Consider a 2-D object consisting of two triangle compartments, as shown in Figure P9.4. Suppose a solution containing a 511 KeV gamma ray emitting radionuclide with concentration f = 0.5….
What is the phase φ(r,t) immediately before and immediately after the π pulse?
A π/2 pulse is applied at t = 0, sending the longitudinal magnetization of a sample into the transverse plane in the direction of the x-axis. At that instant a spatially-varying (but temporally constant) magnetic field B(r) oriented in the z direction is added to the static field B0. The spatiallyvarying Larmor frequency is then given by
and the phase of the precessing sample is given by
A π pulse is then applied at time τ .
(a) What is the phase φ(r,t) immediately before and immediately after the π pulse?
(b) What is the phase φ(r,t) at time TE = 2τ ?
(c) Make a conclusive statement about the use of spin echoes when there are spatially-varying gradients in use.