Magnetic resonance elastography (MRE) is a medical imaging technique that combines magnetic resonance imaging (MRI) with mechanical vibrations to generate maps of viscoelastic properties of biological tissue. It serves as a non-invasive tool to detect and quantify mechanical changes in tissue structure, which can be symptoms or causes of various diseases. Clinical and research applications of MRE include staging of liver fibrosis, assessment of tumor stiffness and investigation of neurodegenerative diseases. The first part of this book is dedicated to the physical and technological principles underlying MRE, with an introduction to MRI physics, viscoelasticity theory and classical waves, as well as vibration generation, image acquisition and viscoelastic parameter reconstruction. The second part of the book focuses on clinical applications of MRE to various organs. Each section starts with a discussion of the specific properties of the organ, followed by an extensive overview of clinical and preclinical studies that have been performed, tabulating reference values from published literature. The book is completed by a chapter discussing technical aspects of elastography methods based on ultrasound.

Magnetic resonance elastography (MRE) is a medical imaging technique that combines magnetic resonance imaging (MRI) with mechanical vibrations to generate maps of viscoelastic properties of biological tissue. It serves as a non-invasive tool to detect and quantify mechanical changes in tissue structure, which can be symptoms or causes of various diseases. Clinical and research applications of MRE include staging of liver fibrosis, assessment of tumor stiffness and investigation of neurodegenerative diseases.The first part of this book is dedicated to the physical and technological principles underlying MRE, with an introduction to MRI physics, viscoelasticity theory and classical waves, as well as vibration generation, image acquisition and viscoelastic parameter reconstruction.The second part of the book focuses on clinical applications of MRE to various organs. Each section starts with a discussion of the specific properties of the organ, followed by an extensive overview of clinical and preclinical studies that have been performed, tabulating reference values from published literature. The book is completed by a chapter discussing technical aspects of elastography methods based on ultrasound.

ForewordPrefaceIntroductionPART I. Magnetic Resonance ImagingNUCLEAR MAGNETIC RESONANCEProtons in a Magnetic FieldPrecession of MagnetizationRelaxationBloch EquationsEchoesMagnetic Resonance ImagingIMAGING CONCEPTSk-Spacek-Space Sampling StrategiesMOTION ENCODING AND MRE SEQUENCESMotion EncodingIntra-Voxel Phase DispersionDiffusion-Weighted MREMRE SequencesPART II. ElasticityVISCOELASTIC THEORYStrainStressInvariantsHooke's LawStrain-Energy FunctionSymmetriesEngineering ConstantsViscoelastic ModelsDynamic DeformationWaves in Anisotropic MediaEnergy Density and FluxShear Wave Scattering from Interfaces and InclusionsPOROELASTICITYNavier Equations for Biphasic MediaPoroelastic Signal EquationPART III. Technical Aspects and Data ProcessingMRE HARDWAREMRI SystemsActuatorsMRE PROTOCOLSNUMERICAL METHODS AND POST-PROCESSINGNoise and Denoising in MREDirectional FiltersNumerical FiltersFinite DifferencesPHASE UNWRAPPINGFlynn's Minimum Discontinuity AlgorithmGradient UnwrappingLaplacian UnwrappingVISCOELASTIC PARAMETER RECONSTRUCTION METHODSDiscretization and NoisePhase GradientAlgebraic Helmholtz InversionLocal Frequency EstimationMultifrequency Inversionk-MDEVFinite Element MethodDirect Inversion for a Transverse Isotropic MediumWaveguide ElastographyMULTI-COMPONENT ACQUISITIONULTRASOUND ELASTOGRAPHYStrain Imaging (SI)Strain-Rate Imaging (SRI)Acoustic Radiation Force Impulse (ARFI) ImagingVibro-Acoustography (VA)Vibration-Amplitude Sonoelastography (VA Sono)Cardiac Time-Harmonic Elastography (cardiac THE)Vibration Phase Gradient (PG) SonoelastographyTime-Harmonic Elastography (1D/2D THE)Crawling Waves (CW) SonoelastographyElectromechanical Wave Imaging (EWI)Pulse Wave Imaging (PWI)Transient Elastography (TE)Point Shear Wave Elastography (pSWE)Shear Wave Elasticity Imaging (SWEI)Comb-Push Ultrasound Shear Elastography (CUSE)Supersonic Shear Imaging (SSI)Spatially Modulated Ultrasound Radiation Force (SMURF)Shear Wave Dispersion Ultrasound Vibrometry (SDUV)Harmonic Motion Imaging (HMI)PART IV. Clinical ApplicationsMRE OF THE HEARTNormal Heart PhysiologyClinical Motivation for Cardiac MRECardiac ElastographyMRE OF THE BRAINGeneral Aspects of Brain MRETechnical Aspects of Brain MREFindingsMRE OF ABDOMEN, PELVIS AND INTERVERTEBRAL DISCLiverSpleenPancreasKidneysUterusProstateIntervertebral DiscMRE OF SKELETAL MUSCLEIn Vivo MRE of Healthy MusclesMRE in Muscle DiseasesELASTOGRAPHY OF TUMORSMicromechanical Properties of TumorsUltrasound Elastography of TumorsMRE of TumorsPART V. OutlookAPPENDICESSimulating the Bloch EquationsProof that eq. (3.8) is SinusoidalProof for eq. (4.1)Wave Intensity Distributions