Reliable Measurement of Cortico-subcortical Functional Connectivity of Human Brain with 7T MRI

Motivation: Studying cortico-subcortical circuits with fMRI is attracting increasing attention, but the reliability of functional connectivity (FC) is often compromised, limiting interpretation. Goal(s): To develop novel multi-echo fMRI sequences to measure reliable BOLD activity for both cortical and subcortical brain regions, by which better SNR can be guaranteed and reliable functional connectivity can be measured. Approach: Participants were measured across 4 sessions. Three sequence-processing combinations were compared for their signal-to-noise ratio and FC stability: 1) single-echo fMRI, 2) multi-echo fMRI, 3) multi-echo ICA. Results: Multi-echo fMRI showed a significant improvement in overall signal quality and FC reliability between the subcortical regions and the neocortex. Impact: This multi-echo fMRI sequence demonstrates a significant boost in signal quality from subcortical regions that suffer from degradation in single-echo sequences. This robustly increases reliability of FC estimates when investigating the roles of subcortex in cognition and disease (e.g. neurodegeneration).