Image noise in Positron Emission Tomography (PET) is the result of statistical fluctuation in projection data. The variance properties of images obtained with the UBC/TRIUMF PETT VI tomograph are studied by analytical methods, computer simulations, and phantom experiments. The PETT VI image reconstruction algorithm is described and analyzed for noise propagation properties. Procedures for estimating both point-wise (pixel) and region of interest (ROI) variances are developed: these include the effects of corrections for non-uniform sampling, detector efficiency variation, object self-attenuation and random coincidences. The analytical expression for image-plane variance is used in computer simulations to isolate the effects of the various data corrections: It is shown that the image precision is degraded due to non-uniform sampling of the projections. The RMS noise is found to be increased by 9% due to the wobble motion employed in PETT VI. Analytical predictions for both pixel and ROI variances are verified with phantom experiments. The average error between measured and predicted ROI variances due to noise in emission data for a set of seven regions placed on a 20 cm cylindrical phantom is 9.5%. Images showing variance distributions due to noise in emission data and due to noise in transmission data are produced from human subject brain scan data collected by the UBC/TRIUMF PET group. The maximum ratio of image variance due to noise in transmission data to that due to noise in emission data is calculated as 2.6 for a typical FDG study, and 0.082 for a typical fluorodopa study. Total RMS noise varies between 0.4% and 11.6% for a typical set of ROI's placed on mid-brain slices reconstructed from these data sets. Procedures are suggested for improving the statistical accuracy of quantitative PET measurements. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

No description available.

No description available.

No description available.

No description available.

No description available.

published_or_final_version / Physics / Master / Master of Philosophy

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Gang Bao; Committee Member: Kurt D. Pennell; Committee Member: Mark M. Goodman; Committee Member: Xiaoping P. Hu; Committee Member: Yadong Wang. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Bibliography: leaves 94-106. / v, 106, [33] leaves, [2] leaves of plates : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Assessment of myocardial metabolism with radiolabelled substrates and positron emission tomography provides a potentially sensitive technique to investigate physiological and pathological cardiac states "in vitro". Prior studies have indicated that overall metabolic activity cannot be estimated from rates of utilization of any one particular substrate. It was hypothesized that acetate labelled with carbon-11 would provide an index of oxidative metabolism, based on fundamental biochemical principles. The hypothesis is confirmed in studies using isolated perfused rabbit hearts and closed chest canine studies. / Thesis (M.D.)--University of Adelaide, Dept. of Medicine, 1995

Les lésions d’athérosclérose sont une des causes majeurs du développement de pathologies cardiovasculaires. Cette pathologie chronique à l’origine inflammatoire est caractérisée par des mécanismes moléculaires et cellulaires complexes. L’activité de minéralisation retrouvée au sein des lésions est un critère clé de l’avancée de la maladie. A l’aide d’un modèle murin d’athérosclérose accélérée et de travaux d’optimisation technique, nous avons exploré la faisabilité de l’exploitation de l’imagerie par tomographie à émission de positons au fluorure de sodium associée à l’imagerie à résonance magnétique de la pathologie dans un modèle murin d’athérosclérose accélérée. Dans ce travail nous avons mis en évidence une activité de minéralisation précoce et soutenue associée à un statut inflammatoire plus avancé chez les animaux insuffisants rénaux. Ajouté à cela, nous avons mis en place un nouveau modèle murin de rétrécissement aortique calcifié par irradiation localisée. / Atherosclerosis lesions are a leading cause of cardiovascular events. Atherosclerosis is a chronic inflammatory disease including complex molecular and cellular mechanisms. Mineralization process within the atherosclerosis lesions is a key feature of the disease development. Using a mouse model of accelerated atherosclerosis and imaging optimisation study, we showed the feasability of sodium fluoride positron emission tomography combined to magnetic resonance imaging to assess molecular activity in a mouse model of accelerated atherosclerosis. We showed that uremic animals had an early and sustained mineralization activity associated to an advanced inflammatory state. Furthermore, we developped a new mouse model of calcified aortic stenosis using targeted radiation exposure.