Lights is almost always detected by its interaction with matter. One of these interaction phenomena is the scattering of light by small particles. A model is developed that estimates the amount of energy that is scattered towards a detector from a beam given the locations of the source, detector and particle. This collection of particles is allowed to be very dense so that a photon scattered from the beam can be scattered several times before leaving the scattering medium. By considering the single-scatter component and multiple-scatter component separately, the model retains the characteristics of both types.

Laser speckle contrast imaging (LSCI) is a non-invasive method for assessment of microcirculatory blood flow. The technique is based on analysis of speckle patterns to build 2D maps of perfusion with high spatial and temporal resolution. A drawback of the method is that it is highly sensitive to motion artifacts since the perfusion estimates are based on quantification of the motion blurring in the images. The camera is today limited to a bulky stand for good measurements, but even as it is fixed, it does not ensure that the patient is completely still. In many clinical settings, it would be advantageous to have a more flexible camera and to be able to detect if an image is influenced by external motion. Multi-exposure laser speckle contrast imaging (MELSCI) is an extension to LSCI that utilizes the contrast from multiple exposure times. The gain in information has paved way for more accurate perfusion estimates. The technique has been limited due to its computational complexity, but recently a real time system has been developed. The goals of this thesis was twofold, firstly find a quantifiable measure of motion artifacts to be able to evaluate and compare LSCI and MELSCI. Secondly, propose an algorithm that detects movements in LSCI recordings. Motion artifacts in LSCI and MELSCI were investigated by developing a setup where repeatable movements could be made. Measurements of a hand influenced by motions of different speeds and directions were acquired and the relative difference between motion and static states were calculated and compared for the two systems. The relative difference of the MELSCI measurements were lower for all speeds above 0.57 mm/s, indicating more robustness to motion artifacts. A detection algorithm using image registration to calculate the instantaneous speed in each frame of the recording was developed. The method successfully detects movements perpendicular to the camera and shows that the intensity images of an LSCI recording can be used to give a direct indication of when movement has occurred.

A elaboração e caracterização de sistemas tão complexos quanto alimentos não são temas que se esgotem ao longo de um único trabalho. Assim, tomando como ponto de partida o desenvolvimento de formulações para sorvetes, são apresentados os princípios gerais da criação e estabilização de um dos gêneros alimentícios mais apreciados n.o mundo todo. O primeiro capítulo aborda interações que ocorrem entre componentes de uso comum na maioria dos alimentos processados e, de modo específico, o papel desempenhado por cada um deles em formulações para sorvetes. São apresentadas características das matérias-primas especiais empregadas no desenvolvimento das formulações propostas, bem como fundamentos de reologia. Tratam-se os princípios gerais do fenômeno speckle, ferramenta bastante útil em caracterizações estruturais, porém ainda pouco explorada na área alimentícia. O segundo capítulo apresenta as formulações para sorvetes que foram elaboradas para este trabalho e os resultados de caracterizações físico-químicas tomadas sobre alguns dos ingredientes utilizados, bem como sobre os produtos finais desenvolvidos. O terceiro capítulo exibe os resultados das avaliações reológicas feitas em ingredientes e misturas formuladas para este estudo. A partir do perfil demonstrado pelos reogramas, interações microscópicas puderam ser cogitadas. Mostram-se também, imagens tomadas por um sistema de videomicroscopia acoplado ao reômetro (módulo Rheoscope), onde puderam ser observadas deformações estruturais em tempo real ocorridas com as amostras durante as avaliações. O quarto capítulo propõe uma nova metodologia de investigação estrutural na qual a análíse dos resultados gerados a partir de um fenômeno de interferência possibilita mapear a evolução da microestrutura de sorvetes ao longo do tempo, quando submetidos a diferentes condições de temperatura. / Elaboration and characterization of systems with high leveI of complexity as foods cannot discussed in an only study. In this work, from development of special ice cream formulations are presenteei the general principIes of creation and stabílízation of one of the most appreciated foodstuffs. In first chapter the interactions that occur among components of current/y use in processed foods and, in a specific manner, the role of each one in ice cream formulations. Characteristics of the special raw materiais employed in development of the proposed formulatíons are presenteei, as well fundamental concepts of rheological behavior. Also, general principies of speckle phenomenon are presented, a very useful tool to structural investigations in several systems, but few explored in food science and technology. In second chapter are presented the ice cream formulations that were elaborated by this research and the results of analysis of both composition and chemical properties taken on some ingredients as well in developed products. In third chapter are exhibited the results from rheological assessments performed in ingredients and formulated ice cream mixes. From rheological curves, microscopic interactions could be cogitated. Images taken by a system of microscopy connected to rheometer shown structural deformatíons in real time occurred with the samples during the evaluations. In fourth chapter is showed a new methodology of structural investigation in which the analysis of results obtained from interference phenomenon allow to generate a map of temporal evolution of ice creams along the time, at different temperature conditions.

