MRI Spin echo sequence and STIR

[yephonethaw]

I would like to ask a question about MRI Spin echo sequence. after first 90 degree RF pulse, the free induction decay occurs. And 180degree refocusing pulse is given again. And echo signal is obtained at TE. My question is that is the the signal highest when the protons are back again in coherence or when they are dephasing again?

 

[Dale]

My question is that is the the signal highest when the protons are back again in coherence or when they are dephasing again?

The signal is the highest at TE, which is when they are in coherence.

 

[yephonethaw]

In STIR, 90 degree read out pulse is given at Time to inversion TI( short TI) where the Mz of fat tissue is zero(null point). After giving 90 defree pulse ,Mz is transferred to Mxy plane and since Mz is zero, can Mxy be also zero?

<< Mentor Note -- related question merged into the OP's existing thread >>

 

[yephonethaw]

I don't understand the highlighted words and the figure.When 90degree RF pulse is given, is Mz which is zero moved back to -Mz or still staying at transverse magnetization plane?

 

[Dale]

After giving 90 defree pulse ,Mz is transferred to Mxy plane and since Mz is zero, can Mxy be also zero?

Yes, that is the basis of most magnetization preparation techniques.