title: Proton MR spectroscopy of pediatric cerebellar tumors.
abstract: OBJECTIVE
  To investigate the role of proton MR spectroscopy in pediatric cerebellar tumor diagnosis.
  
  
  METHODS
  Single voxel pulse sequences with long echo time (135 or 270 milliseconds, voxel size 8 to 19 cm3), were used to obtain proton spectra of primary pediatric cerebellar tumors. Eleven primitive neuroectodermal tumors (patient age, 2 to 12 years; mean, 7 years), 11 low-grade astrocytomas (age, 2 to 16 years; mean, 9 years), 4 ependymomas (age, 1 to 6 years; mean, 4 years), 1 mixed glioma ependymo-astrocytoma (age, 11 years), 1 anaplastic ependymoma (age, 7 years), 1 ganglioglioma (age, 14 years), and 1 malignant teratoma (age, 6 days) were studied. Control cerebellum spectra were acquired from five patients without abnormality in cerebellum (age, 2 to 15 years; mean, 8 years). The signal intensities from choline-containing compounds (Cho), creatine/phosphocreatine (Cr), N-acetyl-aspartate (NAA), and lactate (Lac) were quantified. The mean and standard deviation of metabolite ratios were calculated.
  
  
  RESULTS
  The control spectra ratios (NAA:Cho = 1.49 +/- 0.36, Cr:Cho = 1.13 +/- 0.23) were distinct from the tumor spectra (NAA:Cho = 0.41 +/- 0.27 and Cr:Cho = 0.37 +/- 0.23). Most of primitive neuroectodermal tumors had low NAA:Cho (0.17 +/- 0.09) and Cr:Cho (0.32 +/- 0.19). Compared with primitive neuroectodermal tumors, low-grade astrocytomas and ependymomas had higher NAA:Cho ratio (0.63 +/- 0.19 and 0.39 +/- 0.12). The Cr:Cho ratio was higher for ependymomas (0.60 +/- 0.20) than for astrocytomas (0.27 +/- 0.12) and primitive neuroectodermal tumors. No NAA was found in the malignant teratoma. Lac:Cho ratio was 0.66 +/- 0.40, 0.58 +/- 0.30, and 0.08 +/- 0.12 for astrocytoma, ependymoma, and primitive neuroectodermal tumor, respectively. Lactate was elevated in the mixed glioma ependymo-astrocytoma, ganglioglioma, and teratoma. The NAA and lactate signals were sometimes obscured by lipids in the spectra. Discriminant analysis was carried out using NAA:Cho and Cr:Cho ratios to differentiate the three major tumor types. The sensitivity/specificity values for diagnosing astrocytoma, ependymoma, and primitive neuroectodermal tumor were found to be 0.91/0.84, 0.75/0.92, and 0.82/0.89, respectively, based on this study.
  
  
  CONCLUSIONS
  In many cases, proton MR spectroscopy can be used to help differentiate cerebellar primitive neuroectodermal tumor, low-grade astrocytoma, and ependymoma.
authors.affiliation: Department of Radiology, Children's Hospital of Philadelphia, PA 19104-4345, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Wang
authors.forename: L N
authors.initials: LN
authors.lastname: Sutton
authors.forename: A
authors.initials: A
authors.lastname: Cnaan
authors.forename: J C
authors.initials: JC
authors.lastname: Haselgrove
authors.forename: L B
authors.initials: LB
authors.lastname: Rorke
authors.forename: H
authors.initials: H
authors.lastname: Zhao
authors.forename: L T
authors.initials: LT
authors.lastname: Bilaniuk
authors.forename: R A
authors.initials: RA
authors.lastname: Zimmerman
mesh_terms: D000293:Adolescent; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001254:Astrocytoma / Q000175:diagnosis / Q000378:metabolism; D001923:Brain Chemistry; D002528:Cerebellar Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D002794:Choline / Q000032:analysis; D003401:Creatine / Q000032:analysis; D004806:Ependymoma / Q000175:diagnosis / Q000378:metabolism; D005260:Female; D006801:Humans; D007223:Infant; D007773:Lactates / Q000032:analysis; D019344:Lactic Acid; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D018242:Neuroectodermal Tumors, Primitive / Q000175:diagnosis / Q000378:metabolism; D010725:Phosphocreatine / Q000032:analysis
chemical_list: D007773:Lactates; D010725:Phosphocreatine; D001224:Aspartic Acid; D019344:Lactic Acid; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline