The Impact Of Simulated Image Acquisition Time Reduction On Image Quality And Parameters Of Myocardial Perfusion Imaging Using A Dedicated Cardiac Camera, Alireza Khatami

Electronic Thesis and Dissertation Repository

Heart disease is the second leading cause of death in Canada, highlighting the crucial role of early diagnosis in disease management. Myocardial perfusion imaging (MPI), is widely employed for this purpose, involves injecting a radiopharmaceutical into the body, imaging its distribution with a gamma camera, and revealing cardiac blood flow patterns. A significant challenge in MPI is the lengthy 8 to 10 minutes required for stress and rest imaging, potentially causing patient discomfort and compromising image quality due to movement. In a clinical study with 26 patients, post-processed data manipulation simulated a reduction in MPI imaging time. The findings indicated …

The Combined Effects Of Physical Exercise And Cognitive Training On Gait Speed And Primary Motor Cortex Metabolism In Individuals With Mild Cognitive Impairment: A 1h-Mrs Analysis, Jack Thomas Emsey Elkas

Electronic Thesis and Dissertation Repository

Mild cognitive impairment (MCI) is a transitional stage before dementia. Altered gait in MCI has been associated with progression to dementia. Using magnetic resonance spectroscopy, a relationship between primary motor cortex (M1) neurochemistry and dual task gait speed has been reported in MCI. Interventional research suggests exercise, cognitive training, and vitamin D supplementation may benefit MCI, yet the combined effect of these treatments on gait speed and M1 metabolism is unknown. Participants with MCI (N=75) were assigned to one of five intervention arms and dual task cost on gait speed and M1 metabolism was assessed before and five months after …

Improving The Reliability And Accessibility Of Ct Perfusion Imaging In Acute Ischemic Stroke, Kevin J. Chung

Electronic Thesis and Dissertation Repository

CT perfusion (CTP) imaging is a validated treatment decision support tool in acute ischemic stroke. Automated analysis of CTP cerebral blood flow (CBF) and Tmax maps produces estimates of ischemic core and penumbra volumes used to determine target mismatch profiles for treatment. However, availability and utilization of CTP is low due to diagnostic variability between CTP software and technical, logistical, and radiation dose considerations that may limit its routine adoption. The objective of this doctoral research was to improve the reliability and accessibility of CTP by (1) improving diagnostic agreement between CTP software, (2) enabling perfusion imaging with standard acute …

An Evaluation Of A Deep Learning Approach For Radiation Dose Reduction In 18f-Fdg Pet/Mri Pediatric Epilepsy Imaging, Confidence Raymond

Electronic Thesis and Dissertation Repository

Epilepsy is a degenerative brain disease characterized by abruption of neural activities that result in seizures. The onset of epileptic seizures are usually from a primary source - the epileptogenic foci (EF) which could be distributed to nearby neurons and tissues. Accurate localization of EF is critical in epilepsy cases where drug treatment has failed, and surgery is indicated to resect the EF to alleviate seizure. Typically, hybrid positron emission tomography (PET) and computed tomography (CT) imaging are performed to functionally localize the EF in drug-resistant epilepsy for surgical planning when anatomical abnormalities representing the EF cannot be identified on …

Microvascular Responsiveness To Cardiopulmonary Bypass, Michael O'Neil

Electronic Thesis and Dissertation Repository

Cardiopulmonary bypass can result in multiple organ failure due to mechanisms of ischemia reperfusion injury and the systemic inflammatory response syndrome. The primary objective of this thesis was to investigate and monitor the microvasculature in cardiac surgery patients using multiple methodologies and real-time monitoring techniques. The purpose of our first study was to determine whether pulsatile blood flow during bypass improves microvascular perfusion compared to non-pulsatile flow. We found that changes in sublingual mucosal microcirculation using orthogonal polarization spectral imaging correlate with indices of thenar muscle tissue oxygen saturation and its recovery during a vascular occlusion test using near-infrared spectroscopy …

Indocyanine Green Angiography In Pediatric Colorectal Surgery, Robin B. Wigen

Electronic Thesis and Dissertation Repository

Hirschsprung Disease (HD) and Anorectal Malformations (ARM) are congenital colorectal conditions that necessitate surgical correction via bowel resection with the creation of an anastomosis. Surgical complications, thought to be in part due to malperfusion of the bowel anastomosis, are frequent, as revealed by the retrospective review enclosed. Indocyanine Green Angiography (ICGA) is a process in which water-soluble dye (ICG) is used to assess perfusion of tissue, and it has been employed with success in adult populations to reduce rates of anastomotic leak during colorectal surgery. The systematic review conducted within confirms that this tool has not been extensively studied in …

