Advanced Clinical MRI of the Kidney: Methods and Protocols

Preface
Contents
Contributors
Part I: General Considerations for Kidney MRI
	1: Kidney Anatomy and Physiology
		Anatomy
		Blood Supply, Innervation, and Lymphatics
		Embryology
		Physiology
		Summary
		References
	2: MR Physics, Hardware Considerations, and Practical Steps for Clinical MRI of the Kidney
		Introduction
		The MRI Signal
		MRI Hardware
			The Primary Magnet
			Gradients
			RF Coils
		A Walk Through k-Space
			General Properties of K-Space
			Partial Fourier Techniques and K-Space
				Phase-Conjugate Symmetry
				Read-Conjugate Symmetry
			K-Space Trajectories and Image Reconstruction
		Signal Relaxation Mechanisms and Image Contrasts
			T1 Relaxation
			How to Measure T1 Relaxation Time for Body Imaging
			T2 Relaxation
			How to Measure T2 Relaxation Time for Body Imaging
			T2* Relaxation
			How to Measure T2* Relaxation Time for Body Imaging
			T1ρ Relaxation
			How to Measure T1ρ Relaxation in Body Imaging
			Diffusion-Weighted Imaging
			How to Measure Apparent Diffusion Coefficients for Body Imaging
		Pulse Sequence and Imaging Parameters
		Kidney MRI
			Image Acquisition
			Physiological Monitoring and Motion Consideration
			Respiratory Synchronization
			Signal Averaging
			Swapping Encoding Direction and Saturation Bands
		Practical Points to Consider When Performing a Kidney MRI Study
			Scheduling a Renal MRI Scan
			Patient Positioning
			Physiological Monitoring
			Coil Selection and Image Acquisition
		Fat Suppression Methods
			Inversion Recovery (STIR, Short TI Inversion Recovery)
				Advantages
				Disadvantages
			Spectral Fat Saturation
				Advantages
				Disadvantages
			Dixon Technique
				Advantages
				Disadvantages
		Typical Body Imaging Artifacts and Tips to Mitigate Them
			Motion Artifacts
			Chemical Shift Artifact
			Magnetic Susceptibility and Magnetic Susceptibility Artifact
			Dielectric (Standing Wave) Artifacts
			Gibbs/Ringing or Truncation Artifact
			Aliasing or Wraparound Artifact
			Partial Volume Artifacts
			Slice Overlapping
		Summary
		References
	3: Managing Motion in Kidney MRI
		Introduction
			Kidney Motion
			Kidney Motion Artifacts
			Avoiding Kidney Motion Artifacts
		Periodic Motion Effects
			Physics of Periodic Motion
			Respiration
			Arterial Pulsation
		Periodic Artifact Mitigation
			Breath-Holds
			Gating and Navigation Techniques
			Phase-Encoding Gradient Orientation
			Signal Saturation
			Alternate K-Space Trajectories
				Radial Approaches
				Spiral Approaches
		Random Motion Effects
			Physics of Random Motion
			Patient Bulk Motion
			Peristalsis
				Bowel Peristalsis
				Ureter Peristalsis
		Random Motion Artifact Mitigation
			Sedation
			Motion Tracking
			Fast Imaging Techniques
		Summary
		References
	4: Gadolinium-Based Contrast Agent Safety with Focus on Kidney MRI
		Introduction
		Properties of Currently Used Contrast Agents
		Nephrogenic Systemic Fibrosis
		Gadolinium Retention
		Physiologic Contrast Reactions
		Allergic-Like Contrast Reactions
		GBCM and MRI of the Kidneys
		References
	5: Motion-Insensitive Contrast-Enhanced Dynamic MR Imaging of the Kidneys
		Introduction
		Dynamic MRI Acquisition Techniques
			Conventional Three-Dimensional T1 GRE Dynamic Acquisition
			Motion-Insensitive Golden Angle Radial Sparse Parallel (GRASP) Acquisition
		Conclusion
		References
	6: Clinical Implementation of Image Processing in Kidney MRI
		References
Part II: MRI Methods, Analysis and Clinical Applications
	7: Quantitative MRI of the Kidneys: Rationale and Challenges
		Introduction
		Quantitative Renal Multiparametric MRI
