Select the sequence "Spin echo" and click at the button "On" and then on "Start" and the animation will go.
- TE - echo time
- TR - time between pulses (repitition time)
τ - half echo
FID - free induction decay; MR Signal
As the magnetic field in the large coil of an MRI system is non-homogeneous, the signal intensity rapidly decays, resulting in additional dephasing of the spin. As we know, only a spin which is in phase can produce a measurable signal.
If you click on "read more ...", you will find more explanation about the pulse sequence spin echo