Download or read book Susceptibility Effects in Ultra high Field Magnetic Resonance Imaging of the Human Brain written by Trong-Kha Truong and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In magnetic resonance imaging (MRI), susceptibility differences between deoxygenated blood or iron and surrounding tissue induce mesoscopic static magnetic field (B0) inhomogeneities that provide a valuable contrast mechanism for imaging of the vasculature, functional MRI, and assessment of iron content. On the other hand, susceptibility differences at air/tissue interfaces induce macroscopic B0 inhomogeneities resulting in image artifacts. Ultra-high field (greater than or equal to 7 tesla) MRI benefits from an enhanced susceptibility contrast, but also suffers from more severe susceptibility artifacts. The development of methods to reduce such artifacts while maintaining susceptibility contrast is the objective of this research. Development of susceptibility artifact correction methods requires knowledge of the macroscopic susceptibility effects, which can be quantified by mapping B0, whereas optimization of methods sensitive to susceptibility contrast requires understanding of the mesoscopic susceptibility effects, which can be characterized by relaxation time measurements. We first developed various methods for B0 numerical simulations and experimental mapping. Our simulations showed that air/tissue interfaces at the shoulders induce substantial B0 inhomogeneities in the brain, and that tilting the head backwards can significantly reduce some of these inhomogeneities. We used the B0 simulations and experimental mapping as well as radiofrequency magnetic field (B1) mapping to correlate the B0 and B1 inhomogeneity with the artifacts observed on images of the human brain acquired at 8 T. We then evaluated different susceptibility artifact correction methods at ultra-high field strength using B0 maps, including passive shimming, post-processing, and gradient compensation, and found the latter to be the most effective. Finally, we developed various methods for T2 and T2* relaxation time measurements at ultra-high field strength that are faster and less sensitive to B0 and/or B1 inhomogeneity than existing methods, and demonstrated these advantages in phantom and human studies. New findings obtained in this work will be used to improve ultra-high field MRI of the human brain, particularly for imaging of the venous microvasculature and assessment of iron content.
Download or read book Ultra High Field Magnetic Resonance Imaging written by Pierre-Marie Robitaille and published by Springer Science & Business Media. This book was released on 2007-12-31 with total page 487 pages. Available in PDF, EPUB and Kindle. Book excerpt: The foundation for understanding the function and dynamics of biological systems is not only knowledge of their structure, but the new methodologies and applications used to determine that structure. This volume in Biological Magnetic Resonance emphasizes the methods that involve Ultra High Field Magnetic Resonance Imaging. It will interest researchers working in the field of imaging.
Download or read book Magnetic Resonance Imaging at Ultra High Field written by Richard Ely Burgess and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Even before the development of magnetic resonance imaging, scientists and engineers repeatedly predicted that, despite the theoretical potential of high field, physical and engineering challenges would prevent the practical realization of gains in signal to noise. Many of the arguments used to disparage high field MRI can be divided into issues of uniform excitation, image distortion, and patient safety. In the former category lies challenges such as RF penetration limitations, dielectric resonances, coil self-resonance, coil-sample interactions, and RF power requirements, which may prevent uniform B1 can best be studied with numerical modeling techniques. Within the second category are effects such as chemical shift artifact, susceptibility distortions, and contrast convergence that can be well studied through analytic techniques and methodical manipulation of imaging parameters. In the category of safety belong RF power deposition and magnetohydrodynamic effects. In this thesis, issues of static field safety will be exhaustively explored and investigation of image contrast and quality will be undertaken to assess the potential of the 8 Tesla system for human neuroimaging. This thesis will specifically examine the theoretical risk of cardiac arrhythmia from induced currents and demonstrate the negligible cardiac, cognitive, and physiological bioeffects through animal and human studies. The extent of signal to noise ratio enhancement possible at 8 Tesla will be assessed and harnessed to obtain high resolution whole brain images. In the end, experimental results and analysis show that, despite the presence of artifact, high resolution images of the human brain with unique contrast can be safely obtained at 8 Tesla.
