Macrovascular contributions to high-resolution balanced SSFP- and GE-EPI-based fMRI at 9.4T evaluated using surface-based cortical depth analyses in human visual cortex

Several strategies have been proposed for maximizing neuronal specificity of fMRI by utilizing pulse sequences that are primarily sensitive to signal changes within microvasculature. Here we compare the microvascular sensitivity of high-resolution balanced SSFP and gradient-echo EPI at 9.4T using cortical depth analyses within human visual cortex. Because of the large draining vessels lying along the pial surface, the behavior of fMRI signals as a function of cortical depth can provide helpful insights into the vascular contributions. Our preliminary analyses suggest that, for the protocols used here, both balanced SSFP and EPI show similar cortical depth profiles of BOLD responses