In fast imaging
sequences driven
equilibrium sensitizes the sequence to variations in T2. This
MRI technique turns
transverse magnetization Mxy to the longitudinal axis using a pulse rather than waiting for
T1 relaxation.
The first two pulses form a
spin echo and, at the
peak of the
echo, a
second 90° pulse returns the
magnetization to the z-axis in preparation for a fresh sequence.
In the absence of
T2 relaxation, then all the
magnetization can be returned to the z-axis. Otherwise, T2 signal loss during the sequence will reduce the final z-magnetization.
The advantage of this sequence type is, that both longitudinal and also
transverse magnetization are back to
equilibrium in a shorter amount of time. Therefore,
contrast and signal can be increased while using a shorter TR. This pulse type can be applied to other
sequences like
FSE, GE or IR.
Sequences with driven equilibrium:
Driven
Equilibrium Fast
Gradient Recalled acquisition in the steady state - DE FGR,
Driven
Equilibrium Fourier Transformation - DEFT,
Driven
Equilibrium magnetization preparation - DE prep,
Driven
Equilibrium Fast Spin Echo - DE
FSE.
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