title: Short-echo three-dimensional H-1 MR spectroscopic imaging of patients with glioma at 7 Tesla for characterization of differences in metabolite levels.
abstract: BACKGROUND
  The purpose of this study was to evaluate the feasibility of using a short echo time, three-dimensional H-1 magnetic resonance spectroscopic imaging (MRSI) sequence at 7 Tesla (T) to assess the metabolic signature of lesions for patients with glioma.
  
  
  METHODS
  Twenty-nine patients with glioma were studied. MRSI data were obtained using CHESS water suppression, spectrally selective adiabatic inversion-recovery pulses and automatically prescribed outer-volume-suppression for lipid suppression, and spin echo slice selection (echo time = 30 ms). An interleaved flyback echo-planar trajectory was applied to shorten the total acquisition time (∼10 min). Relative metabolite ratios were estimated in tumor and in normal-appearing white and gray matter (NAWM, GM).
  
  
  RESULTS
  Levels of glutamine, myo-inositol, glycine, and glutathione relative to total creatine (tCr) were significantly increased in the T2 lesions for all tumor grades compared with those in the NAWM (P < 0.05), while N-acetyl aspartate to tCr were significantly decreased (P < 0.05). In grade 2 gliomas, level of total choline-containing-compounds to tCr was significantly increased (P = 0.0137), while glutamate to tCr was significantly reduced (P = 0.0012).
  
  
  CONCLUSIONS
  The improved sensitivity of MRSI and the increased number of metabolites that can be evaluated using 7T MR scanners is of interest for evaluating patients with glioma. This study has successfully demonstrated the application of a short-echo spin-echo MRSI sequence to detect characteristic differences in regions of tumor versus normal appearing brain.
authors.affiliation: Department of Radiology and Biomedical Imaging, University of California, San Francisco, California, USA.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Peder
authors.initials: P
authors.lastname: Larson
authors.forename: Albert P
authors.initials: AP
authors.lastname: Chen
authors.forename: Janine M
authors.initials: JM
authors.lastname: Lupo
authors.forename: Eugene
authors.initials: E
authors.lastname: Ozhinsky
authors.forename: Douglas
authors.initials: D
authors.lastname: Kelley
authors.forename: Susan M
authors.initials: SM
authors.lastname: Chang
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Nelson
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001932:Brain Neoplasms / Q000378:metabolism*; D017352:Echo-Planar Imaging / Q000379:methods; D005240:Feasibility Studies; D005260:Female; D005910:Glioma / Q000378:metabolism*; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008297:Male; D008875:Middle Aged; D057054:Molecular Imaging / Q000379:methods*; D066244:Proton Magnetic Resonance Spectroscopy / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution
chemical_list: D014408:Biomarkers, Tumor
keywords: 7T; glioma; magnetic resonance spectroscopic imaging