Run-time motion and f0 control for 3D-EPI fMRI using short servo navigators

Motivation: Involuntary head motion and field variations are confounding factors in functional MRI. Goal(s): To implement run-time motion and field control for segmented 3D-EPI fMRI using servo navigation. Approach: Orbital navigators are integrated into the sequence for run-time motion and field control. f0-induced EPI phase corrections are applied relative to the central echo time to reduce f0 noise propagation into the EPI signal phase for high echo times and, by this, enable corrections by short navigators. Results: Servo navigation successfully stabilizes in-vivo voxel time series by run-time rigid motion and f0 corrections requiring only 3ms-navigator readouts and sub-second on-the-fly calibration. Impact: Servo navigation achieves run-time motion und field correction for 3D-EPI fMRI with high-precision, short navigators, and rapid on-the-fly calibration. The navigators are automatically drawn from the set imaging volume without external tracking instrumentation enabling plug-and-play motion correction for 3D fMRI.