The B1 magnetic field in the laboratory frame of reference is typically described by two vectors.
One vector rotates clockwise at o and the other counter clockwise at -
o.
In the laboratory frame of reference, the net B1 magnetic field appears as an oscillating vector along the X axis.
In a rotating frame of reference traveling clockwise about Z at o,
the B1 vector component that rotates clockwise in the laboratory frame of reference will be stationary.
The B1 vector component that rotates counter clockwise is traveling about the Z axis at -2
o.
A component that rotates about Z at -2
o is so far from the resonance frequency of the spins that it can be ignored.
Therefore, in the rotating frame of reference, the B1 field appears stationary.
Copyright © 2002 J.P. Hornak.
All Rights Reserved.