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Full-Text Articles in Medicine and Health Sciences
Automation Through Deep-Learning To Quantify Ventilation Defects In Lungs From High-Resolution Isotropic Hyperpolarized 129xe Magnetic Resonance Imaging, Tuneesh Kaur Ranota
Automation Through Deep-Learning To Quantify Ventilation Defects In Lungs From High-Resolution Isotropic Hyperpolarized 129xe Magnetic Resonance Imaging, Tuneesh Kaur Ranota
Electronic Thesis and Dissertation Repository
Obstructive lung diseases are characterized by heterogenous ventilation. Hyperpolarized 129Xe gas lung magnetic resonance imaging (MRI) can examine lung ventilation heterogeneity by acquiring high-resolution isotropic images. The current gold standard of semi-automated (SA) segmentation can be used to quantify non-isotropic 129Xe lung images to generate ventilation defect percent (VDP), however, this method is not suitable for analysis of isotropic voxel 129Xe images due to the large number of slices. Therefore, we used a fully automated deep learning-based (DL) lung algorithm to calculate VDP from isotropic images. SNR, SA and DL-based VDP were calculated, showing a strong positive …
Does An Acute Achilles Tendon Rupture Become A Patient's Achilles Heel In The Long-Term?, Michaela Cm Khan
Does An Acute Achilles Tendon Rupture Become A Patient's Achilles Heel In The Long-Term?, Michaela Cm Khan
Electronic Thesis and Dissertation Repository
It is unknown if deficits in the involved limb following acute Achilles tendon rupture (AATR) persist in the long-term, or differ between patients treated operatively or non-operatively. This study investigated 43 patients 15±1 years post-AATR from a previous randomized controlled trial (RCT) that compared operative and non-operative treatment. Structural characteristics in the Achilles tendon and surrounding musculature were assessed using magnetic resonance imaging. We also performed physical examinations and evaluated performance-based and patient-reported outcomes. Overall, there were substantial differences between the involved and uninvolved limbs in most outcomes. Some outcomes improved over time from the initial RCT to the final …
Investigating In Vivo Brain Metabolite Levels In Concussed Female Athletes And A Murine Model Of Repetitive Closed Head Injury, Amy L. Schranz
Investigating In Vivo Brain Metabolite Levels In Concussed Female Athletes And A Murine Model Of Repetitive Closed Head Injury, Amy L. Schranz
Electronic Thesis and Dissertation Repository
After a concussion there is a complex cascade of events, termed the neurometabolic cascade, that includes changes in ion flux, neurotransmission, and cellular energetics. How this pathophysiological process translates into cognitive deficits remains poorly understood. Magnetic resonance spectroscopy (MRS) provides a non-invasive technique that allows for the quantification of brain metabolites that are involved in these processes, including glutamate and glutamine, which are involved in neurotransmission. Moreover, female athletes are underrepresented in studies on concussion, limiting our knowledge and understanding of sex differences. The overall goal of this thesis was to examine metabolite changes using MRS in female athletes before …
Ultra-High Field Magnetic Resonance Imaging For Stereotactic Neurosurgery, Jonathan Lau
Ultra-High Field Magnetic Resonance Imaging For Stereotactic Neurosurgery, Jonathan Lau
Electronic Thesis and Dissertation Repository
Stereotactic neurosurgery is a subspecialty within neurosurgery concerned with accurate targeting of brain structures. Deep brain stimulation (DBS) is a specific type of stereotaxy in which electrodes are implanted in deep brain structures. It has proven therapeutic efficacy in Parkinson’s disease and Essential Tremor, but with an expanding number of indications under evaluation including Alzheimer’s disease, depression, epilepsy, and obesity, many more Canadians with chronic health conditions may benefit. Accurate surgical targeting is crucial with millimeter deviations resulting in unwanted side effects including muscle contractions, or worse, vessel injury. Lack of adequate visualization of surgical targets with conventional lower field …
Retrospective Motion Correction In Magnetic Resonance Imaging Of The Brain, Patricia Johnson
Retrospective Motion Correction In Magnetic Resonance Imaging Of The Brain, Patricia Johnson
Electronic Thesis and Dissertation Repository
Magnetic Resonance Imaging (MRI) is a tremendously useful diagnostic imaging modality that provides outstanding soft tissue contrast. However, subject motion is a significant unsolved problem; motion during image acquisition can cause blurring and distortions in the image, limiting its diagnostic utility. Current techniques for addressing head motion include optical tracking which can be impractical in clinical settings due to challenges associated with camera cross-calibration and marker fixation. Another category of techniques is MRI navigators, which use specially acquired MRI data to track the motion of the head.
This thesis presents two techniques for motion correction in MRI: the first is …
In Vivo Tracking Of Tumour Associated Macrophages In Breast Cancer With Magnetic Resonance Imaging, Ashley V. Makela
In Vivo Tracking Of Tumour Associated Macrophages In Breast Cancer With Magnetic Resonance Imaging, Ashley V. Makela
Electronic Thesis and Dissertation Repository
Introduction: The environment in which a tumour exists and functions is called the tumour microenvironment (TME). In breast cancer, the presence of tumour associated macrophages (TAMs) in the TME is associated with tumour aggressiveness and poor outcomes. Despite evidence for a link between TAM content and outcome, there are few strategies to measure TAMs and no in vivo approach. Iron or fluorine-19 (19F)-based MRI can be used to detect macrophages post intravenous injection of either an iron or perfluorocarbon (PFC) agent. Iron-based MRI is sensitive but difficult to quantify. 19F MRI is specific and signal is proportional …
Development Of Anatomical And Functional Magnetic Resonance Imaging Measures Of Alzheimer Disease, Samaneh Kazemifar
Development Of Anatomical And Functional Magnetic Resonance Imaging Measures Of Alzheimer Disease, Samaneh Kazemifar
Electronic Thesis and Dissertation Repository
Alzheimer disease is considered to be a progressive neurodegenerative condition, clinically characterized by cognitive dysfunction and memory impairments. Incorporating imaging biomarkers in the early diagnosis and monitoring of disease progression is increasingly important in the evaluation of novel treatments. The purpose of the work in this thesis was to develop and evaluate novel structural and functional biomarkers of disease to improve Alzheimer disease diagnosis and treatment monitoring. Our overarching hypothesis is that magnetic resonance imaging methods that sensitively measure brain structure and functional impairment have the potential to identify people with Alzheimer’s disease prior to the onset of cognitive decline. …
Mapping The Flip Angle In Magnetic Resonance Imaging Using The Accelerated 3d Look-Locker Sequence, Trevor P. Wade
Mapping The Flip Angle In Magnetic Resonance Imaging Using The Accelerated 3d Look-Locker Sequence, Trevor P. Wade
Electronic Thesis and Dissertation Repository
In the ongoing quest to extract more information from MRI images, there has arisen a need to rapidly map the flip angle. This has been primarily driven by the shift to stronger main field strengths, which bring with them improved SNR, but also new difficulties. In particular, the radio frequency field used to excite the magnetization can no longer be assumed uniform at field strengths of 3 Tesla and above. New rapid quantitative imaging techniques, such as DESPOT1 and DESPOT2, rely on accurate knowledge of the flip angle, and while this could safely be assumed to be the prescribed value …