			Studying Renal Morphology
			Assessing Tissue Microstructure with Quantitative Renal MRI
				Diffusion-Weighted Imaging (DWI)
				T1, T1ρ, and T2 Mapping
				Magnetization Transfer
				Quantitative Susceptibility Mapping
				Magnetic Resonance Elastography
			Renal Oxygenation
				Blood Oxygen Level-Dependent (BOLD) MRI
				T2-Relaxation-Under-Spin-Tagging (TRUST) MRI
			Measurement of Renal Blood Flow and Perfusion
				Phase Contrast MRI
				Arterial Spin Labeling
				Dynamic Contrast-Enhanced MRI
		Understanding the Biological Specificity of Multiparametric Renal MRI Measures
		Combining Information from Multiparametric Renal MRI
		Renal Multiparametric MRI Measures in Clinical Studies
		Challenges to Clinical Translational Renal MRI
		Conclusion
		References
	8: T1 Mapping of the Kidney
		Introduction
		Part I: MRI Physics and Acquisition Protocols
			Origins of T1
			Acquisition of Kidney T1 Maps
				Practical Recommendations for Kidney T1 Mapping
		Part II: Post-processing and Data Analysis Methods
			Generation of Kidney T1 Maps
			Quality Control
				Motion
				Cardiac Gating Issues
			Reporting of Kidney T1 Values
		Part III: Clinical Applications
			T1 as a Biomarker for Kidney Disease
			Quantitation and Standardization
			Confounds
				Fat and Iron
				Hydration
				Liver Cirrhosis
				Perfusion
		Conclusion
		References
	9: T2 Mapping of the Kidney
		MRI Physics and Historical Background
		Acquisition Protocols
		Recommendations for Renal T2 Mapping In Vivo
		Post-processing and Data Analysis
		Study Reports and Quality Assurance
		Clinical Applications and Considerations
		Conclusion
		References
	10: Probing Renal Oxygenation with T2*-Sensitized MRI (BOLD-MRI)
		Introduction: The Physiology of Renal Tissue Oxygenation
		MRI Physics and Acquisition Protocols
			Basic Principles of T2*-Sensitized MRI (BOLD-MRI)
			Patient Preparation
			Acquisition Protocol
			Common Image Artifacts
				Bulk Susceptibility Artifacts (Bowel Gas)
				Respiratory Motion Artifacts
		Image Post-processing and Data Analysis Methods
			Image Post-processing
			Data Analysis
		Clinical Studies and Possible Applications
			Chronic Kidney Disease
			Acute Kidney Injury
			Transplantation
			Renovascular Disease/Renal Artery Stenosis
			Drug Research
			Examples of Use in Clinical Practice
		Possible Future Developments and Applications
		References
	11: T1ρ Mapping and Its Applications for Assessment of Renal Fibrosis
		Part 1: MRI Physics and Acquisition Protocols
			Physical Principles and Pulse Sequence Implementation
			Acquisition Protocols
		Part 2: Post-processing and Data Analysis Methods
			Single Locking Frequency
			Multiple Locking Frequencies
		Part 3: Clinical Applications
			Background
			Applications of T1ρ Imaging in the Kidneys
			Mechanism
			Less Promising Noninvasive MRI Methods for Assessment of Renal Fibrosis
			Future Directions
		Conclusions
		References
	12: MR Fingerprinting for Quantitative Kidney Imaging
		Introduction
		MRF Acquisition Protocols
			Conceptual Framework of MRF
			MRF Acquisition Methods
		MRF Post-processing
			Tissue Property Mapping Using Template Matching
			Incorporation of B1 Field Map in Template Matching
			Accelerated MRF Template Matching with SVD Compression
		Clinical Applications
			Polycystic Kidney Disease (PKD)
			Kidney Cancer
			Chronic Kidney Disease
			Kidney Transplant
			Sickle Cell Disease
		References
	13: Magnetization Transfer Imaging
		Introduction
		MRI Physics and Acquisition Protocols
			MRI Physics
				Off-Resonance MT
				On-Resonance MT
			Acquisition Protocols
				MT Protocols
				On-Resonance MT
				Segmentation
