title: Is magnetic resonance spectroscopy capable of detecting metabolic abnormalities in neurofibromatosis type 1 that are not revealed in brain parenchyma of normal appearance?
abstract: BACKGROUND
  Results of magnetic resonance spectroscopy studies in normal-appearing brain and in non-neoplastic brain lesions in individuals with neurofibromatosis type 1 (NF1) have been discrepant.
  
  
  OBJECTIVE
  We used magnetic resonance spectroscopy to analyze the metabolic patterns in the basal ganglia of patients with NF1 and examine their correlation with focal hyperintense lesions in T2-weighted images (T2-weighted hyperintensities).
  
  
  METHODS
  We used magnetic resonance spectroscopy data of 42 individuals with NF1 (18 with and 24 without T2- weighted hyperintensities) and 25 controls matched for gender and age. A single-voxel technique was employed by manually placing a region of interest with a uniform size over a predetermined anatomical region including the globus pallidum and putamen (capsulolenticular region). We further analyzed the ratios of choline/creatine, N-acetyl aspartate (NAA)/creatine, and myoinositol/creatine metabolites and the occurrence of T2-weighted hyperintensities in these regions in individuals with NF1.
  
  
  RESULTS
  There was a significant difference between the NF1 and control groups with regard to the mean values of myoinositol/creatine and choline/creatine, with higher metabolite values observed in the NF1 group (P < 0.001). Only the myoinositol/creatine ratio was able to discriminate between NF1 subgroups with and without T2-weighted hyperintensities. For the NAA/creatine ratio, there was no significant difference between the NF1 and the control groups.
  
  
  CONCLUSIONS
  Magnetic resonance spectroscopy allows the characterization of tissue abnormalities not demonstrable in the structural images of individuals with NF1 through choline and myoinositol metabolite analysis. Yet the preserved NAA values argue against demyelination and axonal degeneration occurring in the region, suggesting instead a functional neuronal stability. Taken in association with the findings of lack of clinical manifestations and the known transient nature of T2-weighted hyperintensities in NF1 as demonstrated by other studies, our results support the current histopathologically driven hypothesis that such T2-weighted hyperintensities may be related to intramyelinic edema.
authors.affiliation: Department of Radiology, Hospital de Base, São José do Rio Preto Medical School, São José do Rio Preto, Brazil. Electronic address: acprjunior@hotmail.com.
authors.forename: Antonio Carlos Pondé
authors.initials: AC
authors.lastname: Rodrigues
authors.affiliation: Department of Radiology, Hospital de Base, São José do Rio Preto Medical School, São José do Rio Preto, Brazil.
authors.forename: José Roberto Lopes
authors.initials: JR
authors.lastname: Ferraz-Filho
authors.affiliation: Department of Radiology, Hospital São Luiz, Grupo Fleury, São Paulo Brazil.
authors.forename: Ulysses S
authors.initials: US
authors.lastname: Torres
authors.affiliation: Division of Neuroradiology, Santa Casa de Misericórdia São Paulo de, São Paulo, Brazil.
authors.forename: Antônio José
authors.initials: AJ
authors.lastname: da Rocha
authors.affiliation: Department of Radiology, Hospital de Base, São José do Rio Preto Medical School, São José do Rio Preto, Brazil.
authors.forename: Marcos Pontes
authors.initials: MP
authors.lastname: Muniz
authors.affiliation: Department of Radiology, Hospital de Base, São José do Rio Preto Medical School, São José do Rio Preto, Brazil.
authors.forename: Antônio Soares
authors.initials: AS
authors.lastname: Souza
authors.affiliation: Center of Research and Attendance in Neurofibromatosis (CEPAN), São José do Rio Preto Medical School, São José do Rio Preto, Brazil.
authors.forename: Eny Maria
authors.initials: EM
authors.lastname: Goloni-Bertollo
authors.affiliation: Center of Research and Attendance in Neurofibromatosis (CEPAN), São José do Rio Preto Medical School, São José do Rio Preto, Brazil.
authors.forename: Érika Cristina
authors.initials: ÉC
authors.lastname: Pavarino
mesh_terms: D000293:Adolescent; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D002794:Choline / Q000378:metabolism; D003401:Creatine / Q000378:metabolism; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007294:Inositol / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D008659:Metabolic Diseases / Q000175:diagnosis* / Q000209:etiology*; D009456:Neurofibromatosis 1 / Q000150:complications*; D055815:Young Adult
chemical_list: D001224:Aspartic Acid; D007294:Inositol; C000179:N-acetylaspartate; D003401:Creatine; D002794:Choline
keywords: MRI; T2-W hyperintensities; brain; magnetic resonance spectroscopy; type 1 neurofibromatosis