I just updated my MRI abbreviations
page with this:
"Modification of the readout gradient amplitudes in EPI, and additionally the relative phases of refocusing pulses in FSE (but not if single shot). Corrects undesired phase shifts such as those due to eddy currents or mechanical vibration. A prescan is required"
So that's what it is, not specifically what it should be used for, but I hope it helps.