Cortical BOLD fMRI with multi-slice EPI at the 1.5-2nL voxel size with a 14T scanner

Motivation: We want to push the limit of spatial resolution to gain robust BOLD fMRI with an ultra-high field scanner. Goal(s): The objective is to develop an ultra-high resolution functional mapping method to specify the vessel-specific hemodynamic and vasodynamic responses with fMRI. Approach: We implanted a Figure-8 RF coil above the mouse skull to boost SNR and implemented high-resolution multi-slice EPI to measure the evoked BOLD signals. Results: We identified the sparsed BOLD signals spreading through the cortical vasculature. These high-resolution results allowed us to identify the smoothing effect to diminish the vessel-specificity of BOLD-fMRI. Impact: To resolve the vessel-specificity of fMRI with ultra-high resolution method at the brain-wide scale would open a new avenue to study hemodynamic and vasodynamic responses given its direct vascular origin.