				Field Mapping and Corrections
		Post-Processing and Data Analysis Methods
			Bound Pool Fraction Calculation
			B0 Field Correction
			B1 Field Correction
		Clinical Applications
			Contrast Enhancement
			Kidney Function
			Kidney Histology—Fibrosis
		Conclusion
		References
	14: Metabolic Imaging: Measuring Fat in the Kidney
		Introduction
		Part 1: MRI Physics and Acquisition Protocols
			Field Strength
			Acquisition
			Water Suppression and Local Power Optimization
			Motion Correction
		Part 2: Post-Processing and Data Analysis Methods
			Quantification of Renal Triglyceride Content
			Reproducibility and Validation of Renal Triglyceride Content
		Part 3: Clinical Applications
			Renal Triglyceride Content and Obesity-Related Kidney Disease
			Dietary Effects on Ectopic Fat Storage in the Kidney
			Effects of Glycemic Control on Renal Triglyceride Content
		Future Outlook
		References
	15: MR Angiography and Phase-Contrast MRI: Measuring Blood Flow in the Kidney
		Introduction
		Phase-Contrast MRI
			Patient Preparation
			PC-MRI Physics and Acquisition Protocol
				2D PC-MRI
				4D Flow MRI
			PC-MRI Post-Processing and Data Analysis Methods
				2D PC-MRI
				4D Flow MRI
			PC-MRI Clinical Applications
				Chronic Kidney Disease
				Acute Kidney Injury
				Renovascular Disease/Renal Artery Stenosis
				Autosomal Dominant Polycystic Kidney Disease
				Renal Transplantation
			Common Issues and Artifacts
				Noise
				Aliasing
				Deviation of Imaging Plane
				Inadequate Temporal Resolution
				Inadequate Spatial Resolution
				Accelerated Flow and Spatial Misregistration
				Phase Offset Errors
		Magnetic Resonance Angiography of the Renal Arteries
			MRA Physics and Acquisition Protocols
				Contrast-Enhanced MRA
					Gadolinium-Based Contrast Agent-Enhanced MRA
					Ferumoxytol-Enhanced MRA
					Safety Considerations Regarding the Use of Contrast Agents
					Common Issues and Artifacts
				Non-Contrast-Enhanced MRA
					Time-of-Flight MRA
					bSSFP
					IFDIR
			MRA Post-Processing and Data Analysis Methods
				Maximum Intensity Projection
				Multiplanar Reconstruction
				Volume Rendering
				Volume Rendering and MPR Compared to MIP
			MRA Clinical Applications
				Renovascular Hypertension
				Renal Transplantation
		Conclusion
		References
	16: Quantitative Susceptibility Mapping of the Kidney
		Introduction
		MRI Physics and Acquisition Protocols
			Magnetic Susceptibility
			QSM Forward Problem
			Magnetic Field Mapping
			Quantitative Susceptibility Mapping (QSM)
				Phase Unwrapping
				Background Field Removal
				Solving the Ill-Posed Inverse Problem
			Challenges in Body QSM
			MRI Sequence Parameters
		Post-Processing Pipeline for QSM
		Possible Clinical Application of Renal QSM
		References
	17: MR Elastography for Evaluation of Kidney Fibrosis
		Part 1: Introduction and MRE Physics
			Magnetic Resonance Elastography
			Modulus of Elasticity
			Generation and Transmission of Mechanical Waves into Tissues
			Imaging the Propagation of Mechanical Waves Using Modified Phase Contrast Sequence
			Generating a Stiffness Map That Quantifies Mechanical Properties of Tissue
		Part 2: Recommended Renal MRE Scanning Protocol
			Patient Preparation
			MRE Protocol
			MRE Quality Control
			Stiffness Measurement
		Part 3: Clinical Applications
			Evaluation of Fibrosis in Native Kidneys in CKD Patients
			Interstitial Fibrosis in Renal Allografts
		Conclusions
		Bibliography
	18: Microstructural Features and Functional Assessment of the Kidney Using Diffusion MRI
		DWI in the Kidney: Background
		Diffusion Measurements and ADC
		IVIM (Microcirculation/Microstructure)
