the real frequency spectrum of the transducer as well as all occurring wave modes in homogeneous transversely isotropic media, whereas other approaches are limited to solutions for single wave modes and single frequencies to reduce the calculation effort. The appropriate optimisations of the mathematical algorithm allow the fast calculation of the complete four-dimensional transient wave field of a phased array transducer in the half-space. The Green’s functions are derived by an analytical solution of the elastodynamic wave equation for the half-space. These functions will be transformed into an equation which will be referred to in this work as four-dimensional directivity pattern. This approach allows the verification of the parameters of a phased array system and their optimisation by iterative calculations in the practical application. To get accurate results in these calculations, the experimental verification of the applied mathematical model for the wave propagation is an essential task. The technique presented in this work applies electrodynamic probes, which provides a simple use. The probes can detect the particle displacement at a solid surface in all three spatial directions. The measured time-functions of the wave field will be compared with the calculated time-functions. They show a good accordance in the phase and the amplitude. This confirms that the applied mathematical model considers completely all in practice occurring wave modes. The results further show that three-dimensional problems in practice can be calculated correctly with this model.

A instabilidade patelar é uma patologia comum dentro da especialidade da cirurgia do joelho. O principal fator estabilizador dessa articulação é o ligamento patelofemoral medial, sendo esta a principal estrutura a ser reconstruída no tratamento cirúrgico da instabilidade patelar. Apesar de sua reconstrução apresentar excelentes resultados clínicos, não se sabe ao certo o real efeito in vivo desse procedimento no movimento da patela ao redor do fêmur. A avaliação da articulação patelofemoral tradicionalmente é feita através de exames de imagem estáticos. Com a evolução dos aparelhos de tomografia computadorizada, se tornou possível realizar esse exame durante movimento ativo, técnica ainda pouco utilizada para estudo de articulações como o joelho. O objetivo deste estudo foi padronizar o uso da tomografia de 320 fileiras de detectores para estudo dinâmico da articulação patelofemoral em pacientes com instabilidade patelar recidivante pré e pós-reconstrução do ligamento patelofemoral medial, analisando o efeito da cirurgia no trajeto da patela ao longo do arco de movimento. Foram selecionados 10 pacientes com instabilidade patelar e indicação de reconstrução do ligamento patelofemoral medial isolada, que foram submetidos à tomografia antes e após um mínimo de 6 meses da cirurgia. Os parâmetros anatômicos avaliados foram os ângulos de inclinação da patela e distância da patela ao eixo da tróclea através de um programa de computador desenvolvido especificamente para esse fim. Foram aplicados os escores clínicos de Kujala e Tegner e calculada a radiação dos exames. O protocolo escolhido para aquisição de imagens na tomografia foi: potencial do tubo de 80 kV, carga transportável de 50 mA, espessura de corte de 0,5 mm e tempo de aquisição de 10 segundos, o que gerou um DLP (dose length product) de 254 mGycm e uma dose efetiva estimada de radiação de 0,2032 mSv. O paciente realizava uma extensão ativa do joelho contra a gravidade. Os resultados não mostraram mudança do trajeto da patela após a reconstrução do ligamento patelofemoral medial, apesar de não ter havido nenhuma recidiva da instabilidade e os escores clínicos apresentarem melhora média de 22,33 pontos no Kujala (p=0,011) e de 2 níveis no Tegner (p=0,017) / Patellar instability is a common pathology in the practice of knee surgeons. The most important stabilizing structure in the patellofemoral joint is the medial patellofemoral ligament. This ligament is the main structure to be reconstructed during surgery for patellofemoral instability. Although clinical results for this procedure are excellent, the real in vivo effect of medial patellofemoral ligament reconstruction on patellar tracking is unknown. The study of this joint is usually made with static imaging. With the recent evolution of tomographers, it is now possible to analyze anatomical structures moving during active range of motion. This technique (dynamic computerized tomography) has not been routinely used to study joints as the knee. This study had the purpose of standardizing the use of 320-detector row computerized tomography for the patellofemoral joint, analyzing patients before and after surgical reconstruction of medial patellofemoral ligament. We selected 10 patients