Download or read book Make Life Visible written by Yoshiaki Toyama and published by Springer Nature. This book was released on 2019-10-02 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: This open access book describes marked advances in imaging technology that have enabled the visualization of phenomena in ways formerly believed to be completelyimpossible. These technologies have made major contributions to the elucidation of the pathology of diseases as well as to their diagnosis and therapy. The volume presents various studies from molecular imaging to clinical imaging. It also focuses on innovative, creative, advanced research that gives full play to imaging technology inthe broad sense, while exploring cross-disciplinary areas in which individual research fields interact and pursuing the development of new techniques where they fuse together. The book is separated into three parts, the first of which addresses the topic of visualizing and controlling molecules for life. Th e second part is devoted to imaging of disease mechanisms, while the final part comprises studies on the application of imaging technologies to diagnosis and therapy. Th e book contains the proceedings of the 12th Uehara International Symposium 2017, “Make Life Visible” sponsored by the Uehara Memorial Foundation and held from June 12 to 14, 2017. It is written by leading scientists in the field and is an open access publication under a CC BY 4.0 license.
Download or read book Biological Magnetic Resonance written by Lawrence Berliner and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Biological magnetic resonance (NMR and EPR) is a rapidly expanding area of research with much activity in most universities and research institutions. International conferences are held biennially with an increasing number of participants. With the introduction of sophisticated and continuously im proving instrumentation, biological magnetic resonance is approaching the state of a common physical method in biochemical, biomedical, and bio logical research. The lack of monograpbs on the subject had been con spicuous for a long time. This gap started to close only recently. However, because of the rapid expansion and intensive research, many texts are dated by the time of their appearance. Therefore we have undertaken the editing of a series that is intended to provide the practicing chemist, biochemist, or biologist with the advances and progress in selected contemporary topics. In seeking to make the series as authoritative as possible, we have invited authors who have not only made significant contributions but who are also currently active in their fields. We hope that their expertise as well as their first hand experience as reflected in the chapters of this volume will be of benefit to the reader, inter alia, in planning his own experiments and in critically evaluating the current literature.
Download or read book Handbook of Neuro Oncology Neuroimaging written by Herbert B. Newton and published by Academic Press. This book was released on 2022-08-21 with total page 1022 pages. Available in PDF, EPUB and Kindle. Book excerpt: With treatment approaches and the field of neuro-oncology neuroimaging changing rapidly, this third edition of the Handbook of Neuro-Oncology Neuroimaging is very relevant to those in the field, providing a single-source, comprehensive, reference handbook of the most up-to-date clinical and technical information regarding the application of neuroimaging techniques to brain tumor and neuro-oncology patients. This new volume will have updates on all of the material from the second edition, and in addition features several new important chapters covering diverse topics such as imaging for the use of Laser Interstitial Thermal Therapy, advanced imaging techniques in radiation therapy, therapeutic treatment fields, response assessment in clinical trials, surgical planning of neoplastic disease of the spine, and more. Sections first overview neuro-oncological disorders before delving into the physics and basic science of neuroimaging and great focus on CT and MRI. The book then focuses on advances in the neuroimaging of brain tumors and neuroimaging of specific tumor types. There is also discussion of neuroimaging of other neuro-oncological syndromes. This book will serve as a resource of background information to neuroimaging researchers and basic scientists with an interest in brain tumors and neuro-oncology. Summarizes translational research on brain imaging for brain tumors Discusses limitations of neuroimaging for diagnosis and treatment Presents advanced imaging technologies, including CT, MRI, and PET Contains new coverage on Laser Interstitial Thermal Therapy, radiation therapy, clinical trials, and more
Download or read book Ultra High Field Neuro MRI written by Karin Markenroth Bloch and published by Elsevier. This book was released on 2023-08-21 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ultra-High Field Neuro MRI is a comprehensive reference and educational resource on the current state of neuroimaging at ultra-high field (UHF), with an emphasis on 7T. Sections cover the MR physics aspects of UHF, including the technical challenges and practical solutions that have enabled the rapid growth of 7T MRI. Individual chapters are dedicated to the different techniques that most strongly benefit from UHF, as well as chapters with a focus on different application areas in anatomical, functional and metabolic imaging. Finally, several chapters highlight the neurological and psychiatric applications for which 7T has shown benefits. The book is aimed at scientists who develop MR technologies and support clinical and neuroscience research, as well as users who want to benefit from UHF neuro MR techniques in their work. It also provides a comprehensive introduction to the field. Presents the opportunities and technical challenges presented by MRI at ultra-high field Describes advanced ultra-high field neuro MR techniques for clinical and neuroscience applications Enables the reader to critically assess the specific UHF advantages over currently available techniques at clinical field strengths
