Purpose: A time of flight approach to the analysis of 4D CT angiography is examined to calculate blood flow in arteries. Materials and Methods: Software was written to track contrast bolus TOF along a central vessel axis. Time density curves were analyzed to determine bolus time to peak at successive vessel cross-sections which were plotted against vessel path length. A line of best fit was plotted through the resulting data and 1/slope provided a measurement of velocity. Results: Validation was successful in simulation and in flow phantoms, though quality of results depended strongly on quality of curve fit. In phantoms and in vivo, accuracy and reproducibility of measurements improved with longer path lengths and, in vivo, depended on the avoidance of venous contamination. Conclusions: Quantitative functional intravascular information such as blood velocity and flow rate may be calculated from 4D CT angiography.

Purpose: A time of flight approach to the analysis of 4D CT angiography is examined to calculate blood flow in arteries. Materials and Methods: Software was written to track contrast bolus TOF along a central vessel axis. Time density curves were analyzed to determine bolus time to peak at successive vessel cross-sections which were plotted against vessel path length. A line of best fit was plotted through the resulting data and 1/slope provided a measurement of velocity. Results: Validation was successful in simulation and in flow phantoms, though quality of results depended strongly on quality of curve fit. In phantoms and in vivo, accuracy and reproducibility of measurements improved with longer path lengths and, in vivo, depended on the avoidance of venous contamination. Conclusions: Quantitative functional intravascular information such as blood velocity and flow rate may be calculated from 4D CT angiography.

Microcirculation plays an essential and functional role in the human body and reflects people’s physical status with microscopic detail. For peripheral microcirculation, nail-fold microscopy is a convenient and non-invasive tool since the capillaries in the nail-fold are well arranged and parallel to the skin, which is advantageous for microscopic visualization. Further, nail-fold capillaroscopy information is widely useful. In diagnosis, various diseases such as systemic lupus erythematosus and cardiac diseases can be detected and predicted at an early stage with capillaroscopic patterns and capillary blood velocity. For medical experiments, capillaroscopic information can be used to monitor drug effects and other medical treatments. Though nail-fold capillaroscopy is of significant convenience, it is not widely used. Currently, there is no commercial product with those functions due to the limitations of the equipment, such as microscope resolution and lens magnification. Besides, there is no concrete standard for measurement procedures or objective rules for quantitive data analysis. This thesis proposes a reliable system estimating nail-fold capillary blood flow velocity. It is tested and applied to the microscope from Optilia. In this work, various image and video processing methods are discussed in detail and tested in practice. Taking computational load and equipment limitations into consideration, the system applies frame enhancement and video stabilization. It uses dual-window and correlation methods to estimate the velocity of red blood cells in nail-fold capillaries. In order to test the reliability of the system, the obtained results are compared with the outcome of direct observation. It turns out that the chosen methods employed in the system provide rational results within 5 pixel bias.

Single Ventricle congenital heart defects with cyanotic mixing between systemic and pulmonary circulations afflict 2 per 1000 live births. The total cavo-pulmonary connection (TCPC), where the superior and inferior vena cavae are sutured to the left and right pulmonary arteries, is the current procedure of choice. It is believed that reducing the fluid mechanical power losses in the TCPC will relieve strain on the single functional ventricle. It is hypothesized that a proposed idealized TCPC design, decreases power losses to a level below that of any other TCPC designs, while providing other advantages and increased flexibility. Physical models with slightly different geometries of the proposed design were created, and in vitro experiments carried out with particle image velocimetry (PIV), phase contrast magnetic resonance imaging (PC-MRI), and control volume flow analysis at physiological flow rates. Computational fluid dynamics (CFD) was used for numerical studies of the same geometries as in the physical models. Power losses were calculated using the control volume method and the viscous power dissipation function. The latter method incorporated registration of high-resolution PC-MRI velocity vectors to tetrahedral meshes followed by inverse interpolation of the vectors onto the meshes. Detailed flow structures were analyzed. Results show that the new design is more energy efficient than any other idealized models. Furthermore, a tool was developed to extract flow and vessel information from PC-MRI datasets obtained from patients with Fontan connections. The tool utilized a display algorithm, which was developed for optimal noise detection in PC-MRI images. This enabled accurate segmentation. Comparing PC-MRI images before and after this accurate segmentation showed that the standard deviations of the pixels at the perimeter of the segmented vessel were statistically significantly smaller after the segmentation in 94.1% of the datasets investigated. The developed tool was able to extract flow, flow in the quadrants of vessels, area of the segmented vessel, velocities and pulsatility indices. The velocity vectors were exported for use as CFD boundary conditions in models reconstructed from patient anatomies. A database was created with patient PC-MRI data from approximately 140 patients, which is probably the largest database in the world.

