Medicine and Health Sciences Commons^™

Pulmonary Imaging To Better Understand Asthma, Sarah Svenningsen

Electronic Thesis and Dissertation Repository

Asthma is characterized using the spirometry measurement of the forced expiratory volume in one second (FEV₁). Simple and inexpensive, FEV₁ provides a global estimate of lung function but this metric cannot regionally identify airways responsible for airflow limitation, asthma symptoms or control. Work that brought about an understanding that airway abnormalities are heterogeneously distributed within the lung in asthma patients has motivated the development of pulmonary imaging approaches, such as hyperpolarized helium-3 (³He) and xenon-129 (¹²⁹Xe) magnetic resonance imaging (MRI). These methods provide a way to visualize and quantify lung regions accessed by …

Dual Optimization Method Of Radiofrequency And Quasistatic Field Simulations For Reduction Of Eddy Currents Generated On 7t Radiofrequency Coil Shielding., Yujuan Zhao, Tiejun Zhao, Shailesh B Raval, Narayanan Krishnamurthy, Hai Zheng, Chad T Harris, William B Handler, Blaine A Chronik, Tamer S Ibrahim

Brain and Mind Institute Researchers' Publications

PURPOSE: To optimize the design of radiofrequency (RF) shielding of transmit coils at 7T and reduce eddy currents generated on the RF shielding when imaging with rapid gradient waveforms.

METHODS: One set of a four-element, 2 × 2 Tic-Tac-Toe head coil structure was selected and constructed to study eddy currents on the RF coil shielding. The generated eddy currents were quantitatively studied in the time and frequency domains. The RF characteristics were studied using the finite difference time domain method. Five different kinds of RF shielding were tested on a 7T MRI scanner with phantoms and in vivo human subjects. …

Preserved Haptic Shape Processing After Bilateral Loc Lesions., Jacqueline C Snow, Melvyn A Goodale, Jody C Culham

Brain and Mind Institute Researchers' Publications

UNLABELLED: The visual and haptic perceptual systems are understood to share a common neural representation of object shape. A region thought to be critical for recognizing visual and haptic shape information is the lateral occipital complex (LOC). We investigated whether LOC is essential for haptic shape recognition in humans by studying behavioral responses and brain activation for haptically explored objects in a patient (M.C.) with bilateral lesions of the occipitotemporal cortex, including LOC. Despite severe deficits in recognizing objects using vision, M.C. was able to accurately recognize objects via touch. M.C.'s psychophysical response profile to haptically explored shapes was also …

Maternal Postsecondary Education Associated With Improved Cerebellar Growth After Preterm Birth., Mikaela L Stiver, Daphne Kamino, Ting Guo, Angela Thompson, Emma G Duerden, Margot J Taylor, Emily W Y Tam

Brain and Mind Institute Researchers' Publications

The preterm cerebellum is vulnerable to impaired development impacting long-term outcome. Preterm newborns (<32 >weeks) underwent serial magnetic resonance imaging (MRI) scans. The association between parental education and cerebellar volume at each time point was assessed, adjusting for age at scan. In 26 infants, cerebellar volumes at term (P = .001), but not birth (P = .4), were associated with 2-year volumes. For 1 cm(3) smaller cerebellar volume (4% total volume) at term, the cerebellum was 3.18 cm(3) smaller (3% total volume) by 2 years. Maternal postsecondary education was not associated with cerebellar volume at term (P = .16). Maternal …

Investigation Of Endogenous In-Vivo Sodium Concentration In Human Prostate Cancer Measured With 23na Magnetic Resonance Imaging, Justin C. Peterson

Electronic Thesis and Dissertation Repository

Prostate cancer (PCa) is the most common malignancy in men. Aggressive prostate tumours must be identified, differentiated from indolent tumours, and treated to ensure survival of the patient. Currently, clinicians use a combination of multi-parametric magnetic resonance imaging (mpMRI) contrasts to improve PCa detection. While these techniques provide very good spatial resolution, the specificity is often insufficient to unequivocally identify malignant lesions.

