title: Increase in glutamate as a sensitive indicator of extracellular matrix integrity in peritumoral edema: a 3.0-tesla proton magnetic resonance spectroscopy study.
abstract: OBJECTIVE
  The authors of previous studies based on diffusion tensor imaging have indicated that there are two types of peritumoral edema-namely, edema with preserved structural integrity of the glial matrix and edema with compromised glial matrix. The authors of this study hypothesized that functionality of the glutamate (Glu)-glutamine shuttle, a vital neuron-glia interaction, may be differentially affected by peritumoral edema. They tested this hypothesis using proton magnetic resonance (MR) spectroscopy on a 3.0-tesla system that is capable of quantifying Glu without need of editing.
  
  
  METHODS
  Twenty-three patients, each with a single brain tumor mass and peritumoral edema (nine high-grade gliomas, eight metastatic brain tumors, and six meningiomas), and nine healthy individuals participated in this study. Single-voxel proton MR imaging targeting the region of peritumoral edema was performed using a 3.0-tesla system. Glutamate levels in the peritumoral edema of nonglial tumors was significantly elevated (p < 0.01) compared with edema associated with glial tumors or normal white matter. The finding confirmed that peritumoral edema in nonglial tumors is distinct from that of glial tumors, as previously indicated in diffusion tensor imaging studies. The authors hypothesized that the former condition represents a compensatory increase in activities of the Glu-glutamine shuttle brought about by simple expansion of the extracellular space due to edema.
  
  
  CONCLUSIONS
  The assessment of Glu concentrations in peritumoral edema using 3.0-tesla proton MR spectroscopy may be developed into an objective index of the structural integrity of the glial matrix.
authors: Center for Integrated Human Brain Science, Brain Research Institute, School of Health Sciences, Faculty of Medicine, University of Niigata, Japan.
authors: Teruo
authors: T
authors: Kimura
authors: Masaki
authors: M
authors: Ohkubo
authors: Hironaka
authors: H
authors: Igarashi
authors: Ingrid L
authors: IL
authors: Kwee
authors: Tsutomu
authors: T
authors: Nakada
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001929:Brain Edema / Q000209:etiology / Q000378:metabolism* / Q000473:pathology; D001932:Brain Neoplasms / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D016022:Case-Control Studies; D005109:Extracellular Matrix / Q000502:physiology*; D005260:Female; D005910:Glioma / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D018698:Glutamic Acid / Q000378:metabolism*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008579:Meningioma / Q000150:complications* / Q000378:metabolism / Q000473:pathology; D008875:Middle Aged
chemical_list: D018698:Glutamic Acid