Medicine and Health Sciences Commons^™

Multi-Nuclear Magnetic Resonance Imaging Of Obstructive Lung Disease, Khadija Sheikh

Electronic Thesis and Dissertation Repository

Obstructive lung diseases such as chronic-obstructive-lung-disease (COPD), bronchiectasis, and asthma are characterized by airflow obstruction. They affect over six million Canadians costing the economy $12 billion/year. Despite decades of research, therapies that modify obstructive-lung-disease progression and control are lacking because patient diagnosis, monitoring, and response to therapy are currently made using airflow measurements that may conceal the independent contributions of underlying pathologies. One goal of obstructive-lung-disease research is to develop ways to identify patients with specific underlying pathological phenotypes to improve patient care and outcomes. Thoracic computed-tomography (CT) and magnetic-resonance-imaging (MRI) provide ways to regionally identify the underlying pathologies associated …

Resting-State Network-Specific Breakdown Of Functional Connectivity During Ketamine Alteration Of Consciousness In Volunteers., Vincent Bonhomme, Audrey Vanhaudenhuyse, Athena Demertzi, Marie-Aurélie Bruno, Oceane Jaquet, Mohamed Ali Bahri, Alain Plenevaux, Melanie Boly, Pierre Boveroux, Andrea Soddu, Jean François Brichant, Pierre Maquet, Steven Laureys

Brain and Mind Institute Researchers' Publications

BACKGROUND: Consciousness-altering anesthetic agents disturb connectivity between brain regions composing the resting-state consciousness networks (RSNs). The default mode network (DMn), executive control network, salience network (SALn), auditory network, sensorimotor network (SMn), and visual network sustain mentation. Ketamine modifies consciousness differently from other agents, producing psychedelic dreaming and no apparent interaction with the environment. The authors used functional magnetic resonance imaging to explore ketamine-induced changes in RSNs connectivity.

METHODS: Fourteen healthy volunteers received stepwise intravenous infusions of ketamine up to loss of responsiveness. Because of agitation, data from six subjects were excluded from analysis. RSNs connectivity was compared between absence of …

Usage Of Swi (Susceptibility Weighted Imaging) Acquired At 7t For Qualitative Evaluation Of Temporal Lobe Epilepsy Patients With Histopathological And Clinical Correlation: An Initial Pilot Study., Benjamin Y M Kwan, Fateme Salehi, Pavlo Ohorodnyk, Donald H Lee, Jorge G Burneo, Seyed M Mirsattari, David Steven, Robert Hammond, Terry M Peters, Ali R Khan

Brain and Mind Institute Researchers' Publications

OBJECTIVES: Ultra high field MRI at 7T is able to provide much improved spatial and contrast resolution which may aid in the diagnosis of hippocampal abnormalities. This paper presents a preliminary experience on qualitative evaluation of 7T MRI in temporal lobe epilepsy patients with a focus on comparison to histopathology.

METHODS: 7T ultra high field MRI data, using T1-weighted, T2*-weighted and susceptibility-weighted images (SWI), were acquired for 13 patients with drug resistant temporal lobe epilepsy (TLE) during evaluation for potential epilepsy surgery. Qualitative evaluation of the imaging data for scan quality and presence of hippocampal and temporal lobe abnormalities were …

Maternal Nutrient Restriction With Fetal Growth Restriction In Guinea Pigs Impacts Brain Development And Neuroimaging Correlates In Neonatal Offspring, Catherine Nevin

Electronic Thesis and Dissertation Repository

Aberrant brain development in utero accompanied by fetal growth restriction (FGR) increases the risk of neurodevelopmental disorders in later life. However there are limited non-invasive biomarkers in the brain for the early identification of said neurodevelopmental disorders in an animal model of FGR. Guinea pig sows were fed either ad libitum (Control) or 70% of the control diet pre-pregnancy, increasing to 90% at mid-pregnancy (MNR) creating appropriately grown (AGA) Control and FGR-MNR neonates, respectively. Three to four weeks corrected post-natal age, neonates were imaged using magnetic resonance imaging (MRI) and spectroscopy (MRS) techniques, and were killed 48-72 hours later for …

Unravelling The Subfields Of The Hippocampal Head Using 7-Tesla Structural Mri, Jordan M. K. Dekraker

