A new design and rationale for 3D orthogonally oversampled k-space trajectories

James G. Pipe, Nicholas R. Zwart, Eric A. Aboussouan, Ryan K. Robison, Ajit Devaraj, Kenneth O. Johnson

Research output: Contribution to journalArticle

57 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1303-1311
Number of pages9
JournalMagnetic Resonance in Medicine
Issue number5
StatePublished - Nov 1 2011



  • k-space trajectory
  • spiral MRI
  • undersampling

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

Cite this

Pipe, J. G., Zwart, N. R., Aboussouan, E. A., Robison, R. K., Devaraj, A., & Johnson, K. O. (2011). A new design and rationale for 3D orthogonally oversampled k-space trajectories. Magnetic Resonance in Medicine, 66(5), 1303-1311. https://doi.org/10.1002/mrm.22918