Medical Biophysics Commons^™

Multisite Comparison Of Mri Defacing Software Across Multiple Cohorts, Athena E. Theyers, Mojdeh Zamyadi, Mark O'Reilly, Robert Bartha, Sean Symons, Glenda M. Macqueen, Stefanie Hassel, Jason P. Lerch, Evdokia Anagnostou, Raymond W. Lam, Benicio N. Frey, Roumen Milev, Daniel J. Müller, Sidney H. Kennedy, Christopher J.M. Scott, Stephen C. Strother, Stephen R. Arnott

Medical Biophysics Publications

With improvements to both scan quality and facial recognition software, there is an increased risk of participants being identified by a 3D render of their structural neuroimaging scans, even when all other personal information has been removed. To prevent this, facial features should be removed before data are shared or openly released, but while there are several publicly available software algorithms to do this, there has been no comprehensive review of their accuracy within the general population. To address this, we tested multiple algorithms on 300 scans from three neuroscience research projects, funded in part by the Ontario Brain Institute, …

Evaluating Anesthetic Protocols For Non-Human Primate Functional Neuroimaging, Megha Verma

Electronic Thesis and Dissertation Repository

Functional magnetic resonance imaging (fMRI) is a non-invasive technique that can be used to measure a proxy of neural activity in vivo with high spatial specificity. One subject can be followed for a long period of time to assess changes in functional brain organization. However, fMRI is extremely sensitive to motion. The challenges of training non-human primates to reduce motion in an MRI scanner motivate the study of anesthesia which is commonly used to substitute for this training. In this thesis, I compare three different commonly used anesthetic protocols: isoflurane, propofol-fentanyl in combination, and fentanyl alone, to test which of …

Kinetic Analysis Of Dominant Intraprostatic Lesion Of Prostate Cancer Using Quantitative Dynamic [18F]Dcfpyl-Pet: Comparison To [18F]Fluorocholine-Pet, Dae Myoung Yang, Fiona Li, Glenn Bauman, Joseph Chin, Stephen Pautler, Madeleine Moussa, Irina Rachinsky, John Valliant, Ting Yim Lee

Medical Biophysics Publications

Purpose: Identification of the dominant intraprostatic lesion(s) (DILs) can facilitate diagnosis and treatment by targeting biologically significant intra-prostatic foci. A PSMA ligand, [ F]DCFPyL (2-(3-{1-carboxy-5-[(6-[ F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid), is better than choline-based [ F]FCH (fluorocholine) in detecting and localizing DIL because of higher tumour contrast, particularly when imaging is delayed to 1 h post-injection. The goal of this study was to investigate whether the different imaging performance of [ F]FCH and [ F]DCFPyL can be explained by their kinetic behaviour in prostate cancer (PCa) and to evaluate whether DIL can be accurately detected and localized using a short duration dynamic positron …

Utilization Of Salvage And Systemic Therapies For Recurrent Prostate Cancer As A Result Of 18F-Dcfpyl Pet/Ct Restaging, Wei Liu, Katherine Zukotynski, Louise Emmett, Hans T. Chung, Peter Chung, Robert Wolfson, Irina Rachinsky, Anil Kapoor, Ur Metser, Andrew Loblaw, Gerard Morton, Tracy Sexton, Michael Lock, Joelle Helou, Alejandro Berlin, Colm Boylan, Susan Archer, Gregory R. Pond, Glenn Bauman

Medical Biophysics Publications

Purpose: Our purpose was to investigate the effect of the addition of prostate-specific membrane antigen (PSMA)-targeted positron emission tomography/computed tomography (PET/CT) in patients with recurrent prostate cancer post-primary radiation therapy. Methods and Materials: A prospective, multi-institutional clinical trial evaluated 2-(3-{1-carboxy-5-[(6-[18F]fluoro-pyridine-3-carbonyl)-amino]-pentyl}-ureido)-pentanedioic acid ( F-DCFPyL) PET/CT restaging in 79 men with recurrent prostate cancer post-primary radiation therapy. We report actual patient management and compare this with proposed management both before and after PSMA-targeted PET/CT. Results: Most patients (59%) had a major change in actual management compared with pre-PET/CT proposed management. The rate of major change was underestimated by immediately post-PET/CT surveys (32%). …

