A Simultaneous Measurement of Opposite-Phase-Encoding EPI in a Single fMRI session for the Reduction of Acquisition Time and SAR at 7T

In high-resolution fMRI using EPI, geometric distortions typically seen in reconstructed images significantly hinder the accurate mapping of activated voxels. One method to correct for distortions is to acquire EPI data with an opposite phase-encoding direction. However, this method is usually implemented with an additional run of the same protocol, leading to a redundant measurement of parallel imaging calibration scans. Here, we present an EPI scheme that measures the opposite-direction data in a single fMRI session, substantially reducing the total acquisition time. We demonstrate more accurate functional mapping with the distortion correction in submillimetre whole-brain visual fMRI at 7T.