Download or read book Quantitative Magnetic Resonance Imaging written by Nicole Seiberlich and published by Academic Press. This book was released on 2020-11-18 with total page 1094 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative Magnetic Resonance Imaging is a ‘go-to’ reference for methods and applications of quantitative magnetic resonance imaging, with specific sections on Relaxometry, Perfusion, and Diffusion. Each section will start with an explanation of the basic techniques for mapping the tissue property in question, including a description of the challenges that arise when using these basic approaches. For properties which can be measured in multiple ways, each of these basic methods will be described in separate chapters. Following the basics, a chapter in each section presents more advanced and recently proposed techniques for quantitative tissue property mapping, with a concluding chapter on clinical applications. The reader will learn: The basic physics behind tissue property mapping How to implement basic pulse sequences for the quantitative measurement of tissue properties The strengths and limitations to the basic and more rapid methods for mapping the magnetic relaxation properties T1, T2, and T2* The pros and cons for different approaches to mapping perfusion The methods of Diffusion-weighted imaging and how this approach can be used to generate diffusion tensor maps and more complex representations of diffusion How flow, magneto-electric tissue property, fat fraction, exchange, elastography, and temperature mapping are performed How fast imaging approaches including parallel imaging, compressed sensing, and Magnetic Resonance Fingerprinting can be used to accelerate or improve tissue property mapping schemes How tissue property mapping is used clinically in different organs Structured to cater for MRI researchers and graduate students with a wide variety of backgrounds Explains basic methods for quantitatively measuring tissue properties with MRI - including T1, T2, perfusion, diffusion, fat and iron fraction, elastography, flow, susceptibility - enabling the implementation of pulse sequences to perform measurements Shows the limitations of the techniques and explains the challenges to the clinical adoption of these traditional methods, presenting the latest research in rapid quantitative imaging which has the possibility to tackle these challenges Each section contains a chapter explaining the basics of novel ideas for quantitative mapping, such as compressed sensing and Magnetic Resonance Fingerprinting-based approaches
Download or read book Parallel Transmission for Magnetic Resonance Imaging of the Human Brain at Ultra High Field written by Martijn Anton Hendrik Cloos and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The focus of this thesis lies on the development, and implementation, of parallel transmission (pTx) techniques in magnetic resonance imaging for flip-angle homogenization throughout the human brain at ultra-high field. In order to allow in-vivo demonstrations, a conservative yet viable safety concept is introduced to control the absorbed radiofrequency (RF) power . Subsequently, novel methods for local SAR control and non-selective RF pulse-design are investigated. The impact of these short and energy-efficient waveforms, referred to as kT-points, is first demonstrated in the context of the small-tip-angle domain. Targeting a larger scope of applications, the kT-points design is then generalized to encompass large flip angle excitations and inversions. This concept is applied to one of the most commonly used T1-weighted sequences in neuroimaging. Results thus obtained at 7 Tesla are compared to images acquired with a clinical setup at 3 Tesla, validating the principles of the kT-points method and demonstrating that pTx-enabled ultra-high field systems can also be competitive in the context of T1-weighted imaging. Finally, simplifications in the global design of the pTx-implementation are studied in order to obtain a more cost-effective solution.
Download or read book Magnetic Source Imaging of the Human Brain written by Zhong-Lin Lu and published by Psychology Press. This book was released on 2003-10-17 with total page 475 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed to acquaint serious students, scientists, and clinicians with magnetic source imaging (MSI)--a brain imaging technique of proven importance that promises even more important advances. The technique permits spatial resolution of neural events on a scale measured in millimeters and temporal resolution measured in milliseconds. Although widely mentioned in literature dealing with cognitive neuroscience and functional brain imaging, there is no single book describing both the foundations and actual methods of magnetoencephalopgraphy and its underlying science, neuromagnetism. This volume fills a long-standing need, as it is accessible to scientists and students having no special background in the field, and makes it possible for them to understand this literature and undertake their own research. A self-contained unit, this book covers MSI from beginning to end, including its relationship to allied technologies, such as electroencephalography and modern functional imaging modalities. In addition, the book: *introduces the field to the non-specialist, providing a framework for the rest of the book; *provides a thorough review of the physiological basis of MSI; *describes the mathematical bases of MSI--the forward and inverse problems; *outlines new signal processing methods that extract information from single-trial MEG; *depicts the early, as well as the most recent versions of MSI technology; *compares MSI with other imaging methodologies; *describes new paradigms and analysis techniques in applying MSI to study human perception and cognition, which are also applicable to EEG; and *reviews some of the most important results in MSI from the most prominent researchers and laboratories around the world.
