Challenges of MRI

Hélène Ratiney is a research fellow at the CNRS and currently head of the NMR and Optics team at the CREATIS laboratory, France. She has developed recognized expertise in the quantification of in vivo spectroscopy signals and also works on pulse design and quantitative MRI.Olivier Beuf is a senior researcher at the CNRS and currently heads the CREATIS laboratory, France. He has extensive experience of MRI applications and a thorough understanding of the associated instrumental and methodological aspects. His recent work focuses on quantitative MRI for tumor characterization and radiation therapy planning.

• Introduction xiiiHélène RATINEY and Olivier BEUFChapter 1 MRI Principles, Hardware Components and Quantification 1Hervé SAINT-JALMES, Hélène RATINEY and Olivier BEUF1.1 Introduction 11.2 Macroscopic magnetization and static magnetic field B0 31.2.1 Nuclear magnetization 31.2.2 Magnet 31.2.3 Roles and orders of magnitude 31.2.4 Technical approaches 41.2.5 Novel technologies 101.3 Description of the magnetization evolution 111.4 Excitation: perturbing the magnetization 121.4.1 Principle 121.4.2 Transmit coil 131.4.3 Radiofrequency signal reception 131.5 Spatial localization in MRI 151.5.1 Principle 151.5.2 Magnetic field gradients 181.6 Signal-to-noise ratio notion in MRI 191.7 Useful signal and information 201.7.1 A "complex" signal in a mathematical and bio-physical sense 201.7.2 From qualitative to quantitative 211.8 Conclusion 231.9 Acknowledgments 241.10 References 24Chapter 2 Radiofrequency Coils: Theoretical Principles and Practical Guidelines 27Aimé LABBÉ and Marie POIRIER-QUINOT2.1 Coil as an electrical resonant circuit 282.1.1 Basic concepts 282.1.2 Coil tuning and matching 302.2 Coil as a source of a magnetic RF field 322.2.1 Polarization and 1 B+ and 1 B− fields 35 2.3 Transmit coil 362.4 Receive coil 382.4.1 Sensitivity factor 382.4.2 Noise regimes 402.5 Decoupling 422.6 RF coil and safety 442.6.1 Specific absorption rate and temperature 452.6.2 Transmission and safety 462.7 Advanced topics and coil challenges 462.8 Conclusion 482.9 References 48Chapter 3 Fast Imaging and Acceleration Techniques 51Nadège CORBIN, Sylvain MIRAUX, Valéry OZENNE, Émeline RIBOT and Aurélien TROTIER3.1 Introduction 513.2 Definition of fast imaging 523.3 Fast accelerated sequences 523.3.1 Sequence optimization 523.3.2 Turbo spin echo and echo-planar imaging 533.3.3 Non-Cartesian methods 553.4 Acceleration methods 583.4.1 Partial Fourier 593.4.2 Parallel imaging 613.4.3 Simultaneous multislice imaging 643.4.4 Iterative reconstruction 653.5 Applications 663.6 References 71Chapter 4 The Basics of Diffusion and Intravoxel Incoherent Motion MRI 75Giulio GAMBAROTA4.1 Introduction 754.2 The history and physics of diffusion 754.3 Diffusion and NMR 804.3.1 First NMR measurements of diffusion 804.3.2 Measurements of diffusion with pulsed gradients: the Stejskal and Tanner method 814.4 Water diffusion in biological tissues 874.5 Diffusion magnetic resonance imaging 894.5.1 Diffusion MRI pulse sequences 894.5.2 Applications of DW-MRI 904.6 IntraVoxel Incoherent Motion MRI 954.7 Conclusion 974.8 References 97Chapter 5 Functional MRI 101Laura Adela HARSAN, Laetitia DEGIORGIS, Marion SOURTY, Éléna CHABRAN and Denis LE BIHAN5.1 BOLD-contrast functional imaging and brain connectivity 1015.1.1 Introduction 1015.1.2 BOLD-contrast functional MRI principles 1025.1.3 fMRI activation paradigms 1115.1.4 Resting fMRI and functional cerebral connectivity mapping 1125.2 Diffusion MRI and brain function 1195.2.1 Introduction 1195.2.2 IVIM fMRI 1215.2.3 Diffusion functional MRI 1215.2.4 Toward functional tractography: a global diffusion framework within the brain connectome 1265.3 Conclusion 1285.4 References 128Chapter 6 Vascular Imaging: Flow and Perfusion 137Sylvain MIRAUX, Frank KOBER and Emmanuel Luc BARBIER6.1 Introduction 1376.2 Contrast agents 1386.2.1 Biological behavior 1386.2.2 Diamagnetism, paramagnetism and superparamagnetism 1396.2.3 Relaxivity effect 1396.2.4 Susceptibility effect 1406.3 Angiography 1416.3.1 White-blood imaging 1426.3.2 Phase contrast imaging 1456.3.3 Black-blood imaging 1466.3.4 Other techniques 1496.3.5 Dynamic angiography 1496.4 Perfusion imaging 1506.4.1 Dynamic susceptibility contrast 1506.4.2 Dynamic contrast-enhanced 1536.4.3 Arterial spin labeling (ASL) 1576.4.4 Experimental approaches 1596.5 Considerations for imaging in humans and small animals 1606.5.1 Angiography in rodents 1626.5.2 Perfusion MRI in rodents 1626.6 References 162Chapter 7 Quantitative Biomechanical Imaging via Magnetic Resonance Elastography 167Olivier BEUF, Philippe GARTEISER, Kevin TSE VE KOON and Jonathan VAPPOU7.1 Fundamentals of magnetic resonance elastography 1677.1.1 Introduction 1677.1.2 MRE signal encoding 1707.1.3 MRE data reconstruction 1757.2 MRE sequences 1787.2.1 Fractional encoding 1787.2.2 Multidirectional encoding 1797.2.3 Diffusion