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Hyperpolarized And Inert Gas Mri

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Hyperpolarized and Inert Gas MRI

Hyperpolarized and Inert Gas MRI Book
Author : Mitchell Albert
Publisher : Academic Press
Release : 2016-10-01
ISBN : 9780128036754
Language : En, Es, Fr & De

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Book Description :

"Hyperpolarized and Inert Gas MRI: Theory and Applications in Research and Medicine" is the first comprehensive volume published on HP gas MRI. Since the 1990 s, when HP gas MRI was invented by Dr. Albert and his colleagues, the HP gas MRI field has grown dramatically. The technique has proven to be a useful tool for diagnosis, disease staging, and therapy evaluation for obstructive lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. HP gas MRI has also been developed for functional imaging of the brain and is presently being developed for molecular imaging, including molecules associated with lung cancer, breast cancer, and Alzheimer s disease. Taking into account the ongoing growth of this field and the potential for future clinical applications, the book pulls together the most relevant and cutting-edge research available in HP gas MRI into one resource. Presents the most comprehensive, relevant, and accurate information on HP gas MRICo-edited by the inventor of HP gas MRI, Dr. Albert, with chapter authors who are the leading experts in their respective sub-disciplinesServes as a foundation of understanding of HP gas MRI for researchers and clinicians involved in research, technology development, and clinical use with HP gas MRICovers all hyperpolarized gases, including helium, the gas with which the majority of HP gas MRI has been conducted"

Hyperpolarized and Inert Gas MRI

Hyperpolarized and Inert Gas MRI Book
Author : Mitchell S. Albert,Francis T Hane
Publisher : Academic Press
Release : 2016-11-17
ISBN : 0128037040
Language : En, Es, Fr & De

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Book Description :

Hyperpolarized and Inert Gas MRI: Theory and Applications in Research and Medicine is the first comprehensive volume published on HP gas MRI. Since the 1990’s, when HP gas MRI was invented by Dr. Albert and his colleagues, the HP gas MRI field has grown dramatically. The technique has proven to be a useful tool for diagnosis, disease staging, and therapy evaluation for obstructive lung diseases, including asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis. HP gas MRI has also been developed for functional imaging of the brain and is presently being developed for molecular imaging, including molecules associated with lung cancer, breast cancer, and Alzheimer’s disease. Taking into account the ongoing growth of this field and the potential for future clinical applications, the book pulls together the most relevant and cutting-edge research available in HP gas MRI into one resource. Presents the most comprehensive, relevant, and accurate information on HP gas MRI Co-edited by the co-inventor of HP gas MRI, Dr. Albert, with chapter authors who are the leading experts in their respective sub-disciplines Serves as a foundation of understanding of HP gas MRI for researchers and clinicians involved in research, technology development, and clinical use with HP gas MRI Covers all hyperpolarized gases, including helium, the gas with which the majority of HP gas MRI has been conducted

Investigation of Lung Structure function Relationships Using Hyperpolarized Noble Gases

Investigation of Lung Structure function Relationships Using Hyperpolarized Noble Gases Book
Author : Robert P. Thomen
Publisher : Unknown
Release : 2016
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Magnetic Resonance Imaging (MRI) is an application of the nuclear magnetic resonance (NMR) phenomenon to non-invasively generate 3D tomographic images. MRI is an emerging modality for the lung, but it suffers from low sensitivity due to inherent low tissue density and short T2*. Hyperpolarization is a process by which the nuclear contribution to NMR signal is greatly enhanced to more than 100,000 times that of samples in thermal equilibrium. The noble gases 3He and 129Xe are most often hyperpolarized by transfer of light angular momentum through the electron of a vaporized alkali metal to the noble gas nucleus (called Spin Exchange Optical Pumping). The enhancement in NMR signal is so great that the gas itself can be imaged via MRI, and because noble gases are chemically inert, they can be safely inhaled by a subject, and the gas distribution within the interior of the lung can be imaged. The mechanics of respiration is an elegant physical process by which air is is brought into the distal airspaces of the lungs for oxygen/carbon dioxide gas exchange with blood. Therefore proper description of lung function is intricately related to its physical structure, and the basic mechanical operation of healthy lungs -- from pressure driven airflow, to alveolar airspace gas kinetics, to gas exchange by blood/gas concentration gradients, to elastic contraction of parenchymal tissue -- is a process decidedly governed by the laws of physics. This dissertation will describe experiments investigating the relationship of lung structure and function using hyperpolarized (HP) noble gas MRI. In particular HP gases will be applied to the study of several pulmonary diseases each of which demonstrates unique structure-function abnormalities: asthma, cystic fibrosis, and chronic obstructive pulmonary disease. Successful implementation of an HP gas acquisition protocol for pulmonary studies is an involved and stratified undertaking which requires a solid theoretical foundation in NMR and hyperpolarization theory, construction of dedicated hardware, development of dedicated software, and appropriate image analysis techniques for all acquired data. The author has been actively involved in each of these and has dedicated specific chapters of this dissertation to their description. First, a brief description of lung structure-function investigations and pulmonary imaging will be given (chapter 1). Brief discussions of basic NMR, MRI, and hyperpolarization theory will be given (chapters 2 and 3) followed by their particular methods of implementation in this work (chapters 4 and 5). Analysis of acquired HP gas images will be discussed (chapter 6), and the investigational procedures and results for each lung disease examined will be detailed (chapter 7). Finally, a quick digression on the strengths and limitations of HP gas MRI will be provided (chapter 8).

