Front Cover

Hyperpolarized and Inert Gas MRI

Copyright Page

Dedication

Contents

List of Contributors

Preface

Introduction

The Promise of Hyperpolarized-Gas MR Studies

The Choice of 3He or 129Xe

The Invention of Hyperpolarized-Gas MRI

Anecdotal Prolegomena

Progress in the Field

References

1 MRI Acquisition Techniques

Nonequilibrium Magnetization

High Diffusivity

Signal Loss From Diffusion

Diffusion-Weighted Imaging

Relaxation Times and Partial Pressure of Oxygen

Design Considerations for GRE Imaging

Flip Angles and Phase-Encoding Order for Spoiled-GRE Pulse Sequences

Slice Profile and Slice Order

Balanced Steady-State Free Precession

129Xe Gas Exchange and Uptake

Dissolved 129Xe in the Lung

Excitation Considerations

Taking Advantage of Chemical Shift

Closing Remarks

References

2 The Physics of Hyperpolarized Gas MRI

Introduction

HP Gases: Properties and Considerations

General Properties

Spin Relaxation Mechanisms of HP Gases

Storage and Delivery Considerations for HP Gases

Pulse Sequence Considerations

Methods for Generating HP Gases

Dynamic Nuclear Polarization

Spin-Exchange Optical Pumping

SEOP History and Theoretical Background

SEOP Instrumentation

Stopped-Flow Polarizers

Continuous-Flow Polarizers

SEOP Gas Mixes and Operating Regimes

SEOP Characterization

Applications of SEOP-Prepared HP Gases

Metastability Exchange Optical Pumping

MEOP History and Theoretical Background

MEOP Laser Technology

MEOP Compressor Technology

MRI Applications of MEOP-Polarized Gases

Parahydrogen-Induced Polarization

Principles

PHIP Instrumentation

Potential for Biomedical Applications of HP Propane

HP Gases: Summary and Outlook

References

3 Dynamic Imaging of Lung Ventilation and Gas Flow With Hyperpolarized Gas MRI

Introduction

MRI Methodology

Sequence Design and k-Space Sampling

2D Single-Shot Sequences

2D Multishot Sequences

3D Dynamic Imaging

Physical Considerations for Dynamic Imaging

Spin Polarization

Breathing Factors

Local Static Magnetic Field Homogeneity

Localized Diffusion

Clinical and Physiological Applications of Dynamic HP Gas MRI

Quantification of Dynamic Data

Airway Caliber Measurement

Lung Motion

Flow Imaging

Time-Resolved Breath-Hold Imaging

Time-Resolved Multibreath Imaging

References

4 Persistence of Ventilation Defects in Asthmatics

HP Gas MRI of the Normal Lung

HP Gas MRI in Asthma

Variable Versus Persistent Ventilation Defects

Appearance of Ventilation Defects Over Time

Effect of Bronchoconstricting Agent

Effect of Bronchodilators

Summary

References

5 Hyperpolarized 3He Gas MRI Studies of Pulmonary Disease

Introduction

Emphysema

What Is It?

Hyperpolarized Noble Gas Diffusion-Weighted MRI

3He MRI ADC: Anatomical and Technique Validation

3He MRI ADC: Early Work

Airway Disease

What Is It?

