UTE/ZTE Functional MRI with Helical Cone Trajectories

Motivation: fMRI is a neuroimaging technique which uses the BOLD contrast to map neuronal activity. A fast UTE/ZTE sequence can help understanding T1-related changes during neural activation. Goal(s): To advance UTE/ZTE sequence using helical cone trajectories with improved sampling efficiency. Approach: By replacing radial spokes with helical cones in the UTE/ZTE sequence, we improved sampling efficiency and benchmarked this method in a task-based visual fMRI study with healthy volunteers at 3T. Results: Helical cones achieved a 164.7% increase in tSNR compared to its radial counterpart. ZTE demonstrated high sensitivity to localized activity changes, with helical cones preserving the sensitivity at 5-fold undersampling. Impact: Helical cone trajectories using oscillating gradients improve sampling efficiencies, allowing for higher temporal resolution by more aggressive radial undersampling and accelerated fMRI. This technique holds potential beyond fMRI and can benefit other dynamic MRI applications.