No campo da medicina diagnóstica através de imagens, o baixo custo e a característica não-invasiva da ultrassonografia modo-B favoreceram as pesquisas que analisam a relação entre a espessura íntima-média (EIM) da artéria carótida e o desenvolvimento de doenças cardiovasculares. Outra técnica de ultrassonografia, baseada no efeito Doppler, também tem sido extensivamente empregada em ambientes clínicos para a medição da velocidade e do fluxo de sangue das artérias periféricas, oferecendo uma abordagem distinta para estudar as doenças cardiovasculares. Neste trabalho, métodos computacionais foram implementados e analisados para extrair informações quantitativas de artérias a partir de imagens 2D. Os ensaios com imagens em modo-B contemplaram a combinação de técnicas de filtragem e algoritmos de contornos ativos para a detecção das interfaces das paredes arteriais e medições da EIM e do diâmetro da luz (DL). Um modelo matemático e 7 imagens reais da artéria carótida comum foram utilizados neste estudo que, dentre as diversas combinações de filtros e algoritmos, apresentou resultados quantitativos similares no cálculo do DL. Para a EIM, porém, a reduzida dimensão da camada íntima-média proporcionou variações indesejadas dos cálculos. Para medir a velocidade do sangue utilizando o modo Doppler, um método semiautomático foi incorporado a um aplicativo computacional para a detecção da envoltória do espectro do gráfico de velocidades. Uma análise comparativa entre sistemas de ultrassonografia comerciais operados por especialistas e este aplicativo incluiu a velocidade de pico sistólico e a integral de velocidade e tempo (VTI) das artérias carótida comum e braquial e de exames ecocardiográficos. A análise de Bland-Altman e o coeficiente de correlação validaram esta metodologia que, complementada pela interface gráfica amigável do aplicativo, pode auxiliar os clínicos em seus estudos de larga escala, baseados nas imagens Doppler ultrassonográficas, com as seguintes vantagens: redução do tempo operacional e de resultados subjetivos e aumento do grau de reprodutibilidade dos resultados. / In the field of image-based diagnostic medicine, low cost and noninvasive B-mode ultrasound technique have supported the researches which investigates the relation between the carotid intima-media thickness (IMT) and the development of cardiovascular diseases. Other ultrasound technique, that offers a different approach to study these diseases, is based on Doppler effect and has also been extensively used in clinical sites to measure blood velocity and flow in peripheral arteries. In this work, computational methods were implemented and analyzed to extract quantitative data from 2D images of arteries. Tests with B-mode images covered the combination of filtering techniques and active contour algorithms, in order to detect the arterial wall interfaces and to measure IMT and lumen diameter (LD). One mathematical model and seven real images of the common carotid artery were used in this study which, among several filters and algorithms combinations, showed similar quantitative results for DL measurements. However, for IMT, the small thickness of intima-media layer led to undesirable variation results. To measure blood velocity by using Doppler mode, a semi-automatic methodology was implemented in a computational tool to detect the spectrum envelope of the velocity graphic. A comparative analysis between commercial ultrasound systems operated by specialists and this tool included systolic peak velocities and velocity-time integral (VTI) of the common carotid and brachial arteries and of echocardiographic exams. Bland-Altmans analysis and the correlation coefficient validated this methodology which, besides the user friendly graphical interface of the tool, may help the clinicians for their large-scale studies based on Doppler ultrasound images, with the following advantages: to save operational time, to lower subjective results, and to support measurement reproducibility.

