Distortion-Free High-Resolution FMRI at 9.4 T

Philipp Ehses¹, ², Juliane Budde¹, G. Shajan¹, Klaus Scheffler¹, ²

SNR benefits allow for significantly higher resolution in BOLD fMRI at ultra-high fields. On the flip side, faster T₂^* relaxation leads to blurring and increased B₀ field inhomogeneities aggravate distortion artifacts in EPI BOLD imaging at higher fields. In this work, a single-echo gradient-echo sequence is presented, that is optimized for high BOLD SNR by combining the concept of echo-shifting with an interleaved slice order. The method is demonstrated in finger tapping experiments on a human 9.4T system. The result is a BOLD activation map with 1mm isotropic resolution virtually free from distortions.