[fDAS] fMRI principle (1)

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1. fMRI Hardware
1.1. Magnet
1.2. Gradient Coil
1.3. RF Coil
1.4. Computer system

2. Spin Physics
2.1. What is a spin?
- = B ( is fixed value. B is a strength of magnetic field)
-  E = h (h is a Planck's constant)
- Energy state
- spin packet

2.2. T1 process

- T1 is the time to reduce the difference between the longitudinal magnetization (M_Z) and its equilibrium value by a factor of e.
- spin lattice relaxation time

2.3. procession
- every molecular have procession. It will rotate about the Z axis at the Lamour frequency.

2.4. T2 process

- T2 is the time which describes the return to equilibrium of the transverse magnetization by a factor of e.
- spin-spin relaxation time
- always T2 < T1

2.5. T2*
- 1/T₂* = 1/T₂ + 1/T_2inhomo.
- inhomogeneity = molecular interactions + variations in B_o
- Molecular interaction is what we wanna observe as a Neuroscientist.

2.6. rotating frame
- to easily observe real situation


3. NMR spectroscopy
3.1. FID(Free Induction of Decay)

3.2. 90-FID, Spin-echo sequence
- TR : repetition time, the time between 90 degree pulses.
- TE : echo time, the time between 90 degree pulse and the maximum amplitude in the echo


## Every images in this post are from Joseph P. Hornak, Ph. D.'s hompage.