Introdução: A doença falciforme (DF) é a afecção hematológica hereditária de maior prevalência no mundo, sendo que a anemia falciforme (AF) é a forma mais grave com elevada morbidade e mortalidade. Alterações cardíacas são reconhecidamente associadas à AF, como aumento cavitário, hipertensão arterial pulmonar e disfunção diastólica do ventrículo esquerdo. No entanto, ainda não existe consenso quanto à função sistólica ventricular nesses pacientes. O objetivo deste estudo foi o de investigar a função ventricular de pacientes com anemia falciforme utilizando o strain e o twist ventricular obtidos pelo speckle tracking bidimensional, e reconhecer os indivíduos sob maior risco cardiovascular, em que a instituição precoce de tratamento específico poderá beneficiar essa população. Métodos: Foram recrutados 40 pacientes com anemia falciforme (23,5 ± 9,3 anos; 24 homens) e 40 controles saudáveis pareados por sexo e idade, submetidos à entrevista estruturada, ecocardiograma transtorácico, cintilografia pulmonar ventilação perfusão e coleta de amostras de sangue. Todos os indivíduos foram submetidos à avaliação ecocardiográfica convencional padrão e subsequente avaliação offline do strain sistólico biventricular e estudo rotacional do ventrículo esquerdo utilizando speckle-tracking ecocardiográfico. Resultados: Os pacientes com AF apresentaram volume do VE indexado, massa do VE indexado, pressão arterial pulmonar e E/E\' médio superiores aos controles. As medidas de FE do VE, excursão sistólica do plano da tricúspide (TAPSE), Strain Global do VE (longitudinal, circunferencial, radial) e Strain Global do VD (longitudinal) não evidenciaram diferenças entre os grupos. Twist VE se mostrou reduzido em comparação aos controles (7,4 ± 1,2? vs 10,7 ± 1,8? , P <0,0001 ) e Tempo de pico de rotação apical prolongado (366,7 ± 26,1ms vs 344,6 ± 11,7ms , P <0,0001 ). Algumas variáveis se mostraram fortemente relacionadas ao twist VE, como índice de gravidade clínico (Rho= - 0,97, Z value= - 6,05, P < 0,0001), relação E/E\' médio (r = 0,94, F valor= 156.9, p<0,0001), IVDFVE (índice do volume diastólico final do ventrículo esquerdo)(r = 0,81 e p<0,0001) e pressão sistólica arterial pulmonar (r = 0,72 e p<0,0001). Conclusões: Os resultados deste trabalho indicam que o twist ventricular esquerdo derivado do speckle tracking bidimensional encontra-se alterado em pacientes com anemia falciforme e função sistólica ventricular preservada, avaliada pela metodologia convencional, e existe forte correlação entre o twist ventricular esquerdo e o índice clínico de gravidade, relação E/E\', índice do volume diastólico final do ventrículo esquerdo e pressão sistólica arterial pulmonar. / Background: Sickle cell disease (SCD) is the most prevalent hematological condition in the world, with sickle cell anemia (SCA) being its most serious form, displaying a high level of morbidity and mortality. Cardiac changes are known to be associated with SCA, including an increase in cardiac chamber size, pulmonary hypertension and left ventricle diastolic dysfunction. However, there is still no consensus regarding the ventricular systolic function in these patients. The purpose of this study is to investigate the ventricular function of patients with sickle cell anemia utilizing the strain and ventricular twist, obtained by two-dimensional speckle tracking, as well as to identify individuals with higher cardiovascular risk, in which early application of specific treatment could benefit this group of people. Methods: 40 patients were recruited with sickle cell anemia (ages 23.5 ± 9.3 years; 24 males) and 40 healthy control individuals paired by gender and age, submitted to structured interviews, transthoracic echocardiogram, pulmonary scintigraphy and collection of blood samples. All individuals were submitted to a standard echocardiographic evaluation and subsequent off line evaluation of the biventricular systolic strain and rotational study of the left ventricle using echocardiographic speckle-tracking. Results: Patients with SCA presented LV volume indices, LV mass Indices, pulmonary arterial pressure and E/ E\' ratios statistically higher than the control individuals. Measurements of Ejection Fraction (EF) of the left ventricle, tricuspid annular plane systolic excursion (TAPSE), Overall LV Strain (Longitudinal, Circumferential, and Radial) and Overall RV Strain (Longitudinal) did not present differences between the groups. LV twist was significantly lower in relation to the control group (7,4 ± 1,2? vs 10,7 ± 1,8? , P <0,0001 ) and prolonged time to peak apical rotation (366.7 ± 26.1ms vs 344.6 ± 11.7ms , P <0.0001 ). In addition, some variables showed themselves to be strongly related to LV twist such as the clinical severity index ( Rho= - 0.97, Z value= - 6.05, P < 0.0001), E/E\' Ratio (r = 0.94, F value=156.9 e p<0.0001) ), left ventricle end diastolic volume index (LVEDV index) (r = 0,81, p<0,0001) and pulmonary systolic arterial pressure (r = 0.72 e p<0.0001). Conclusions: The results of this study indicate that the left ventricular twist derived from two-dimensional speckle tracking is altered in patients with sickle cell anemia and a preserved ventricular systolic function, evaluated using conventional methodology and that there is a strong correlation between left ventricular twist and the clinical severity index, E/E\' ratio, left ventricle end diastolic volume index and the pulmonary systolic arterial pressure.

A rejeição é uma das principais complicações após transplante cardíaco (TC). A biópsia endomiocárdica do ventrículo direito (BEVD) continua a ser o padrão-ouro para seu diagnóstico. Há uma necessidade de alternativas não invasivas que permitam um diagnóstico seguro e precoce de rejeição cardíaca, antes do início dos sintomas clínicos. A ecocardiografia com speckle tracking (EST) permite a análise da dinâmica de contração ventricular, possibilitando a detecção precoce de disfunção miocárdica. Os objetivos deste estudo foram comparar os parâmetros da dinâmica ventricular obtidos com a EST em pacientes transplantados e indivíduos não transplantados cardíacos e avaliar o valor da EST e da dosagem sérica de troponina I e peptídeo cerebral natriurético (BNP), como ferramentas não invasivas para a detecção precoce de rejeição celular aguda significativa (RCA) após o TC. Entre janeiro de 2014 e novembro de 2017, foram estudados, prospectivamente, 49 pacientes transplantados cardíacos com função sistólica normal, tanto do ventrículo esquerdo (VE) como do direito (VD) submetidos à BEVD para vigilância ou por suspeita clínica de rejeição. A RCA foi definida como >= 2R pelos critérios da Sociedade Internacional para Transplante de Coração e Pulmão. Quarenta e nove indivíduos saudáveis pareados por idade e sexo constituíram o grupo controle. Todos os pacientes foram submetidos à ecocardiografia convencional e à EST. Os pacientes transplantados foram submetidos, horas antes da BEVD, à dosagem de troponina I e BNP séricos. Parâmetros ecocardiográficos clássicos, strain e strain rate longitudinal global, radial e circunferencial do VE, além de strain longitudinal da parede livre do VD (SLPL-VD) foram analisados. Os 49 pacientes transplantados