No campo da medicina diagnóstica através de imagens, o baixo custo e a característica não-invasiva da ultrassonografia modo-B favoreceram as pesquisas que analisam a relação entre a espessura íntima-média (EIM) da artéria carótida e o desenvolvimento de doenças cardiovasculares. Outra técnica de ultrassonografia, baseada no efeito Doppler, também tem sido extensivamente empregada em ambientes clínicos para a medição da velocidade e do fluxo de sangue das artérias periféricas, oferecendo uma abordagem distinta para estudar as doenças cardiovasculares. Neste trabalho, métodos computacionais foram implementados e analisados para extrair informações quantitativas de artérias a partir de imagens 2D. Os ensaios com imagens em modo-B contemplaram a combinação de técnicas de filtragem e algoritmos de contornos ativos para a detecção das interfaces das paredes arteriais e medições da EIM e do diâmetro da luz (DL). Um modelo matemático e 7 imagens reais da artéria carótida comum foram utilizados neste estudo que, dentre as diversas combinações de filtros e algoritmos, apresentou resultados quantitativos similares no cálculo do DL. Para a EIM, porém, a reduzida dimensão da camada íntima-média proporcionou variações indesejadas dos cálculos. Para medir a velocidade do sangue utilizando o modo Doppler, um método semiautomático foi incorporado a um aplicativo computacional para a detecção da envoltória do espectro do gráfico de velocidades. Uma análise comparativa entre sistemas de ultrassonografia comerciais operados por especialistas e este aplicativo incluiu a velocidade de pico sistólico e a integral de velocidade e tempo (VTI) das artérias carótida comum e braquial e de exames ecocardiográficos. A análise de Bland-Altman e o coeficiente de correlação validaram esta metodologia que, complementada pela interface gráfica amigável do aplicativo, pode auxiliar os clínicos em seus estudos de larga escala, baseados nas imagens Doppler ultrassonográficas, com as seguintes vantagens: redução do tempo operacional e de resultados subjetivos e aumento do grau de reprodutibilidade dos resultados. / In the field of image-based diagnostic medicine, low cost and noninvasive B-mode ultrasound technique have supported the researches which investigates the relation between the carotid intima-media thickness (IMT) and the development of cardiovascular diseases. Other ultrasound technique, that offers a different approach to study these diseases, is based on Doppler effect and has also been extensively used in clinical sites to measure blood velocity and flow in peripheral arteries. In this work, computational methods were implemented and analyzed to extract quantitative data from 2D images of arteries. Tests with B-mode images covered the combination of filtering techniques and active contour algorithms, in order to detect the arterial wall interfaces and to measure IMT and lumen diameter (LD). One mathematical model and seven real images of the common carotid artery were used in this study which, among several filters and algorithms combinations, showed similar quantitative results for DL measurements. However, for IMT, the small thickness of intima-media layer led to undesirable variation results. To measure blood velocity by using Doppler mode, a semi-automatic methodology was implemented in a computational tool to detect the spectrum envelope of the velocity graphic. A comparative analysis between commercial ultrasound systems operated by specialists and this tool included systolic peak velocities and velocity-time integral (VTI) of the common carotid and brachial arteries and of echocardiographic exams. Bland-Altmans analysis and the correlation coefficient validated this methodology which, besides the user friendly graphical interface of the tool, may help the clinicians for their large-scale studies based on Doppler ultrasound images, with the following advantages: to save operational time, to lower subjective results, and to support measurement reproducibility.

Spectroscopic techniques allow for studies of materials and organisms on the atomic and molecular level. Examples of such techniques are nuclear magnetic resonance (NMR) spectroscopy—one of the principal techniques to obtain physical, chemical, electronic and structural information about molecules—and magnetic resonance imaging (MRI)—an important medical imaging technique for, e.g., visualization of the internal structure of the human body. The less well-known spectroscopic technique of nuclear quadrupole resonance (NQR) is related to NMR and MRI but with the difference that no external magnetic field is needed. NQR has found applications in, e.g., detection of explosives and narcotics. The first part of this thesis is focused on detection and identification of solid and liquid explosives using both NQR and NMR data. Methods allowing for uncertainties in the assumed signal amplitudes are proposed, as well as methods for estimation of model parameters that allow for non-uniform sampling of the data. The second part treats two medical applications. Firstly, new, fast methods for parameter estimation in MRI data are presented. MRI can be used for, e.g., the diagnosis of anomalies in the skin or in the brain. The presented methods allow for a significant decrease in computational complexity without loss in performance. Secondly, the estimation of blood flow velo-city using medical ultrasound scanners is addressed. Information about anomalies in the blood flow dynamics is an important tool for the diagnosis of, for example, stenosis and atherosclerosis. The presented methods make no assumption on the sampling schemes, allowing for duplex mode transmissions where B-mode images are interleaved with the Doppler emissions.