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Basic principles and applications Home MRI. Basic principles and applications. Brown, Ph. Semelka, M. All rights reserved.
Magnetic resonance imaging
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For general information on our other products and services please contact our Customer Care Department within the U. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print, however, may not be available in electronic format. Brown, Richard C. Includes bibliographical reference and index. ISBN 1. Magnetic resonance imaging.
Semelka, Richard C. N83B We minimized the use of intense mathematical formalism and attempted to show the underlying foundation for MRI as it is currently used. Our attempt was to provide a resource for those medical personnel who needed accurate and detailed information yet could not devote time to study an in-depth theoretical treatise. In the third edition, we have maintained the organization of the first two editions.
We have divided the description of MRI physics into two chapters—the first a more introductory presentation and the second presenting more advanced concepts. We have included a discussion of issues related to ultra-high magnetic field scanning, as these systems are now commercially available. Most of the figures have also been revised and updated. As in most projects of this type, a number of persons aided us and we are grateful to them. First, we would like to thank the technical staff at the Siemens Training and Development Center and the faculty, fellows, and staff at the University of North Carolina for their interest in this project and their assistance in its completion.
MacFall, and H. Finally, we would like to thank our families for their support and patience during the time that this revision was prepared. MARK A. We minimized the use of intense mathematical formalism and attempted to stress the practical aspects of MRI as it is currently used. Our attempt was to provide a resource for those medical personnel who needed accurate and detailed information yet could not devote time to study an indepth theoretical treatise.
In the second edition, we have maintained the basic organization of the first edition. The first three chapters describe the basic principles behind magnetic resonance as they are applied in the production of image contrast. Chapters 4 through 6 describe the principles used for spatial localization of the MR signal and many of the common techniques that are commercially implemented.
The next three chapters describe variations on the resulting basic techniques that increase tissue contrast or ensure the quality of the measurement. Chapters 10 through 12 illustrate some of the major applications of MRI in current use and some areas in which new applications have been developed since the first edition. These include MR spectroscopy and diffusion-weighted imaging.
Chapter 13 describes the major hardware components common to all MRI systems. The final chapters describe the use of contrast agents and the principles that should be considered in developing clinical protocols. We would like to thank many people who aided us in the production of this endeavor. First, we would like to thank the technical staff at the xi fpref. We would also like to thank James R.
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MacFall for providing Figure Finally, we would like to thank our families for their support and patience during the time that this manuscript was prepared. Much of this evolution has been accomplished through changes in localization techniques and new mechanisms of contrast.
Even so, many of the fundamental principles governing image contrast and localization have changed little since they were first determined. Our purpose in writing this book is to present the basic concepts of MRI in a fashion that is comprehensible to a wide range of readers. We include equations in the text for completeness, but the general reader should not be daunted by their presence. Their understanding is not a prerequisite to understanding the accompanying text. We feel that this approach will provide the reader with the tools necessary to assess the various imaging techniques and to understand and apply the contrast mechanisms inherent in each one.
This book is organized into five general sections. The first three chapters describe the source of the magnetic resonance signal and how its manipulation provides the contrast within an image. Chapters 4, 5, and 6 describe the concepts of spatial localization and various imaging techniques that are commonly used. The next xiii fpref. The final chapters provide an overview of contrast agents in clinical use and clinical applications and concepts to consider in developing imaging protocols.
Nuclear spin or, more precisely, nuclear spin angular momentum, is one of several intrinsic properties of an atom and its value depends on the precise atomic composition.
ISBN 13: 9780471330622
Every element in the Periodic Table except argon and cerium has at least one naturally occurring isotope that possesses spin. Thus, in principle, nearly every element can be examined using MR, and the basic ideas of resonance absorption and relaxation are common to all of these elements.
The precise details will vary from nucleus to nucleus and from system to system. Atoms consist of three fundamental particles: protons, which possess a positive charge; neutrons, which have no charge; and electrons, which have a negative charge. The protons and neutrons are located in the nucleus or core of an atom, whereas the electrons are located in shells or orbitals surrounding the nucleus.
The characteristic chemical reactions of elements depend upon the particular number of each of these particles.
Mri by Brian M. Dale, Mark A. Brown | Waterstones
The properties most commonly used to categorize elements are the atomic number and the atomic weight. The atomic number is the number of protons in the nucleus, and is the primary index used to differentiate between atoms. All atoms of an element have the same atomic number.
The atomic weight is the sum of the number of protons and the number of neutrons. Atoms with the same atomic number but different atomic weights are called isotopes. Brown and R. The nucleus can be considered to be constantly rotating about an axis at a constant rate or velocity.
Brown, Mark A.
This self-rotation axis is perpendicular to the direction of rotation Figure A limited number of values for the spin are found in nature; that is, the spin, I, is quantized to certain discrete values. These values depend on the atomic number and atomic weight of the particular nucleus.
There are three groups of values for I: zero, half-integral values, and integral values. Such a nucleus does not interact with an external magnetic field and cannot be studied using MR. A nucleus has an integral value for I e. A nucleus has a half-integral value for I e. Table lists the spin and isotopic composition for some elements commonly found in biological systems.
The 1H nucleus, consisting of a single proton, is a natural choice for probing the body using MR techniques for several reasons. Its response to an applied magnetic field is one of the largest found in nature. Finally, the human body is composed of tissues that contain primarily water and fat, both of which contain hydrogen.
Figure A rotating nucleus with a positive charge produces a magnetic field known as the magnetic moment oriented parallel to the axis of rotation left side of figure.
This arrangement is analogous to a bar magnet in which the magnetic field is considered to be oriented from the south to the north pole right side. A rigorous mathematical description of a nucleus with spin and its interactions requires the use of quantum mechanical principles, but most of MR can be described using the concepts of classical mechanics, particularly in describing the actions of a nucleus with spin.