title: HYPR TOF: time-resolved contrast-enhanced intracranial MR angiography using time-of-flight as the spatial constraint.
abstract: OBJECTIVE
  To investigate the feasibility of using time-of-flight (TOF) images as a constraint in the reconstruction of a series of highly undersampled time-resolved contrast-enhanced MR images (HYPR TOF), to allow simultaneously high temporal and spatial resolution and increased SNR.
  
  
  METHODS
  Ten healthy volunteers and three patients with aneurysms underwent a HYPR TOF study, which includes a clinical routine TOF scan followed by a first pass time-resolved contrast-enhanced exam using an undersampled three-dimensional (3D) projection trajectory (VIPR). Image quality, waveform fidelity and signal to background variation ratio measurements were compared between HYPR TOF images and VIPR images without HYPR reconstruction.
  
  
  RESULTS
  Volunteer results demonstrated the feasibility of using the clinical routine TOF as the spatial constraint to reconstruct the first pass time-resolved contrast-enhanced MRA acquired using highly undersampled 3D projection trajectory (VIPR). All the HYPR TOF images are superior to the corresponding VIPR images with the same temporal reconstruction window on both spatial resolution and SNR.
  
  
  CONCLUSIONS
  HYPR TOF improves the spatial resolution and SNR of the rapidly acquired dynamic images without losing the temporal information.
authors.affiliation: Department of Medical Physics, University of Wisconsin, Madison, Wisconsin, USA. yijingwu@wisc.edu
authors.forename: Yijing
authors.initials: Y
authors.lastname: Wu
authors.forename: Steven R
authors.initials: SR
authors.lastname: Kecskemeti
authors.forename: Kevin
authors.initials: K
authors.lastname: Johnson
authors.forename: Kang
authors.initials: K
authors.lastname: Wang
authors.forename: Howard
authors.initials: H
authors.lastname: Rowley
authors.forename: Oliver
authors.initials: O
authors.lastname: Wieben
authors.forename: Charles
authors.initials: C
authors.lastname: Mistretta
authors.forename: Patrick
authors.initials: P
authors.lastname: Turski
mesh_terms: D000783:Aneurysm / Q000175:diagnosis* / Q000473:pathology; D003198:Computer Simulation; D003287:Contrast Media / Q000494:pharmacology; D003952:Diagnostic Imaging / Q000379:methods; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D013997:Time Factors
chemical_list: D003287:Contrast Media