Radiology Commons^™

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 …

Vertebral Endplate Structural Defects: Measurement, Prevalence And Associated Factors, Aliyu Lawan

Electronic Thesis and Dissertation Repository

Objective: To synthesize current knowledge on the association of endplate structural defects (EPSD) with back pain (BP), improve EPSD measurement, and investigate EPSD prevalence, distribution, and association with age and body mass index (BMI).

Methods: In study 1, a systematic review was conducted on five databases for studies reporting on the association between EPSD and BP. Studies 2 and 3 used CTs and mCTs of 19 embalmed cadavers to examine the diagnostic accuracy of common EPSD assessment methods, and to develop and validate a novel method. Study 4 used the novel method on 200 adult males’ MRI to estimate EPSD …

Sarcopenia In Head And Neck Cancer: A Prognostic Analysis, Nedeljko Jovanovic

Electronic Thesis and Dissertation Repository

Introduction: In head and neck cancer (HNC), loss of skeletal muscle mass (SMM), or sarcopenia, is a strong prognostic factor for outcomes. However, inconsistencies in its assessment limit our understanding of the relationship between sarcopenia and nutrition-related outcomes. This project evaluated the significance of sarcopenia as described in the literature and as demonstrated in a cohort of HNC patients.

Methods: A scoping review was first conducted followed by a retrospective cohort study with data collected from 194 oropharyngeal carcinoma patients treated with definitive radiation/chemoradiation. Sarcopenia was assessed from computed tomography (CT) imaging at the third cervical vertebra (C3) and the …

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 …

Technical Adaptations For Cardiac Sodium Mri, Taylor L. Marcus

Electronic Thesis and Dissertation Repository

Cardiac sodium (Na⁺) MRI has the potential to unveil relationships between chronic kidney disease (CKD) and cardiovascular disease (CVD). Unfortunately, this modality requires many technical adaptations before it’s possible to extract and compare image data between individuals. This study investigated whether cardiac electrocardiogram (ECG) gating could improve image quality, and whether a uniform phantom could increase signal uniformity if a surface coil is used to acquire the image. Healthy participants were imaged with a custom-built surface coil and 3.0-T MR system. Cardiac gated images presented with a decreased signal-to-noise ratio (SNR), but intensity correction significantly increased image signal …

Quantitative Mri And 3d-Printing For Monitoring Periprosthetic Joint Infection, Greg Hong

Electronic Thesis and Dissertation Repository

Joint replacements are becoming increasingly commonplace with over 130,000 joint arthroplasties being performed annually in Canada. Although joint replacement surgery is highly successful, implants do occasionally fail and need to be replaced via costly and difficult revision surgery. Periprosthetic joint infection (PJI) has recently become the leading reason for revision of both hip and knee replacements, which is unfortunate because PJI is difficult to diagnose and treat effectively; diagnosis is made particularly difficult by the lack of established non-invasive (imaging) means of evaluating PJI. This thesis aims to demonstrate that magnetic resonance imaging (MRI) has potential for diagnosing and monitoring …

The Natural History Of Modic Changes - A 5- And 15-Year Follow-Up Study, Parnian Saremi

Electronic Thesis and Dissertation Repository

Modic changes (MCs), defined as bone marrow lesions adjacent to the vertebral endplate seen on MRI, have been associated with back pain. There are different types of MCs, with different histopathological correlates. This community-based study sample comprised 110 men from the Twin Spine Study, with baseline, 5-year, and 15-year follow-up MRIs. Following training and reliability testing, 1320 endplates (T12-S1) were evaluated for MC presence, type, and dimensions at each time point. Results demonstrated that Type 2 Modic Changes (MC2) were the most common type, with approximately half located at the two lowest disc levels. However, Type 1 Modic Changes (MC1) …

Quantitative Magnetic Resonance Imaging Of Knee Articular Cartilage And Effusion-Synovitis: The Structural Response To Changes In Joint Loading, Hayden F. Atkinson

Electronic Thesis and Dissertation Repository

Knee osteoarthritis (OA) is a progressive degenerative condition that can affect all tissues within the joint. Methods to measure early changes in joint structures and the effect of interventions are required. The purpose of this thesis was to investigate aspects of quantitative magnetic resonance imaging (MRI) as outcome measures in knee OA studies. Specifically, changes in articular cartilage composition and/or effusion-synovitis were examined in people with or at risk for knee OA and healthy controls, and after altering joint loads.

Chapter 2 is a systematic review that studied articular cartilage composition using MRI T2 and T1ρ relaxation in patients at …

Assessment Of Post-Treatment Imaging Changes Following Radiotherapy Using Magnetic Susceptibility Techniques, Jean-Guy Belliveau

Electronic Thesis and Dissertation Repository

Radiation therapy (RT) is a common treatment for brain neoplasms and is used alone or in combination with other therapies. The use of RT has been found to be successful in controlling tumors and extending the overall survival of patients; however, there are many unanswered questions regarding radiotherapy effects in the normal brain surrounding or infiltrated by tumor. Changes to the vascular and parenchyma have been documented, and more recently inflammatory mechanisms have been postulated to play a role in radiation injury. Traditional imaging techniques used within the clinic (CT and MRI) are often lacking in their ability to differentiate …

Optimizing Respiratory Gated Intensity Modulated Radiation Therapy Planning And Delivery Of Early-Stage Non-Small Cell Lung Cancer, Ilma Xhaferllari

Electronic Thesis and Dissertation Repository

Stereotactic ablative body radiotherapy (SABR) is the standard of care for inoperable early-stage non-small cell lung cancer (NSCLC) patients. However, thoracic tumours are susceptible to respiratory motion and, if unaccounted for, can potentially lead to dosimetric uncertainties. Respiratory gating is one method that limits treatment delivery to portions of the respiratory cycle, but when combined with intensity-modulated radiotherapy (IMRT), requires rigorous verification. The goal of this thesis is to optimize respiratory gated IMRT treatment planning and develop image-guided strategies to verify the dose delivery for future early-stage NSCLC patients.