Download or read book Advancing Ultra high Field MRI Functional and Structural Applications written by and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic resonance imaging (MRI) has shown to be a valuable tool for studying the human brain, allowing in-vivo visualization of structures and anatomy in great detail, especially at Ultra-High field strengths (≥ 7T). MRI is not limited by anatomical and structural information. It can study the brain’s anatomy, functionality, connectivity (functional and structural), and chemical metabolism. Functional MRI (fMRI), for instance, enables the investigation of brain function mechanisms in-vivo with a non-invasive advantage compared to other tools. The present thesis focuses on advanced MRI techniques for ultra-high field strength (≥ 7T), specifically for neuroscience applications. Combined with the higher field strength, these techniques provide better imaging quality and precise brain activity measurement. For example, high-quality anatomical T1 weighted images are essential for several MRI applications, notably, to serve as an anatomical reference in fMRI and gray matter segmentation. Unfortunately, increased field strength also induces non-uniformities in the transmit field (B1+) that can compromise image contrast non-uniformly. One of the goals of the present thesis was to investigate new strategies to overcome this issue. Regarding the functional brain investigation, the gradient-echo (GRE) is the typical method of choice for fMRI applications. Despite its high sensitivity to deoxyhemoglobin variations and widespread availability, the gradient-echo (GRE) BOLD signal is predominantly driven by the large draining vessels resulting in a limited spatial specificity, especially for 7T or higher field strength applications in which the BOLD sensitivity (susceptibility effect) is higher compared to lower static field scanners. In this context, we investigated an alternative fMRI method called vascular space occupancy (VASO) that promises higher spatial specificity than the typical GRE BOLD. To achieve the aim of this thesis, we used four approaches (chapters 2-5).
Download or read book Introduction to Functional Magnetic Resonance Imaging written by Richard B. Buxton and published by Cambridge University Press. This book was released on 2009-08-27 with total page 479 pages. Available in PDF, EPUB and Kindle. Book excerpt: Functional Magnetic Resonance Imaging (fMRI) has become a standard tool for mapping the working brain's activation patterns, both in health and in disease. It is an interdisciplinary field and crosses the borders of neuroscience, psychology, psychiatry, radiology, mathematics, physics and engineering. Developments in techniques, procedures and our understanding of this field are expanding rapidly. In this second edition of Introduction to Functional Magnetic Resonance Imaging, Richard Buxton – a leading authority on fMRI – provides an invaluable guide to how fMRI works, from introducing the basic ideas and principles to the underlying physics and physiology. He covers the relationship between fMRI and other imaging techniques and includes a guide to the statistical analysis of fMRI data. This book will be useful both to the experienced radiographer, and the clinician or researcher with no previous knowledge of the technology.
Download or read book In Vivo NMR Spectroscopy written by Robin A. de Graaf and published by John Wiley & Sons. This book was released on 2019-03-11 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents basic concepts, experimental methodology and data acquisition, and processing standards of in vivo NMR spectroscopy This book covers, in detail, the technical and biophysical aspects of in vivo NMR techniques and includes novel developments in the field such as hyperpolarized NMR, dynamic 13C NMR, automated shimming, and parallel acquisitions. Most of the techniques are described from an educational point of view, yet it still retains the practical aspects appreciated by experimental NMR spectroscopists. In addition, each chapter concludes with a number of exercises designed to review, and often extend, the presented NMR principles and techniques. The third edition of In Vivo NMR Spectroscopy: Principles and Techniques has been updated to include experimental detail on the developing area of hyperpolarization; a description of the semi-LASER sequence, which is now a method of choice; updated chemical shift data, including the addition of 31P data; a troubleshooting section on common problems related to shimming, water suppression, and quantification; recent developments in data acquisition and processing standards; and MatLab scripts on the accompanying website for helping readers calculate radiofrequency pulses. Provide an educational explanation and overview of in vivo NMR, while maintaining the practical aspects appreciated by experimental NMR spectroscopists Features more experimental methodology than the previous edition End-of-chapter exercises that help drive home the principles and techniques and offer a more in-depth exploration of quantitative MR equations Designed to be used in conjunction with a teaching course on the subject In Vivo NMR Spectroscopy: Principles and Techniques, 3rd Edition is aimed at all those involved in fundamental and/or diagnostic in vivo NMR, ranging from people working in dedicated in vivo NMR institutes, to radiologists in hospitals, researchers in high-resolution NMR and MRI, and in areas such as neurology, physiology, chemistry, and medical biology.