		DTI (Anisotropy)
		Advanced/Hybrid Models
			Flow Anisotropy
			Encoding Variations
		Advanced Readouts (SMS, RS-EPI, rFOV, Non-Cartesian)
		Diffusion Data Acquisition Methods
		DW-EPI for ADC
		DW-EPI for IVIM
		DW-EPI for DTI
		Motion Management
		Clinical Applications of Renal DWI
			Chronic Kidney Disease
			Kidney Transplant
			Kidney Cancer
		Summary
		References
	19: Arterial Spin Labeled MRI for Quantitative Non-Contrast Perfusion Measurement of the Kidneys
		Introduction
		Part 1: MRI Physics and Acquisition Protocols
			Labeling Schemes
				Pulsed Arterial Spin Labeling
				Pseudo Continuous Arterial Spin Labeling (pCASL)
			Acquisition Methods
				2D Acquisitions
				3D Acquisitions
			Post-Label Delay (PLD)
				Background Suppression (BGS)
				Inflow Saturation
			ASL Acquisition Protocol
				Patient Preparation
				Hardware Considerations
				FAIR Labeling Parameters
				pCASL Labeling Parameters
				Readout Parameters
				Other Sequence Considerations
		Part 2: Post-Processing and Data Analysis Methods
			Data Processing
			Perfusion Quantification
			Data Analysis
		Part 3: Clinical Applications
		Conclusion
		References
	20: Gadolinium-Based Functional MR Urography: From Image Acquisition to Interpretation
		Introduction
		Patient Preparation
		Image Acquisition
		Postprocessing
			Signal Intensity–Transit Time Curves
			Temporal Parameters (Fig. 20.1d)
				Time to Peak
				Calyceal Transit Time
				Renal Transit Time (RTT)
			Functional Parameters
				Differential Renal Function (DRF)
				Patlak Plots
			Patlak Maps
			Blood Volume Maps
			Normal Curves
		Clinical Applications and Interpretation
		References
	21: Tools and Techniques to Map Glomerular Distribution and Nephron Function Using MRI
		Introduction
			Nephron Number and Cationic Ferritin–Enhanced MRI
		Applications in Pre-clinical Models of Human Disease
			Kidney Phenotyping with CFE-MRI
				Kidney Preparation and Ex Vivo Imaging
			In Vivo CFE-MRI
				Hardware and Experimental Preparations
				In Vivo Imaging
			Imaging Kidney Function in Isolated Perfused Kidneys with MRI
				Preparing the Kidney
				Hardware Considerations
				Imaging
			Post-processing, Analysis, and Validation
		Applications in the Human Kidney
			Assessment of Human Allografts with CFE-MRI
				Preparing the Kidney
				Imaging
			Post-processing of Nephron Features and Other Structural Features
			Multi-modal Imaging of Glomeruli with Positron Emission Tomography (PET) and MRI
		Conclusion
		References
Part III: Advanced Methods and Applications
	22: CEST MRI for Monitoring Kidney Diseases
		Introduction
		Part I: CEST MRI Physics and Acquisition Protocols
			Principles of CEST Imaging
			CEST Contrast Agents
			CEST pH Imaging
			Basic Strategies for CEST MRI Acquisition
			Additional Considerations
				Acquisition Strategies to Account for Motion
				Acquisition Strategies to Account for B0 and B1 Field Inhomogeneity
				Acquisition Strategies to Account for Fat
		Part II: Post-processing and Data Analysis Methods
			Z-spectra Analysis
			pH Mapping Using Ratiometric Analysis
		Part III: Results and Clinical Applications
			Endogenous CEST MRI of the Kidney
			Exogenous pH Imaging for Abdominal Applications
			Limitations and Future Perspectives
		References
	23: Renal Sodium 23Na-MRI for Clinical Applications
		Introduction
			Kidney Handling of Sodium
		MRI Physics and Acquisition Protocols
			Scanner Hardware
			Image Acquisition and Reconstruction
			Sodium Standards
		Post-processing and Data Analysis
			Quantitative Sodium MRI in the Human Kidney
		Summary and Technical Future Directions
		Clinical Applications