Rna Isolation In Duchenne Muscular Dystrophy (Dmd) Mice Models, Salem Abu Al-Burak

Undergraduate Student Research Internships Conference

Fibrosis is a progressive and typically irreversible disease process characterized by the excessive deposition of collagen in organs and in tissues of the musculoskeletal (MSK) system^1,2. This process, which causes loss of organ and tissue function, can be initiated by micro-traumas³, an excessive and/or prolonged immune response¹, the activation and proliferation of fibrosis-inducing progenitor cells⁴, and a pro-fibrotic extra-cellular microenvironment⁵. In parallel with the events that initiate fibrosis, genetic or environmental influences may cause cells and tissues to become predisposed to fibrosis development prior to initiation. This suggests that these …

Functional Characterization Of A High-Throughput In Vitro Model To Predict Faecal Microbiota Transplantation (Fmt) Donor Success, Catherine M. Andary

Undergraduate Student Research Internships Conference

Faecal microbiota transplantation (FMT) involves the administration of donor faecal matter to a diseased recipient with the goal of remodeling the host microbiome to provide health benefits. In recent years, FMT has emerged as a potential therapy for a variety of microbiome-associated diseases such as atherosclerosis. Trimethylamine (TMA) is an atherosclerosis-linked metabolite generated by the gut microbiota from dietary precursors which is then oxidized to trimethylamine N-oxide (TMAO) by the liver, contributing to increased gut permeability. It has been shown that FMT may alter or restore the gut microbiome of recipients to reduce plasma TMAO levels. Despite its potential, the …

Intracranial Eeg Patient Analysis: Seizure Reduction In Refractory Epilepsy Following Depth Electrode Insertion, Shreyashish Roy-Chowdhury

Undergraduate Student Research Internships Conference

Rationale: The implantation effect describes an immediate reduction in seizure frequency following the insertion of intracranial electrodes. There is limited information regarding which patients will experience a reduction of seizures and the reason for the implantation effect. This study focuses on describing predictor factors for the reduction in seizure frequency in patients with medically resistant epilepsy implanted with depth electrodes.

Methods: We conducted a retrospective chart review of 89 patients who underwent intracranial electroencephalography (iEEG) monitoring with depth electrodes. Sixty-five of these patients had no subsequent therapeutic interventions and had a 3-6 month follow-up. Patients were grouped as either responders …

In-Vitro Validation Of Intratumoral Modulation Therapy For Glioblastoma, Abdulla Elsaleh

Undergraduate Student Research Internships Conference

Intratumoral modulation therapy (IMT) is a novel electrotherapy used to treat brain cancer tumours using electric fields applied directly to the tumours through implanted electrodes. Previous research has validated IMT's effectiveness and provided computer-simulated optimizations for IMT electric fields. This work validates these computer optimizations in-vitro, using a PCB construct to deliver electric fields, and bioluminescence imaging to assess cell viability.

We found electric field strength to correlate with cell viability, and found that rotating (phase-shifted) electric fields did not produce significant improvements in IMT efficacy. Future work will investigate different IMT frequencies and other parameters, while providing biological replicates …

To Develop A Clinically Friendly Multi-Segment Kinematic And Kinetic Foot Model And Test It On Pre-/Post-Hto Patients With Medial Knee Osteoarthritis And Knee Varus, Songlin Zhu

Electronic Thesis and Dissertation Repository

This study aims to develop a clinically useful multi-segment foot model that will enable the analysis of foot kinematics and kinetics in an optical motion capture laboratory setting. This study will also test the new multi-segment foot model on patients with knee osteoarthritis and varus knee alignment that is corrected by high tibial osteotomy (HTO). The multi-segment foot model divides the foot into four functional segments: the hindfoot, midfoot, forefoot and hallux. An X-Z-Y-Cardan angle rotation convention was used to determine intersegmental dorsi/plantar flexion, inversion/eversion, and internal/external rotation. Joint moments, joint powers and medio-longitudinal arch (MLA) height/length ratio were also …

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 …

Identification Of Dna Methylation Episignatures For Classification And Phenotype/Genotype Correlation In Mendelian Neurodevelopmental Disorders, John Reilly

