Principles of Magnetic Resonance Imaging: Physics Concepts, Pulse Sequences, & Biomedical Applications
Yi Wang PhD
Principles of Magnetic Resonance Imaging provides a contemporary (2016) introduction to the fundamental concepts of MRI and connects these concepts to the latest MRI developments. Graphic illustrations are used to visualize the complete solution to the Bloch Equation and to clarify underlying biophysical processes, simplified calculations and specific examples are used to add precision in appreciating abstract concepts, and insightful interpretations and clinical examples are presented to appreciate biomedical information in MRI signal. This book contains three parts: I. Section the body into voxels. Part I 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? Part II examines the effects of the biophysical processes in a voxel on MRI signal. A unified distributional evaluation of the phase factor in a voxel and intuitive biophysical models are developed for MRI signal dependence on Spin fluctuation in a 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 B_0 field, which leads to magnetic susceptibility and chemical shift. The connection of MRI contrast physics to biomedical applications is visualized in the following three terms: 1) cellularity for T2 weighted imaging and diffusion weighted imaging (the latter emphasizing cellular geometry), 2) vascularity for T1 weighted imaging with Gadolinium injection, MR perfusion, and MR angiography, and 3) biomolecularity for MR spectroscopy, and tissue magnetism with emphasis on biometallic imaging. III. How to operate MRI? Part III describes MRI safety issues, hardware, software, MRI scanning, and routine MRI protocols. This MRI book also uses basic concepts to demonstrate and expose students to the latest technological innovations, including: B_(1+)and B_(1-) mapping; Chemical exchange saturation transfer (CEST); Electric property tomography (EPT); Magnetic particle imaging (MPI); MR elastography (MRE); Moving spin tagging including ASL, TRUST, SPAMM and DENSE; Navigator motion compensation; Parallel or accelerated imaging including SENSE, GRAPPA, compressed sensing, simultaneous multiple slices and other Bayesian approaches; Quantitative susceptibility mapping (QSM).