Apparatus for Preparing a Solution of a Hyperpolarized Noble Gas for NMR and MRI Analysis

Apparatus for Preparing a Solution of a Hyperpolarized Noble Gas for NMR and MRI Analysis Book
Author : Anonim
Publisher : Unknown
Release : 2008
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

NMR MRI with Hyperpolarized Gas and High Tc SQUID

NMR MRI with Hyperpolarized Gas and High Tc SQUID  Book
Author : Anonim
Publisher : Unknown
Release : 2000
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

A method and apparatus for the detection of nuclear magnetic resonance (NMR) signals and production of magnetic resonance imaging (MRI) from samples combines the use of hyperpolarized inert gases to enhance the NMR signals from target nuclei in a sample and a high critical temperature (Tc) superconducting quantum interference device (SQUID) to detect the NMR signals. The system operates in static magnetic fields of 3 mT or less (down to 0.1 mT), and at temperatures from liquid nitrogen (77K) to room temperature. Sample size is limited only by the size of the magnetic field coils and not by the detector. The detector is a high Tc SQUID magnetometer designed so that the SQUID detector can be very close to the sample, which can be at room temperature.

Hyperpolarized Noble Gas Magnetic Resonance Imaging and Dynamic Spectroscopy for Investigation of Rat Models of Lung Inflammation

Hyperpolarized Noble Gas Magnetic Resonance Imaging and Dynamic Spectroscopy for Investigation of Rat Models of Lung Inflammation Book
Author : Matthew Stephen Fox
Publisher : Unknown
Release : 2012
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Imaging of the lungs using non-ionizing approaches such as hyperpolarized 3He and 129Xe magnetic resonance imaging (MRI) is a useful tool both for research and clinical applications. This work focused on development of 129Xe MRI techniques to investigate inflammation in rat lungs. A rodent model of inflammation, specifically radiationinduced lung injury (RILI) was developed using a collimated 60Co source. A quantitative MRI technique measuring absolute ventilated lung volume (values obtained from rats using the previously established 3He method and those obtained with 129Xe, the usefulness of 129Xe for future investigations of.

Hyperpolarized Noble Gas Magnetic Resonance Imaging of the Ex Vivo Rodent Lung

Hyperpolarized Noble Gas Magnetic Resonance Imaging of the Ex Vivo Rodent Lung Book
Author : D. M. L. Lilburn
Publisher : Unknown
Release : 2015
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Hyperpolarized Noble Gas Magnetic Resonance Imaging of the Ex Vivo Rodent Lung book written by D. M. L. Lilburn, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Pulmonary Structure and Function in Chronic Obstructive Pulmonary Disease Evaluated Using Hyperpolarized Noble Gas Magnetic Resononance Imaging

