Brain tumors: interest of magnetic resonance spectroscopy for the diagnosis and the prognosis.

Magnetic resonance spectroscopy (MRS) is a tool for a non-invasive monitori ng of brain tumor metabolism. In vivo proton MRS became possible with the d evelopment of whole-body high-field magnets. First, it allows to distinguis h brain tumors from abscesses. Second, along with other imaging techniques, it permits the differentiation of primary brain tumors, mainly gliomas, fr om tumors of various origins such as meningiomas or metastasis. However, it s ability to give a grading of gliomas stays controversial. Choline, a mark er of cell membrane proliferation, could give information on the degree, of malignancy but reports on its role are somewhat contradictory. Brain tumor biopsy and histology stay mandatory In the, management of brain tumors. In vitro MRS spectra obtained from tumor extracts show that the signal at 3.2 ppm, the so-called "cholin peak", corresponds to several compounds among th em, glycerophosphocholine, phosphocholine, and choline. Their repartition d iffers with the grade of the tumor. In vivo proton MRS is the only metaboli c technique of non-invasive monitoring of treated brain tumors. It can sepa rate recurrence from radionecrosis. Improved methodology and avaibility of MR imagers will strengthen its importance in the future.