Melvyn Boon King Ooi1,2, Sascha Krueger3, William J. Thomas2, Truman R. Brown1,2
1Biomedical Engineering, Columbia University, New York, NY, United States; 2Radiology, Columbia University, New York, NY, United States; 3Philips Research Europe, Hamburg, Germany
Head motion is a fundamental problem in fMRI. A prospective, slice-by-slice compensation strategy for rigid-body motion is presented for EPI sequences. Before the acquisition of each EPI-slice, a short tracking pulse-sequence is used to measure the positions of three micro RF-coil "active markers" integrated into a headband worn by the subject. During head motion, the rigid-body transformation that realigns these markers to their initial positions is fed back to update the image-plane maintaining it at a fixed orientation relative to the head before the next EPI-slice is acquired. EPI time-series are obtained that demonstrate real-time image-plane realignment during volunteer motion.