Brain tumors studied by in vitro multinuclear MRS

MR Tosi, PhD a, G Bottura, Professor b, G Fini, Professor b, A Tinti, PhD b and V Tugnoli, PhD b

a Istituto di Citomorfologia Normale e Patologica del CNR, Bologna, Italy b University of Bologna Biochemistry Department, Bologna, Italy

Aim: Brain cell extracts were analysed by Magnetic Resonance Spectroscopy (MRS) to identify metabolites typical of the healthy brain and of different brain tumors. Methods: Specimens were collected from 3 peritumoral healthy tissues, 15 glioblastomas, 3 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas, 4 oligodendrogliomas, 3 anaplastic ependymomas, 3 ependymomas, 3 subependymomas, 3 chordomas and 10 meningiomas. Water soluble and lipophilic metabolites from these tissues were studied by multinuclear MRS. Results: MRS analysis of the aqueous extracts identified several metabolites. N-acetyl-aspartate is distinctive of healthy brain and decreases in all brain tumors. Highest grade gliomas, characterized by an elevated biochemical heterogeneity, have a metabolic profile distinctive from that of lower grade tumors. Ependymal tumors are well differentiated by their 1H MRS spectra. Non neuroectodermal neoplasms are characterized by high amounts of betaine and alanine. Lipids detected directly on the specimens (ex vivo MRS) can be related to necrosis, thereby indicating a high grade neoplasm. 1H,13C and 31P MRS also identify the lipid components: cholesteryl esters, present only in the highest grade gliomas, can play an important role in cellular proliferation. The involvement of the enzymatic system responsible for cholesterol esterification should be further investigated. Conclusions: Detailed information on the biochemical composition of brain tissues will improve in vivo.

KEY WORDS: Brain tissues, Magnetic Resonance Spectroscopy, Neoplasm.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Diagnostic Markers.