AMERICAN BOARD OF MEDICAL PHYSICS,
INC.
STUDY
GUIDE 2010
"Part
II - Magnetic Resonance Imaging"
Contents
- Exam Announcement
- The Physics of
Nuclear Magnetic Resonance
- MR Imaging Theory
and Image Reconstruction
- MR Image
Characteristics & Artifacts
- Advanced Imaging
Techniques and System Features
- Contrast
Enhancement, MR Angiography and Cardiac MRI
- MR Technology and
Equipment Quality Control
- Site Planning and
Safety Considerations for MRI
- Suggested
References
back to the American Board of Medical
Physics main page
Announcement
The American Board of Medical Physics offers Certification in
Magnetic Resonance Imaging by examination, which began in 1998.
Applicants who wish to waive the requirement to take the Part I
examination, should submit written documentation indicating that they
have already passed the Part I examination or its equivalent.
Upon successfully passing the prerequisite examination (Part
I) in General Medical Physics and both written (Part II) and oral (Part
III) examinations in Magnetic Resonance Imaging specialty, the
candidates may identify themselves as Certified Medical Physicists or Diplomates of the American Board
of Medical Physics.
The
Examination Panel
Terry M. Button, Ph.D., Chair
Geoffrey D. Clarke, Ph.D., Co-Chair
Jerry D. Allison, Ph.D.
Matthew Bernstein, Ph.D.
Michael Dennis, Ph.D.
Dick
J. Drost, Ph.D.
Jeffrey L. Duerk, Ph.D.
Joel
P. Felmlee, Ph.D.
Carl
R. Keener, Ph.D.
Lisa Lemen, Ph.D.
Douglas Morris, Ph.D.
John
D. Hazle, Ph.D.
Edward
F. Jackson, Ph.D.
Pottumarthi Prasad, Ph.D.
Ronald R. Price, Ph.D.
Michael Smith, Ph.D.
Wlad Sobol, Ph.D.
Examination
Content Outline
|
Subject
|
Weight
|
|
The Physics of Nuclear Magnetic
Resonance
|
15
|
|
MR Imaging Theory and Image
Reconstruction
|
15
|
|
MR Image Characteristics
& Artifacts
|
15
|
|
Advanced Imaging Techniques
& System Features
|
15
|
|
Contrast Enhancement, MR
Angiography & Cardiac MRI
|
15
|
|
MR Technology and Equipment
Quality Control
|
15
|
|
Site Planning and Safety of MR
Examinations
|
10
|
The Physics of Nuclear Magnetic
Resonance
Review of basic physics
- Fundamental
Properties of Magnetic Fields
- Magnetic Dipole
and its Field
- Magnetic Moment in
a Magnetic Field
The nuclear magnetic resonance phenomenon
- Quantum Description (Anomalous
Zeeman Effect)
- Equilibrium
Magnetization
- Resonant Frequency
and the Bo Magnetic Field - The Larmor Equation
- Semi-Classical Net
Magnetization Vector Model
- Descriptions of
Spin Dynamics in the Rotating Frame
Relaxation mechanisms, longitudinal relaxation (T1) and
transverse relaxation (T2)
- Relaxation
Mechanism Physics (Physical Interactions Between Spins)
- Molecular Dynamics
(Correlation Times)
- Relaxation
Mechanisms in Biological Tissues
- Relaxation
Mechanisms and Bo Magnetic Field Strength
- Bloch's
Phenomenological System of Equations for Relaxation
Radio frequency (RF) pulses and the free induction decay (FID)
- Nutation of Magnetization Due to
Radio Frequency (RF) Pulses
- Larmor Equation in the Rotating
Frame
- Determination of Nutation (Flip) Angle
- On-Resonance and
Off-Resonance Effects
- Effects of
Transverse Relaxation (T2) and Bo Field
Inhomogeneities
- Refocusing 180o
Pulses and the Spin Echo
The measurement of relaxation times
- The Saturation
Recovery Experiment
- The Inversion
Recovery Experiment
- Hahn's Spin
Echoes, Stimulated Echoes and Diffusion Effects on the NMR Signal
- Measuring T2 with
the Carr-Purcell-Meiboom-Gill
(CPMG) Experiment
- Mechanisms for
J-Coupling
Back to "Contents"
MR Imaging Theory and Image
Reconstruction
General methods for MR imaging
- Properties and
Limitations of the Fourier Transform in MRI
- Reconstruction
from Projections
- Fourier Transform
MR Imaging
- Application of
Sampling Theory to Magnetic Resonance Imaging
- The Nyquist Limit
Mathematics of a Fourier Transform
- Continuous and
Discrete Fourier Transforms
- Fourier Shift
Theorem
- Convolution
Theorem
- Common Fourier
Transform Pairs (Gaussian, Sinc,
etc.)
Signal frequencies vs. spatial frequencies
- Definition of
k-Space
- Relationship
between k-Space Sampling Interval and Image Field-of-View
- Relationship
between k-Space Sampling Range and Image Resolution
- Truncation
Artifact (Gibbs ringing)
- Partial Sampling
of k-Space and Exploiting Conjugate Symmetry
Slice selection
- Relationship
Between the RF Pulse Bandwidth and the Slice Thickness
- Relationship
Between the Slice-Select Gradient and the Slice Thickness
- Nonlinear Effects
of RF Pulses on the Net Magnetization
- Defining Slice
Thickness and Location - Practical Implementation
- Optimization of
Slice Profiles (Pulse Crafting)
Frequency encoding
- Relationship
between Gradient Strength and Receiver Bandwidth
- Relationship
between Gradient Strength and Digitizer Dwell Time
- Relationship
between Gradient Strength and Image Field-of-View
Phase encoding
- Relationship
between Gradient Strength and Image Field of View
- Strategies for
Incrementing the Phase Encoding Gradient
- Phase Dispersion
Within and Between Voxels
Other applications for magnetic field gradients
- Strategies for
Imaging in Oblique Planes
- Selective Spoiling
of Magnetization with Gradient Pulses
- Dephasing and Rephasing Gradient Fields
Specific MR imaging protocols
- Identification of
Gradient and RF pulses and Signal Digitization in Sequence Timing
Diagrams
- Relaxation Effects
on the MR Signal and Pulse Sequence Timing (T1-weighting, T2-weighting,
etc.)
- Effects of Imaging
Parameters on Signal-to-Noise Ratio and Spatial Resolution
Image reconstruction
- Steps in Image
Reconstruction
- Analog and Digital
Filtering Processes
- Interpolation
(Zero-Filling)
- Image Quality
Trade-offs in Image Enhancement through Filtering
- 3-Dimensional
Fourier Transform Reconstruction
- Rectangular Field
of View
MR Image Characteristics
& Artifacts
Fundamental relation between signal and noise in MR images
- Imaging Parameters
Affecting Image Signal-to-Noise Ratio
- Properties of MR
Image Noise (Rician
Distribution)
- Contrast-to-Noise
Ratio (CNR) versus Signal-to-Noise Ratio (SNR)
- Fractional NEX
(NSA) (conjugate symmetry, 0.5 or 0.75 NEX versus 1.5 NEX with no phase
wrap)
- Clinical Utility
of Image Quality obtained using Spin Echo MR Images
Manipulation of MR image contrast
- Definitions of
Spin Density Weighting, T1 Weighting, and T2 Weighting
- Relaxation
Properties of Fat, CSF, Muscle and Brain
- Signal Averaging,
Partial Field-of-View, and Total Scan Time
Imaging with nonstationary
states:
- Fast Spin
Echo (Turbo Spin Echo)
- Magnetization
Prepared Fast Sequences (Including Centric Encoding)
- Relationship
between Image Resolution and Contrast in Fast Spin Echo Imaging
- Single-Shot Fast
Spin Echo Imaging (RARE)
Volume (3D) acquisition
- Generic Pulse
Sequence Timing Considerations
- Relationship
Between Resolution, Signal-to-Noise Ratio and Coverage in 3DFT MR
Imaging
- Slice Thickness
and Contiguity in 3DFT MR Imaging
Acquisition and MR imaging options
- Slice Ordering,
Slice Gaps, Coverage and Slice Cross-Talk
- Sequential vs.
Interleaved Acquisition of Slices
- Concatenated
Scanning and Segmented k-Space Scanning
- Off-Center Slices
(in Frequency- and Phase-Encoding Directions; Role of Post-Processing)
- Strategies to
Avoid Wrap-Around in the Readout and Phase-Encoding Directions
- Variable Bandwidth
and Signal-to-Noise Ratio
- Fat/Water
Suppression Strategies (Chemical Selective Saturation, STIR and FLAIR)
- Fractional RF and
Incrementing Partial Flip Angles
Artifacts
- Sources and
Remedies for Blocking, Banding, Pixelation,
and Similar Artifacts
- Origin, Properties
and Methods to Reduce, Including:
- Chemical Shift
Artifacts
- Truncation
Artifact
- Susceptibility
Artifacts
- Motion Artifacts
- Wrap-around
Artifacts (Aliasing)
- Geometric
Distortion
- Image Ghosting
Back to "Contents"
Advanced MR Imaging Techniques
& System
Features
Gradient Echoes (also called Field Echoes and FAST Imaging):
- The Mechanism of
Gradient Echo Formation
- Comparison
of T2- and T2*-contrast in Spin Echo and Gradient Echo
Protocols
- Imaging
Magnetization in Steady State Free Precession
- Classification of
Commercial Protocols: GRASS, FLASH, FISP, true FISP, spoiled GRASS,
etc.
- Use of Variable
Flip Angle Sequences
Diffusion phenomena
in MRI
- The Physics of
Diffusion
- Relationship
Between Diffusion Effects and Relaxation on the Spin Echo Signal
- Relationships of
the Apparent Diffusion Coefficient to Tissue Structure
- Diffusion Weighted
Imaging and T2 "Shine Through"
- Practical
Requirements for Measuring Apparent Diffusion Coefficients
MR Spectroscopy and Chemical Shift Imaging (CSI)
- Nuclei Useful for
Clinical MR Spectroscopy
- Methods of Water
Saturation for In Vivo MRS
- Eddy Current
Compensation and In Vivo MRS
- Basic Single
Volume MRS Acquisition Methods: PRESS and STEAM
- Basic Pulse
Sequence for 3DFT Chemical Shift Imaging
- Scan Time versus
Voxel Size Tradeoffs
- Clinical
Importance and Spectral Features of Brain Metabolites Containing
Protons
- Relaxation
Properties of Brain Metabolites Containing Protons
Blood Oxygen Level Dependent (BOLD) Imaging (sometimes called fMRI)
- Physiological
Explanation for the BOLD Contrast Effect
- Generic Pulse
Sequence for BOLD-Weighted Echo Planar Imaging
- Methods for BOLD
Data Analysis (t-Test, Correlation, etc.)
- Typical Protocols
for BOLD Imaging of Visual Cortex & Motor and Somatosensory Strips
Processing and reconstruction options
- Uses of
Phased-Array Coils
- SENSE and SMASH
- Maximum Intensity
Reconstructions (MIP)
- 3-Dimensional
Reconstruction
- Multi-Planar
Reformatting
- Surface Rendering
Back to "Contents"
Contrast Enhancement, MR
Angiography and Cardiac MRI
The physics of paramagnetic contrast agents
- Types of
Gadolinium Contrast Agents and Their Differences
- The Role of
Dipole-Dipole Interactions in Determining the Longitudinal Relaxation
Rate
- Relationships
Between Correlation Times and Relaxation Times
- Methods and Theory
of Using Gadolinium Contrast Agents to Increase Susceptibility
Mechanisms of relaxation enhancement in tissues
- Contrast Effects
of Blood at Various Lesion Ages and Oxygenation States
- Extra-Cellular,
Interstitial, and Intra-Vascular Contrast Agents and their Applications
- Clinical Uses of
Contrast Agents in Brain, Body and Angiography
- Toxicity and
Adverse Reactions
Flow effects in MR imaging
- Flow-Induced
Changes in the Magnitude of the MRI Signal
- Flow-Induced
Changes in the Phase of the MRI Signal
- Controlling Flow
Effects through Spatial Saturation
- Controlling Flow
Effects through Gradient Moment Nulling
(MAST, Flow Comp, etc.)
- Flow
Void: Flow Effects at Vessel Branches, Bifurcations and Stenoses
Magnetization Transfer Contrast (MTC) in MRI
- Theoretical
Description of Bound and Free Water Compartments in Tissue
- Tissues for Which
MTC is Practical
- Methods for
Implementing MTC in Pulse Sequences
- Magnetization
Transfer Effects in Fast Spin Echo Imaging
Time of Flight (TOF) Angiography
- Differential
Effects in the Saturation of Spins in Moving Blood and Stationary
Tissue
- Pulse Sequence
Considerations for Optimizing TOF Angiography
- Advantages and
Limitations of 2D TOF Angiography
- Methods to Improve
Blood-Soft Tissue Contrast in TOF Angiography
- Tilted Optimized Nonsaturating Excitation (TONE,
RAMP, etc.)
- Advantages and
Limitations of 3D TOF Angiography
- Sources of
"Venetian Blind" Artifacts in MR Angiography
- Methods for
First-Pass Angiography using Intravascular Contrast Agents
Phase contrast MR imaging
- Theory of Phase
Difference and Complex Difference MR Angiography
- Advantages and
Limitations of 2D and 3D Phase-Contrast Angiography
- Strategies for
Setting the VENC and Avoiding Phase-Wrap
- Data Processing
and Interpretation Steps for Quantitative Flow Measurements
Motion suppression techniques
- Simple Respiratory
Compensation with Bellows
- Methods and
Instrumentation for MRI Triggering using Pulsed Oximetry
- Prospective
Cardiac Gating: Heart Rate, Gating Delay and Trigger
Windows
- Advantages and
Limitations of Retrospective Gating
- Advantages and
Problems with Navigator Echo Compensation Schemes
Cardiac MR imaging
- Acquisition
Planning: Anatomical Locations and Cardiac Phases
- k-Space
Segmentation: Cardiac Phases, Reduced Field of View and Phase-Encoding
Group Size
- Applications of
Echo-Planar Imaging in Cardiological
Diagnosis
- Methods for
Black-Blood Heart Imaging
- Approaches to
Coronary Angiography
Back to "Contents"
MR Technology & Equipment
Quality Control
The elements of an MR scanner
- Superconducting
versus Open Magnets: Engineering Constraints in Design
- Magnetic Field
Gradients: Coil Design and Power Supply Considerations
- General Theory of Quadrature RF Coils, Surface RF
Coils and Phased-Array RF Coils
- Generic Flow
Diagram of an RF Receiver and Digitization System for an MRI
Scanner
- Issues involving
the Computer Control, Operator Interface, Image Display and Data
Archiving
- Laser Camera
Interfaces, Network Interfaces and DICOM Data Conversion Issues
Quality control (QC) procedures
- Tests and Phantom
Required for the ACR MRI Accreditation Program
- Daily QC Tasks to
be Performed by the Technologist
- Weekly QC Tasks to
be Performed by the Technologist
- Annual QC Tests
and Record Reviews to be Performed by the Medical Physicist
- Rules for Adequate
Data Collection and Record Keeping
- The Role of
Medical Physicist, Technologist, Radiologist and Service Engineer in QC
Acceptance Testing
of the MR unit
- Phantoms and
Phantom Materials Required for Acceptance Testing
- Inspecting Records
on Magnet Homogeneity, RF Phase Stability & Cryogen Boil-off
- Initial Evaluation
of the Magnet Subsystem
- Initial Evaluation
of the RF Subsystem
- Initial Evaluation
of the Gradient Subsystem
- Baseline MRI
System Performance Checks
Site Planning & Safety
Considerations
Known and theoretical physiological effects
- Constant Magnetic
Fields
- Time-Varying
Magnetic Fields
- Radiofrequency
Magnetic Fields
FDA guidelines for patient safety
- Permanent Magnetic
Field Strength Limitations
- Limitations on
Rapidly Switching Gradient Fields (dB/dt)
- Factors
Influencing Specific Absorption Rates (SAR) in Various MRI Scanning
Procedures
- NEMA Definition of
Acoustic Noise and Methods for its Measurement
- Safety Issues with
Paramagnetic Contrast Agents (Dose and Clearance Issues)
Cryogen safety and magnetic field safety procedures
- Handling of
Special Cases - Pacemakers, Metallic Implants, Clothing
- Methods and
Policies for Patient Screening
- Policies for
Pregnant Workers and Pregnant Patients
- Current Loops and
ECG Leads in MRI
Site planning for MRI
- Methods for
Measuring the Bo Magnetic Fringe Fields
- Strategies for
Protecting the MR System: Policy, Signage, Personnel Restrictions
& Shielding
- Design and Testing
of RF and Static Magnetic Field Shielding
- Strategies for
Measuring Instrument and Device Compatibility with the MRI
System
Back to "Contents"
EXAMPLES
OF TEST ITEMS
Type A
(one question per item):
1.
The magnetic field homogeneity of a MRI magnet is specified in terms of:
C.
(2) and (4) only are correct
D.
(4) only is correct
E.
All are correct
PUBLISHED
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McRobbie DW, Moore EA,
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Manning WJ, Pennell DJ.
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Prince MR, Grist T, Debatin
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WEB SITES
MRI Page at CDRH: http://www.fda.gov/cdrh/index.html
http://www.mrisafety.com/
Just what it says
ReviseMRI.com: Study materials for physicists and other clinical scientists learning the basics of MRI.
NMR Physics Lectures: http://208.7.154.206/gmoyna/NMR_lectures/NMR_lectures.html
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