Pulmonary Structure and Function in Chronic Obstructive Pulmonary Disease Evaluated Using Hyperpolarized Noble Gas Magnetic Resononance Imaging Book
Author : Miranda Kirby
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Chronic obstructive pulmonary disease (COPD) is the 4th leading cause of death worldwide and accounts for the highest rate of hospital admission s in Canada . The need for sensitive regional and surrogate measurements of lung structure and function in COPD continues to motivate the development of non-radiation based and sensitive imaging approaches, such as hyperpolarized helium-3 (3 He) and xenon-129 (129 Xe) magnetic resonance imaging (MRI). The static ventilation images acquired using these approaches allows us to directly visualize lung regions accessed by the hyperpolarized gas during a breath-hold, as well as quantify the regions without signal referred to as the percentage of the thoracic cavity occupied by ventilation defects (VDP). The lung micro-structure can also be probed using diffusion-weighted imaging which takes advantage of the rapid diffusion of 3 He and 129 Xe atoms to generate surrogate measurements of alveolar size, referred to as the apparent diffusion coefficient (ADC). Here we evaluated COPD lung structure and function using hyperpolarized gas MRI measurements longitudinally, following treatment and in early disease. In COPD ex-smokers, we demonstrated 3 He VDP and ADC worsened significantly in only 2 years although there was no change in age-matched healthy volunteers, suggestive of disease progression. We also evaluated COPD ex-smokers pre - and post - bronchodilator and showed regional improvements in gas distribution following bronchodilator therapy regardless of spirometry-based responder classification ; the ADC measured in these same COPD ex-smokers also revealed significant reductions in regional gas trapping post-bronchodilator. Although 3 He MRI has been more widely used, the limited global quantities necessitates the transition to hyperpo larized 129 Xe, and therefore we directly compared 3 He and 129 Xe MRI in the same COPD ex - smokers and showed significantly greater gas distribution abnormalities for 129 Xe compared to 3 He MRI that were spatially and significantly related to lung regions with elevated ADC . Finally, we demonstrated that ex - smokers with normal spirometry but abnormal diffusion capacity of the lung for carbon monoxide (D L CO) ha d significantly worse symptoms, exercise capacity and 3 He ADC than ex - smokers with normal D L CO . These important findings indicate that hyperpolarized gas MRI can be used to improve our understanding of lung structural and functional changes in COPD.

Enhancement of NMR and MRI in the Presence of Hyperpolarized Noble Gases

Enhancement of NMR and MRI in the Presence of Hyperpolarized Noble Gases Book
Author : Anonim
Publisher : Unknown
Release : 2004
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

The present invention relates generally to nuclear magnetic resonance (NMR) techniques for both spectroscopy and imaging. More particularly, the present invention relates to methods in which hyperpolarized noble gases (e.g., Xe and He) are used to enhance and improve NMR and MRI. Additionally, the hyperpolarized gas solutions of the invention are useful both in vitro and in vivo to study the dynamics or structure of a system. When used with biological systems, either in vivo or in vitro, it is within the scope of the invention to target the hyperpolarized gas and deliver it to specific regions within the system.

Optimization of Hyperpolarized Noble Gas Magnetic Resonance Imaging

Optimization of Hyperpolarized Noble Gas Magnetic Resonance Imaging Book
Author : Lei Zhao
Publisher : Unknown
Release : 2000
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Optimization of Hyperpolarized Noble Gas Magnetic Resonance Imaging book written by Lei Zhao, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Nuclear Magnetic Resonance Imaging with Hyper polarized Noble Gases

Nuclear Magnetic Resonance Imaging with Hyper polarized Noble Gases Book
Author : Anonim
Publisher : Unknown
Release : 1997
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

This is the final report of a six-month, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The nuclei of noble gases can be hyper polarized through a laser-driven spin exchange to a degree many orders of magnitude larger than that attainable by thermal polarization without requiring a strong magnetic field. The increased polarization from the laser pumping enables a good nuclear magnetic resonance (NMR) signal from a gas. The main goal of this project was to demonstrate diffusion-weighted imaging of such hyper-polarized noble gas with magnetic resonance imaging (MRI). Possible applications include characterizing porosity of materials and dynamically imaging pressure distributions in biological or acoustical systems.

Hyperpolarized Noble Gas MRI of Human Lungs in 150G Magnetic Field

Hyperpolarized Noble Gas MRI of Human Lungs in 150G Magnetic Field Book
Author : Adelaide Zhang
Publisher : Unknown
Release : 2000
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Hyperpolarized Noble Gas MRI of Human Lungs in 150G Magnetic Field book written by Adelaide Zhang, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Hyperpolarized Xenon 129 Magnetic Resonance

Hyperpolarized Xenon 129 Magnetic Resonance Book
Author : Thomas Meersmann,Eike Brunner
Publisher : Royal Society of Chemistry
Release : 2015-04-14
ISBN : 1849738890
Language : En, Es, Fr & De

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Book Description :

Providing the first comprehensive book on the current state of hyperpolarized Xenon-129 NMR and MRI, this book is guaranteed to appeal to a wide range of scientists interested in this growing field. It is intended to create synergy between the various communities working with this noble gas. Covering all topics from the production of the hyperpolarized gas to its applications, the editors have invited a leading team of experts to combine the physical chemistry within the various topics and across disciplines. The scope will range from the fundamental aspects of optical pumping to practical aspects of hyperpolarizers and hp-xenon handling. The applications section will focus on hyperpolarized xenon-129 detected in the dissolved phase or micro porous media where the chemical shift of xenon-129 can be used as a diagnostic probe. Appealing to researchers in the biomedical field and materials sciences, this reference book will provide background reading and future looking material in one place.