MRE 1807.2.4 Optimal control MRE 1807.3 Main targeted organs and applications 1837.3.1 Liver MRE 1837.3.2 Brain MRE 1867.3.3 MRE and other organs 1877.3.4 Other applications 1897.4 Conclusion 1927.5 Acknowledgments 1937.6 References 193Chapter 8 Imaging of Dipolar Interactions in Biological Tissues: ihMT and UTE 199Guillaume DUHAMEL, Olivier GIRARD, Paulo LOUREIRO DE SOUSA and Lucas SOUSTELLE8.1 Introduction 1998.2 Origins of ultrashort T2 2018.2.1 Dipolar coupling in NMR 2018.2.2 Dipolar resonance line broadening 2038.2.3 Motional averaging 2058.3 Imaging of the inhomogeneous magnetization transfer 2068.3.1 Dipolar order and radiofrequency saturation 2068.3.2 Dipolar order and inhomogeneous magnetization transfer 2098.3.3 Specificity of the ihMT signal and relaxation of the dipolar order 2128.3.4 Specificity of the ihMT signal to myelin 2158.3.5 Research outlook 2168.4 Ultrashort echo time imaging 2178.4.1 Definition of T2 ranges 2178.4.2 Distribution of short T2 values in cerebral tissue 2188.4.3 What are the technical challenges for detecting signals with ultrashort T2? 2188.4.4 What are the challenges for the characterization of signals with ultrashort T2 in the cerebral tissue? 2228.4.5 Applications: myelin imaging 2248.5 Conclusion 2268.6 References 227Chapter 9 In Vivo MR Spectroscopy and Metabolic Imaging 233Julien FLAMENT, Hélène RATINEY and Fawzi BOUMEZBEUR9.1 Introduction 2339.2 In vivo MR spectroscopy 2349.2.1 Free induction decay signal 2359.2.2 Chemical shift and dipolar coupling 2379.2.3 Metabolites investigated in MRS 2419.2.4 Principle of signal localization 2419.2.5 Signal editing, suppression and inversion 2459.2.6 Experimental considerations in MRS 2479.3 Processing and quantification of MRS signals 2479.3.1 Good practices for preprocessing MRS/CSI data 2479.3.2 Quantification method 2529.4 Chemical exchange saturation transfer imaging 2579.4.1 General principle 2589.4.2 Conditions for CEST effect 2589.4.3 Saturation transfer 2629.4.4 Characterization of the magnetization transfer 2649.5 Non-proton nuclei MR spectroscopy or imaging 2669.5.1 Nuclei of interest in metabolic MRS/MRI 2669.5.2 Applications overview 2679.6 Conclusion 2709.7 References 270Chapter 10 Physical-model-constrained MRI: Fast Multiparametric Quantification 277Benjamin LEPORQ, Thomas CHRISTEN and Ludovic DE ROCHEFORT10.1 Introduction 27710.2 Multiparametric MRI based on chemical-shift-sensitive acquisitions 27810.2.1 Signal’s origin and chemical-shift-encoded acquisitions 27810.2.2 Physical models and optimization methods for the quantification 27910.2.3 Clinical and preclinical applications 28510.3 Multiparametric MRI using steady-state acquisitions in repeated fast sequences 28710.3.1 Steady state in a stationary sequence without transverse effects 28710.3.2 Transverse effects considerations for describing steady states 28810.3.3 Uses in multiparametric quantitative imaging 29310.3.4 Clinical and preclinical applications 29510.3.5 Conclusion 29710.4 MRI fingerprinting 29710.4.1 Concept 29710.4.2 Different types of measurements 29910.4.3 Technical developments 30210.4.4 Applications and perspectives 30410.5 Conclusion 30410.6 References 305Chapter 11 Interventional MRI 311Bruno QUESSON and Valéry OZENNE11.1 Introduction to interventional MRI 31111.1.1 Intervention planning 31111.1.2 Pre-operatory imaging 31211.1.3 Post-operative follow-up imaging 31211.2 Technical considerations in interventional MRI 31411.2.1 Choice of the MRI acquisition sequence 31411.2.2 Image reconstruction 31511.2.3 Image analysis and display 31511.2.4 Motion management 31611.3 Interventional MRI hardware 31711.3.1 Intracorporeal medical devices 31711.3.2 Extracorporeal therapeutic medical devices 31911.4 MR-Linac 31911.5 MRI thermometry for guided thermal therapies 32111.5.1 Principle of MRI thermometry 32111.5.2 Practical implementation, advantages and limitations of MRI thermometry 32511.6 High-intensity focused ultrasound 32711.6.1 General principles 32711.6.2 Application domains 33011.7 Perspectives of interventional MRI 33111.8 References 332Chapter 12 Ultra-high Field Imaging 335Virginie CALLOT and Alexandre VIGNAUD12.1 Historical overview 33512.2 Quest toward higher field MR systems - why? 33712.2.1 Advantages and benefits of ultra-high field systems 33712.2.2 Disadvantages and challenges 34312.3 Quest toward higher fields - how? 34712.3.1 Technical constraints 34712.3.2 Physiological constraints, contraindications and safety 34812.4 Main applications and novel opportunities 34912.4.1 Cerebrovascular diseases 35012.4.2 Brain tumors 35212.4.3 Focal epilepsy 35312.4.4 Multiple sclerosis 35312.4.5 Sodium imaging 35412.4.6 Creating new normalization spaces (templates) 35512.4.7 Imaging of the cartilage and muscle injuries 35612.5 Parallel transmission: technical solutions and imaging 35712.6 Conclusion 35912.7 Acknowledgments 36112.8 References 361List of Authors 369Index 373