Magnetic field gradient pulse applied to effectively remove transverse magnetization by producing a rapid variation of its phase along the direction of the gradient. This is done after the echo so that transverse magnetization is destroyed prior to the next excitation pulse, to spoil any remaining xy-magnetization or to refocus the xy-magnetization.
For example, when used to remove the unwanted signal resulting from an imperfect 180° refocusing RF pulse, a corresponding compensating gradient pulse may be applied prior to the refocusing RF pulse in order to avoid spoiling the desired transverse magnetization resulting from the initial excitation. Also called homospoil pulse.

Magnetic field gradient pulse used to create spatial variation of phase of transverse magnetization. For example, it may be applied prior to signal detection in the presence of a magnetic field gradient with opposite polarity (or of the same polarity if separated by a refocusing RF pulse) so that the resulting gradient echo signal will represent a more complete sampling of the Fourier transformation of the desired image.

See also Spoiler Gradient Pulse.

Use of a magnetic field gradient to effectively eliminate residual transverse magnetization by producing a strong position dependence of phase within a resolution element. See Spoiler Gradient Pulse.

The use of varying phase or timing of the RF pulses to prevent setting up a condition of steady state free precession, e.g. in rapid excitation MR imaging.

See also Spoiler Gradient Pulse and Rapid Excitation Magnetic Resonance Imaging.

(RE MRI) There are several approaches to speeding up the MRI data acquisition process by repeating the excitation by RF pulses in times short compared to T1, typically using small flip angles and gradient echo refocusing. When TR is also on the order of or shorter than T2, the repeated RF pulses will tend to refocus transverse magnetization remaining from prior excitations, setting up a condition of steady state free precession, and a dependence of signal strength (and image contrast) on both T1 and T2.
This can be modified in various ways, particularly:
1) to spoil the tendency to build up a steady state by reducing coherence between excitations, e.g. by variation of the phase or timing of consecutive RF pulses or of the strength of spoiler gradient pulses, thus increasing the relative dependence of signal strength on T1 or
2) acquire the signal when it is refocusing immediately prior to the next RF pulse, thus increasing the relative dependence of signal strength on T2.

See also Ultrafast Gradient Echo Sequence.