Fundamental Studies Applications for the Development of Novel MRI Contrast Agents

Fundamental Studies   Applications for the Development of Novel MRI Contrast Agents Book
Author : Laura L. Walkup
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Since its discovery in the mid-1950s, the phenomenon of nuclear magnetic resonance (NMR) has been recognized as a powerful, nondestructive analytical technique capable of probing the structure and dynamics of many systems--ranging in size from simple organic molecules, through large biomolecular complexes, and even the tissues of the human body by use of magnetic resonance imaging (MRI). Indeed, MRI is perhaps the most well-known application of MR, and in the clinic, MRI is growing in popularity as an alternative to other imaging modalities such as computerized tomography (CT), positron emission tomography (PET), and x-ray, all of which rely on ionizing forms of radiation to generate images. Both NMR and MRI operate on the same physical principles as discussed in Chapter 1: the manipulation of populations of nuclear spins in different energy states using radiofrequency (rf) pulses. This dissertation work focuses on the development of two different types of MRI contrast agents: hyperpolarized 129 Xe gas and superparamagnetic iron oxide nanoparticles (SPIONs). The largest 'Achilles' Heel' of MR techniques is their inherent lack of detection sensitivity due to the exceedingly small magnitude of the nuclear spins, giving rise to small thermal polarizations. Chapter 2 reviews strategies for improving the MR spin polarization, and the following chapter focuses on the physics of one such strategy--spin-exchange optical pumping (SEOP), which is used to prepare highly spin-polarized noble gases (e.g., 3 He and 129 Xe). SEOP is a two-step process whereby first, the electronic spins of an alkali metal vapor become polarized via the absorption of circularly-polarized resonant laser light, and second, the electronic spin polarization is transferred from the alkali metal atoms to the nuclear spins of the noble gas atoms via collisions; Chapter 4 discussed the experimental considerations and implementation of SEOP. Hyperpolarized noble gases prepared via SEOP have a wide variety of MR applications, reviewed in Chapter 5, including use in pulmonary MRI where the hyperpolarized noble gas provides contrast in the lung-space. The development of hyperpolarized 129 Xe as contrast for pulmonary MRI has suffered on two fronts: firstly, due to the physics of SEOP, generating large volumes of highly spin-polarized gas is challenging, and secondly, the commercial devices used to perform SEOP and prepare the hyperpolarized gas, so-called 'hyperpolarizers', are expensive and proprietary, which has limited access to the technology to researchers and clinics. Chapter 7 discusses the design and construction of a fully automated, clinical-scale, 'open-source' 129 Xe hyperpolarizer with the purpose of developing an accessible, lower cost, mostly 'off-the-shelf' alternative to commercial polarizers. The hyperpolarizer operates at high Xe densities and provides high polarizations and currently is housed at Brigham and Women's Hospital where it has received full FDA/IRB approval and is involved in in vivo pulmonary imaging studies. Preliminary developments and results from a second-generation 129 Xe hyperpolarizer are discussed in Chapter 8 which includes improvements in the optical design, gas handling manifold, and SEOP oven. The 'open-source' hyperpolarizer design allow for greater access to hyperpolarized gas technology, and in time, as more laboratories adopt the design and expand upon it, a community of scientists and clinicians using hyperpolarized gas will grow and facilitate the sharing of ideas. The final SEOP-related chapter discusses fundamental studies of N 2 temperatures during SEOP conducted in situ with Raman spectroscopy which shed light on the thermalization of energy during SEOP and the interrelation between key experimental SEOP parameters. The second aspect of MRI contrast discussed is the use of SPIONs as environmentally- sensitive contrast agents, and the synthesis and applications of SPIONs are reviewed in Chapter 6. Among other features, SPIONs offer high biological tolerability and flexible surface chemistry to allow for functionalization which can be exploited to yield differential MR response in different chemical environments. One general biological parameter of interest is tissue pH where local reductions in pH are associated with a variety of conditions including inflammation and cancers, and Chapter 10 focuses on the development of melamine dendron-functionalized SPIONs as pH-sensitive MRI contrast agents. Also discussed is a model for understanding how SPION clustering affects MR response. Such contrast agents could be developed as molecular imaging agents capable of mapping tumor pH in vivo.