			Renal Sodium MRI in Healthy Individuals
			Renal Sodium MRI of Kidney Transplantation
			Renal Sodium MRI of Hypertension
			Renal Sodium MRI of Kidney Damage and Chronic Kidney Disease
			Sodium MRI of Extremity Skin and Muscle in Patients with Kidney Disease
		Conclusion
		References
	24: Hyperpolarized 13C Renal Magnetic Resonance Imaging: Practical Considerations for Clinical Use
		MRI Physics and Acquisition Protocols
			Basic Concepts Behind d-DNP Hyperpolarized 13C MRI
			Renal Functional and Metabolic Investigations Using 13C-Pyruvate MRI
			Practical Considerations for Hyperpolarized 13C MRI Kidney Exams
		Post-Processing and Data Analysis
		Clinical Applications
		Notes
		References
	25: Bridging the Gap Between Imaging and Biopsy
		Introduction
		Percutaneous Renal Biopsy Procedure
		Other Renal Biopsy Techniques
		Personnel
		Tissue Sample Preparation
			Biopsy Adequacy
		Microscopic Examination
		Generalizations About Glomerular Diseases
		Renal Transplant Biopsy
			Targeted Biopsy
		Limitations
		Conclusion
		References
	26: Renal Modeling and 3D Printing
		Introduction
		MRI Acquisition Protocols
		Post-Processing and Data Analysis Methods
			Anatomy and Segmentation
			Clinical Review of Segmentation
			Printing Design and Considerations
			Quality Control and Storage
		Clinical Applications
		Future Directions
		References
	27: Radiomics and Texture Analysis
		Introduction
		Steps of a Radiomics Project
			Image Acquisition
			Image Segmentation: Identification of the Region of Interest
			Image Processing
			Image Interpolation
			Image Normalization
			Image Intensity Discretization
			Feature Extraction
			Feature Selection and Modeling
		Radiomics as Applied to Renal Magnetic Resonance Imaging
			Radiomics for the Identification of Renal Masses
			Radiomics and Characterization of Renal Cell Carcinoma Biology
			Radiomics in the Treatment Assessment of Renal Cell Carcinoma
			Applications in Chronic Renal Diseases
			Evaluation of Renal Pathology
		Limitation of Radiomics and Future Directions
		Conclusion
		References
	28: The Role of Artificial Intelligence in Automated Data Analysis of the Kidney
		Introduction
		Detection and Segmentation
			Machine Learning-Based Segmentation
			Deep Learning-Based Detection and Segmentation
			Performance Metrics in Detection and Segmentation Tasks
			Unbalanced Dataset Handling
		Classification
			Radiomics and Machine Learning-Based Classification
			Deep Learning-Based Classification
			Performance Metrics in Classification Tasks
		Other Applications
			Image Synthesis
			Image Reconstruction
		Implementing a Deep Learning Algorithm
			Data Availability and Data Curation
			Downloading/Cloning Algorithms from Code Repositories
		Discussion
		References
	29: Ultra-high Field MRI of the Kidney
		Introduction
		Clinical Practice and Potential of Ultra-High Field Renal MRI
		Current State-of-the-Art in Ultra-High Field Renal MRI
			Anatomical Imaging and Angiography
			Quantitative Imaging
				T1 and T2 Measurements
				Blood Oxygenation Level Dependent MRI
				Arterial Spin Labeling
			X-Nuclei Imaging in the Kidneys
				Sodium Imaging
				Phosphorus Spectroscopy and Spectroscopic Imaging
			Kidney Imaging at 10.5 T
		Challenges and Opportunities of Renal MRI at 7 T
			RF Inhomogeneity
			SAR Limitations
			Availability of 7 T Scanners
		Conclusion and Discussion
		References
	30: Quantification of Renal Metabolic Rate of Oxygen
		Introduction
		Quantification of Whole-Organ MRO2
		Measurements of Venous Oxygenation and Blood Flow Rate
			Susceptometry
			T2-Based Oximetry
		Conclusion
		Reference
Index