Diagnostic imaging played a substantial role in the management and treatment of patients during the Severe Acute Respiratory Syndrome (SARS) outbreak when daily chest radiographs were performed as a measure of disease severity and respiratory status. This thesis was performed to address several issues relating to the radiological spectrum of SARS, its temporal pattern on chest radiograph and high resolution computed tomography (HRCT) during the course of disease, and relationships between severity of opacities quantified on chest radiographs and clinical parameters including treatment response. Radiological parameters that could discriminate SARS from non-SARS community-acquired pneumonia (CAP) were also studied. Unifocal unilateral ground glass opacities was the dominant radiographic abnormality at presentation that progressed rapidly to maximal disease within 9.35 ± 4.09 (median 9, range 3-21) days after onset of symptoms with bilateral consolidation in 62.5% of patients. Complete resolution and significant residual disease was noted in 50% and 20% of cases respectively at end of assessment period. There was a temporal pattern of lung abnormalities on HRCT with ground glass opacity and consolidation at presentation. Reticulation developed after the first week and was present in 50% of patients at ?four weeks. HRCT was useful in illustrating parenchymal abnormalities in patients with normal radiographs at presentation. Severity of lung abnormalities quantified on chest radiograph at different time points of disease correlated with clinical and laboratory parameters such as SaO2 and liver transaminases ALT and AST. Significant relationships were also found between radiographic parameters, and O2 supplementation and treatment response. There are discriminating differences in the radiographic pattern, rate of radiographic progression, and zone of involvement between SARS and non-SARS CAP. / published_or_final_version / Medicine / Master / Doctor of Medicine

In recent years, multi-resolution techniques have become increasingly popular in the image processing community. New techniques have been developed with applications ranging from edge detection, texture recognition, image registration, multi-resolution features for image classification and more. The central focus of this two-part thesis is the multi-resolution analysis of images. In the first part, we used multi-resolution approaches to help with the classification of a set of protein crystal images. In the second, similar approaches were used to help register a set of 3D image volumes that would otherwise be computationally prohibitive without leveraging multi-resolution techniques. Specifically, the first part of this work proposes a classification framework that is being developed in collaboration with NorthEast Structural Genomics Consoritum (NESG) to assist in the automated screening of protein crystal images. Several groups have previously proposed automated algorithms to expedite such analysis. However, none of the classifiers described in the literature are sufficiently accurate or fast enough to be practical in a structural genomics production pipeline. The second part of this work proposes a 3D image registration algorithm to register regions of emphysema as quantified by densitometry on lung CT with MR lung volumes. The ability to register quantitatively-determined regions of emphysema with perfusion MRI will allow for further exploration of the pathophysiology of Chronic Obstructive Pulmonary Disorder (COPD). The registration method involves the registration of CT volumes at different levels of inspiration (total lung capacity to functional residual capacity [FRC]) followed by another registration between FRC-CT and FRC-MR volume pairs.

Polarized helium-3 is used as a contrast agent for lungs magnetic resonance imaging that has recently reached the pre-clinical applications. One method to hyperpolarize 3He is the metastability exchange optical pumping (MEOP). Optical pumping is performed in standard conditions at low pressure (~ 1 mbar) and low magnetic field (~ 1 Gauss). In this work, the complete update of a low field polarizer dedicated to small animal lungs imaging is presented. The implementation of a new 10 W laser, new peristaltic compressor and others components resulted in a production of 3-4 scc/min for a polarization between 30 to 40%. Images of rat lungs made with better resolution and a new dynamic radial sequence are presented as a validation of the system. Since few years, MEOP has also been studied at higher pressures and higher magnetic fields in small sealed cells. It showed that, thanks to hyperfine decoupling effect induced by high magnetic field, it was also possible to efficiently polarize at higher pressure (67 mbar). Experiments done at 4.7 and 1.5 T are reported in this work. The first ones show a benefic (higher polarization values) and a negative effect (lower production rates) of the magnetic field. The seconds highlight the advantage of using an annular beam shape of the laser that matches the distribution of 23S state atoms at higher pressure. Nuclear polarization values of 66.4% at 32 mbar and 31% at 267 mbar were obtained in 20 mL sealed cells and a 10 times increase in the production rate compare to best standard conditions. These promising results were the first motivation for building a high-field polarizer working inside MRI scanner in hospital. The design and the construction of such a polarizer are described in detail in the last part of the dissertation. The polarizer produces hyperpolarize 3He at 30-40% with a 4 times higher flow than the low field polarizer (10-15 scc/min). The first good quality human lungs images made in Poland with healthy volunteers are the main result of this work.