title: MR spectroscopic evaluation of brain tissue damage after treatment for pediatric brain tumors.
abstract: OBJECTIVE
  The aim of this study was to evaluate the metabolic profile of uninvolved brain tissue after treatment for pediatric brain tumors.
  
  
  METHODS
  A group of 24 patients aged 4-18 years was analyzed after combined treatment for brain tumors. In this group, there were nine medulloblastomas, seven low-grade gliomas, three high-grade gliomas, two ependymomas and three children with conservatively treated diffuse brainstem gliomas.
  
  
  METHODS
  Short echo-time (TE = 30 ms) point-resolved spectra were acquired using a 2 T clinical scanner (Elscint Prestige). The ratios of signal intensities for N-acetylaspartate (NAA), choline (Cho), myo-inositol (mI), lactate (Lac), and lipids (Lip) were calculated using the creatine (Cr) signal as an internal reference. The spectra were acquired both from the tumor bed and from contralateral uninvolved brain tissue; only control spectra were analyzed. The first examination was made between the third and sixth month after therapy (24 spectra), the second examination occurred 8-12 months after treatment (15 spectra available), and the third was performed approximately 18 months after completion of therapy (eight spectra available). The results were compared using the t-test for dependent samples.
  
  
  RESULTS
  At all time points, the metabolite ratios showed alterations indicating brain tissue damage. The most important were the decrease of NAA/Cr and increase of Lac/Cr and Lip/Cr ratios. The mean NAA/Cr values were 0.91, 0.91, and 0.86, respectively, for the three examinations, while the Lac/Cr and Lip/Cr values were 1.66, 2.11, 1.19 and 12.24, 12.05, 5.69, respectively. Interestingly, in children with supratentorial tumors, a significant increase in NAA/Cr value was observed (from 0.82 to 1.11 in the first and second examinations, respectively; p = 0.0487), which may be indicative of neuronal function recovery.
  
  
  CONCLUSIONS
  MRS examinations of uninvolved brain tissue indicate long-lasting metabolic disturbances. However, the NAA/Cr ratio increase may be a sign of at least partial recovery of metabolic function of the brain.
authors.affiliation: Department of Radiotherapy, Maria Skłodowska-Curie Memorial Cancer Center and Institute of Oncology, Gliwice Branchul, Gliwice, Poland. blamek@gmail.com
authors.forename: Sławomir
authors.initials: S
authors.lastname: Blamek
authors.forename: Dawid
authors.initials: D
authors.lastname: Larysz
authors.forename: Kornelia
authors.initials: K
authors.lastname: Ficek
authors.forename: Maria
authors.initials: M
authors.lastname: Sokół
authors.forename: Leszek
authors.initials: L
authors.lastname: Miszczyk
authors.forename: Rafał
authors.initials: R
authors.lastname: Tarnawski
mesh_terms: D000293:Adolescent; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism* / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology* / Q000628:therapy; D002648:Child; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D004806:Ependymoma / Q000473:pathology / Q000628:therapy; D005260:Female; D005910:Glioma / Q000473:pathology / Q000628:therapy; D006801:Humans; D008055:Lipids; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008297:Male; D008527:Medulloblastoma / Q000473:pathology / Q000628:therapy; D014057:Tomography, X-Ray Computed
chemical_list: D008055:Lipids; D001224:Aspartic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline