The echo planar (EPI) is the fastest acquisition method in MRI (100 ms / slice), but with limited spatial resolution. It is based on:
an excitation pulse, possibly preceded by magnetization preparation
continuous signal acquisition in the form of a gradient echo train, to acquire total or partial k-space (single shot or segmented acquisition)
readout and phase-encoding gradients adapted to spatial image encoding, with several possible trajectories to fill k-space (constant [nonblipped] or intermittent [blipped] phase encoding gradient, spiral acquisition etc.)