Hyperpolarized 3He MRI Static Ventilation Imaging

3He MRI Ventilation Defects: Anatomic and Technique Validation

3He MRI Ventilation Defects: Early Work

3He MRI: Relationship to Outcomes

Early Disease Changes

Symptoms

Exacerbations

Longitudinal Studies

Treatment Studies

Future Directions

Conclusions

References

6 Pediatric Imaging and Cystic Fibrosis

Introduction

HP Gas MRI Technique and Special Considerations in Children

HP Gas MRI Technique

Special Considerations in Children

Pediatric Applications of HP Gas MRI

Cystic Fibrosis

Current Knowledge

Future Lines of Research

Lung Growth

Chronic Lung Disease of Prematurity

Congenital Diaphragmatic Hernia

Clinical Translation

Conclusion

References

7 Hyperpolarized Gas MRI of Radiation-Induced Lung Injury

Introduction

Pathogenesis of RILI

Application of Hyperpolarized 3He MRI to RILI

Application of Hyperpolarized 129Xe MRI to RILI

129Xe in the Gas Phase

129Xe ADC and Anisotropy

Morphometry

129Xe in the Dissolved-Phase

Gas Exchange and Dynamic 129Xe Spectroscopy

Imaging 129Xe Dissolved-Phase Changes Associated With RILI

Discussion and Future Directions

Acknowledgments

References

8 Development and Application of Mouse Imaging Using Hyperpolarized Xenon

Introduction

Continuous Production and Delivery of HP 129Xe Gas

129Xe Polarizer

Improvements in 129Xe Polarizer

HP Gas Delivery to the Lung by Spontaneous Breathing

Typical Experimental Setup

Some Features of HP 129Xe MR Signal

Spectral Pattern of 129Xe in Mice

Signal Dynamics of 129Xe in Spontaneously Breathing Mice

Gas-Phase 129Xe MRI

Mouse Lung MRI at a Lower Xe Concentration

Fast Imaging Techniques

Ventilation Imaging

Dissolved-Phase 129Xe MR Measurements

Dissolved-Phase 129Xe MRS

Dissolved-Phase 129Xe MRI

Conclusions

References

9 Quantitative Ventilation Imaging Using Hyperpolarized Gas and Multibreath Imaging Sequences

Introduction

Quantitative Ventilation Metrics

An Overview of Quantitative Ventilation Imaging Methods

Noncontrast CT

Oxygen-Enhanced, Proton MRI

Single-Photon Emission Computed Tomography

Positron Emission Tomography

Other Methods for Mapping Ventilation

Hyperpolarized 3He/129Xe Imaging of Specific/Fractional Ventilation

Overview of Quantitative Imaging Using HP Gas

Correction for Oxygen-Induced Relaxation

Correction for Ex Vivo Relaxation

Correction for Instrumental/Anatomical DV and Collateral Ventilation

A Modified Sequence Suitable for Large Animal and Human Studies

Animal Models

Human Imaging

Measurement Reproducibility and Validity

A Multiparameter Sequence for Lung Function Imaging

Conclusions

References

10 PAO2 Mapping Using HP Gas MRI

Introduction

Theoretical and Technical Development

Theory of Oxygen-Induced HP Noble Gas Relaxation

Acquisition Schemes for Decoupling O2-Relaxation and RF-Induced Depolarization

Pulse Sequence Development

Breathing Protocol

Mitigating Error Caused by Signal Transfer During Breath-Hold

PAO2 as a Clinical Marker

Validation

Reproducibility

Pathological Relevance

Sensitivity and Specificity

Future Directions for PAO2 Imaging Research

References

11 Hyperpolarized Xenon-129 Dissolved-Phase Magnetic Resonance Imaging

Introduction

Measurement of Pulmonary Gas Exchange and Uptake by 129Xe Spectroscopy

Indirect Imaging of Dissolved-Phase 129Xe

Direct Imaging of Dissolved-Phase 129Xe

Conclusions and Outlook

References

12 Lung Morphometry With HP Gas Diffusion MRI: From Theoretical Models to Experimental Measurements

Introduction

Diffusion of HP Gases in Lung Airspaces

Weibel Geometrical Model of Lung Acinar Airways

Anisotropic Diffusion of Gas in Acinar Airways: Microscopically Anisotropic—Macroscopically Isotropic Model

Phenomenological Theory of Anisotropic Diffusion in Acinar Airways

Accuracy Analysis: Effects of Acinar Airways Branching and Distribution of Geometrical Parameters

