Recovery of Signal Loss Due to In-Plane Susceptibility Gradients in Gradient Echo EPI by Acquiring Extended Phase-Encoding Lines

Kwan-Jin Jung^1,2

The in-plane susceptibility gradient causes an echo shift which results in signal loss and ripple artifact in gradient echo imaging. This become more severe in the gradient echo EPI due to a low gradient strength applied in the phase-encoding direction during the long echo train. An approach of using the z-shim in the PE direction was developed. However, this method has the same disadvantage of increasing the scan time two or three times as in the through-plane z-shimming. A new approach is to acquire the echo signals that are shifted outside the regular data acquisition time by acquiring more echoes outside the regular TDAQ. This will recover the signal loss as well as remove the ripple artifact without increasing the scan time significantly.