FMRI David Norris
15 important questions on FMRI David Norris
How is T1 characterized?
How is T2 characterized?
Which two causes are there for transverse relaxation?
- intrinsic cause from spin-spin interaction. This is T2
- Extrinsic cause from the external magnetic field.
1 and 2 combined is T2* decay
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By which quantity is the signal intensity measured?
What will any process that causes T1 relaxation also cause?
How is transverse relaxation independent o T1 relaxation caused?
What is inversion recovery?
How is T2* measured?
T2* is measured by examining the full width at half the maximum height. The faster the FID decays (shorter T2*) the broader the line will be.
What will happen if TR is short compared to T1?
What TR and TE will we use for T1 contrast?
there's an optimal TR value that maximally differentiates between two tissues that
differ in T1;
Short TE to minimize T2 contrast.
What contrast do you get with a long TR and a long TE?
What contrast do you get with a long TR and a short TE?
Do you get a good contrast with a short TR and a long TE?
A long TE leads to strong signal for tissue with a long T2.
The two effect tend to cancel.
Which contrast is usually used for diagnosis in medicine?
Which contrast is used and what are the blakc dots?
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