title: Proton MR spectroscopic characteristics of pediatric pilocytic astrocytomas.
abstract: OBJECTIVE
  We report the common characteristics of juvenile pilocytic astrocytomas revealed by proton MR spectroscopy.
  
  
  METHODS
  Eight children with pilocytic astrocytomas were studied with proton MR spectroscopy. The selected sampling volume was approximately 4 cm3, obtained from solid tumor. To localize the sampling volume, we used point-resolved spectroscopy (PRESS) and stimulated-echo acquisition mode (STEAM) techniques to acquire long- and short-TE spectra, respectively. Spectra from PRESS and STEAM sequences were processed using Lorentzian-to-Gaussian transformation and exponential apodization, respectively. For PRESS (2000/270) spectra, peaks of creatine, choline, N-acetylaspartate (NAA), and lactate resonances were integrated; for STEAM (2000/20) spectra, we measured the amplitude of the peaks at 3.2, 2.0, 1.3 and 0.9 ppm.
  
  
  RESULTS
  An elevated lactate doublet was observed in the PRESS spectra. The choline/NAA ratio was 3.40. The amplitude ratios of the lipid pattern (0.9, 1.3 and 2.0 ppm) to choline were all below one.
  
  
  CONCLUSIONS
  Despite the benign histology of the tumor, which generally lacks necrosis, a lactate signal was detected in all eight patients studied. A dominant lipid pattern was not observed.
authors.affiliation: Imaging Research Center, Department of Radiology, Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Hwang
authors.forename: G F
authors.initials: GF
authors.lastname: Egnaczyk
authors.forename: E
authors.initials: E
authors.lastname: Ballard
authors.forename: R S
authors.initials: RS
authors.lastname: Dunn
authors.forename: S K
authors.initials: SK
authors.lastname: Holland
authors.forename: W S
authors.initials: WS
authors.lastname: Ball
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001254:Astrocytoma / Q000175:diagnosis* / Q000378:metabolism; D001932:Brain Neoplasms / Q000175:diagnosis* / Q000378:metabolism; D002648:Child; D002675:Child, Preschool; D002794:Choline / Q000378:metabolism; D006801:Humans; D007223:Infant; D019344:Lactic Acid / Q000378:metabolism; D050356:Lipid Metabolism; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D011522:Protons
chemical_list: D011522:Protons; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate; D002794:Choline