Electronic Thesis and Dissertation Repository

ABSTRACT: Diagnosis for neurodevelopmental disorders poses numerous challenges, related to the lack of specific findings and limited understanding of clinical impact of the majority of genetic variation. Epigenomics mechanisms involve chemical modifications in DNA that involve a range of cellular mechanisms. DNA methylation is an epigenetic mechanism involving addition and removal of methyl groups to cytosine residues. These methylation signals form episignatures; patterns of methylation that can be used as biomarkers capable of differentiating neurodevelopmental disorders. EpiSigns have enabled molecular diagnosis of a number of genetic conditions, classification of variants of unknown significance, and provided insights into the pathophysiology of …

Delineation Of Ascending Aortic Medial Degeneration Using Diffusion Tensor Imaging, Justin A. Ching-Johnson

Electronic Thesis and Dissertation Repository

Thoracic aortic aneurysms (TAAs) are a life-threatening dilation of the thoracic aorta that can lead to catastrophic dissection or rupture. In TAAs, the structure of the aortic wall is perturbed. Current imaging approaches assess lumen dimensions but lack the ability to delineate aortic wall architecture, a key determinant of aortic integrity. Diffusion tensor imaging (DTI) is an MRI modality which can reveal tissue microstructure through diffusion characteristics. In this thesis I investigated the potential for DTI to evaluate TAA architecture. A porcine model of aortic wall degeneration was developed, and DTI scans were performed on healthy and degenerated porcine ascending …

Biomechanical Analysis Of Ligament Modelling Techniques And Femoral Component Malrotation Following Tka, Liam A. Montgomery

Electronic Thesis and Dissertation Repository

Previous studies have demonstrated that satisfaction and revision rates following total knee arthroplasty (TKA) are lower than those of comparable surgeries such as total hip replacements. A leading cause for these revisions is joint instability which may be due to improper ligament balancing or poorly aligned surgical implants. One of the methods used to investigate biomechanical forces and kinematics is computational modelling of the post-operative TKA knee.

A unique knee model was used to investigate the biomechanical and kinematic effects of ligament model complexity, as well as the effects of simulating ligament wrapping versus ignoring ligament wrapping. We then used …

Validation Of Arterial Spin Labeling For Longitudinal Monitoring And Differential Diagnosis Of Frontotemporal Dementia, Tracy Ssali

Electronic Thesis and Dissertation Repository

Frontotemporal dementia (FTD) is a devastating neurodegenerative disease characterized by a rapid decline in behavioural, language, and motor abilities. Advances in the understanding of FTD genetics and pathophysiology, and the subsequent development of novel disease modifying treatments have highlighted the need for tools to assess their efficacy. While structural magnetic resonance imaging (MRI) and functional imaging with ¹⁸F-flurodeoxyglucose (FDG) positron emission tomography (PET) are used for clinical diagnosis, structural changes are subtle at the early stages and PET imaging is expensive and access limited. Given the coupling of cerebral blood flow (CBF) to energy metabolism, an attractive alternative is …

The Effect Of Obesity On Revision Total Knee Arthroplasty: Functional Outcome, Ninety-Day Costs, Reoperations, Readmissions And Cost-Effectiveness, Mohamad Nasser Eddine

Electronic Thesis and Dissertation Repository

The demand for revision total knee arthroplasty (RTKA) is increasing due to obesity and an aging population. The purpose of this study is to evaluate the effect of different body mass index (BMI) categories on RTKA using a retrospective cohort analysis. The first part was to assess patients’ functionality post-RTKA. The second part was to determine the survival of RTKA and re-revision rate. The third part was to explore the complication and readmission rates, and to estimate the 90-day costs of RTKA. We found the most common indication for RTKA in super obese patients is infection, unlike other BMI categories, …

Using Hyperspectral Near-Infrared Spectroscopy And Diffuse Correlation Spectroscopy To Monitor The Effects Of Phenylephrine In The Microcirculation, Laura Mawdsley

Electronic Thesis and Dissertation Repository

The microcirculation is the site of oxygen exchange in the body, and little work has been done to determine if different microvascular beds respond similarly to a simultaneous vascular challenge. A hybrid microvascular monitoring device was developed that uses hyperspectral near-infrared spectroscopy and diffuse correlation spectroscopy to simultaneously monitor the brain and skeletal muscle. Experiments were conducted on Sprague Dawley rats (n=6, 156g±6.4g) to discern the effect that phenylephrine (0.1 mL bolus, 10 mg/kg) has on the mean arterial pressure (MAP), hemoglobin concentration, and blood flow in each microvasculature. Hemoglobin concentration increased by 2.1±0.2 mmol in the brain, and decreased …

The Cost-Effectiveness Of A Midvastus Versus Standard Medial Parapatellar Surgical Approach For Total Knee Arthroplasty, Ishita Joshi

