(GRASE) A hybrid sequence with a combination of gradient and spin echosequences. If multiple image lines are obtained during a single echo, the imaging pulse sequence type is a GRASE sequence.
Production of spin echo by repeated RF pulses. First observed using equal (90°) RF pulses, now commonly used to describe refocusing of transverse magnetization by a 180° RF pulse.
By choosing long echo delay times, the spins in a Hahn echo first dephase for a long time, then rephase, which makes the Hahn pulse sequence more susceptible to diffusion effects.
(HASTE) A pulse sequence with data acquisition after an initial preparation pulse for contrast enhancement with the use of a very long echo train (Single shotTSE), whereat each echo is individually phase encoded.
This technique is a heavily T2 weighted, high speed sequence with partial Fourier technique, a great sensitivity for fluid detection and a fast acquisition time of about 1 sec per slice. This advantage makes it possible for using breath-hold with excellent motionless MRI, e.g. used for liver and lung imaging.