Retrospective treatment plans were generated for various IMRT delivery techniques, including …

Non-Invasive Imaging For The Assessment Of Cardiac Dose And Function Following Focused External Beam Irradiation, Omar El-Sherif

Electronic Thesis and Dissertation Repository

Technological advances in imaging and radiotherapy have led to significant improvement in the survival rate of breast cancer patients. However, a larger proportion of patients are now exhibiting the less understood, latent effects of incidental cardiac irradiation that occurs during left-sided breast radiotherapy. Here, we examine the utility of four-dimensional computed tomography (4D-CT) for the accurate assessment of cardiac dose; and a hybrid positron emission tomography (PET) magnetic resonance imaging (MRI) system to longitudinally study radiation-induced cardiac effects in a canine model.

Using 4D-CT and deformable dose accumulation, we assessed the variation caused by breathing motion in the estimated dose …

Role Of Cerebrovascular Abnormality In Neurodegenerative Disease And Subcortical Ischemic Disease: Ct Perfusion And Pet Imaging, Jun Yang

Electronic Thesis and Dissertation Repository

Clinical studies indicate that about 30% ~ 50% of patients have cognitive impairment after the first or recurrent stroke. Ischemic injury, particularly subcortical lesions, caused by stroke has been demonstrated to further exacerbate cognitive impairment of Alzheimer’s disease (AD) and vascular dementia. However, the mechanisms whereby cerebrovascular abnormalities contribute to neurodegeneration at early stage of disease and eventually to cognitive decline remain unclear. CT perfusion and positron emission tomography (PET) were used to investigate early mechanisms in a rat comorbid model of cerebral ischemia (CI) and β-amyloid (Aβ, a pathological hallmark of AD) toxicity, and in patients with small subcortical …

Magnetic Resonance Imaging Compatible Remote Catheter Navigation System, Mohammad Ali Tavallaei

Electronic Thesis and Dissertation Repository

Many vascular and cardiac diseases are diagnosed and treated using a medical technique known as percutaneous transluminal catheter intervention (PTC). In PTC, the interventionalist inserts a catheter into the vasculature, and using the vessel as the guiding passageway, the catheter is navigated to desired anatomical targets where it would be used for various purposes such as catheter ablation for the treatment/management of cardiac arrhythmias. The catheterization procedure is conventionally guided with x-ray fluoroscopic imaging and more recently, but rarely, with Magnetic Resonance Imaging (MRI). X-ray imaging irradiates the patient directly during the procedure, and the staff and interventionalists indirectly through …

Image Fusion And Axial Labeling Of The Spine, Brandon Miles

Electronic Thesis and Dissertation Repository

In order to improve radiological diagnosis of back pain and spine disease, two new algorithms have been developed to aid the 75% of Canadians who will suffer from back pain in a given year. With the associated medical imaging required for many of these patients, there is a potential for improvement in both patient care and healthcare economics by increasing the accuracy and efficiency of spine diagnosis. A real-time spine image fusion system and an automatic vertebra/disc labeling system have been developed to address this. Both magnetic resonance (MR) images and computed tomography (CT) images are often acquired for patients. …

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 …

Optimization Of A Boundary Element Approach To Electromagnet Design With Application To A Host Of Current Problems In Magnetic Resonance Imaging, Chad T. Harris

Electronic Thesis and Dissertation Repository

Magnetic resonance imaging (MRI) has proven to be a valuable methodological approach in both basic research and clinical practice. However, significant hardware advances are still needed in order to further improve and extend the applications of the technique. The present dissertation predominantly addresses gradient and shim coil design (sub-systems of the MR system).

A design study to investigate gradient performance over a set of surface geometries ranging in curvature from planar to a full cylinder using the boundary element (BE) method is presented. The results of this study serve as a guide for future planar and pseudo-planar gradient systems for …

Mri-Based Attenuation Correction In Emission Computed Tomography, Harry R. Marshall

Electronic Thesis and Dissertation Repository

The hybridization of magnetic resonance imaging (MRI) with positron emission tomography (PET) or single photon emission computed tomography (SPECT) enables the collection of an assortment of biological data in spatial and temporal register. However, both PET and SPECT are subject to photon attenuation, a process that degrades image quality and precludes quantification. To correct for the effects of attenuation, the spatial distribution of linear attenuation coefficients (μ-coefficients) within and about the patient must be available. Unfortunately, extracting μ-coefficients from MRI is non-trivial. In this thesis, I explore the problem of MRI-based attenuation correction (AC) in emission tomography.

In particular, I …

Hearts And Minds: Examining The Evolution Of The Egyptian Excerebration And Evisceration Traditions Through The Impact Mummy Database, Andrew D. Wade

Electronic Thesis and Dissertation Repository

Egyptian mummification and funerary rituals were a transformative process, making the deceased a pure being; free of disease, injury, and disfigurements, as well as ethical and moral impurities. Consequently, the features of mummification available to specific categories of individuals hold social and ideological significance. This study refutes long-held classical stereotypes, particularly dogmatic class associations; demonstrates the apocryphal nature of universal heart retention; and expands on the purposes of excerebration and evisceration implied by synthetic and radiological analyses.

Features of the embalming traditions, specifically the variable excerebration and evisceration traditions, represented the Egyptian view of death. Fine-grain analyses, through primary imaging …