Multi
echo imaging
sequences use a series of echoes acquired as a train following after a single
excitation pulse. Multiple symmetrical or
asymmetrical echoes can be acquired, typically
T2 weighted. In
spin echo imaging, each
echo is formed by a 180° pulse, but also a
FSE (
TSE, RARE) or EPI sequence can be used.
As a difference to a normal fast
spin echo sequence, in multi
echo imaging, separate images are produced from each
echo of the train with different T2 weightings. The signal height reduces with transverse relaxation. This drop in signal can be used to calculate a pure T2 image.
See also
Fast Spin Echo.