Disease-Related Cortical Thinning In Presymptomatic Granulin Mutation Carriers, Sergi Borrego-Écija, Roser Sala-Llonch, John Van Swieten, Barbara Borroni, Fermín Moreno, Mario Masellis, Carmela Tartaglia, Caroline Graff, Daniela Galimberti, Robert Laforce, James B. Rowe, Elizabeth Finger, Rik Vandenberghe, Fabrizio Tagliavini, Alexandre De Mendonça, Isabel Santana, Matthis Synofzik, Simon Ducharme, Johannes Levin, Adrian Danek, Alex Gerhard, Markus Otto, Chris Butler, Giovanni Frisoni, Sandro Sorbi, Carolin Heller, Martina Bocchetta, David M. Cash, Rhian S. Convery, Katrina M. Moore, Jonathan D. Rohrer, Raquel Sanchez-Valle

Medical Biophysics Publications

Mutations in the granulin gene (GRN) cause familial frontotemporal dementia. Understanding the structural brain changes in presymptomatic GRN carriers would enforce the use of neuroimaging biomarkers for early diagnosis and monitoring. We studied 100 presymptomatic GRN mutation carriers and 94 noncarriers from the Genetic Frontotemporal dementia initiative (GENFI), with MRI structural images. We analyzed 3T MRI structural images using the FreeSurfer pipeline to calculate the whole brain cortical thickness (CTh) for each subject. We also perform a vertex-wise general linear model to assess differences between groups in the relationship between CTh and diverse covariables as gender, age, the estimated years …

Community Health Interventions To Reduce The Burden Of Radon-Related Lung Cancer, Benjamin Weaver

Family Medicine Clerkship Student Projects

Exposure to radon is the second leading cause of lung cancer in the United States. One in seven homes in Vermont has elevated levels of radon, but most patients are unaware of radon as a risk factor for lung cancer or that radon testing and mitigation services are available to them. To promote increased testing and mitigation of radon we screened patients presenting to a Family Medicine practice in Vermont about whether they had had these services done in their home. We also developed a patient education resource for providers to give to patients who had more questions about radon …

Case – 18F-Dcfpyl-Positron Emission Tomography/Computed Tomography (Pet/Ct) Time Of Imaging, Golmehr Sistani, Ur Metser, Glenn S. Bauman, David T. Laidley, Stephen E. Pautler, Katherine A. Zukotynski

Medical Biophysics Publications

No abstract provided.

Cortical Thickness Estimation In Individuals With Cerebral Small Vessel Disease, Focal Atrophy, And Chronic Stroke Lesions, Miracle Ozzoude, Joel Ramirez, Pradeep Reddy Raamana, Melissa F. Holmes, Kirstin Walker, Christopher J.M. Scott, Fuqiang Gao, Maged Goubran, Donna Kwan, Maria C. Tartaglia, Derek Beaton, Gustavo Saposnik, Ayman Hassan, Jane Lawrence-Dewar, Dariush Dowlatshahi, Stephen C. Strother, Sean Symons, Robert Bartha, Richard H. Swartz, Sandra E. Black

Medical Biophysics Publications

Background: Regional changes to cortical thickness in individuals with neurodegenerative and cerebrovascular diseases (CVD) can be estimated using specialized neuroimaging software. However, the presence of cerebral small vessel disease, focal atrophy, and cortico-subcortical stroke lesions, pose significant challenges that increase the likelihood of misclassification errors and segmentation failures. Purpose: The main goal of this study was to examine a correction procedure developed for enhancing FreeSurfer’s (FS’s) cortical thickness estimation tool, particularly when applied to the most challenging MRI obtained from participants with chronic stroke and CVD, with varying degrees of neurovascular lesions and brain atrophy. Methods: In 155 CVD participants …

Detection And Quantification Of Cells Using Magnetic Particle Imaging And Magnetic Microspheres, Kierstin P. Melo