with patellofemoral instability referred to isolated medial patellofemoral ligament reconstruction surgery, and submitted them to a dynamic computerized tomography before and at a minimum of 6 months after surgery. Patellar tilt angles and shift distance were analyzed using a computer software specifically designed for this purpose. Kujala and Tegner scores were applied and the radiation of the exams was recorded. The protocol for imaging acquisition was: tube potential of 80 kV, 50 mA, slice thickness of 0.5 mm and 10 seconds of acquisition duration. This produced a DLP (dose length product) of 254 mGycm and a radiation effective estimated dose of 0.2032 mSv. There were no changes in patellar tracking after medial patellofemoral ligament reconstruction. There was no instability relapse. Clinical scores showed an average improvement of 22.33 points for Kujala (p=0.011) and of 2 levels for Tegner (p=0.017)

Die zerstörungsfreie Ultraschallprüfung von akustisch anisotropen Werkstoffen stellt auch heute noch eine Herausforderung dar. Die Gefügestruktur in solchen Materialien beeinflusst die Wellenausbreitung derart, dass es zum einen zu starken Streuungen durch die großflächigen Korngrenzen und zum anderen, aufgrund der akustischen Anisotropie, zu einer Richtungsabhängigkeit der Schallgeschwindigkeiten kommt. In den vergangenen Jahren wurden bereits Lösungsansätze zur mathematischen Modellierung der Schallausbreitung in anisotropen Materialien vorgestellt. Diese basieren in der Regel auf FEM- bzw. FIT- Algorithmen, die durch die Diskretisierung des gesamten Volumens einen hohen Rechenaufwand erfordern und in der täglichen Prüfpraxis aufgrund ihrer Komplexität bei der Parametrierung nur bedingt einsetzbar sind. Aus diesem Grund wird hier ein Ansatz zur Schallfeldberechnung gewählt, der auf die praktische Anwendung von Gruppenstrahler-Prüfköpfen zugeschnitten ist. Während sich andere Verfahren auf einzelne Wellenanteile und monofrequente Lösungen beschränken, um den Rechenaufwand zu reduzieren, können mit diesem Ansatz die reale Signalform des Prüfkopfes sowie alle auftretenden Wellenanteile in homogenen transversalisotropen Medien berücksichtigt werden. Durch entsprechende Optimierungen im Berechnungsalgorithmus lässt sich das gesamte vierdimensionale Schallfeld eines Gruppenstrahler-Prüfkopfes im Halbraum in kürzester Zeit berechnen. Die analytische Lösung der Wellengleichung für den Halbraum in Form einer Greenschen Funktion wird dabei in eine Gleichung umgeformt, die hier als vierdimensionale Punktrichtwirkung bezeichnet wird. Dieser Modellansatz ermöglicht es, die Parameter eines Gruppenstrahlersystems in der praktischen Anwendung zu überprüfen und durch iterative Rechnungen zu optimieren. Mit Hilfe einer einfach zu handhabenden Visualisierungstechnik ist es möglich diesen Modellansatz mit realen Schallfeldmessungen zu vergleichen. Dazu werden mit elektrodynamischen Sonden die einzelnen Komponenten des dreidimensionalen Vektors der Teilchenverschiebung an der Oberfläche von Festkörpern abgetastet. Die an den Messpunkten ermittelten Zeitfunktionen des Verschiebungsvektors werden dann dem berechneten Zeitverlauf der Wellenausbreitung gegenübergestellt. Die berechneten und gemessenen Schallfelder stimmen in der Phasenlage und im Amplitudenverlauf gut überein. Die Ergebnisse zeigen, dass mit dem verwendeten Rechenmodell alle in der Realität auftretenden Wellenanteile vollständig berücksichtigt werden und dreidimensionale Problemstellungen aus der Praxis mit diesem Modell korrekt berechnet werden können. / The non-destructive ultrasonic testing of acoustic anisotropic materials is an important challenge. The texture of these materials causes a strong scattering of the sound wave by the extensive grain boundaries and a direction dependent sound velocity by the acoustic anisotropy. Several approaches for the modelling of the sound propagation in anisotropic materials were presented in the last years. These approaches are normally based on FEM or FIT algorithms using a discretisation of the complete volume. Their calculation needs extensive time and a very complex parameterisation. Thus these algorithms are not suitable in practice of ultrasonic testing. In this work an approach is presented that is optimised for the application of phased array transducers. The new approach considers the real frequency spectrum of the transducer as well as all occurring wave modes in homogeneous transversely isotropic media, whereas other approaches are limited to solutions for single wave modes and single frequencies to reduce the calculation effort. The appropriate optimisations of the mathematical algorithm allow the fast calculation of the complete four-dimensional transient wave field of a phased array transducer in the half-space. The Green’s functions are derived by an