Liyong Chen1, 2, An T. Vu1, 2, Junqian Xu3, Kamil Ugurbil3, Essa S. Yacoub3, David Feinberg, 24
1Advanced MRI Technologies, LLC, Sebastopol, CA, United States; 2Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States; 3CMRR, University of Minnesota, Minneapolis, MN, United States; 4Advanced MRI Technologies, Sebastopol, CA, United States
Multiplexed EPI utilizes multiband (MB) rf pulses and simultaneous image refocusing (SIR) to reduce the sampling TR of fMRI experiments. Here we evaluate different combinations of MB and SIR for accelerations up to N=48 images per EPI echo train. We found that for high accelerations, N>=8, multiplexed EPI with SIR 2 gave improvement over accelerations with MB alone in terms of tSNR, BOLD CNR, and BOLD information content. TRs around 600 300 ms gave the best single trial classification accuracy, suggesting significant BOLD information exists at very high temporal frequencies and demonstrating the importance of highly accelerated EPI for fMRI.