Electronic Thesis and Dissertation Repository

Probing the functions of human hippocampal subfields is a promising area of research in cognitive neuroscience. However, defining subfield borders in Magnetic Resonance Imaging (MRI) is challenging. Here, we present a user-guided, semi-automated protocol for segmenting hippocampal subfields on T2-weighted images obtained with 7-Tesla MRI. The protocol takes advantage of extant knowledge about regularities in hippocampal morphology and ontogeny that have not been systematically considered in prior related work. An image feature known as the hippocampal ‘dark band’ facilitates tracking of subfield continuities, allowing for unfolding and segmentation of convoluted hippocampal tissue. Initial results suggest that this protocol offers sufficient …

Hyperpolarized 3he Magnetic Resonance Imaging Phenotypes Of Chronic Obstructive Pulmonary Disease, Damien Pike

Electronic Thesis and Dissertation Repository

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the world. Identifying clinically relevant COPD phenotypes has the potential to reduce the global burden of COPD by helping to alleviate symptoms, slow disease progression and prevent exacerbation by stratifying patient cohorts and forming targeted treatment plans. In this regard, quantitative pulmonary imaging with hyperpolarized 3He magnetic resonance imaging (MRI) and thoracic computed tomography (CT) have emerged as ways to identify and measure biomarkers of lung structure and function. 3He MRI may be used as a tool to probe both functional and structural properties of the lung …

Cerebral Functional Connectivity Periodically (De)Synchronizes With Anatomical Constraints., Raphaël Liégeois, Erik Ziegler, Christophe Phillips, Pierre Geurts, Francisco Gómez, Mohamed Ali Bahri, B T Thomas Yeo, Andrea Soddu, Audrey Vanhaudenhuyse, Steven Laureys, Rodolphe Sepulchre

Brain and Mind Institute Researchers' Publications

This paper studies the link between resting-state functional connectivity (FC), measured by the correlations of fMRI BOLD time courses, and structural connectivity (SC), estimated through fiber tractography. Instead of a static analysis based on the correlation between SC and FC averaged over the entire fMRI time series, we propose a dynamic analysis, based on the time evolution of the correlation between SC and a suitably windowed FC. Assessing the statistical significance of the time series against random phase permutations, our data show a pronounced peak of significance for time window widths around 20-30 TR (40-60 s). Using the appropriate window …

Hyperpolarized 3he Magnetic Resonance Imaging Ventilation Defects In Asthma: Relationship To Airway Mechanics, Del Leary, Sarah Svenningsen, Fumin Guo, Swati Bhatawadekar, Grace Parraga, Geoffrey N Maksym

Medical Biophysics Publications

In patients with asthma, magnetic resonance imaging (MRI) provides direct measurements of regional ventilation heterogeneity, the etiology of which is not well-understood, nor is the relationship of ventilation abnormalities with lung mechanics. In addition, respiratory resistance and reactance are often abnormal in asthmatics and the frequency dependence of respiratory resistance is thought to reflect ventilation heterogeneity. We acquiredMRIventilation defect maps, forced expiratory volume in one-second (FEV1), and airways resistance (Raw) measurements, and used a computational airway model to explore the relationship of ventilation defect percent (VDP) with simulated measurements of respiratory system resistance (Rrs) and reactance (Xrs).MRIventilation defect maps were …

Propofol-Induced Frontal Cortex Disconnection: A Study Of Resting-State Networks, Total Brain Connectivity, And Mean Bold Signal Oscillation Frequencies., Pieter Guldenmund, Ithabi S Gantner, Katherine Baquero, Tushar Das, Athena Demertzi, Pierre Boveroux, Vincent Bonhomme, Audrey Vanhaudenhuyse, Marie-Aurélie Bruno, Olivia Gosseries, Quentin Noirhomme, Muriëlle Kirsch, Mélanie Boly, Adrian M Owen, Steven Laureys, Francisco Gómez, Andrea Soddu

Brain and Mind Institute Researchers' Publications

Propofol is one of the most commonly used anesthetics in the world, but much remains unknown about the mechanisms by which it induces loss of consciousness. In this resting-state functional magnetic resonance imaging study, we examined qualitative and quantitative changes of resting-state networks (RSNs), total brain connectivity, and mean oscillation frequencies of the regional blood oxygenation level-dependent (BOLD) signal, associated with propofol-induced mild sedation and loss of responsiveness in healthy subjects. We found that detectability of RSNs diminished significantly with loss of responsiveness, and total brain connectivity decreased strongly in the frontal cortex, which was associated with increased mean oscillation …