analytical solution of the elastodynamic wave equation for the half-space. These functions will be transformed into an equation which will be referred to in this work as four-dimensional directivity pattern. This approach allows the verification of the parameters of a phased array system and their optimisation by iterative calculations in the practical application. To get accurate results in these calculations, the experimental verification of the applied mathematical model for the wave propagation is an essential task. The technique presented in this work applies electrodynamic probes, which provides a simple use. The probes can detect the particle displacement at a solid surface in all three spatial directions. The measured time-functions of the wave field will be compared with the calculated time-functions. They show a good accordance in the phase and the amplitude. This confirms that the applied mathematical model considers completely all in practice occurring wave modes. The results further show that three-dimensional problems in practice can be calculated correctly with this model.

This thesis reflects on how to develop an African leadership that can contribute to the effective transformation of the African continent. After analysing the concept of leadership and categorising it for better understanding, the mission of the church as a developer of leaders par excellence has been examined and its potentials and limits assessed. Then, the thesis studied the specific extent of poor African leadership and its dire socio-political consequences in a sub-Saharan African country; so, the context of DR Congo was analysed. After that the contribution of the notion of African Renaissance to the whole debate of leadership development in Africa was assessed and the social, economic and political climate of the continent analysed. The poor and deficient African leadership has been identified as the main cause of rampant conflicts and wars, a slow economic development and lack of transformation in the continent. Given that church leadership seemed so poor and inefficient, the thesis has recommended that the African church needed primarily to transform its own leadership to be able to effectively develop transformational political leadership. The analysis of African institutions already involved in the development of an African leadership for socio-political transformation has shown that Christianising African leadership and socio-political institutions alone was not enough. So, the thesis has proposed a comprehensive socio-political discipleship for the transformation of both individuals and their communities. In a nutshell, the discipleship includes a socio-political intercession1, a four-dimensional discipleship, a socio-political psychotherapy and a church involvement project for socio-political transformation. / Christian Spirituality, Church History & Missiology / D. Th. (Missiology, with specialisation in Urban Ministry)

This thesis reflects on how to develop an African leadership that can contribute to the effective transformation of the African continent. After analysing the concept of leadership and categorising it for better understanding, the mission of the church as a developer of leaders par excellence has been examined and its potentials and limits assessed. Then, the thesis studied the specific extent of poor African leadership and its dire socio-political consequences in a sub-Saharan African country; so, the context of DR Congo was analysed. After that the contribution of the notion of African Renaissance to the whole debate of leadership development in Africa was assessed and the social, economic and political climate of the continent analysed. The poor and deficient African leadership has been identified as the main cause of rampant conflicts and wars, a slow economic development and lack of transformation in the continent. Given that church leadership seemed so poor and inefficient, the thesis has recommended that the African church needed primarily to transform its own leadership to be able to effectively develop transformational political leadership. The analysis of African institutions already involved in the development of an African leadership for socio-political transformation has shown that Christianising African leadership and socio-political institutions alone was not enough. So, the thesis has proposed a comprehensive socio-political discipleship for the transformation of both individuals and their communities. In a nutshell, the discipleship includes a socio-political intercession1, a four-dimensional discipleship, a socio-political psychotherapy and a church involvement project for socio-political transformation. / Christian Spirituality, Church History and Missiology / D. Th. (Missiology, with specialisation in Urban Ministry)