Utilizing specialized MRI hardware developed for sensitive in-vivo detection of sodium, this work has investigated differences in sodium concentration between healthy and malignant prostate tissue. Patients with biopsy-proven PCa underwent conventional mpMRI and sodium MRI followed by radical …

Copd: Do Imaging Measurements Of Emphysema And Airway Disease Explain Symptoms And Exercise Capacity?, Miranda Kirby, Damien Pike, Don D Sin, Harvey O Coxson, David G Mccormack, Grace Parraga

Medical Biophysics Publications

PURPOSE: To determine the role of imaging measurements of emphysema and airway disease in determining chronic obstructive pulmonary disease (COPD) symptoms and exercise limitation in patients with COPD, particularly in patients with mild-to-moderate disease.

MATERIALS AND METHODS: Participants (n = 116) with Global Initiative for Chronic Obstructive Lung Disease (GOLD) grade U (unclassified) or grade I-IV COPD provided informed consent to an ethics board-approved HIPAA-compliant protocol and underwent spirometry and plethysmography, completed the St George's Respiratory Questionnaire (SGRQ), completed a 6-minute walk test for the 6-minute walk distance (6MWD), and underwent hyperpolarized helium 3 ((3)He) magnetic resonance (MR) imaging and …

Hand Use Predicts The Structure Of Representations In Sensorimotor Cortex., Naveed Ejaz, Masashi Hamada, Jörn Diedrichsen

Brain and Mind Institute Researchers' Publications

Fine finger movements are controlled by the population activity of neurons in the hand area of primary motor cortex. Experiments using microstimulation and single-neuron electrophysiology suggest that this area represents coordinated multi-joint, rather than single-finger movements. However, the principle by which these representations are organized remains unclear. We analyzed activity patterns during individuated finger movements using functional magnetic resonance imaging (fMRI). Although the spatial layout of finger-specific activity patterns was variable across participants, the relative similarity between any pair of activity patterns was well preserved. This invariant organization was better explained by the correlation structure of everyday hand movements than …

Changes In Visual And Sensory-Motor Resting-State Functional Connectivity Support Motor Learning By Observing., Heather R Mcgregor, Paul L Gribble

Brain and Mind Institute Researchers' Publications

Motor learning occurs not only through direct first-hand experience but also through observation (Mattar AA, Gribble PL. Neuron 46: 153-160, 2005). When observing the actions of others, we activate many of the same brain regions involved in performing those actions ourselves (Malfait N, Valyear KF, Culham JC, Anton JL, Brown LE, Gribble PL. J Cogn Neurosci 22: 1493-1503, 2010). Links between neural systems for vision and action have been reported in neurophysiological (Strafella AP, Paus T. Neuroreport 11: 2289-2292, 2000; Watkins KE, Strafella AP, Paus T. Neuropsychologia 41: 989-994, 2003), brain imaging (Buccino G, Binkofski F, Fink GR, Fadiga L, …

Fusion Analysis Of Functional Mri Data For Classification Of Individuals Based On Patterns Of Activation., Mahdi Ramezani, Purang Abolmaesumi, Kris Marble, Heather Trang, Ingrid Johnsrude

Brain and Mind Institute Researchers' Publications

Classification of individuals based on patterns of brain activity observed in functional MRI contrasts may be helpful for diagnosis of neurological disorders. Prior work for classification based on these patterns have primarily focused on using a single contrast, which does not take advantage of complementary information that may be available in multiple contrasts. Where multiple contrasts are used, the objective has been only to identify the joint, distinct brain activity patterns that differ between groups of subjects; not to use the information to classify individuals. Here, we use joint Independent Component Analysis (jICA) within a Support Vector Machine (SVM) classification …

Validation Of In Vivo 2d Displacements From Spiral Cine Dense At 3t, Gregory J. Wehner, Jonathan D. Suever, Christopher M. Haggerty, Linyuan Jing, David K. Powell, Sean M. Hamlet, Jonathan D. Grabau, Walter Dimitri Mojsejenko, Xiaodong Zhong, Frederick H. Epstein, Brandon K. Fornwalt

Saha Cardiovascular Research Center Faculty Publications

BACKGROUND: Displacement Encoding with Stimulated Echoes (DENSE) encodes displacement into the phase of the magnetic resonance signal. Due to the stimulated echo, the signal is inherently low and fades through the cardiac cycle. To compensate, a spiral acquisition has been used at 1.5T. This spiral sequence has not been validated at 3T, where the increased signal would be valuable, but field inhomogeneities may result in measurement errors. We hypothesized that spiral cine DENSE is valid at 3T and tested this hypothesis by measuring displacement errors at both 1.5T and 3T in vivo.

METHODS: Two-dimensional spiral cine DENSE and tagged …

High-Field Functional Imaging Of Pitch Processing In Auditory Cortex Of The Cat., Blake E. Butler, Amee J Hall, Stephen G Lomber

Brain and Mind Institute Researchers' Publications

The perception of pitch is a widely studied and hotly debated topic in human hearing. Many of these studies combine functional imaging techniques with stimuli designed to disambiguate the percept of pitch from frequency information present in the stimulus. While useful in identifying potential "pitch centres" in cortex, the existence of truly pitch-responsive neurons requires single neuron-level measures that can only be undertaken in animal models. While a number of animals have been shown to be sensitive to pitch, few studies have addressed the location of cortical generators of pitch percepts in non-human models. The current study uses high-field functional …

Automatic Segmentation Of The Hippocampus For Preterm Neonates From Early-In-Life To Term-Equivalent Age., Ting Guo, Julie L Winterburn, Jon Pipitone, Emma G Duerden, Min Tae M Park, Vann Chau, Kenneth J Poskitt, Ruth E Grunau, Anne Synnes, Steven P Miller, M Mallar Chakravarty

Brain and Mind Institute Researchers' Publications

INTRODUCTION: The hippocampus, a medial temporal lobe structure central to learning and memory, is particularly vulnerable in preterm-born neonates. To date, segmentation of the hippocampus for preterm-born neonates has not yet been performed early-in-life (shortly after birth when clinically stable). The present study focuses on the development and validation of an automatic segmentation protocol that is based on the MAGeT-Brain (Multiple Automatically Generated Templates) algorithm to delineate the hippocampi of preterm neonates on their brain MRIs acquired at not only term-equivalent age but also early-in-life.

METHODS: First, we present a three-step manual segmentation protocol to delineate the hippocampus for preterm …

Fusion Analysis Of First Episode Depression: Where Brain Shape Deformations Meet Local Composition Of Tissue., Mahdi Ramezani, Purang Abolmaesumi, Amir Tahmasebi, Rachael Bosma, Ryan Tong, Tom Hollenstein, Kate Harkness, Ingrid Johnsrude

Brain and Mind Institute Researchers' Publications

Computational neuroanatomical techniques that are used to evaluate the structural correlates of disorders in the brain typically measure regional differences in gray matter or white matter, or measure regional differences in the deformation fields required to warp individual datasets to a standard space. Our aim in this study was to combine measurements of regional tissue composition and of deformations in order to characterize a particular brain disorder (here, major depressive disorder). We use structural Magnetic Resonance Imaging (MRI) data from young adults in a first episode of depression, and from an age- and sex-matched group of non-depressed individuals, and create …

Prolonged In Vivo Retention Of A Cathepsin D Targeted Optical Contrast Agent In A Mouse Model Of Alzheimer's Disease., Jonatan A Snir, Mojmir Suchy, Keith St Lawrence, Robert H E Hudson, Stephen H Pasternak, Robert Bartha

Brain and Mind Institute Researchers' Publications

BACKGROUND: Cathepsin D (CatD) is a lysosomal protease that is elevated early in Alzheimer's disease (AD). We have previously developed a Targeted contrast agent (CA) to detect CatD activity in vivo, consisting of a magnetic resonance imaging/fluorescent moiety linked to a cell penetrating peptide (CPP) by means of a CatD cleavage site and have demonstrated its uptake in the brain of an AD mouse model.

OBJECTIVE: The purpose of this study was to characterize the in vivo retention of a near infra-red fluorescent dye labeled version of this CA.

METHODS: Six adult C57Bl/6 wild-type mice and six adult 5XFAD transgenic …