Electronic Thesis and Dissertation Repository

The minimally invasive midvastus (MMV) surgical approach for total knee arthroplasty (TKA) is a less invasive technique that has been proposed to accelerate recovery over standard TKA, however, advantages are not yet definitively established. We investigated the cost-effectiveness of MMV TKA versus the standard medial parapatellar (MPP) approach for TKA alongside a randomized controlled trial in patients with knee osteoarthritis. Patients reported resource use as well as indirect costs, and health outcomes were measured using the EQ-5D-5L and the Western Ontario and McMaster Universities Osteoarthritis Index over the 12-month study period. The results of our net benefit regression analysis suggest …

Rapid Recovery Of Cerebral Blood Content And Oxygenation In Adults From Time-Resolved Near-Infrared Spectroscopy, David J. F. Cohen

Electronic Thesis and Dissertation Repository

Patient neurological outcomes following cardiac surgery are improved when near-infrared spectroscopy (NIRS) is used to optimize intraoperative cerebral oxygen delivery. However, current NIRS analysis methods have difficulties monitoring adult brains due to contamination from the extracerebral layer (ECL).

The objective of this thesis is to develop a time-resolved (TR) NIRS data analysis method for monitoring adult cerebral oxygen saturation (ScO2) and total hemoglobin (HbT) by assuming the head is composed of two layers – the ECL and the brain. We tested the validity of this assumption using in silico data from an adult human head using two approaches; a few-wavelength, …

Novel Imaging Tools Reveal The Dynamics Of The Myocardial Growth Hormone Secretagogue Receptor In Heart Disease And Heart Failure, Rebecca Sullivan

Electronic Thesis and Dissertation Repository

Heart disease (HD) is the leading cause of mortality worldwide. Currently, diagnosis is based on clinical features, imaging, and circulating cardiac biomarkers. Cardiac imaging technologies, such as echocardiography and cardiac magnetic resonance imaging (cMRI), enable the non-invasive detection of changes in heart function. Although these modalities can detect changes in structure and anatomy, it is usually at later stages, where prevention may not be possible. In conjunction with imaging, circulating biomarkers of heart failure (HF), notably B-type natriuretic peptide (BNP) and cardiac troponin I and T, can be detected with increased levels in the blood. These biomarkers are associated with …

Predicting Dissatisfaction With Total Knee Arthroplasty, Joseph S. Munn

Electronic Thesis and Dissertation Repository

Total knee arthroplasty (TKA) is a common and effective treatment for end-stage osteoarthritis. However, approximately 20% of patients are consistently found to be dissatisfied or unsure of their satisfaction with their TKA at 1-year post-surgery. Two strategies for reducing dissatisfaction have appeared in the literature. The first aims to reduce the number of dissatisfied patients who will undergo surgery by identifying patients likely to be dissatisfied pre-surgery. The second aims to implement interventions that improve patient satisfaction by generating realistic expectations for outcomes and by association improving met expectations scores. It may be possible to improve the performance of these …

Estimating Partial Body Ionizing Radiation Exposure By Automated Cytogenetic Biodosimetry, Ben Shirley, Peter Rogan

Biochemistry Publications

Purpose: Inhomogeneous exposures to ionizing radiation can be detected and quantified with the dicentric chromosome assay (DCA) of metaphase cells. Complete automation of interpretation of the DCA for whole-body irradiation has significantly improved throughput without compromising accuracy, however, low levels of residual false positive dicentric chromosomes (DCs) have confounded its application for partial-body exposure determination.

Materials and methods: We describe a method of estimating and correcting for false positive DCs in digitally processed images of metaphase cells. Nearly all DCs detected in unirradiated calibration samples are introduced by digital image processing. DC frequencies of irradiated calibration samples and those exposed …

An Approach For The In-Vivo Characterization Of Brain And Heart Inflammation In Duchenne Muscular Dystrophy, Joanne Tang

Electronic Thesis and Dissertation Repository

Duchenne muscular dystrophy (DMD) is a neuromuscular disorder caused by dystrophin loss—notably within muscles and CNS neurons. DMD presents as cognitive weakness, progressive skeletal and cardiac muscle degeneration until pre-mature death from cardiac or respiratory failure. Innovative therapies improved life expectancy, but this is accompanied by increased late-onset heart failure and emergent cognitive degeneration. Thus, there is an increasing need to both better understand and track disease pathophysiology in the dystrophic heart and brain prior to onset of severe degenerative symptoms. Chronic inflammation is strongly associated with skeletal and cardiac muscle degeneration, however chronic neuroinflammation’s role is largely unknown in …