cardíacos (média etária 45,2 ± 11,5 anos, 28 homens) foram submetidos a 66 biópsias entre 6-12 meses após o TC. A RCA foi detectada em 17 (26%) e ausência de RCA em 49 (74%) biópsias. Strain e strain rate longitudinal, circunferencial e radial globais do VE e SL-PLVD foram significantemente menores, em valores absolutos, nos grupos dos transplantados cardíacos do que no grupo controle. O SL-PLVD apresentou valor absoluto menor no grupo com RCA do que no sem RCA (-18,28 ± 4,8% versus -22,11 ± 2,9%; p < 0,001). Um valor de SL-PLVD < 17,57% (valor absoluto) teve sensibilidade de 71%, especificidade de 90%, valor preditivo positivo de 75%, acurácia de 84% e valor preditivo negativo de 88% para detecção de RCA. A dosagem da troponina I foi significantemente mais alta em pacientes com RCA (p < 0,01). A mediana para este grupo foi 0,19 [intervalo interquartil 0,09-1,31 ng/mL], versus 0,05 [intervalo interquartil, 0,01-0,18ng/mL] para o grupo sem RCA. Na análise multivariada, o SL-PLVD foi o único preditor independente de RCA com razão de chance de 1,70 (intervalo de confiança de 95% = 1,17- 2,48); p = 0,006. Concluiu-se que o SL-PLVD derivado da EST foi marcador sensível e específico de RCA. Estes dados sugerem que esta técnica é adequada para detectar alterações na deformação ventricular direita durante um episódio de RCA / Rejection is a major complication after heart transplantation (HT). Right ventricular endomyocardial biopsy (EMB) remains the gold standard for diagnosis of rejection. There is a need for non-invasive alternatives that allow for a safe and early diagnosis of cardiac rejection prior to the onset of clinical symptoms. Speckle tracking echocardiography (STE) enables the analysis of left and right ventricular contraction dynamics, thus allowing for the early detection of myocardial dysfunction. The aims of the present study were to compare ventricular dynamics parameters obtained by STE in heart transplanted patients and control individuals. We also aimed to assess the value of STE, troponin I, and brain natriuretic peptide (BNP) serum levels as noninvasive tools for the early detection of significant acute cellular rejection (ACR) after HT. From January 2014 to November 2017, we prospectively studied 49 transplanted patients with normal left and right ventricular systolic function, who had undergone EMB for either surveillance or clinical suspicion of rejection. ACR was defined as >= 2R graded according to the revised International Society for Heart and Lung Transplantation by EMB. A total of 49 age- and sex-matched healthy individuals formed the control group. All studied patients underwent conventional echocardiography with the analysis of STE. The transplanted group also had their serum troponin I and BNP levels measured hours before undergoing EMB. Classic echocardiographic parameters left ventricular global longitudinal strain (LV-GLS), radial and circumferential strain and strain rate, and right ventricular free wall longitudinal strain (RV-FWLS) were analyzed. The 49 heart transplanted patients (mean age 45.2 ± 11.5 years, 28 men) underwent 66 biopsies, 6-12 months after HT. ACR was detected in 17 (26%) and no ACR in 49 (74%) of biopsies. LV-GLS, circumferential and radial strain and strain rate and RVFWLS values were significantly lower in heart transplant group than in control group. RV-FWLS was lower (absolute value) in the group with ACR than in the group without ACR (-18.28 ± 4.8% versus -22.11 ± 2.9%; p < 0.001). A RVFWLS < 17.57% had 71% sensitivity, 90% specificity, 75% positive predictive value, 84% accuracy, and 