title: Assessing global invasion of newly diagnosed glial tumors with whole-brain proton MR spectroscopy.
abstract: OBJECTIVE
  Because of their invasive nature, high-grade glial tumors are uniformly fatal. The purpose of this study was to quantify MR imaging-occult, glial tumor infiltration beyond its radiologic margin through its consequent neuronal cell damage, assessed by the global concentration decline of the neuronal marker N-acetylaspartate (NAA).
  
  
  METHODS
  Seventeen patients (10 men; median age, 39 years; age range, 23-79 years) with radiologically suspected (later pathologically confirmed) supratentorial glial neoplasms, and 17 age- and sex-matched controls were studied. Their whole-brain NAA (WBNAA) amounts were obtained with proton MR spectroscopy: for patients on the day of surgery (n = 17), 1 day postsurgery (n = 15), and once for each control. To convert into concentrations, suitable for intersubject comparison, patients' global NAA amounts were divided by their brain volumes segmented from MR imaging. Least squares regression was used to analyze the data.
  
  
  RESULTS
  Pre- and postoperative WBNAA (mean +/- SD) of 9.2 +/- 2.1 and 9.7 +/- 1.8 mmol/L, respectively, in patients were indistinguishable (P = .369) but significantly lower than in controls (12.5 +/- 1.4 mmol/L). Mean resected tumor size (n = 15) was approximately 3% of total brain volume.
  
  
  CONCLUSIONS
  The average 26% WBNAA deficit in the patients, which persisted following surgical resection, cannot be explained merely by depletion within the approximately 3% MR imaging-visible tumor volume or an age-dependent effect. Although there could be several possible causes of such widespread decline--perineuronal satellitosis, neuronal deafferentation, Wallerian and retrograde degeneration, vasogenic edema, functional diaschisis, secondary vascular changes--most are a direct or indirect reflection of extensive, MR imaging-occult, microscopic tumor cell infiltration, diffusely throughout the otherwise "normal-appearing" brain.
authors.affiliation: Department of Radiology, New York University School of Medicine, New York, NY 10016, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Cohen
authors.forename: Edmond A
authors.initials: EA
authors.lastname: Knopp
authors.forename: Henry
authors.initials: H
authors.lastname: Rusinek
authors.forename: James S
authors.initials: JS
authors.lastname: Babb
authors.forename: David
authors.initials: D
authors.lastname: Zagzag
authors.forename: Oded
authors.initials: O
authors.lastname: Gonen
mesh_terms: D000328:Adult; D000368:Aged; D001224:Aspartic Acid / Q000031:analogs & derivatives / Q000032:analysis; D001921:Brain / Q000473:pathology; D001923:Brain Chemistry; D005260:Female; D005910:Glioma / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D015173:Supratentorial Neoplasms / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology* / Q000601:surgery
chemical_list: D001224:Aspartic Acid; C000179:N-acetylaspartate