Validation of Lung Morphometry Technique

Microscopically Anisotropic—Macroscopically Isotropic Model

Validation Against Direct Histology

Applications of In Vivo Lung Morphometry Technique

Changes in Lung Microstructure Throughout Adult Lifespan

Early Emphysematous Changes in Lung Microstructure of Current and Former Smokers

In Vivo Lung Morphometry of Lungs After Pneumonectomy

Morphometric Changes in the Human Pulmonary Acinus During Inflation

3He Gas T2* Transverse Relaxation Properties

ADC Measurements in Lungs

Concluding Remarks

Acknowledgment

References

Appendix

13 CT and MRI Gas Ventilation Imaging of the Lungs

Introduction

CT Assessment of Lung Ventilation

Newer CT Methods to Assess Lung Ventilation

CT Gas Ventilation Imaging of the Lungs

MRI Hyperpolarized Gas Ventilation Imaging of the Lungs

MRI Nonpolarized Gas Ventilation Imaging of the Lungs

Oxygen-Enhanced MRI Ventilation Imaging of the Lungs

Summary

References

14 Hyperpolarized Gas MRI of the Lung in Asthma

Asthma and the Role of Imaging

Obstructive Physiology in Asthma

Asthma Mechanisms and Phenotypes

Meaning of Ventilation Defects in Asthma

Spatial Heterogeneity

Temporal Heterogeneity

Structure and Function Associations

Role of HP Gas MRI in the Study of Asthma Phenotypes

Exercise-Induced Asthma

Severe Asthma

Childhood Asthma

Future Work and Outlook

Interface of COPD and Asthma

Role for Xenon-MRI

Multimodal Studies of Inflammation in Asthma

Pulmonary MRI as an Image-Biomarker

Acknowledgments

References

15 Oxygen-Enhanced MR Imaging for Lung: Basics and Clinical Applications

Introduction

Related Respiratory Physiology for Oxygen-Enhanced MR Imaging

Theory of Oxygen Enhancement

Oxygen-Enhanced MR Sequence Design

Basic Studies of Oxygen-Enhanced MR Imaging

Clinical Study of Oxygen-Enhanced MR Imaging

Advantages and Disadvantages of Oxygen-Enhanced MR Imaging Compared With Hyperpolarized Noble Gas MR Imaging

Conclusion

References

16 Brain Imaging Using Hyperpolarized Xenon MRI

Introduction

Existing Brain Imaging Techniques

Spectral Properties of 129Xe

129Xe Brain Imaging

Neurovascular Pathologies

HP Xenon as a Functional Imaging Modality

Conclusions

References

17 Xenon Biosensor HyperCEST MRI

Introduction

Indirect Imaging and Spectroscopy Detection Through Saturation Transfer

CEST Detection: Special Considerations for Hyperpolarized 129Xe Versus 1H

Xenon Hosts

Sensor Design—Targeting Options

Probing Microenvironments

Saturation Schemes and Image Encoding

Outlook

References

18 Pulmonary Imaging Using 19F MRI of Inert Fluorinated Gases

Introduction

Properties of Inert Fluorinated Gases

Static Breath-Hold Imaging

Dynamic Imaging

Volume Measurements

Washin/Washout Measurements

Fractional Ventilation

Gravitational Distribution of Ventilation

Diffusion Imaging

V/Q Measurement

Conclusions

Acknowledgments

References

19 Surface Quadrupolar Relaxation (SQUARE) Contrast in Pulmonary MRI With Hyperpolarized 83Kr

83Kr—A Spin I=9/2 Isotope

Hyperpolarized 83Kr, Quadrupolar Relaxation, and the Apparent Polarization, Papp

Why It All Matters—Surface Quadrupolar Relaxation of HP 83Kr

The HP 83Kr Ventilation System and Initial Pulmonary Measurements

Detailed NMR Spectroscopic Measurements of 83Kr T1 Relaxation as a Function of Inhalation Volume

HP 83Kr SQUARE T1 Contrast of an Animal Model of Emphysema

Perspectives for Clinical Applications of 83Kr MRI

Acknowledgments

References

20 Overview & Future Directions

Conclusion

References

Index

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