Magnetic Resonance Imaging With Nonlinear Gradient Fields

​Within the past few decades MRI has become one of the most important imaging modalities in medicine. For a reliable diagnosis of pathologies further technological improvements are of primary importance. This study deals with a radically new approach of image encoding. Gradient linearity has ever since been an unquestioned technological design criterion. With the advent of parallel imaging, this approach may be questioned, making way of much a more flexible gradient hardware that uses encoding fields with an arbitrary geometry. The theoretical basis of this new imaging modality – PatLoc imaging – are comprehensively presented, suitable image reconstruction algorithms are developed for a variety of imaging sequences and imaging results – including in vivo data – are explored based on novel hardware designs.

A comprehensive survey of the analytical treatment of MRI physics and engineering. It brings readers to a position where they are able to cope with the problems that arise when applying MRI to medical problems or when (sub)systems or sequences for new applications are designed. Special attention is paid to the treatment of intrinsic artefacts of the different sequences, which can be described in a mathematically uniform way for the different scan methods. The book contains numerous images, showing specific properties of the different scan methods, which include RARE, GRACE, EPI, and Spiral Scan. The ideal step-up to reach the required level for independent research or development in the field of MRI applications or system design.

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.

New edition explores contemporary MRI principles and practices Thoroughly revised, updated and expanded, the second edition of Magnetic Resonance Imaging: Physical Principles and Sequence Design remains the preeminent text in its field. Using consistent nomenclature and mathematical notations throughout all the chapters, this new edition carefully explains the physical principles of magnetic resonance imaging design and implementation. In addition, detailed figures and MR images enable readers to better grasp core concepts, methods, and applications. Magnetic Resonance Imaging, Second Edition begins with an introduction to fundamental principles, with coverage of magnetization, relaxation, quantum mechanics, signal detection and acquisition, Fourier imaging, image reconstruction, contrast, signal, and noise. The second part of the text explores MRI methods and applications, including fast imaging, water-fat separation, steady state gradient echo imaging, echo planar imaging, diffusion-weighted imaging, and induced magnetism. Lastly, the text discusses important hardware issues and parallel imaging. Readers familiar with the first edition will find much new material, including: New chapter dedicated to parallel imaging New sections examining off-resonance excitation principles, contrast optimization in fast steady-state incoherent imaging, and efficient lower-dimension analogues for discrete Fourier transforms in echo planar imaging applications Enhanced sections pertaining to Fourier transforms, filter effects on image resolution, and Bloch equation solutions when both rf pulse and slice select gradient fields are present Valuable improvements throughout with respect to equations, formulas, and text New and updated problems to test further the readers' grasp of core concepts Three appendices at the end of the text offer review material for basic electromagnetism and statistics as well as a list of acquisition parameters for the images in the book. Acclaimed by both students and instructors, the second edition of Magnetic Resonance Imaging offers the most comprehensive and approachable introduction to the physics and the applications of magnetic resonance imaging.

Principles of Magnetic Resonance Imaging provides a contemporary introduction of the fundamental concepts of MRI and connects these concepts to the latest MRI developments. Graphic illustrations are used to clarify underlying biophysical processes, simplified calculations are derived to add precision in appreciating abstract concepts, and insightful interpretations are presented for biomedical information in MRI signal. This book contains three parts. I. Section the body into voxels, which describes the Fourier encoding matrix for an imaging system, realization of Fourier encoding using the gradient field in magnetic resonance, and k-space sampling. II. What's in a voxel, which examines the effects of the biophysical processes in a voxel on MRI signal. Intuitive biophysical models are developed for MRI signal dependence on Spin fluctuation in thermal microenvironment, which leads to T1/T2 relaxation rates reflecting cellular contents in a water voxel. Micro- and macro physiological motion, which includes diffusion, perfusion, flow and biomechanical motion. Molecular electron response to the B0 field, which leads to magnetic susceptibility and chemical shift. III. How to operate MRI, which describes MRI safety issue, hardware, software, MRI scanning and routine MRI protocols. This book also uses basic concepts to demonstrate and expose students to the latest technological innovations in MRI, including: B1+ B1- mapping, Electric property tomography (EPT), Quantitative susceptibility mapping (QSM), Chemical exchange saturation transfer (CEST), Contrast agents, Molecular MRI, Spin tagging (SPAMM and DENSE), MR elastography, Parallel imaging including SENSE and GRAPPA, Compressed sensing and Bayesian approach.

