Improved Self-Referenced Parallel MRI Imaging in EPI by Using UNFOLD to Remove Nyquist Ghosts

W Scott Hoge¹, Huan Tan², Robert A. Kraft²

Self-referenced parallel MR imaging techniques have advantages in imaging scenarios that monitor changes. Their use with EPI is limited, however, due Nyquist or N/2 ghosting artifacts. These artifacts occur when data acquired on alternate positive and negative readout gradients is inconsistent. Recently, Nyquist ghost removal approaches that do not require a reference scan have been proposed. These methods interleave data from multiple frames---which reduces the effective temporal resolution. We propose using UNFOLD with a modified acquisition trajectory to eliminate Nyquist ghosts in multi-image EPI acquisitions, enabling the use of self-referenced pMRI reconstruction techniques while maintaining a high EPI imaging frame-rate.