Abstract #3881

Segmented spin-echo BOLD fMRI using a variable flip angle FLEET acquisition with recursive RF pulse design for high spatial resolution fMRI

Avery JL Berman^1,2, William A Grissom³, Thomas Witzel^1,2, Daniel J Park¹, Olivia Viessmann^1,2, Kawin Setsompop^1,2,4, and Jonathan R Polimeni^1,2,4

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Charlestown, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Vanderbilt University Institute of Imaging Science, Nashville, TN, United States, ⁴Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Spin-echo (SE) EPI has long been desired for fMRI acquisitions with reduced macrovascular sensitivity; however, to achieve a purely T2-weighted signal, requires sampling a short window around the spin-echo—generally achieved by a segmented readout. Segmented EPI is well-known to be temporally unstable due to sensitivity to subject motion between segments. Here we propose a reordering of the EPI segments, known as FLEET, combined with a variable flip angle excitation to maximize the image signal level and a recursive RF pulse design to maintain consistent slice profiles at the spin-echo. We demonstrate the feasibility of this approach at 3T.

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