Medicine and Health Sciences Commons^™

Development Of A Translational Animal Model Of Sepsis, Nathaniel E. Hayward

Electronic Thesis and Dissertation Repository

Sepsis is an excessive inflammatory response to infection that leads to multiple organ failure. The high mortality rates in the intensive care unit have remained stagnant, which can be attributed to the disconnect between the bench and the bedside. There is a global need for an animal model of sepsis that is more relevant to the clinical scenario. We developed an in vivo rat model of sepsis, with a high level of instrumentation, to monitor macrovascular and microvascular changes over the course of a feces-induced peritonitis (FIP) .

In addition, early fluid resuscitation of septic patients is associated with better …

Effects Of A Power-Line Frequency Magnetic Field On Human Cognitive Processing, Michael Corbacio

Electronic Thesis and Dissertation Repository

Extremely low frequency (ELF, < 300 Hz) magnetic fields (MFs) have been reported to modulate human cognitive performance. However, little research has investigated MF exposures comparable to the highest levels experienced in some occupations. This research evaluated the impact of a 60 Hz, 3 mT MF on human cognitive performance. Ninety-nine participants completed the double-blind protocol performing a selection of psychometric tests under two consecutive MF exposure conditions (exposure vs. no exposure). A significant interaction effect on a working memory test (digit span forward - F=5.21, p

The Impact Of Lateral Electron Disequilibrium On Stereotactic Body Radiation Therapy Of Lung Cancer, Brandon Disher

Electronic Thesis and Dissertation Repository

Stereotactic Body Radiation Therapy (SBRT) is an effective treatment option for patients with inoperable early-stage lung cancer. SBRT uses online image-guidance technology [e.g. cone-beam CT (CBCT)] to focus small-fields of high energy x-rays onto a tumour to deliver ablative levels of radiation dose (e.g. 54 Gy) in a few treatment fractions (e.g. 3). For the combination of these treatment parameters and a low density lung, lateral electron disequilibrium (LED) can potentially occur, reducing lung and tumour doses. The goal of this thesis was to determine the impact of LED on stereotactic body radiation therapy for lung cancer.

The effect of …

Improving Acute Stroke Management With Ct Perfusion Imaging: Approaches To Treatment Guidance And Brain Tissue Salvage, Christopher D. D'Esterre

Electronic Thesis and Dissertation Repository

CT Perfusion (CTP) provides measurement of perfusion at the capillary level which can be used to characterize tissue viability, and blood-brain-barrier (BBB) compromise. Using CTP, the goals of this research are to: 1) select patients that will benefit from acute stroke treatment, and 2) determine if pre-stroke neuroprotection reduces stroke severity.

Chapter two investigates the cerebral blood volume (CBV) parameter in a small acute ischemic stroke (AIS) patient set. Overestimation of the acute CBV defect is caused by incomplete wash-out of the CT contrast due to a shortened CTP acquisition time (“truncation artifact”).

In chapter three we examine the prognostic …

Delta Relaxation Enhanced Magnetic Resonance - Development And Application Of A Field-Cycling Contrast Mechanism, Yonathan Araya

Electronic Thesis and Dissertation Repository

Delta relaxation enhanced magnetic resonance (dreMR) is a novel imaging method capable of producing contrast proportional only to the concentration of the bound form of the targetable contrast agent using a dynamic field-cycling technique. The characteristic high relaxivity magnetic field dependence of bound paramagnetic contrast agents enables suppression of tissue contrast from unbound agents and unenhanced tissue, thereby increasing probe specificity. The dreMR technique requires an auxiliary actively shielded field-shifting insert electromagnet to modulate the strength of the main clinical magnetic field as a function of time during the relaxation and evolution periods of a pulse sequence.

Ablavar (approved for …

Magnetic Resonance Imaging Of Brain Tissue Abnormalities: Transverse Relaxation Time In Autism And Tourette Syndrome And Development Of A Novel Whole-Brain Myelin Mapping Technique, Yann Gagnon

Electronic Thesis and Dissertation Repository

The transverse relaxation time (T2) is a fundamental parameter of magnetic resonance imaging sensitive to tissue microstructure and water content, thus offering a non-invasive approach to evaluate abnormalities of brain tissue in-vivo. Prevailing hypotheses of two childhood psychiatric disorders were tested using quantitative T2 imaging and automated region of interest (ROI) analyses. In autism, the under-connectivity theory, which proposes aberrant connectivity within white matter (WM) was assessed, finding T2 to be eleveted in the frontal and parietal lobes, while dividing whole brain data into neurodevelopmentally relevant WM ROIs found increased T2 in bridging and radiate WM. In Tourette syndrome, tissue …

Atlas-Based Attenuation Correction For Pet/Mri, John Christian Patrick

Electronic Thesis and Dissertation Repository

Attenuation correction (AC) in PET/MRI is difficult as there is no clear relationship between MR signal and 511 keV attenuation coefficients (μ). One strategy is to align a pre-defined atlas of μ to the PET/MRI for AC. However, atlas design may influence quantitative accuracy of AC. In this thesis we compare 3 atlas design strategies and evaluate their performance in an oncology patient population. The 3 strategies were: correction with BMI-dependent atlases; gender-dependent atlases, and a gender- and sex-independent atlas. Patients were imaged with FDG PET/CT and 3T MRI. The atlases were created and then used for PET AC of …

Investigating Adenosine’S Role In Controlling The Cerebral Metabolic Rate Of Oxygen Following Hypoxia-Ischemia, Mustafa Ridha

Electronic Thesis and Dissertation Repository

The cerebral metabolic rate of oxygen (CMRO2) has been shown to be an early indicator of hypoxia-ischemia (HI); however, the mechanisms controlling post-HI CMRO2 are not clear. One potential mechanism is the activation of the adenosine A1 receptor due to increased adenosine concentrations during the insult. The present study investigated if the specific adenosine A1 antagonist, DPCPX, would reduce the typical reduction in CMRO2 and electrical cortical activity following HI. Measurements of CMRO2 and electrical cortical activity were obtained on piglets by near-infrared spectroscopy (NIRS) and amplitude-integrated electroencephalography (aEEG), respectively. The post-HI measurements of CMRO2 and mean aEEG background voltage …