Fundamentals of In Vivo Magnetic Resonance
Authoritative reference explaining why and how the most important, radiation-free technique for elucidating tissue properties in the body works
In Vivo Magnetic Resonance helps readers develop an understanding of the fundamental physical processes that take place inside the body that can be probed by magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS), uniquely bridging the gap between the physics of magnetic resonance (MR) image formation and the in vivo processes that influence the detected signals, thereby equipping the reader with the mathematical tools essential to study the spin interactions leading to various contrast mechanisms.
With a focus on clinical relevance, this book equips readers with practical knowledge that can be directly applied in medical settings, enabling informed decision-making and advancements in the field of medical imaging. The material arises from the lecture notes for a Stanford University Department of Radiology course taught for over 15 years.
Aided by clever illustrations, the book takes a step-by-step approach to explain complex concepts in a comprehensible manner. Readers can test their understanding by working on approximately 60 sample problems.
Written by two highly qualified authors with significant experience in the field, In Vivo Magnetic Resonance includes information on:
The fundamental imaging equations of MRI
Quantum elements of magnetic resonance, including linear vector spaces, Dirac notation, Hilbert Space, Liouville Space, and associated mathematical concepts
Nuclear spins, covering external and internal interactions, chemical shifts, dipolar coupling, J-coupling, the spin density operator, and the product operator formalism
In vivo MR spectroscopy methods
MR relaxation theory and the underlying sources of image contrast accessible via modern clinical MR imaging techniques
With comprehensive yet accessible coverage of the subject and a wealth of learning resources included throughout, In Vivo Magnetic Resonance is an ideal text for graduate students in the fields of physics, biophysics, biomedical physics, and materials science, along with lecturers seeking classroom aids.
Preface xi About the Companion Website xv 1 Introduction 1 1.1 A Brief History of MR 1 1.2 NMR versus MRI 3 1.3 The Roadmap 5 2 Classical Description of MR 11 2.1 Nuclear Magnetism 11 2.2 Net Magnetization and the Bloch Equations 13 2.3 Rf Excitation and Reception 14 2.4 Spatial Localization 15 2.5 The MRI Signal Equation 16 2.6 Summary 19 Exercises 20 Historical Notes 23 3 Quantum Mechanical Description of MR 27 3.1 Introduction 27 3.1.1 Why Quantum Mechanics for Magnetic Resonance? 27 3.1.2 Historical Developments 27 3.1.3 Wave Functions 29 3.2 Mathematics of QM 32 3.2.1 Linear Vector Spaces 32 3.2.2 Dirac Notation and Hilbert Space 33 3.2.3 Liouville Space 36 3.3 The Six Postulates of QM 38 3.3.1 Postulate 1 38 3.3.2 Postulate 2 38 3.3.3 Postulate 3 39 3.3.4 Postulate 4 39 3.3.5 Postulate 5 39 3.3.6 Postulate 6 40 3.4 MR in Hilbert Space 44 3.4.1 Review of Spin Operators 44 3.4.2 Single Spin in a Magnetic Field 44 3.4.3 Ensemble of Spins in a Magnetic Field 46 3.5 MR in Liouville Space 49 3.5.1 Statistical Mixture of Quantum States 50 3.5.2 The Density Operator 51 3.5.3 The Spin-lattice Disconnect 52 3.5.4 Hilbert Space versus Liouville Space 52 3.5.5 Observations About the Spin Density Operator 53 3.5.6 Solving the Liouville von Neuman Equation 55 3.6 Summary 57 Exercises 58 Historical Notes 61 4 Nuclear Spins 67 4.1 Review of the Spin Density Operator and the Hamiltonian 67 4.2 External Interactions 68 4.3 Internal Interactions 69 4.3.1 Chemical Shift 71 4.3.2 Dipolar Coupling 72 4.3.3 J Coupling 72 4.4 Summary 75 Exercises 75 Historical Notes 78 5 Product Operator Formalism 81 5.1 The Density Operator, Populations, and Coherences 81 5.1.1 Spin Systems and Associated Density Operators 81 5.1.2 Density Matrix Calculations 85 5.2 POF for Single-Spin Coherence Space 88 5.3 POF for Two-Spin Coherence Space 90 5.4 Branch Diagrams 94 5.5 Multiple Quantum Coherences and 2D NMR 97 