Differentiating diffuse World Health Organization grade II and IV astrocytomas with ex vivo magnetic resonance spectroscopy

Neurosurgery. 2013 Feb;72(2):186-95; discussion 195. doi: 10.1227/NEU.0b013e31827b9c57.

Abstract

Background: The prognosis and treatment of astrocytomas, which are primary brain tumors, vary depending on the grade of the tumor, necessitating a precise preoperative classification. Magnetic resonance spectroscopy (MRS) provides information about metabolites in tissues and is an emerging noninvasive tool to improve diagnostic accuracy in patients with intracranial neoplasia.

Objective: To investigate whether ex vivo MRS could differentiate World Health Organization grade II (A-II) and IV astrocytomas (glioblastomas; GBM) and to correlate MR spectral profiles with clinical parameters.

Methods: Patients with A-II and GBM (n = 58) scheduled for surgical resection were enrolled. Tumor specimens were collected during surgery and stored in liquid nitrogen before being analyzed with high-resolution magic angle spinning MRS. The tumors were histopathologically classified according to World Health Organization criteria as GBM (n = 48) and A-II (n = 10).

Results: Multivariate analysis of ex vivo proton high-resolution magic angle spinning spectra MRS showed differences in the metabolic profiles of different grades of astrocytomas. A-II had higher levels of glycerophosphocholine and myo-inositol than GBM. The latter had more phosphocholine, glycine, and lipids. We observed a significant metabolic difference between recurrent and nonrecurrent GBM (P < .001). Primary GBM had more phosphocholine than recurrent GBM. A significant correlation (P < .001) between lipid and lactate signals and histologically estimated percentage of necrosis was observed in GBM. Spectral profiles were not correlated with age, survival, or magnetic resonance imaging-defined tumor volume.

Conclusion: Ex vivo MRS can differentiate astrocytomas based on their metabolic profiles.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Aspartic Acid / metabolism
  • Astrocytoma / classification*
  • Astrocytoma / diagnosis*
  • Astrocytoma / genetics
  • Brain Neoplasms / classification*
  • Brain Neoplasms / diagnosis*
  • Brain Neoplasms / genetics
  • Choline / metabolism
  • Creatine / metabolism
  • Female
  • Humans
  • Isocitrate Dehydrogenase / genetics
  • Isocitrate Dehydrogenase / metabolism
  • Magnetic Resonance Imaging*
  • Magnetic Resonance Spectroscopy*
  • Male
  • Middle Aged
  • Multivariate Analysis
  • Mutation / genetics
  • Predictive Value of Tests
  • Principal Component Analysis
  • Severity of Illness Index
  • World Health Organization

Substances

  • Aspartic Acid
  • Isocitrate Dehydrogenase
  • IDH1 protein, human
  • Creatine
  • Choline