Physics

Question 1

T1 relaxation describes recovery/decay of the transverse/longitudinal magnetization after an rf-pulse?

How do you get contrast in a T2 image?

Answer 1

• T1 = recovery of longitudinal magnetization after an rf pulse
  
  • After 1 T1 period, 63% of magnetization has recovered due to interactions with surrounding lattice (spin lattice relaxation); Mz(t) = M0 x (1-e^[-t/T1]). Longitudinal magnetization has completely recovered (> 99%) after 5 T1 times.​
• T2 = decay of transverse magnetization after an rf-pulse
  
  • ​T2 relaxation describes the decay of precessing transverse magnetization after an rf-pulse. After 1 T2 period 63% of magnetization has decayed due to interactions with surrounding spins (spin-spin relaxation); Mxy(t) = M0 x e^(-t/T2). Transverse magnetization as measured with a spin-echo sequence has completely decayed (> 99%) after 5 T2 times.