1H‐ and 31P‐MR spectroscopy of primary and recurrent human brain tumors in vitro: malignancy‐characteristic profiles of water soluble and lipophilic spectral components

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Abstract
In vitro NMR spectrocopy was performed on specimen of human brain tumors. From all patients, tissue samples of primary tumors and their first recurrences were examined. 31P‐ and 1H‐spectra were recorded from samples of meningioma, astrocytoma and glioblastoma. A double extraction procedure of the tissue samples permitted acquisition of information from the membrane fraction and from the cytosolic fraction. 31P‐spectra were used to analyze the lipophilic fraction (phospholipids of the membrane) of the tissue extracts, while the 1H‐spectra reflected information on the metabolic alterations of the hydrophilic, cytosolic fraction of the tissue. The tumor types showed distinctive spectral patterns in both the 31P‐ and the 1H‐spectra. Based on the total detectable 31P signal, the level of phosphatidylcholine was about 34% lower in primary astrocytomas than in primary glioblastomas (p = 0.0003), whereas the level of sphingomyelin was about 45% lower in primary gioblastomas than in primary astrocytomas (p = 0.0061). A similar tendency of these phospholipids was observed when comparing primary and recurrent astrocytoma samples from the same individuals [+15% (p = 0.0103) and −23% (p = 0.0314) change, respectively]. 1H‐spectra of gliomas were characterized by an increase of the ratios of alanine, glycine and choline over creatine as a function of the degree of malignancy. In agreement with findings in the 31P‐spectra, the 1H‐spectra of recurrent astrocytomas showed metabolic profiles of increased malignancy in comparison to their primary occurrence. Since gliomas tend to increase in malignancy upon recurrence, this may reflect evolving tumor metabolism. 1H‐spectra of meningiomas showed the highest ratio of alanine over creatine accompanied by a near absence of myo‐inositol. Phospholipid profiles of meningiomas showed higher fractional contents of phosphatidylcholine along with lower phosphatidylserine compared to astrocytomas, while higher phosphatidylethanolamine and sphingomyelin fractional contents distinguished meningiomas from glioblastomas. The extraction method being used in this study combined with high‐resolution 1H‐ and 31P‐MRS provides a wide range of biochemical information, which enables differentiation not only between tumor types but also between primary and recurrent gliomas, reflecting an evolving tumor metabolism. Copyright © 2001 John Wiley & Sons, Ltd.