This book is intended as a text/reference for students, researchers, and professors interested in physical and biomedical applications of Magnetic Resonance Imaging (MRI). Both the theoretical and practical aspects of MRI are emphasized. The book begins with a comprehensive discussion of the Nuclear Magnetic Resonance (NMR) phenomenon based on quantum mechanics and the classical theory of electromagnetism. The first three chapters of this book provide the foundation needed to understand the basic characteristics of MR images, e.g.,image contrast, spatial resolution, signal-to-noise ratio, common image artifacts. Then MRI applications are considered in the following five chapters. Both the theoretical and practical aspects of MRI are emphasized. The book ends with a discussion of instrumentation and the principles of signal detection in MRI. Clear progression from fundamental physical principles of NMR to MRI and its applications Extensive discussion of image acquisition and reconstruction of MRI Discussion of different mechanisms of MR image contrast Mathematical derivation of the signal-to-noise dependence on basic MR imaging parameters as well as field strength In-depth consideration of artifacts in MR images Comprehensive discussion of several techniques used for rapid MR imaging including rapid gradient-echo imaging, echo-planar imaging, fast spin-echo imaging and spiral imaging Qualitative discussion combined with mathematical description of MR techniques for imaging flow

This book is not intended as a general text on MRI. It is written as an intro duction to the field, for nonexperts. We present here a simple exposition of certain aspects of MRI that are important to understand to use this valuable diagnostic tool intelligently in a clinical setting. The basic principles are presented nonmathematically, using no equations and a minimum of symbols and abbreviations. For those requiring a deeper understanding of MRI, this book will help facilitate the transition to standard texts. Chapters 1 through 4 provide a general introduction to the phenomenon of nuclear magnetic resonance and how it is used in imaging. Chapter 1 discus ses magnetic resonance, using a compass needle as an example. In Chapter 2, the transition to the magnetic resonance of the atomic nucleus is made. Chapter 3 describes the principles of imaging. In Chapter 4, the terms T 1 and T 2 are described and their relationship to tissue characterization; the fun damental role of thermal magnetic noise in T 1 and T 2 is discussed.

In vivo magnetic resonance imaging (MRI) has evolved into a versatile and critical, if not ‘gold standard’, imaging tool with applications ranging from the physical sciences to the clinical ‘-ology’. In addition, there is a vast amount of accumulated but unpublished inside knowledge on what is needed to perform a safe, in vivo MRI. The goal of this comprehensive text, written by an outstanding group of world experts, is to present information about the effect of the MRI environment on the human body, and tools and methods to quantify such effects. By presenting such information all in one place, the expectation is that this book will help everyone interested in the Safety and Biological Effects in MRI find relevant information relatively quickly and know where we stand as a community. The information is expected to improve patient safety in the MR scanners of today, and facilitate developing faster, more powerful, yet safer MR scanners of tomorrow. This book is arranged in three sections. The first, named ‘Static and Gradient Fields’ (Chapters 1-9), presents the effects of static magnetic field and the gradients of magnetic field, in time and space, on the human body. The second section, named ‘Radiofrequency Fields’ (Chapters 10-30), presents ways to quantify radiofrequency (RF) field induced heating in patients undergoing MRI. The effect of the three fields of MRI environment (i.e. Static Magnetic Field, Time-varying Gradient Magnetic Field, and RF Field) on medical devices, that may be carried into the environment with patients, is also included. Finally, the third section, named ‘Engineering’ (chapters 31-35), presents the basic background engineering information regarding the equipment (i.e. superconducting magnets, gradient coils, and RF coils) that produce the Static Magnetic Field, Time-varying Gradient Magnetic Field, and RF Field. The book is intended for undergraduate and post-graduate students, engineers, physicists, biologists, clinicians, MR technologists, other healthcare professionals, and everyone else who might be interested in looking into the role of MRI environment on patient safety, as well as those just wishing to update their knowledge of the state of MRI safety. Those, who are learning about MRI or training in magnetic resonance in medicine, will find the book a useful compendium of the current state of the art of the field.