Electronic Thesis and Dissertation Repository

Magnetic particle imaging (MPI) is an emerging imaging modality that specifically detects superparamagnetic iron oxide nanoparticles (SPIOs). Our lab has shown that cell tracking with magnetic resonance imaging (MRI) has very high sensitivity, but low specificity and quantification of iron labeled cells is difficult. MPI cell tracking could overcome these limitations. A Momentum^TM MPI system was installed at Robarts in August 2019 and this is the first project to be completed using MPI. In Chapter 2 a series of in vitro experiments are reported which tested the repeatability and reproducibility of imaging SPIO labeled cell samples. There are no …

Improving Hydrid Pet/Mri Cardiovascular Imaging With Improved Hardware Design And Attenuation Correction Coefficient, Adam Helmy Farag

Electronic Thesis and Dissertation Repository

According to the World Health Organization (WHO) report in 2019, cardiovascular diseases (CVD) cause 52% of all illness-related deaths globally and are considered to be the second most common cause of death in Canada. CVD is also estimated to cost the Canadian economy about $21.2 billion in direct and indirect costs. With these figures, it is vital to develop the most effective and accurate methods and tools to diagnose accurately CVD and their causes. One of the promising tools for accurate diagnostic and therapeutic of CVD is the integrated Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) PET/MRI technology, …

Histologic Tissue Components Provide Major Cues For Machine Learning-Based Prostate Cancer Detection And Grading On Prostatectomy Specimens, Wenchao Han, Carol Johnson, Mena Gaed, José A. Gómez, Madeleine Moussa, Joseph L. Chin, Stephen Pautler, Glenn S. Bauman, Aaron D. Ward

Medical Biophysics Publications

Automatically detecting and grading cancerous regions on radical prostatectomy (RP) sections facilitates graphical and quantitative pathology reporting, potentially benefitting post-surgery prognosis, recurrence prediction, and treatment planning after RP. Promising results for detecting and grading prostate cancer on digital histopathology images have been reported using machine learning techniques. However, the importance and applicability of those methods have not been fully investigated. We computed three-class tissue component maps (TCMs) from the images, where each pixel was labeled as nuclei, lumina, or other. We applied seven different machine learning approaches: three non-deep learning classifiers with features extracted from TCMs, and four deep learning, …

A Telescope Gwas Analysis Strategy, Based On Snps-Genes-Pathways Ensamble And On Multivariate Algorithms, To Characterize Late Onset Alzheimer’S Disease, Margherita Squillario, Giulia Abate, Federico Tomasi, Veronica Tozzo, Annalisa Barla, Daniela Uberti, Michael W. Weiner, Paul Aisen, Ronald Petersen, Jack R. Clifford, William Jagust, John Q. Trojanowki, Arthur W. Toga, Laurel Beckett, Robert C. Green, Andrew J. Saykin, John Morris, Leslie M. Shaw, Zaven Khachaturian, Greg Sorensen, Maria Carrillo, Lew Kuller, Marc Raichle, Steven Paul, Peter Davies, Howard Fillit, Franz Hefti, Davie Holtzman, M. Marcel Mesulam, William Potter, Peter Snyder, Tom Montine

Medical Biophysics Publications

Genome–wide association studies (GWAS) have revealed a plethora of putative susceptibility genes for Alzheimer’s disease (AD), with the sole exception of APOE gene unequivocally validated in independent study. Considering that the etiology of complex diseases like AD could depend on functional multiple genes interaction network, here we proposed an alternative GWAS analysis strategy based on (i) multivariate methods and on a (ii) telescope approach, in order to guarantee the identification of correlated variables, and reveal their connections at three biological connected levels. Specifically as multivariate methods, we employed two machine learning algorithms and a genetic association test and we considered …

Challenges And Opportunities With Causal Discovery Algorithms: Application To Alzheimer’S Pathophysiology, Xinpeng Shen, Sisi Ma, Prashanthi Vemuri, Gyorgy Simon, Michael W. Weiner, Paul Aisen, Ronald Petersen, Clifford R. Jack, Andrew J. Saykin, William Jagust, John Q. Trojanowki, Arthur W. Toga, Laurel Beckett, Robert C. Green, John Morris, Leslie M. Shaw, Zaven Khachaturian, Greg Sorensen, Maria Carrillo, Lew Kuller, Marc Raichle, Steven Paul, Peter Davies, Howard Fillit, Franz Hefti, David Holtzman, M. Marcel Mesulam, William Potter, Peter Snyder, Adam Schwartz, Tom Montine, Ronald G. Thomas

