title: Echo-planar imaging with prospective slice-by-slice motion correction using active markers.
abstract: Head motion is a fundamental problem in functional magnetic resonance imaging and is often a limiting factor in its clinical implementation. This work presents a rigid-body motion correction strategy for echo-planar imaging sequences that uses micro radiofrequency coil "active markers" for real-time, slice-by-slice prospective correction. Before the acquisition of each echo-planar imaging-slice, a short tracking pulse-sequence measures the positions of three active markers integrated into a headband worn by the subject; the rigid-body transformation that realigns these markers to their initial positions is then fed back to dynamically update the scan-plane, maintaining it at a fixed orientation relative to the head. Using this method, prospectively-corrected echo-planar imaging time series are acquired on volunteers performing in-plane and through-plane head motions, with results demonstrating increased image stability over conventional retrospective image-realignment. The benefit of this improved image stability is assessed in a blood oxygenation level dependent functional magnetic resonance imaging application. Finally, a non-rigid-body distortion-correction algorithm is introduced to reduce the remaining signal variation.
authors.affiliation: Department of Biomedical Engineering, Columbia University, New York, New York, USA. mbooi@stanford.edu
authors.forename: Melvyn B
authors.initials: MB
authors.lastname: Ooi
authors.forename: Sascha
authors.initials: S
authors.lastname: Krueger
authors.forename: Jordan
authors.initials: J
authors.lastname: Muraskin
authors.forename: William J
authors.initials: WJ
authors.lastname: Thomas
authors.forename: Truman R
authors.initials: TR
authors.lastname: Brown
mesh_terms: D015415:Biomarkers; D017352:Echo-Planar Imaging / Q000379:methods*; D006801:Humans; D009038:Motion
chemical_list: D015415:Biomarkers