88% negative predictive value for detection of ACR. The troponin I level was significantly higher in patients with ACR (p < 0.01). The median value for this group was 0.19 [interquartile interval 0.09-1.31 ng/mL] vs. 0.05 [interquartile interval 0.01-0.18 ng/mL] for the group without ACR. In the multivariate analysis, RV-FWLS was the only independent predictor of ACR, with odds ratio of 1.70 (CI 95% = 1.17-2.48); p=0.006. We concluded that STE-derived RV-FWLS was a sensitive and specific marker of ACR. Our data suggest that this is a suitable technique for noninvasive detection of changes in the right ventricular deformation during an episode of ACR

Bakgrund: Ekokardiografi har en betydande roll i diagnostisering av vänster kammare. Genom undersökning av segmentell och global longitudinell strain samt strain rate kan regional och global kinetik bedömas. Vid kontraktion och relaxation deformeras myokardiet varvid segmentell strain mäter deformationen av respektive segment uttryckt i procent medan strain rate mäter hastigheten av deformationen. Genom summering av medelvärdet från alla segment erhålls global longitudinell strain. Syfte: Syftet med studien var att jämföra ultraljudbaserade segmentell och global strain samt strain rate i vänster kammare. Jämförelse har gjorts mellan mätningar utförd av erfaren biomedicinsk analytiker samt mindre erfarna biomedicinska analytikerstudenter. Metod: Kvantitativ studie där 10 testpersoner undersökts ekokardiografiskt. Bildtagningen och mätresultaten insamlades med Siemens Acuson SC2000. Sammanställning av insamlade mätvärden gjordes på Microsoft Excel och Microsoft Word i diagram och tabeller. För jämförelse av strain segmentellt och globalt samt strain rate har analysmetoden Related-Samples Wilcoxon Signed Rank Test använts. Resultat: Resultatet visade enbart en statistisk signifikant skillnad (p &lt;0,05) vid segmentell strain i basala segmenten i apikala projektioner mellan erfaren biomedicinsk analytiker och student 1. Konklusion: Datamaterialet är inte tillräckligt för att kunna generalisera resultatet till en större population. Det behövs fortsatta studier inom området för att dra en mer säkerställd slutsats. / Background: Echocardiography has a major role for assessment of the left ventricle. By using segmental and global longitudinal strain and strain rate both regional and global kinetics can be assessed. Segmental strain measures deformation of the myocardium as strain rate measures the velocity of the deformation. By summing the average from all segments, global longitudinal strain is obtained. Purpose:  To compare heart ultrasound-based segmental and global strain and strain rate in the left ventricle. Comparisons have been made between experienced biomedical laboratory scientist and less experienced biomedical laboratory scientist’s students. Method: Quantitative study were 10 test subjects have been examined echocardiographically. Imaging and measurements were collected with Siemens Acuson SC2000. Compilation of collected measurements were made on Microsoft Excel and Microsoft Word in charts and tables. For comparison of segmental and global strain and strain rate the analysis method Related-Samples Wilcoxon Signed Rank Test were used. Result: The result shows only one statistically significant difference (p &lt;0.05) of segmental strain in the basal segments of apical projections between experienced biomedical laboratory scientist and student 1.  Conclusion: The data material is not enough to generalize the result to a larger population. Further studies are needed to draw a more secure conclusion.

