title: MR spectroscopy of the prostate at 3T: measurements of relaxation times and quantification of prostate metabolites using water as an internal reference.
abstract: OBJECTIVE
  We performed single-voxel magnetic resonance spectroscopy (MRS) of the human prostate at 3 tesla using a surface coil to measure prostate water, choline (Cho), creatine (Cr), and citrate (Cit) relaxation times T1, T2, and to estimate concentrations of Cho, Cr, and Cit in healthy volunteers.
  
  
  METHODS
  In nine of 17 healthy volunteers, we performed experiments to estimate relaxation time, and we used the spectra of the other eight to compute metabolite concentrations. Spectra were processed by LCModel and AMARES (advanced method for accurate, robust, and efficient spectral fitting) algorithms. T1 and T2 values were obtained by monoexponential fitting of the spectral intensities. Metabolite concentrations were estimated using prostate tissue water as an internal concentration reference.
  
  
  RESULTS
  Relaxation times are reported for prostate water (T1, 2163±166 ms; T2, 110±18 ms), Cho (T1, 987±71 ms; T2, 239±24 ms), Cr (T1, 1128±149 ms; T2, 188±20 ms), and Cit (T1, 476±70 ms; T2, 228±42 ms). Mean concentrations in healthy prostate were Cho, 2.6±0.3 mM, Cr, 5.8±1.3 mM, and Cit, 26.9±5.5 mM.
  
  
  CONCLUSIONS
  We observed metabolite relaxation times and concentrations consistent with published values of healthy volunteers at 1.5 and 3T. T1 values increased and T2 slightly decreased with magnetic field strength. Our preliminary patient results indicate that water-referenced quantitative MRS of the human prostate is a promising tool for monitoring therapeutic effects and detecting tumor relapse, i.e., in situations when Cit intensity is small or undetectable.
authors.affiliation: Department of Radiology, Uppsala University Hospital.
authors.forename: Jan
authors.initials: J
authors.lastname: Weis
authors.forename: Francisco
authors.initials: F
authors.lastname: Ortiz-Nieto
authors.forename: Håkan
authors.initials: H
authors.lastname: Ahlström
mesh_terms: D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D001834:Body Water / Q000378:metabolism; D002794:Choline / Q000378:metabolism*; D019343:Citric Acid / Q000378:metabolism*; D003401:Creatine / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D012016:Reference Values
chemical_list: D014408:Biomarkers, Tumor; D019343:Citric Acid; D003401:Creatine; D002794:Choline