Chest MRI An Issue of Magnetic Resonance Imaging Clinics of North America

Chest MRI  An Issue of Magnetic Resonance Imaging Clinics of North America  Book
Author : Prachi P. Agarwal
Publisher : Elsevier Health Sciences
Release : 2015-06-14
ISBN : 0323376061
Language : En, Es, Fr & De

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Book Description :

Chest MRI is explored in this important issue in MRI Clinics of North America. Articles include: MRI of Mediastinal Masses; State of the art: MR Imaging of the Thymus; Novel MR Applications for Pleural Evaluation; MRI Imaging of Chest Wall Tumors; MR Imaging of the Lungs with Hyperpolarized Gases: Technique and Applications; Lung Cancer Assessment with MR Imaging: An Update; PET/MRI in Chest Diseases; Imaging Pulmonary Arterial Thromboembolism: Challenges and Opportunities; MR Imaging of the Thoracic Aorta; MR Imaging of Thoracic Veins; State of the Art MR Imaging in Vascular Thoracic Outlet Syndrome; Pediatric Chest MR Applications, and more!

Fluorine Magnetic Resonance Imaging

Fluorine Magnetic Resonance Imaging Book
Author : Ulrich Flogel,Eric Ahrens
Publisher : CRC Press
Release : 2016-10-26
ISBN : 1315340933
Language : En, Es, Fr & De

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Book Description :

Over the past decade, fluorine (19F) magnetic resonance imaging (MRI) has garnered significant scientific interest in the biomedical research community owing to the unique properties of fluorinated materials and the 19F nucleus. Fluorine has an intrinsically sensitive nucleus for MRI. There is negligible endogenous 19F in the body and thus there is no background signal. Fluorine-containing compounds are ideal tracer labels for a wide variety of MRI applications. Moreover, the chemical shift and nuclear relaxation rate can be made responsive to physiology via creative molecular design. This book is an interdisciplinary compendium that details cutting-edge science and medical research in the emerging field of 19F MRI. Edited by Ulrich Flögel and Eric Ahrens, two prominent MRI researchers, this book will appeal to investigators involved in MRI, biomedicine, immunology, pharmacology, probe chemistry, and imaging physics.

RF Coils Design for Small Animal MRI Lung Imaging at 3T Using Hyperpolarized 129Xe and Inert Fluorinated Gases

RF Coils Design for Small Animal MRI Lung Imaging at 3T Using Hyperpolarized 129Xe and Inert Fluorinated Gases Book
Author : Tao Li
Publisher : Unknown
Release : 2013
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

"This thesis described the investigation, construction and testing of two sets of RF coils for their applications in novel lung MRI imaging techniques. In the first part of the thesis, a quadrature-driven birdcage coil for rat lung MRI using inert fluorinated gases was developed. Methods for coil tuning and impedance matching were presented and discussed. The sensitivity improvement resulted from a quadrature-driven mode was quantitatively measured, and compared to the linear reference. A dual-angle method (DAM) was studied and implemented to quantitatively measure the B 1 field homogeneity, and a B1 field map was generated at the center of the coil. In vivo rat lung imaging experiments were conducted using the constructed coil, and the multi-slice images acquired from the rat lung were presented. In the second part of the thesis, a 1 H-129 Xe double-birdcage coil for rat lung MRI using hyperpolarized 129 Xe gas was developed. The Q factors of each coil was measured and compared before and after the double-birdcage structure was formed. The coupling between the two coils was tested, and a geometrical decoupling method was implemented and optimized. Imaging scans using thermal xenon phantom and saline syringe phantom were conducted with image registration post-processing performed, and the dual-frequency scan ability of the developed coil was verified and evaluated. "-- from abstract.