In Vivo Mri Signatures Of Hippocampal Subfield Pathology In Intractable Epilepsy., Maged Goubran, Boris C Bernhardt, Diego Cantor-Rivera, Jonathan C Lau, Charlotte Blinston, Robert R Hammond, Sandrine De Ribaupierre, Jorge G Burneo, Seyed M Mirsattari, David A Steven, Andrew G Parrent, Andrea Bernasconi, Neda Bernasconi, Terry M Peters, Ali R Khan

Brain and Mind Institute Researchers' Publications

OBJECTIVES: Our aim is to assess the subfield-specific histopathological correlates of hippocampal volume and intensity changes (T1, T2) as well as diff!usion MRI markers in TLE, and investigate the efficacy of quantitative MRI measures in predicting histopathology in vivo.

EXPERIMENTAL DESIGN: We correlated in vivo volumetry, T2 signal, quantitative T1 mapping, as well as diffusion MRI parameters with histological features of hippocampal sclerosis in a subfield-specific manner. We made use of on an advanced co-registration pipeline that provided a seamless integration of preoperative 3 T MRI with postoperative histopathological data, on which metrics of cell loss and gliosis were quantitatively …

Pulmonary Ct And Mri Phenotypes That Help Explain Chronic Pulmonary Obstruction Disease Pathophysiology And Outcomes, Eric A Hoffman, David A Lynch, R Graham Barr, Edwin J R Van Beek, Grace Parraga

Medical Biophysics Publications

Pulmonary x-ray computed tomographic (CT) and magnetic resonance imaging (MRI) research and development has been motivated, in part, by the quest to subphenotype common chronic lung diseases such as chronic obstructive pulmonary disease (COPD). For thoracic CT and MRI, the main COPD research tools, disease biomarkers are being validated that go beyond anatomy and structure to include pulmonary functional measurements such as regional ventilation, perfusion, and inflammation. In addition, there has also been a drive to improve spatial and contrast resolution while at the same time reducing or eliminating radiation exposure. Therefore, this review focuses on our evolving understanding of …

Planning Ahead: Object-Directed Sequential Actions Decoded From Human Frontoparietal And Occipitotemporal Networks., Jason P Gallivan, Ingrid S Johnsrude, J Randall Flanagan

Brain and Mind Institute Researchers' Publications

Object-manipulation tasks (e.g., drinking from a cup) typically involve sequencing together a series of distinct motor acts (e.g., reaching toward, grasping, lifting, and transporting the cup) in order to accomplish some overarching goal (e.g., quenching thirst). Although several studies in humans have investigated the neural mechanisms supporting the planning of visually guided movements directed toward objects (such as reaching or pointing), only a handful have examined how manipulatory sequences of actions-those that occur after an object has been grasped-are planned and represented in the brain. Here, using event-related functional MRI and pattern decoding methods, we investigated the neural basis of …

This Is What Copd Looks Like, Khadija Sheikh, Harvey O Coxson, Grace Parraga

Medical Biophysics Publications

Despite decades of research, and the growing healthcare and societal burden of chronic obstructive pulmonary disease (COPD), therapeutic COPD breakthroughs have not occurred. Sub-optimal COPD patient phenotyping, an incomplete understanding of COPD pathogenesis and a scarcity of sensitive tools that provide patient-relevant intermediate endpoints likely all play a role in the lack of new, efficacious COPD interventions. In other words, COPD patients are still diagnosed based on the presence of persistent airflow limitation measured using spirometry. Spirometry measurements reflect the global sum of all the different possible COPD pathologies and perhaps because of this, we lose sight of the different …

A Selective Impairment Of Perception Of Sound Motion Direction In Peripheral Space: A Case Study., Lore Thaler, Joseph Paciocco, Mark Daley, Gabriella D Lesniak, David W Purcell, J Alexander Fraser, Gordon N Dutton, Stephanie Rossit, Melvyn A Goodale, Jody C Culham

