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Published on: February 8, 2019
Double Asymmetric Spin Echo EPI (dASE-EPI) Enables fMRI of the Entire Rat Brain at 9.4 T
Kyle A Johnson1, Hanbing Lu2, Jason W Sidabras1
1Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, USA.
Purpose:
Development and evaluation of a double asymmetric spin echo planar imaging (dASE-EPI) sequence to balance sensitivity to blood oxygenation level-dependent (BOLD) contrast with mitigation of susceptibility-induced intravoxel spin dephasing in ultra high-field rodent brain imaging.
Methods:
A dASE-EPI pulse sequence was implemented and resting-state BOLD fMRI was acquired in the rat brain. Data acquired with dASE-EPI were compared to conventional gradient-recalled EPI. Functional connectivity analyses were performed to assess detection of established networks and to evaluate signal recovery in regions affected by susceptibility (e.g., amygdala, hypothalamic nuclei).
Results:
dASE-EPI was found to provide BOLD sensitivity that was non-inferior to conventional GRE-EPI while substantially reducing susceptibility-related signal loss. Established functional networks including the bilateral insular, bilateral sensory, and default mode network were reliably detected with dASE-EPI. Functional connectivity of the amygdala, which was obscured in GRE-EPI, was recoverable with the proposed sequence.
Conclusion:
The proposed dASE-EPI pulse sequence is a viable solution when studying brain regions which suffer from severe susceptibility artifacts.
