W. Scott Hoge1, Hong Pan1, Huan Tan2, Emily Stern1, Robert A. Kraft2
1Radiology, Brigham & Women's Hospital, Boston, MA, United States; 2Virginia-Tech Wake Forest School of Biomedical Engineering, Winston-Salem, NC, United States
Echo planar imaging often suffers from signal dropout in regions with high susceptibility. This is particularly problematic for fMRI studies of the brain near the nasal sinuses. Z-shim methods are one approach to recover this lost signal, where a z gradient is employed prior to the EPI readout to counter phase accumulation in the signal dropout region. Single-shot z-shim methods give improved temporal resolution, but with a cost of longer echo trains, which increases geometric distortion. Here, we employ parallel MR imaging (pMRI) to shorten the EPI echo train in a single-shot z-shim method. Temporal encoding complements the approach, to counter Nyquist ghost effects and improve the pMRI calibration. Temporal signal stability is shown to be comparable to a two-shot z-shim method.