Abstract #3304

Improved physiology-induced temporal stability achieved with variable-flip-angle FLEET multi-shot Echo Planar Time-resolved Imaging (EPTI)

Zhangxuan Hu^1,2, Avery J.L. Berman^1,2,3,4, Zijing Dong^1,2, William A. Grissom⁵, Timothy G. Reese^1,2, Fuyixue Wang^1,2, Lawrence L. Wald^1,2,6, and Jonathan R. Polimeni^1,2,6

¹Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Boston, MA, United States, ²Department of Radiology, Harvard Medical School, Boston, MA, United States, ³Department of Physics, Carleton University, Ottawa, ON, Canada, ⁴University of Ottawa Institute of Mental Health Research, Royal Ottawa, Mental Health Centre, Ottawa, ON, Canada, ⁵Department of Biomedical Engineering, Case School of Engineering, Case Western Reserve University, Cleveland, OH, United States, ⁶Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, United States

Synopsis

Keywords: fMRI Acquisition, fMRI

Motivation: EPTI is a new highly-efficient imaging approach that addresses limitations of EPI by providing high-resolution distortion- and blurring-free imaging for fMRI. However, shot-to-shot phase-variations induced by physiological processes in conventional multi-shot EPTI can introduce instabilities into the reconstructed time-series data.

Goal(s): Improving physiology-induced temporal stability of multi-shot EPTI.

Approach: Combing multi-shot EPTI with the VFA-FLEET method, which minimizes shot-to-shot phase-variations by reordering the multi-shot acquisitions while maximizing the signal level by using a variable-flip-angle train and recursive RF pulse design.

Results: In vivo fMRI data acquired at 7T demonstrate that the physiological instabilities of multi-shot EPTI can be substantially reduced with proposed method.

Impact: Here we test whether temporal instabilities in conventional multi-shot EPTI time-series caused by physiological variability can be reduced by combining EPTI with the variable-flip-angle FLEET method. This combination can improve the usability and robustness of EPTI for high-resolution fMRI studies.

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