(CE-FAST) In this technique, the MR signal is sampled immediately prior to each RF pulse. Because the signal is formed by a true spin echo, its contrast is predominantly T2-, rather than T2*-based and is less sensitive to artifacts and signal losses related to field non-uniformity and susceptibility variation. While the signal to noise ratio is limited, the CE-FAST method has the advantage of good contrast.

See Contrast Enhanced Gradient Echo Sequence and Gradient Echo Sequence.

(CE-FFE-T1) A T1 weighted gradient echo sequence.

See Spoiled Gradient Echo Sequence.

(CE-FFE-T2) A T2* weighted gradient echo sequence.

See Coherent Gradient Echo and Contrast Enhanced Gradient Echo Sequence.

Contrast enhanced GRE sequences provide T2 contrast but have a relatively poor SNR. Repetitive RF pulses with small flip angles together with appropriate gradient profiles lead to the superposition of two resonance signals.
The first signal is due to the free induction decay FID observed after the first and all ensuing RF excitations.
The second is a resonance signal obtained as a result of a spin echo generated by the second and all addicted RF-pulses.
Hence it is absent after the first excitation, it is a result of the free induction decay of the second to last RF-excitation and has a TE, which is almost 2TR. For this echo to occur the gradients have to be completely symmetrical relative to the half time between two RF-pulses, a condition that makes it difficult to integrate this pulse sequence into a multiple slice imaging technique. The second signal not only contains echo contributions from free induction decay, but obviously weakened by T2-decay. Since the echo is generated by a RF-pulse, it is truly T2 rather than T2* weighted. Correspondingly it is also less sensitive to susceptibility changes and field inhomogeneities.
Companies use different acronyms to describe certain techniques.
Different terms (see also acronyms) for these gradient echo pulse sequences:
CE-FAST Contrast Enhanced Fourier Acquired Steady State,
CE-FFE Contrast Enhanced Fast Field Echo,
CE-GRE Contrast Enhanced Gradient-Echo,
DE-FGR Driven Equilibrium FGR,
FADE FASE Acquisition Double Echo,
PSIF Reverse Fast Imaging with Steady State Precession,
SSFP Steady State Free Precession,
T2 FFE Contrast Enhanced Fast Field Echo (T2 weighted).
In this context, 'contrast enhanced' refers to the pulse sequence, it does not mean enhancement with a contrast agent.

Spoiled gradient echo sequences use a spoiler gradient on the slice select axis during the end module to destroy any remaining transverse magnetization after the readout gradient, which is the case for short repetition times.
As a result, only z-magnetization remains during a subsequent excitation. This types of sequences use semi-random changes in the phase of radio frequency pulses to produce a spatially independent phase shift.
Companies use different acronyms to describe certain techniques.

Different terms for these gradient echo pulse sequences:
CE-FFE-T1 Contrast Enhanced Fast Field Echo with T1 Weighting,
GFE Gradient Field Echo,
FLASH Fast Low Angle Shot,
PS Partial Saturation,
RF spoiled FAST RF Spoiled Fourier Acquired Steady State Technique,
RSSARGE Radio Frequency Spoiled Steady State Acquisition Rewound Gradient Echo
S-GRE Spoiled Gradient Echo,
SHORT Short Repetition Techniques,
SPGR Spoiled Gradient Recalled (spoiled GRASS),
STAGE T1W T1 weighted Small Tip Angle Gradient Echo,
T1-FAST T1 weighted Fourier Acquired Steady State Technique,
T1-FFE T1 weighted Fast Field Echo.
In this context, 'contrast enhanced' refers to the pulse sequence, it does not mean enhancement with a contrast agent.