title: Triple-quantum-filtered sodium imaging at 9.4 Tesla.
abstract: OBJECTIVE
  Efficient acquisition of triple-quantum-filtered (TQF) sodium images at ultra-high field (UHF) strength.
  
  
  METHODS
  A three-pulse preparation and a stack of double-spirals were used for the acquisition of TQF images at 9.4 Tesla. The flip angles of the TQ preparation were smoothly reduced toward the edge of k-space along the partition-encoding direction. In doing so, the specific absorption rate could be reduced while preserving the maximal signal intensity for the partitions most relevant for image contrast in the center of k-space. Simulations, phantom and in vivo measurements were used to demonstrate the usefulness of the proposed method.
  
  
  RESULTS
  A higher sensitivity (∼ 20%) was achieved compared to the standard acquisition without flip angle apodization. Signals from free sodium ions were successfully suppressed irrespective of the amount of apodization used. B0 corrected TQF images with a nominal resolution of 5 × 5 × 5 mm(3) and an acceptable signal-to-noise ratio could be acquired in vivo within 21 min.
  
  
  CONCLUSIONS
  Conventional TQF in combination with flip angle apodization permits to exploit more efficiently the increased sensitivity available at 9.4T.
authors.affiliation: Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany.|High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Mirkes
authors.affiliation: High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Shajan
authors.affiliation: High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.|Graduate School of Neural & Behavioural Sciences, University of Tübingen, Tübingen, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bause
authors.affiliation: High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Kai
authors.initials: K
authors.lastname: Buckenmaier
authors.affiliation: High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.|Graduate School of Neural & Behavioural Sciences, University of Tübingen, Tübingen, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Hoffmann
authors.affiliation: Department for Biomedical Magnetic Resonance, University of Tübingen, Tübingen, Germany.|High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Scheffler
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000000981:diagnostic imaging*; D003198:Computer Simulation; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio; D012964:Sodium / Q000737:chemistry*
chemical_list: D012964:Sodium
keywords: Sodium MRI; triple-quantum filtering; ultra-high field