title: Human brain MR spectroscopy thermometry using metabolite aqueous-solution calibrations.
abstract: OBJECTIVE
  To estimate absolute brain temperature using proton MR spectroscopy ((1)H-MRS) and mean brain-body temperature difference of healthy human volunteers.
  
  
  METHODS
  Chemical shift difference between temperature-dependent water spectral line position and temperature-stable metabolite spectral reference was used for the estimations of absolute brain temperature. Temperature calibrations constants were obtained from the spectra of the N-acetyl aspartate (NAA line at approximately 2.0 ppm), glycero-phosphocholine (GPC line at approximately 3.2 ppm), and creatine (Cr line at approximately 3.0 ppm) aqueous solutions with pH values within physiologically pertinent ranges. Single-voxel PRESS sequence (TR/TE 2000/80 ms) was used for this purpose. Brain temperature was determined by averaging the temperatures computed from water-Cho, water-Cr, and water-NAA chemical shift differences.
  
  
  RESULTS
  The mean brain temperature of 18 healthy volunteers was 38.1 +/- 0.4 degrees C and mean brain-body (rectal) temperature difference was 1.3 +/- 0.4 degrees C.
  
  
  CONCLUSIONS
  Improved accuracy of the temperature constants and averaging the temperatures computed from water-Cho, water-Cr, and water-NAA chemical shift differences increased the reliability of the brain temperature estimations.
authors.affiliation: Department of Surgical Sciences, Anesthesiology and Intensive Care, Uppsala University Hospital, Uppsala, Sweden.
authors.forename: Lucian
authors.initials: L
authors.lastname: Covaciu
authors.forename: Sten
authors.initials: S
authors.lastname: Rubertsson
authors.forename: Francisco
authors.initials: F
authors.lastname: Ortiz-Nieto
authors.forename: Håkan
authors.initials: H
authors.lastname: Ahlström
authors.forename: Jan
authors.initials: J
authors.lastname: Weis
mesh_terms: D000293:Adolescent; D000328:Adult; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D001831:Body Temperature; D001921:Brain / Q000473:pathology*; D002138:Calibration; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019047:Phantoms, Imaging; D015203:Reproducibility of Results
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate