A Selection of Slides on MRI Basics

Feel free to reprint these slides for educational purposes. For commercial use, please contact Mark Cohen.

Thanks for your interest.

The Slides:

Basic MR Principles
The Larmor Relation	Magnetic Field Gradients	Magnetic Susceptibility (1)	Magnetic Susceptibility (2)
The Resonance Phenomenon	RF Pulses convert between longitudinal & transverse magnetization	Partial Saturation Sequence	In-Phase precession
Out of Phase Precession	Sampling Time and Gradient Requirements	Signal Losses in Inhomogeneous Fields	Signal Losses from Spin Dephasing
The Spin Echo Sequence	T1 and TR	What is T1?	T2 and TE
What is T2?	Making an MR Image	Some Fourier Transform Pairs
Fourier transform Pairs	The Transverse Relaxation Rate	Proton Responses to Magnetic Fields	Free Proton Orientations
Protons in an Applied Field	The Spin Property of Protons	The Hahn Echo (1)	The Hahn Echo (2)
Imaging System Components	Calculating Imaging Time	Effects of a 90 degree pulse	Magnetization after a 90 degree pulse
The Chemical Shift Artfifact	Contrast Emphasis	Contrast vs. TR and TE	Contrast vs. T1/TR
Contrast vs. T2/TE	Conventional MRI	Determinants of MR Imaging Time	Fourier Transform of a Square Wave
The Slice Selection Process	Spatial Encoding Summary	Spin Decay

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Image Quality
Factors affecting MR image quality	Determinants of MR Imaging Time	The Chemical Shift Artfifact	Contrast to Noise Ratio vs. TE
Contrast to Noise Ratio vs. TR	Contrast to Noise Ratio	Field of View vs. SNR	Effects of FOV reduction
TE and SNR	TR and SNR	Effects of Longer TE	Effects of Longer TR
Longitudinal Relaxation	Matrix Size	Noise in MR Images	The MR Signal is Refractory
The MR Signal is Transient	Averaging (NEX) vs. SNR	Origin of the Chemical Shift Artifact	Image Quality Outline
Effects of Reduced Voxel Volume	Pickup of signal and noise	Optimal Slice Order	Slice Thickness vs. SNR
SNR and Voxel Size	Determinants of SNR	T1 and T2 are Correlated	Interslice Crosstalk
TR and Image Quality (1)

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K-Space
K-Space	Properties of K-Space	Slice Selection in K-Space	K-Space Filling Strategies
K-Space Trajectory (1)	K-Space Trajectory (2)	Low k values encode large features	High k-space values encode small features
Regular Sampling of k-space	Equivalent k-space Strategies (1)	Equivalent k-space Strategies (2)	Spin Echo Slice Selection

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Fast Imaging
Why does MRI Take so long?	Calculating Imaging Time	Signal and Flip Angle	Magnetization Loss vs RF Flip Angle
Flip Angles and Contrast	Flip Angle vs. TR and T1 contrast	SNR vs. TR/T1	The FLASH Sequence
The FLASH magnetization cycle	FLASH Timing Diagram	The Gradient Echo Sequence	Magnetic Susceptibility (1)
Magnetic Susceptibility (2)	T2 and T2*	The is no 180 degree pulse in FLASH Sequences	TR and Flip Angle Combinations
Turbo FLASH	Sampling time and Gradient Requirements	FISP timing diagram	The GRASS (FISP) magnetization cycle
The CE-FAST Sequence	The Instascan (EPI) k-space trajectory	The Instascan Pulse Sequence	The RARE sequence
Spin Echo Instascan (EPI)	The Spin Echo Sequence	The SSFP Sequence	Fast Imaging Outline

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Surface Coils
Surface Coil Sensitivity (1)	Surface Coil Sensitivity (1)	What is a Surface Coil?	Surface Coil Advantages
Disadvantages of Surface Coils

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Functional MRI
Consequences of Brain Activation	Deoxyhemoglobin	Effects of Increased Flow