A elaboração e caracterização de sistemas tão complexos quanto alimentos não são temas que se esgotem ao longo de um único trabalho. Assim, tomando como ponto de partida o desenvolvimento de formulações para sorvetes, são apresentados os princípios gerais da criação e estabilização de um dos gêneros alimentícios mais apreciados n.o mundo todo. O primeiro capítulo aborda interações que ocorrem entre componentes de uso comum na maioria dos alimentos processados e, de modo específico, o papel desempenhado por cada um deles em formulações para sorvetes. São apresentadas características das matérias-primas especiais empregadas no desenvolvimento das formulações propostas, bem como fundamentos de reologia. Tratam-se os princípios gerais do fenômeno speckle, ferramenta bastante útil em caracterizações estruturais, porém ainda pouco explorada na área alimentícia. O segundo capítulo apresenta as formulações para sorvetes que foram elaboradas para este trabalho e os resultados de caracterizações físico-químicas tomadas sobre alguns dos ingredientes utilizados, bem como sobre os produtos finais desenvolvidos. O terceiro capítulo exibe os resultados das avaliações reológicas feitas em ingredientes e misturas formuladas para este estudo. A partir do perfil demonstrado pelos reogramas, interações microscópicas puderam ser cogitadas. Mostram-se também, imagens tomadas por um sistema de videomicroscopia acoplado ao reômetro (módulo Rheoscope), onde puderam ser observadas deformações estruturais em tempo real ocorridas com as amostras durante as avaliações. O quarto capítulo propõe uma nova metodologia de investigação estrutural na qual a análíse dos resultados gerados a partir de um fenômeno de interferência possibilita mapear a evolução da microestrutura de sorvetes ao longo do tempo, quando submetidos a diferentes condições de temperatura. / Elaboration and characterization of systems with high leveI of complexity as foods cannot discussed in an only study. In this work, from development of special ice cream formulations are presenteei the general principIes of creation and stabílízation of one of the most appreciated foodstuffs. In first chapter the interactions that occur among components of current/y use in processed foods and, in a specific manner, the role of each one in ice cream formulations. Characteristics of the special raw materiais employed in development of the proposed formulatíons are presenteei, as well fundamental concepts of rheological behavior. Also, general principies of speckle phenomenon are presented, a very useful tool to structural investigations in several systems, but few explored in food science and technology. In second chapter are presented the ice cream formulations that were elaborated by this research and the results of analysis of both composition and chemical properties taken on some ingredients as well in developed products. In third chapter are exhibited the results from rheological assessments performed in ingredients and formulated ice cream mixes. From rheological curves, microscopic interactions could be cogitated. Images taken by a system of microscopy connected to rheometer shown structural deformatíons in real time occurred with the samples during the evaluations. In fourth chapter is showed a new methodology of structural investigation in which the analysis of results obtained from interference phenomenon allow to generate a map of temporal evolution of ice creams along the time, at different temperature conditions.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A cobertura regular de quase todo o planeta por sistemas de radar de abertura sintÃtica (synthetic aperture radar - SAR) orbitais e o uso de sistemas aerotransportados tÃm propiciado novos meios para obter informaÃÃes atravÃs do sensoriamento remoto de vÃrias regiÃes de nosso planeta, muitas delas inacessÃveis. Este trabalho trata do processamento de imagens digitais geradas por radar de abertura sintÃtica, especificamente da segmentaÃÃo, que consiste do isolamento ou particionamento dos objetos relevantes presentes em uma cena. A segmentaÃÃo de imagens digitais visa melhorar a interpretaÃÃo das mesmas em procedimentos subseqÃentes. As imagens SAR sÃo corrompidas por ruÃdo coerente, conhecido por speckle, que mascara pequenos detalhes e zonas de transiÃÃo entre os objetos. Tal ruÃdo à inerente ao processo de formaÃÃo dessas imagens e dificulta tarefas como a segmentaÃÃo automÃtica dos objetos existentes e a identificaÃÃo de seus contornos. Uma possibilidade para efetivar a segmentaÃÃo de imagens SAR consiste na filtragem preliminar do ruÃdo speckle, como etapa de tratamento dos dados. A outra possibilidade, aplicada neste trabalho, consiste em segmentar diretamente a imagem ruidosa, usando