Medical Biophysics Publications

Causal Structure Discovery (CSD) is the problem of identifying causal relationships from large quantities of data through computational methods. With the limited ability of traditional association-based computational methods to discover causal relationships, CSD methodologies are gaining popularity. The goal of the study was to systematically examine whether (i) CSD methods can discover the known causal relationships from observational clinical data and (ii) to offer guidance to accurately discover known causal relationships. We used Alzheimer’s disease (AD), a complex progressive disease, as a model because the well-established evidence provides a “gold-standard” causal graph for evaluation. We evaluated two CSD methods, Fast …

Fam222a Encodes A Protein Which Accumulates In Plaques In Alzheimer’S Disease, Tingxiang Yan, Jingjing Liang, Ju Gao, Luwen Wang, Hisashi Fujioka, Michael W. Weiner, Norbert Schuff, Howard J. Rosen, Bruce L. Miller, David Perry, Paul Aisen, Paul Aisen, Arthur W. Toga, Gustavo Jimenez, Michael Donohue, Devon Gessert, Kelly Harless, Jennifer Salazar, Yuliana Cabrera, Sarah Walter, Lindsey Hergesheimer, Arthur W. Toga, Karen Crawford, Scott Neu, Lon S. Schneider, Sonia Pawluczyk, Mauricio Becerra, Liberty Teodoro, Bryan M. Spann, Ronald Petersen, Clifford R. Jack, Matthew Bernstein

Medical Biophysics Publications

Alzheimer’s disease (AD) is characterized by amyloid plaques and progressive cerebral atrophy. Here, we report FAM222A as a putative brain atrophy susceptibility gene. Our cross-phenotype association analysis of imaging genetics indicates a potential link between FAM222A and AD-related regional brain atrophy. The protein encoded by FAM222A is predominantly expressed in the CNS and is increased in brains of patients with AD and in an AD mouse model. It accumulates within amyloid deposits, physically interacts with amyloid-β (Aβ) via its N-terminal Aβ binding domain, and facilitates Aβ aggregation. Intracerebroventricular infusion or forced expression of this protein exacerbates neuroinflammation and cognitive dysfunction …

Social Cognition Impairment In Genetic Frontotemporal Dementia Within The Genfi Cohort, Lucy L. Russell, Caroline V. Greaves, Martina Bocchetta, Jennifer Nicholas, Rhian S. Convery, Katrina Moore, David M. Cash, John Van Swieten, Lize Jiskoot, Fermin Moreno, Raquel Sanchez-Valle, Barbara Borroni, Robert Laforce, Mario Masellis, Maria Carmela Tartaglia, Caroline Graff, Emanuela Rotondo, Daniela Galimberti, James B. Rowe, Elizabeth Finger, Matthis Synofzik, Rik Vandenberghe, Alexandre De Mendonça, Fabrizio Tagliavini, Isabel Santana, Simon Ducharme, Chris Butler, Alex Gerhard, Johannes Levin, Adrian Danek, Markus Otto, Jason D. Warren

Medical Biophysics Publications

A key symptom of frontotemporal dementia (FTD) is difficulty interacting socially with others. Social cognition problems in FTD include impaired emotion processing and theory of mind difficulties, and whilst these have been studied extensively in sporadic FTD, few studies have investigated them in familial FTD. Facial Emotion Recognition (FER) and Faux Pas (FP) recognition tests were used to study social cognition within the Genetic Frontotemporal Dementia Initiative (GENFI), a large familial FTD cohort of C9orf72, GRN, and MAPT mutation carriers. 627 participants undertook at least one of the tasks, and were separated into mutation-negative healthy controls, presymptomatic mutation carriers (split …

Hyperpolarized Carbon-13 Magnetic Resonance Measurements Of Tissue Perfusion And Metabolism, Keith Michel

Dissertations & Theses (Open Access)

Hyperpolarized Magnetic Resonance Imaging (HP MRI) is an emerging modality that enables non-invasive interrogation of cells and tissues with unprecedented biochemical detail. This technology provides rapid imaging measurements of the activity of a small quantity of molecules with a strongly polarized nuclear magnetic moment. This polarization is created in a polarizer separate from the imaging magnet, and decays continuously towards a non-detectable thermal equilibrium once the imaging agent is removed from the polarizer and administered by intravenous injection. Specialized imaging strategies are therefore needed to extract as much information as possible from the HP signal during its limited lifetime.

