title: Three-dimensional MR spectroscopic imaging using adiabatic spin echo and hypergeometric dual-band suppression for metabolic mapping over the entire brain.
abstract: Large lipid and water signals in MR spectroscopic imaging (MRSI) complicate brain metabolite quantification. In this study, we combined adiabatic hypergeometric dual-band (HGDB) lipid and water suppression with gradient offset independent adiabatic (GOIA) spin echo to improve three-dimensional (3D) MRSI of the entire brain.
  
  
  
  3D MRSI was acquired at 3T with a 32-channel coil. HGDB pulses were used before excitation and during echo time. A brain slab was selected with GOIA-W(16,4) pulses, weighted phase encoded stack of spirals, and real-time motion/shim correction. HGDB alone or in combination with OVS and MEGA (MEscher-GArwood) was compared with OVS only and no suppression.
  
  
  
  The combined HGDB pulses suppressed lipids to 2%-3% of their full unsuppressed signal. The HGDB lipid suppression was on average 5 times better than OVS suppression. HGDB+MEGA provided 30% more suppression compared with a previously described HGDB+OVS scheme. The number of voxels with good metabolic fits was significantly larger in the HGDB data (91%-94%) compared with the OVS data (59%-80%).
  
  
  
  HGDB pulses provided efficient lipid and water suppression for full brain 3D MRSI. The HGDB suppression is superior to traditional OVS, and it can be combined with adiabatic spin echo to provide a sequence that is robust to B1inhomogeneity. Magn Reson Med 77:490-497, 2017. © 2016 International Society for Magnetic Resonance in Medicine.
authors: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.|Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Morteza
authors: M
authors: Esmaeili
authors: Department of Circulation and Medical Imaging, Norwegian University of Science and Technology, Trondheim, Norway.
authors: Tone F
authors: TF
authors: Bathen
authors: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors: Bruce R
authors: BR
authors: Rosen
authors: Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, USA.
authors: Ovidiu C
authors: OC
authors: Andronesi
mesh_terms: D000328:Adult; D000465:Algorithms; D001921:Brain / Q000378:metabolism*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D055442:Metabolome / Q000502:physiology*; D057054:Molecular Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013113:Spin Labels
chemical_list: D013113:Spin Labels
keywords: adiabatic spin echo (ASE); brain; hypergeometric dual band (HGDB); lipid suppression; magnetic resonance spectroscopy imaging (MRSI)