seus pixels originais como fonte de informaÃÃo. Para isso, à desenvolvida uma metodologia de segmentaÃÃo baseada em crescimento e fusÃo estatÃstica de regiÃes, que requer alguns parÃmetros para controlar o processo. As vantagens da utilizaÃÃo dos dados originais para realizar a segmentaÃÃo de imagens de radar sÃo a eliminaÃÃo de etapas de prÃ-processamento e o favorecimento da detecÃÃo das estruturas presentes nas mesmas. à realizada uma avaliaÃÃo qualitativa e quantitativa das imagens segmentadas, sob diferentes situaÃÃes, aplicando a tÃcnica proposta em imagens de teste contaminadas artificialmente com ruÃdo multiplicativo. Este segmentador à aplicado tambÃm no processamento de imagens SAR reais e os resultados sÃo promissores. / The regular coverage of the planet surface by spaceborne synthetic aperture radar (SAR)and also airborne systems have provided alternative means to gather remote sensing information of various regions of the planet, even of inaccessible areas. This work deals with the digital processing of synthetic aperture radar imagery, where segmentation is the main subject. It consists of isolating or partitioning relevant objects in a scene, aiming at improving image interpretation and understanding in subsequent tasks. SAR images are contaminated by coherent noise, known as speckle, which masks small details and transition zones among the objects. Such a noise is inherent in radar image generation process, making difficult tasks like automatic segmentation of the objects, as well as their contour identification. To segment radar images, one possible way is to apply speckle filtering before segmentation. Another one, applied in this work, is to perform noisy image segmentation using the original SAR pixels as input data, without any preprocessing,such as filtering. To provide segmentation, an algorithm based on region growing and statistical region merging has been developed, which requires some parameters to control the process. This task presents some advantages, as long as it eliminates preprocessing steps and favors the detection of the image structures, since original pixel information is exploited. A qualitative and quantitative performance evaluation of the segmented images is also executed, under different situations, by applying the proposed technique to simulated images corrupted with multiplicative noise. This segmentation method is also applied to real SAR images and the produced results are promising.

Cette thèse porte sur le développement et l’évaluation de techniques d’imagerie en échocardiographie. L’objectif est de proposer des méthodes d’imagerie ultrasonore ultrarapide pour estimer le mouvement cardiaque 2-D et 3-D.Première modalité d’imagerie du cœur, l’échocardiographie conventionnelle permet la mesure des déformations myocardiques à 80 images/s. Cette cadence d’imagerie est insuffisante pour quantifier les mouvements de la totalité du myocarde lors de tests d’efforts, utiles en évaluation clinique, au cours desquels le rythme cardiaque est augmenté. De plus, la résolution temporelle actuelle en échocardiographie 3-D limite ses applications, pourtant essentielles pour une caractérisation complète du cœur.Les contributions présentées ici sont 1) le développement et l’évaluation, pour l’application cardiaque, d’une méthode originale d’estimation de mouvement 2-D par imagerie ultrarapide et marquage des images, 2) l’étude de faisabilité de la mesure globale des déformations cardiaques avec une méthode innovante d’imagerie ultrasonore ultrarapide 2-D et 3) la généralisation de cette approche en 3-D pour l’imagerie des volumes cardiaques à haute résolution temporelle. Cette technique est basée sur l’émission d’ondes divergentes, et l’intégration d’une compensation de mouvement dans le processus de formation des volumes cardiaques.La méthode proposée permet l’estimation des mouvements cardiaques 2-D et l’échocardiographie ultrarapide 3-D. L’évaluation de notre approche pour la quantification des déformations myocardiques locales 2-D et 3-D pourrait permettre de proposer des pistes innovantes pour poursuivre nos études et améliorer le diagnostic en routine clinique / This PhD work focuses on the development and the evaluation of imaging techniques in echocardiography. Our objective is to propose ultrafast ultrasound imaging methods for 2-D and 3-D cardiac motion estimations.Echocardiography is one of the most widespread modality for cardiovascular imaging. Conventional clinical scanners allow measurement of myocardial velocities and deformations at 80 images / s. In some situations, it can be recommended to increase the heart rate during a stress echocardiographic examination. Motion estimation of the whole myocardium at such heart rates is