In …

Optimization Of Multi-Electrode Implant Configurations And Programming For The Delivery Of Non-Ablative Electric Fields In Intratumoral Modulation Therapy., Erin Iredale, Andrew Deweyert, Douglas A Hoover, Jeff Z Chen, Susanne Schmid, Matthew O Hebb, Terry M Peters, Eugene Wong

Medical Biophysics Publications

PURPOSE: Application of low intensity electric fields to interfere with tumor growth is being increasingly recognized as a promising new cancer treatment modality. Intratumoral modulation therapy (IMT) is a developing technology that uses multiple electrodes implanted within or adjacent tumor regions to deliver electric fields to treat cancer. In this study, the determination of optimal IMT parameters was cast as a mathematical optimization problem, and electrode configurations, programming, optimization, and maximum treatable tumor size were evaluated in the simplest and easiest to understand spherical tumor model. The establishment of electrode placement and programming rules to maximize electric field tumor coverage …

Brain Metabolite Levels In Sedentary Women And Non-Contact Athletes Differ From Contact Athletes, Amy L. Schranz, Gregory A. Dekaban, Lisa Fischer, Kevin Blackney, Christy Barreira, Timothy J. Doherty, Douglas D. Fraser, Arthur Brown, Jeff Holmes, Ravi S. Menon, Robert Bartha

Medical Biophysics Publications

White matter tracts are known to be susceptible to injury following concussion. The objective of this study was to determine whether contact play in sport could alter white matter metabolite levels in female varsity athletes independent of changes induced by long-term exercise. Metabolite levels were measured by single voxel proton magnetic resonance spectroscopy (MRS) in the prefrontal white matter at the beginning (In-Season) and end (Off-Season) of season in contact (N = 54, rugby players) and non-contact (N = 23, swimmers and rowers) varsity athletes. Sedentary women (N = 23) were scanned once, at a time equivalent to the Off-Season …

Impact Of Graded Passive Cycling On Hemodynamics, Cerebral Blood Flow, And Heart Function In Healthy Adults And Septic Icu Patients, Jennifer Chen

Electronic Thesis and Dissertation Repository

Sepsis is a life-threatening dysregulation of host response to an infectious insult, which often leads to multi-organ failure. Sepsis survivors suffer from post-intensive care syndrome in part due to their prolonged bed rest and lack of mobility. Although early mobilization has been championed as a mechanism to counter the adverse effects associated with ICU immobility, due to sedation and mechanical ventilation, active early mobilization is not often administered in septic patients due to worries of hemodynamic instability and potential for inducing adverse events. Passive exercise is a mobilization modality that circumvents the need for patients to be conscious and participatory …

Neural Effects Of Oxytocin And Mimicry In Frontotemporal Dementia: A Randomized Crossover Study, Lindsay D. Oliver, Chloe Stewart, Kristy Coleman, James H. Kryklywy, Robert Bartha, Derek G.V. Mitchell, Elizabeth C. Finger

Medical Biophysics Publications

OBJECTIVE: To determine whether intranasal oxytocin, alone or in combination with instructed mimicry of facial expressions, would augment neural activity in patients with frontotemporal dementia (FTD) in brain regions associated with empathy, emotion processing, and the simulation network, as indexed by blood oxygen-level dependent (BOLD) signal during fMRI. METHODS: In a placebo-controlled, randomized crossover design, 28 patients with FTD received 72 IU intranasal oxytocin or placebo and then completed an fMRI facial expression mimicry task. RESULTS: Oxytocin alone and in combination with instructed mimicry increased activity in regions of the simulation network and in limbic regions associated with emotional expression …