title: Improving proton MR spectroscopy of brain tissue for noninvasive diagnostics.
abstract: OBJECTIVE
  To examine preprocessing methods affecting the potential use of Magnetic Resonance Spectroscopy (MRS) as a noninvasive modality for detection and characterization of brain lesions and for directing therapy progress.
  
  
  METHODS
  Two reference point re-calibration with linear interpolation (to compensate for magnetic field nonhomogeneity), weighting of spectra (to emphasize consistent peaks and depress chemical noise), and modeling based on chemical shift locations of 97 biomarkers were investigated. Results for 139 categorized scans were assessed by comparing Leave-One-Out (LOO) cross-validation and external validation.
  
  
  RESULTS
  For distinction of nine brain tissue categories, use of re-calibration, variance weighting, and biomarker modeling improved LOO classification of MRS spectra from 31% to 95%. External validation of the two best nine-category models on 47 unknown samples gave 96% or 100% accuracy, respectively, compared with pathological diagnosis.
  
  
  CONCLUSIONS
  Preprocessing of MRS spectra can significantly improve their diagnostic utility for automated consultation of pattern recognition models. Use of several techniques in combination greatly increases available proton MRS information content. Accurate assignment of unknowns among nine tissue classes represents a significant improvement, for a much more demanding task, than has been previously reported.
authors.affiliation: Division of Systems Biology, National Center for Toxicological Research, US FDA, Jefferson, Arkansas 72079, USA.
authors.forename: Pierre
authors.initials: P
authors.lastname: Alusta
authors.forename: Inessa
authors.initials: I
authors.lastname: Im
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Pearce
authors.forename: Richard D
authors.initials: RD
authors.lastname: Beger
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Kretzer
authors.forename: Dan A
authors.initials: DA
authors.lastname: Buzatu
authors.forename: Jon G
authors.initials: JG
authors.lastname: Wilkes
mesh_terms: D015415:Biomarkers / Q000737:chemistry; D001921:Brain / Q000473:pathology; D001931:Brain Mapping / Q000379:methods; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D002138:Calibration; D001330:Electronic Data Processing; D006801:Humans; D007091:Image Processing, Computer-Assisted; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008495:Medical Oncology / Q000379:methods*; D010363:Pattern Recognition, Automated; D011522:Protons; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D011522:Protons