challenging with the conventional imaging systems. In addition, the low temporal resolution of the current conventional 3-D echocardiography limits quantitative applications, which would be needed for a complete characterization of the heart.The three contributions presented here are 1) the development and evaluation of an original method for 2-D cardiac motion estimation, with ultrafast imaging and image tagging, 2) the feasibility study of the global myocardial deformation measurement using an innovative 2-D ultrafast ultrasound imaging method and 3) the generalization of this approach in three dimensions for high frame-rate 3-D echocardiography. This method is based on the transmission of divergent waves and the integration of motion compensation, during the imaging process, to produce high-quality volumetric images of the heart.The proposed method allows 2-D cardiac motion estimation and 3-D echocardiography at high frame-rate. The evaluation of our approach for local 2-D and 3-D myocardial deformation measurements should permit to conduct further study in order to improve medical diagnosis

Les travaux présentés dans cette thèse portent sur l’imagerie computationnelle active et passive en micro-ondes. L’utilisation d’une cavité chaotique comme composants compressif est étudiée tant théoriquement (modèle mathématique, résolution algorithmique du problème inverse) et expérimentalement. L’idée sous-jacente est de remplacer un réseau d’antennes par une unique cavité réverbérante dont un réseau d’ouvertures sur la face avant permet de coder l’information spatiale d’une scène dans la réponse temporelle de la cavité. La réverbération des ondes électromagnétique à l’intérieur de la cavité fournit les degrés de liberté nécessaires à la reconstruction d’une image de la scène. Ainsi il est possible de réaliser en temps réel une image haute-résolution d’une scène à partir d’une unique réponse impulsionnelle. Les applications concernent la sécurité ou l’imagerie à travers les murs. Dans ce travail, la conception et la caractérisation d’une cavité chaotique ouverte sont effectuées. L’utilisation de ce dispositif pour réaliser en actif des images de cibles de diverses formes est démontrée. Le nombre de degrés de liberté est ensuite amélioré en modifiant les conditions aux limites grâce à l’ajout lampes fluorescentes. L’interaction des ondes avec ces éléments plasma permet de créer de nouvelles configurations de la cavité, améliorant ainsi la résolution des images. L’imagerie compressive est ensuite appliquée à la détection et localisation passive du rayonnement thermique naturel de sources de bruit, à partir de la corrélation des signaux reçus sur deux voies. Enfin, une méthode novatrice d’imagerie interférométrique de cibles est présentée. Elle est basée sur la reconstruction de la réponse impulsionnelle entre deux antennes à partir du bruit thermique micro-ondes émis par un réseau de néons. Ces travaux constituent une avancée vers les systèmes d’imagerie futurs. / The broad topic of the presented Ph.D focuses on active and passive microwave computational imaging. The use of a chaotic cavity as a compressive component is studied both theoretically (mathematical model, algorithmic resolution of the inverse problem) and experimentally. The underlying idea is to replace an array of antennas with a single reverberant cavity with an array of openings on the front panel that encodes the spatial information of a scene in the temporal response of the cavity. The reverberation of electromagnetic waves inside the cavity provides the degrees of freedom necessary to reconstruct an image of the scene. Thus it is possible to create a high-resolution image of a scene in real time from a single impulse response. Applications include security or imaging through walls. In this work, the design and characterization of an open chaotic cavity is performed. Using this device, active computational imaging is demonstrated to produce images of targets of various shapes. The number of degrees of freedom is further improved by changing the boundary conditions with the addition of commercial fluorescent lamps. The interaction of the waves with these plasma elements allows new cavity configurations to be created, thus improving image resolution. Compressive imaging is next applied to the passive detection and localization of natural thermal radiation from noise sources, based on the correlation of signals received over two channels. Finally, an innovative method of interferometric target imaging is presented. It is based on the reconstruction of the impulse response between two antennas from the microwave thermal noise emitted by a network of neon lamps. This work constitutes a step towards for future imaging systems.