5.6 Polarization Transfer 100 5.7 Spectral Editing 103 5.7.1 J-difference Editing 103 5.7.2 Multiple-quantum Filtering 104 5.8 Summary 105 Exercises 106 Historical Notes 111 6 In vivo MRS 113 6.1 1H MRS 113 6.1.1 Acquisition Methods 113 6.1.2 Detectable Metabolites and Applications 120 6.2 31P-MRS 126 6.3 13C-MRS 127 6.3.1 Acquisition Methods 127 6.3.2 13C Infusion Studies 132 6.3.3 Hyperpolarized 13 c 132 6.4 Deuterium Metabolic Imaging 138 6.5 23Na-MRI 140 6.6 Summary 140 Exercises 141 7 Relaxation Fundamentals 145 7.1 Basic Principles 145 7.1.1 Molecular Motion 145 7.1.2 Stochastic Processes 147 7.1.3 A Simple Model of Relaxation 150 7.2 Dipolar Coupling 153 7.2.1 The Solomon Equations 153 7.2.2 Calculating Transition Rates 155 7.2.3 Nuclear Overhauser Effect 158 7.3 Chemical Exchange 160 7.3.1 Introduction 160 7.3.2 Effects on Longitudinal Magnetization 161 7.3.3 Effects on Transverse Magnetization 162 7.3.4 Examples 164 7.4 In Vivo Water 167 7.4.1 Hydration Layers 167 7.4.2 Tissue Relaxation Times 168 7.4.3 Magic Angle Effects 169 7.4.4 Magnetization Transfer Contrast (MTC) 170 7.4.5 Chemical Exchange Saturation Transfer (CEST) 172 7.4.5.1 Amide Proton (–NH) Transfer (APT) 173 7.4.5.2 Hydroxyl (–OH) CEST 173 7.4.5.3 Amine (–NH2) CEST 173 7.5 Summary 174 Exercises 174 Historical Notes 179 8 Redfield Theory of Relaxation 181 8.1 Perturbation Theory and the Interaction Frame of Reference 181 8.2 The Master Equation of NMR 182 8.3 Calculating Relaxation Times 185 8.4 Relaxation Mechanisms 187 8.4.1 Dipolar Coupling Revisited 187 8.4.2 Scalar Relaxation of the 1 st Kind and 2 nd Kind 189 8.4.3 Chemical Shift Anisotropy (CSA) 191 8.5 Relaxation in the Rotating Frame 191 8.5.1 Physics of T1ρ 192 8.5.2 The Spin-Lock Experiment 194 8.5.3 Choosing the Optimum Spin-Lock Frequency 195 8.5.4 Rf Power Considerations 200 8.5.5 Adiabatic Spin-Lock 201 8.5.6 Applications 202 8.6 Illustrative Redfield Theory Examples 202 8.6.1 Hyperpolarized 13C-urea 202 8.6.2 Hyperpolarized 13C-Pyr 203 8.7 Summary 207 Exercises 208 Historical Notes 210 9 MRI Contrast Agents 213 9.1 Paramagnetic Relaxation Enhancement 213 9.1.1 Solomon–Bloembergen–Morgan Theory 215 9.1.2 Gd3+-Based T1 Contrast Agents 218 9.2 T2and T∗2Contrast Agents 219 9.2.1 T2, Diffusion, and Outer-Sphere Relaxation 219 9.2.2 SPIOs and USPIOs 219 9.3 PARACEST Contrast Agents 220 9.4 Contrast Agents in the Clinic 221 9.4.1 Gd-Based Agents 222 9.4.2 Iron-Based Agents 223 9.5 Summary 225 Exercises 225 10 In vivo Examples 229 10.1 Relaxation Properties of the Brain 229 10.1.1 Morphological Imaging 229 10.1.2 Perfusion Imaging 229 10.1.3 Diffusion-weighted Imaging (DWI) 230 10.1.4 Imaging Myelin 232 10.1.5 Susceptibility-weighted Imaging (SWI) 232 10.2 Relaxation Properties of Blood 233 10.2.1 Hemoglobin and Red Blood Cells 233 10.2.2 MRI Blood Oximetry 235 10.2.3 Functional Magnetic Resonance Imaging (fMRI) 236 10.2.4 MRI of Hemorrhage 238 10.3 Relaxation Properties of Cartilage 241 10.3.1 T2Mapping 243 10.3.2 DWI 244 10.3.3 T1ρ Mapping and Dispersion 244 10.3.4 gagCEST 245 10.3.5 dGEMRIC 245 10.3.6 Ultrashort TE (UTE) Imaging 246 10.3.7 Sodium MRI 246 10.3.8 Summary 248 10.4 Synopsis 248 Exercises 249 Further Readings 251 Quantum Mechanics 251 Spin Physics 251 Magnetic Resonance Imaging (MRI) 251 In vivo Magnetic Resonance Spectroscopy 251 Relaxation Theory 252 Clinical MRI 252 References 253 Index 265
Daniel M. Spielman, PhD, is Professor of Radiology at Stanford University, Stanford, CA, USA. He is a fellow of both the American Institute for Medical & Biological Engineering (AIMBE) and International Society of Magnetic Resonance in Medicine (ISMRM), and has received multiple teaching awards including the ISMRM Outstanding Teacher Award (2005) and Stanford Department of Radiology Research Faculty of the Year (2022). Keshav Datta, PhD, is Vice President, Research & Development, at VIDA Diagnostics Inc., Coralville, IA, USA, a precision lung health company, accelerating therapies to patients through AI-powered lung intelligence. He is also a Consulting Research Scientist at Stanford University, Stanford, CA, USA.
