[A study of lyophylized human brain tumor tissue using MAS 1H-MRS spectroscopy]

Proton magnetic spectroscopy of brain tumor extracts, and more recently magic angle spinning proton magnetic resonance spectroscopy (MAS 1H-MRS) of intact cooled tissue specimens have been used for tumor classification. The aim of this study was to obtain MAS 1H-MRS spectra of lyophilised and pulverised specimens of various brain tumors and to assess their utility for tumor type recognition.

Tissue samples of intracranial tumors were obtained at surgery and frozen immediately in liquid nitrogen. A part of each sample was subjected to a routine histopathological examination, while the rest was lyophilised, pulverised, and subjected to high-speed magic angle spinning MRS using Bruker DSX-400 WB AVANCE spectrometer and rotation speed up to 33 kHz.

MAS 1H-MRS spectra of 39 samples (including 16 glioblastomas or gliosarcomas, 10 meningiomas and 5 craniopharyngiomas) were obtained. Invariably the spectra were dominated by broad lipid resonances, reflecting "NMR visible" protons in methyl,methylene and methine groups of fatty acid chains. Resolution of the spectra was markedly higher for glioblastomas/gliosarcomas and craniopharyngiomas than for meningiomas.

Lyophylization of brain tumor specimens eliminates signals of watersoluble metabolites and results in a loss of discriminative power of the 1H-MRS analysis. Resolution of the spectra is increased for tumors that accumulate lipids extracellularly, but is not related to tumor histological grade.