title: Diffusion-weighted chemical shift imaging of human brain metabolites at 7T.
abstract: OBJECTIVE
  Diffusion-weighted chemical shift imaging (DW-CSI) of brain metabolites poses significant challenges associated with the acquisition of spectroscopic data in the presence of strong diffusion weighting gradients. We present a reproducible DW-CSI acquisition and processing scheme that addresses most of the potential sources of instability and provides reproducible and anatomically meaningful diffusion-weighted and apparent diffusion coefficient (ADC) metabolite maps.
  
  
  METHODS
  A real-time navigator-based acquisition scheme was used, allowing instantaneous reacquisition of corrupted k-space data and postprocessing correction of gradient-induced phase fluctuations. Eddy current correction based on residual water resonance was implemented and improved the quality of the data significantly.
  
  
  RESULTS
  Highly reproducible diffusion-weighted metabolite maps of three highest concentration brain metabolites are shown. The navigator-based accept/reject strategy and the postacquisition corrections improved the stability of the DW-CSI signal and the reproducibility of the resulting DW-CSI maps significantly. The metabolite ADC values could be related to the underlying tissue cellular composition.
  
  
  CONCLUSIONS
  Robust investigation of DW-CSI of brain metabolites is feasible and may provide information complementary to that obtained from more sensitive but less specific methods such as diffusion tensor imaging.
authors.affiliation: C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Ayse Ece
authors.initials: AE
authors.lastname: Ercan
authors.affiliation: Department of Electrical Engineering, Faculty of Engineering, Mahidol University, Nakornpathom, Thailand.
authors.forename: Aranee
authors.initials: A
authors.lastname: Techawiboonwong
authors.affiliation: C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Versluis
authors.affiliation: C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: Webb
authors.affiliation: C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, Netherlands.
authors.forename: Itamar
authors.initials: I
authors.lastname: Ronen
mesh_terms: D000328:Adult; D016477:Artifacts; D001921:Brain / Q000378:metabolism*; D001923:Brain Chemistry; D001931:Brain Mapping / Q000379:methods*; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008297:Male; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
keywords: brain metabolites; chemical shift imaging; diffusion; tissue microstructure