Inherent Geometry Correction for Diffusion EPI Using the Reference Echoes as Navigators

Figure 1

Schematic representation of the EPI readout with phase encoding blip gradients (top), and nonphase–encoded reference readout (bottom) used as navigator to probe the phase errors. Since both readouts are identical, each echo at index n has accumulated the same phase error in both acquisitions, which phase from the navigator can be used to recover unperturbed k-space.