title: A new design and rationale for 3D orthogonally oversampled k-space trajectories.
abstract: A novel center-out 3D trajectory for sampling magnetic resonance data is presented. The trajectory set is based on a single Fermat spiral waveform, which is substantially undersampled in the center of k-space. Multiple trajectories are combined in a "stacked cone" configuration to give very uniform sampling throughout a "hub," which is very efficient in terms of gradient performance and uniform trajectory spacing. The fermat looped, orthogonally encoded trajectories (FLORET) design produces less gradient-efficient trajectories near the poles, so multiple orthogonal hub designs are shown. These multihub designs oversample k-space twice with orthogonal trajectories, which gives unique properties but also doubles the minimum scan time for critical sampling of k-space. The trajectory is shown to be much more efficient than the conventional stack of cones trajectory, and has nearly the same signal-to-noise ratio efficiency (but twice the minimum scan time) as a stack of spirals trajectory. As a center-out trajectory, it provides a shorter minimum echo time than stack of spirals, and its spherical k-space coverage can dramatically reduce Gibbs ringing.
authors.affiliation: Keller Center for Imaging Innovation, Neuroimaging Research, Barrow Neurological Institute, Phoenix, Arizona, USA. jim.pipe@chw.edu
authors.forename: James G
authors.initials: JG
authors.lastname: Pipe
authors.forename: Nicholas R
authors.initials: NR
authors.lastname: Zwart
authors.forename: Eric A
authors.initials: EA
authors.lastname: Aboussouan
authors.forename: Ryan K
authors.initials: RK
authors.lastname: Robison
authors.forename: Ajit
authors.initials: A
authors.lastname: Devaraj
authors.forename: Kenneth O
authors.initials: KO
authors.lastname: Johnson
mesh_terms: D001921:Brain / Q000033:anatomy & histology; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000379:methods*