title: Fast and efficient free induction decay MR spectroscopic imaging of the human brain at 9.4 Tesla.
abstract: The purpose of this work was to develop a fast and efficient MRSI-FID acquisition scheme and test its performance in vivo. The aim was to find a trade-off between the minimal total acquisition time and signal-to-noise ratio of the acquired spectra.
  
  
  
  Measurements were performed on a 9.4 Tesla system. Sequence optimization included redesign of water suppression, optimization of the sequence gradients, and improvement of the sampling efficiency by minimizing the read-out time. This resulted in an acquisition time of 2:47 and 22:13 minutes for 2D (TR = 57 ms; 3-mm in-plane resolution) and 3D MRSI (TR = 57 ms; 16 slices; 3-mm isotropic resolution), respectively.
  
  
  
  Despite strong T1weighting and first-order phase problems, it was possible to obtain spectra of an acceptable quality. The average line width calculated for the tCr peak across the entire field of view was 26.9 ± 9.6 Hz for 2D and 30.0 ± 11.3 Hz for 3D MRSI. In 3D measurements, the percent fraction of voxels fitted with Cramer-Rao lower bounds below 10% was 53.3 ± 4.1%, 63.4 ± 8.4%, and 81.0 ± 2.9% for Glu, tCr, and tNAA, respectively.
  
  
  
  Considering the typically long duration of high-resolution MRSI, the proposed technique may be of interest for clinical applications and/or studies that focus on following the biochemistry of dynamic processes. Magn Reson Med 78:1281-1295, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors.affiliation: Department of Biomedical Magnetic Resonance, Eberhard-Karls University of Tübingen, Tübingen, Germany.|High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Grzegorz L
authors.initials: GL
authors.lastname: Chadzynski
authors.affiliation: High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.|Graduate Training Centre of Neuroscience, Eberhard-Karls University of Tübingen, Tübingen, Germany.
authors.forename: Jonas
authors.initials: J
authors.lastname: Bause
authors.affiliation: High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Gunamony
authors.initials: G
authors.lastname: Shajan
authors.affiliation: High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Rolf
authors.identifier: 0000-0002-6137-9590
authors.initials: R
authors.lastname: Pohmann
authors.affiliation: Department of Biomedical Magnetic Resonance, Eberhard-Karls University of Tübingen, Tübingen, Germany.|High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Scheffler
authors.affiliation: Department of Biomedical Magnetic Resonance, Eberhard-Karls University of Tübingen, Tübingen, Germany.|High-field Magnetic Resonance Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany.
authors.forename: Philipp
authors.initials: P
authors.lastname: Ehses
mesh_terms: D001921:Brain / Q000000981:diagnostic imaging*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio
keywords: fast MRSI; free induction decay; sidebands; ultra-high fields