Download or read book Magnetic Resonance and Brain Function Approaches from Physics written by Società italiana di fisica and published by IOS Press. This book was released on 1999 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the last decade, NMR has set the basis for the understanding of the function and disfunction of the human brain. Particularly, Magnetic Resonance Imaging (MRI) has a leading position among the methodologies used for investigation and diagnostic of the Central Nervous System. In the 1990's the objective of finding new investigating means drove scientists towards different approaches, including: 1) Blood Oxygen Level Dependent (BOLD) MRI; 2) Double Magnetic Resonance (DMR); 3) Hyperpolarized Gases. These 3 methods are aimed at detecting brain metabolites with increasing sensitivity and resolution. This Enrico Fermi Course is of interest to researchers who work at the development of these interdisciplinary areas, i.e. physicists, chemists, engineers, but also the biomedical aspects of brain function in connection to the NMR potentialities.
Download or read book Ultra Low Field Nuclear Magnetic Resonance written by Robert Kraus Jr. and published by Oxford University Press. This book was released on 2014-02-26 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is designed to introduce the reader to the field of NMR/MRI at very low magnetic fields, from milli-Tesla to micro-Tesla, the ultra-low field (ULF) regime. The book is focused on applications to imaging the human brain, and hardware methods primarily based upon pre-polarization methods and SQUID-based detection. The goal of the text is to provide insight and tools for the reader to better understand what applications are best served by ULF NMR/MRI approaches. A discussion of the hardware challenges, such as shielding, operation of SQUID sensors in a dynamic field environment, and pulsed magnetic field generation are presented. One goal of the text is to provide the reader a framework of understanding the approaches to estimation and mitigation of low signal-to-noise and long imaging time, which are the main challenges. Special attention is paid to the combination of MEG and ULF MRI, and the benefits and challenges presented by trying to accomplish both with the same hardware. The book discusses the origin of unique relaxation contrast at ULF, and special considerations for image artifacts and how to correct them (i.e. concomitant gradients, ghost artifacts). A general discussion of MRI, with special consideration to the challenges of imaging at ULF and unique opportunities in pulse sequences, is presented. The book also presents an overview of some of the primary applications of ULF NMR/MRI being pursued.
Download or read book Handbook of MRI Pulse Sequences written by Matt A. Bernstein and published by Elsevier. This book was released on 2004-09-21 with total page 1041 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Resonance Imaging (MRI) is among the most important medical imaging techniques available today. There is an installed base of approximately 15,000 MRI scanners worldwide. Each of these scanners is capable of running many different "pulse sequences", which are governed by physics and engineering principles, and implemented by software programs that control the MRI hardware. To utilize an MRI scanner to the fullest extent, a conceptual understanding of its pulse sequences is crucial. Handbook of MRI Pulse Sequences offers a complete guide that can help the scientists, engineers, clinicians, and technologists in the field of MRI understand and better employ their scanner. Explains pulse sequences, their components, and the associated image reconstruction methods commonly used in MRI Provides self-contained sections for individual techniques Can be used as a quick reference guide or as a resource for deeper study Includes both non-mathematical and mathematical descriptions Contains numerous figures, tables, references, and worked example problems
Download or read book Quantitative MRI of the Spinal Cord written by Julien Cohen-Adad and published by Academic Press. This book was released on 2014-01-16 with total page 331 pages. Available in PDF, EPUB and Kindle. Book excerpt: Quantitative MRI of the Spinal Cord is the first book focused on quantitative MRI techniques with specific application to the human spinal cord. This work includes coverage of diffusion-weighted imaging, magnetization transfer imaging, relaxometry, functional MRI, and spectroscopy. Although these methods have been successfully used in the brain for the past 20 years, their application in the spinal cord remains problematic due to important acquisition challenges (such as small cross-sectional size, motion, and susceptibility artifacts). To date, there is no consensus on how to apply these techniques; this book reviews and synthesizes state-of-the-art methods so users can successfully apply them to the spinal cord. Quantitative MRI of the Spinal Cord introduces the theory behind each quantitative technique, reviews each theory’s applications in the human spinal cord and describes its pros and cons, and suggests a simple protocol for applying each quantitative technique to the spinal cord. Chapters authored by international experts in the field of MRI of the spinal cord Contains “cooking recipes —examples of imaging parameters for each quantitative technique—designed to aid researchers and clinicians in using them in practice Ideal for clinical settings