Optimizing Preprocessing Of Fmri Data To Maximize Correspondence Of Functional Anatomy Across Individuals, Nargess Ghazaleh

Electronic Thesis and Dissertation Repository

In movie-activation fMRI, intersubject correlation (ISC) indicates a functional correspondence across viewers. Brains di↵er in shape; spatial normalization and smoothing enhance inter-subject functional overlap. We compare three normalization methods and six smoothing levels to discover which method yields the best functional overlap, indexed by ISC. This is key to optimizing data analysis in clinical studies using movie-activation fMRI in future. In a 3T scanner, 44 healthy subjects watched an 8-min movie. Both normalization and smoothing a↵ected the strength and extent of the ISC. ISC values were more robust for ANTs and DARTELthanforSPM12andwere(asymptotically)thestrongestat12mmsmoothing. When image data are preprocessed with high-dimensional volumetric …

Estimating Partial Body Ionizing Radiation Exposure By Automated Cytogenetic Biodosimetry, Peter Rogan

Biochemistry Publications

Purpose: Inhomogeneous exposures to ionizing radiation can be detected and quantified with the Dicentric Chromosome Assay (DCA) of metaphase cells. Complete automation of interpretation of the DCA for whole body irradiation has significantly improved throughput without compromising accuracy, however low levels of residual false positive dicentric chromosomes (DCs) have confounded its application for partial body exposure determination.

Materials and Methods: We describe a method of estimating and correcting for false positive DCs in digitally processed images of metaphase cells. Nearly all DCs detected in unirradiated calibration samples are introduced by digital image processing. DC frequencies of irradiated calibration …

The Migration And Wear Of Reverse Total Shoulder Arthroplasty, Madeleine L. Van De Kleut

Electronic Thesis and Dissertation Repository

Reverse total shoulder arthroplasty (RTSA) inverts the ball and socket geometry of the shoulder. Though projected to become the most common shoulder replacement in the next decade, RTSA suffers from a high complication and revision rate, with implant loosening requiring revision. As the number of indications and demand from younger patients for RTSA continues to grow, there is the need to identify implant fixation techniques that promote longevity.

Radiostereometric analysis (RSA) is the current standard for measuring implant migration, which, if continuous in the first year postoperatively is highly predictive of later loosening and failure. RSA has also been used …

Hybrid Optical System For Studying The Dynamic Regulation Of Blood Flow/Metabolism In The Adult Brain, Marwan Shahid

Electronic Thesis and Dissertation Repository

Cerebral blood flow (CBF) and oxygen delivery are tightly controlled to meet neuronal energy demands; however, studying dynamic neurovascular coupling in the human brain is challenging due to the lack of methods that can measure rapid changes in CBF and tissue oxygenation. This report presents an in-house-developed hybrid time-resolved near-infrared spectroscopy/diffuse correlation spectroscopy (TR-NIRS/DCS) device and its use to track dynamic CBF and tissue oxygen saturation (StO₂) responses simultaneously with sub-second resolution following a vasodilatory stimulus (i.e., a hypercapnic challenge).

Cerebrovascular reactivity (CVR) experiments were performed on 10 healthy participants (mean age: 27 years) using a computer-controlled gas …

Ganglioside Detection From Formalin Fixed Human Brain Tissue Utilizing Maldi Imaging Mass Spectrometry, Aaron Harris

Electronic Thesis and Dissertation Repository

Matrix assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) is largely performed on fresh frozen tissue whereas clinical tissue samples stored long term are fixed in formalin, and the fixation process is thought to cause signal suppression for lipid molecules. Studies show that fresh frozen brain tissue sections washed with ammonium formate (AF) solution prior to matrix application in the MALDI-IMS procedure display an increase in signal intensity and sensitivity for lipid molecules while maintaining molecular spatial distribution. Work in this thesis compares MALDI data of ganglioside molecules from fresh frozen and post-fixed rat brain samples, and post-fixed human …

Machine Learning Towards General Medical Image Segmentation, Clara Tam

Electronic Thesis and Dissertation Repository

The quality of patient care associated with diagnostic radiology is proportionate to a physician's workload. Segmentation is a fundamental limiting precursor to diagnostic and therapeutic procedures. Advances in machine learning aims to increase diagnostic efficiency to replace single applications with generalized algorithms. We approached segmentation as a multitask shape regression problem, simultaneously predicting coordinates on an object's contour while jointly capturing global shape information. Shape regression models inherent point correlations to recover ambiguous boundaries not supported by clear edges and region homogeneity. Its capabilities was investigated using multi-output support vector regression (MSVR) on head and neck (HaN) CT images. Subsequently, …