Radio Frequency Coil and Pulse Sequence Design for Hyperpolarised Noble Gas MRI of the Human Lungs and Brain

Radio Frequency Coil and Pulse Sequence Design for Hyperpolarised Noble Gas MRI of the Human Lungs and Brain Book
Author : Madhwesha Rama Rao
Publisher : Unknown
Release : 2015
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Download Radio Frequency Coil and Pulse Sequence Design for Hyperpolarised Noble Gas MRI of the Human Lungs and Brain book written by Madhwesha Rama Rao, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Imaging of the Airways

Imaging of the Airways Book
Author : David P. Naidich
Publisher : Lippincott Williams & Wilkins
Release : 2005
ISBN : 9780781757683
Language : En, Es, Fr & De

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Book Description :

Written by recognized authorities on thoracic imaging, this volume is the first to examine all modalities—both noninvasive and invasive—for visualizing the airways. Emphasis is placed on correlating CT images with bronchoscopy, to aid in interpreting CT findings and in performing interventional bronchoscopic procedures. After a review of airway imaging techniques and anatomy, the book presents correlating CT and bronchoscopic images for a wide range of pathologic entities. Detailed chapters examine the trachea and central bronchi, the diagnosis of bronchiectasis, and the use of CT in diagnosing small airway disease. A chapter on functional imaging of the airways is also included.

Investigation of Neonatal Pulmonary Structure and Function Via Proton and Hyperpolarized Gas Magnetic Resonance Imaging

Investigation of Neonatal Pulmonary Structure and Function Via Proton and Hyperpolarized Gas Magnetic Resonance Imaging Book
Author : Nara Savoye Higano
Publisher : Unknown
Release : 2017
ISBN : 0987650XXX
Language : En, Es, Fr & De

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Book Description :

Magnetic resonance imaging (MRI) is a modality that utilizes the phenomenon of nuclear magnetic resonance (NMR) to yield tomographic images of the body. Proton (1H) MRI has historically been successful in soft tissues but has suffered in the lung due to a variety of technical challenges, such as the low proton-density, rapid T2* relaxation time of the lung parenchymal tissue, and inherent physiological motion in the chest. Recent developments in radial ultrashort echo time (UTE) MRI have in part overcome these issues. In addition, there has been much progress in techniques for hyperpolarization of noble gases (3He and 129Xe) out of thermal equilibrium via spin exchange optical pumping, which can greatly enhance the gas NMR signal such that it is detectable within the airspaces of the lung on MRI.The lung is a unique organ due to its complex structural and functional dynamics, and its early development through the neonatal (newborn) period is not yet well understood in normal or abnormal conditions. Pulmonary morbidities are relatively common in infants and are present in a majority of patients admitted to the neonatal intensive care unit, often stemming from preterm birth and/or congenital defects. Current clinical lung imaging in these patients is typically limited to chest x-ray radiography, which does not provide tomographic information and so has lowered sensitivity. More rarely, x-ray computed tomography (CT) is used but exposes infants to ionizing radiation and typically requires sedation, both of which pose increased risks to pediatric patients. Thus the opportunity is ripe for application of novel pulmonary MRI techniques to the infant population. However, MR imaging of very small pulmonary structure and microstructure requires fundamental changes in the imaging theory of both 1H UTE MRI and hyperpolarized gas diffusion MRI. Furthermore, such young patients are often non-compliant, yielding a need for new and innovative techniques for monitoring respiratory and bulk motion.This dissertation describes methodology development and provides experimental results in both 1H UTE MRI and hyperpolarized 3He and 129Xe gas diffusion MRI, with investigation into the structure and function of infant lungs at both the macrostructural and microstructural level. In particular, anisotropically restricted gas diffusion within infant alveolar microstructure is investigated as a measurement of airspace size and geometry. Additionally, the phenomenon of respiratory and bulk motion-tracking via modulation of the k-space center's magnitude and phase is explored and applied via UTE MRI in various neonatal pulmonary conditions to extract imaging-based metrics of diagnostic value. Further, the proton-density regime of pulmonary UTE MRI is validated in translational applications. These techniques are applied in infants with various pulmonary conditions, including patients diagnosed with bronchopulmonary dysplasia, congenital diaphragmatic hernia, esophageal atresia/tracheoesophageal fistula, tracheomalacia, and no suspected lung disease. In addition, explanted lung specimens from both infants with and without lung disease are examined.Development and implementation of these techniques involves a strong understanding of the physics-based theory of NMR, hyperpolarization, and MR imaging, in addition to foundations in hardware, software, and image analysis techniques. This thesis first outlines the theory and background of NMR, MRI, and pulmonary physiology and development (Part I), then proceeds into the theory, equipment, and imaging experiments for hyperpolarized gas diffusion MRI in infant lung airspaces (Part II), and finally details the theory, data processing methods, and applications of pulmonary UTE MRI in infant patients (Part III). The potential for clinical translation of the neonatal pulmonary MRI methods presented in this dissertation is very high, with the foundations of these techniques firmly rooted in the laws of physics.