title: Experimental O-space turbo spin echo imaging.
abstract: OBJECTIVE
  Turbo spin echo (TSE) imaging reduces imaging time by acquiring multiple echoes per repetition (TR), requiring fewer TRs. O-space can also require fewer TRs by using a combination of nonlinear magnetic gradient fields and surface coil arrays. Although to date, O-space has only been demonstrated for gradient echo imaging, it is valuable to combine these two techniques. However, collecting multiple O-space echoes per TR is difficult because of the different local k-space trajectories and variable T2-weighting.
  
  
  METHODS
  A practical scheme is demonstrated to combine the benefits of TSE and O-space for highly accelerated T2-weighted images. The scheme uses a modified acquisition order and filtered projection reconstruction to reduce artifacts caused by T2 decay, while retaining T2 contrast that corresponds to a specific echo time.
  
  
  RESULTS
  The experiments revealed that the proposed method can produce highly accelerated T2-weighted images. Moreover, the method can generate multiple images with different T2 contrasts from a single dataset.
  
  
  CONCLUSIONS
  The proposed O-space TSE imaging method requires fewer echoes than conventional TSE and fewer repetitions than conventional O-space imaging. It retains resilience to undersampling, clearly outperforming Cartesian SENSE at high levels of undersampling, and can generate undistorted images with a range of T2 contrast from a single acquired dataset.
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
authors.forename: Haifeng
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
authors.forename: Leo
authors.initials: L
authors.lastname: Tam
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
authors.forename: Emre
authors.initials: E
authors.lastname: Kopanoglu
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
authors.forename: Dana C
authors.initials: DC
authors.lastname: Peters
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.|Department of Biomedical Engineering, Yale University, New Haven, CT, USA.
authors.forename: R Todd
authors.initials: RT
authors.lastname: Constable
authors.affiliation: Department of Diagnostic Radiology, Yale University, New Haven, CT, USA.
authors.forename: Gigi
authors.initials: G
authors.lastname: Galiana
mesh_terms: D000465:Algorithms; D017352:Echo-Planar Imaging / Q000379:methods*; D017711:Nonlinear Dynamics; D019047:Phantoms, Imaging
keywords: O-space imaging; fast spin echo; nonlinear gradients; parallel imaging; rapid acquisition with refocusing echoes; turbo spin echo