Brain and Mind Institute Researchers' Publications

It is still an open question if the auditory system, similar to the visual system, processes auditory motion independently from other aspects of spatial hearing, such as static location. Here, we report psychophysical data from a patient (female, 42 and 44 years old at the time of two testing sessions), who suffered a bilateral occipital infarction over 12 years earlier, and who has extensive damage in the occipital lobe bilaterally, extending into inferior posterior temporal cortex bilaterally and into right parietal cortex. We measured the patient's spatial hearing ability to discriminate static location, detect motion and perceive motion direction in …

Pulmonary Imaging Biomarkers Of Gas Trapping And Emphysema In Copd: (3)He Mr Imaging And Ct Parametric Response Maps, Dante P I Capaldi, Nanxi Zha, Fumin Guo, Damien Pike, David G Mccormack, Miranda Kirby, Grace Parraga

Medical Biophysics Publications

PURPOSE: To directly compare magnetic resonance (MR) imaging and computed tomography (CT) parametric response map (PRM) measurements of gas trapping and emphysema in ex-smokers both with and without chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS: Participants provided written informed consent to a protocol that was approved by a local research ethics board and Health Canada and was compliant with the HIPAA (Institutional Review Board Reg. #00000940). The prospectively planned study was performed from March 2014 to December 2014 and included 58 ex-smokers (mean age, 73 years ± 9) with (n = 32; mean age, 74 years ± 7) and …

Structural Brain Injury In Patients With Disorders Of Consciousness: A Voxel-Based Morphometry Study., Pieter Guldenmund, Andrea Soddu, Katherine Baquero, Audrey Vanhaudenhuyse, Marie-Aurélie Bruno, Olivia Gosseries, Steven Laureys, Francisco Gómez

Brain and Mind Institute Researchers' Publications

MAIN OBJECTIVE: Disorders of consciousness (DOC; encompassing coma, vegetative state/unresponsive wakefulness syndrome (VS/UWS) and minimally conscious state minus/plus (MCS-/+)) are associated with structural brain injury. The extent of this damage remains poorly understood and merits a detailed examination using novel analysis techniques. Research design/methods and procedures: This study used voxel-based morphometry (VBM) on structural magnetic resonance imaging scans of 61 patients with DOC to examine grey and white matter injury associated with DOC, time spent in DOC, aetiology and diagnosis.

MAIN OUTCOMES AND RESULTS: DOC and time spent in DOC were found to be associated with widespread structural brain injury, …

Correlation Between Resting State Fmri Total Neuronal Activity And Pet Metabolism In Healthy Controls And Patients With Disorders Of Consciousness., Andrea Soddu, Francisco Gómez, Lizette Heine, Carol Di Perri, Mohamed Ali Bahri, Henning U Voss, Marie-Aurélie Bruno, Audrey Vanhaudenhuyse, Christophe Phillips, Athena Demertzi, Camille Chatelle, Jessica Schrouff, Aurore Thibaut, Vanessa Charland-Verville, Quentin Noirhomme, Eric Salmon, Jean-Flory Luaba Tshibanda, Nicholas D Schiff, Steven Laureys

Brain and Mind Institute Researchers' Publications

INTRODUCTION: The mildly invasive 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is a well-established imaging technique to measure 'resting state' cerebral metabolism. This technique made it possible to assess changes in metabolic activity in clinical applications, such as the study of severe brain injury and disorders of consciousness.

OBJECTIVE: We assessed the possibility of creating functional MRI activity maps, which could estimate the relative levels of activity in FDG-PET cerebral metabolic maps. If no metabolic absolute measures can be extracted, our approach may still be of clinical use in centers without access to FDG-PET. It also overcomes the problem of recognizing individual …

Design And Evaluation Of An Mri-Compatible Linear Motion Stage., Mohammad Ali Tavallaei, Patricia M Johnson, Junmin Liu, Maria Drangova

Medical Biophysics Publications

PURPOSE: To develop and evaluate a tool for accurate, reproducible, and programmable motion control of imaging phantoms for use in motion sensitive magnetic resonance imaging (MRI) appli cations.

METHODS: In this paper, the authors introduce a compact linear motion stage that is made of nonmagnetic material and is actuated with an ultrasonic motor. The stage can be positioned at arbitrary positions and orientations inside the scanner bore to move, push, or pull arbitrary phantoms. Using optical trackers, measuring microscopes, and navigators, the accuracy of the stage in motion control was evaluated. Also, the effect of the stage on image signal-to-noise …