Brain Tumors in Which Lactate and Lipid Have Been Detected: A Proton Magnetic Resonance Spectroscopy Study

ABSTRACT

To determine the spectral pattern of metabolites in 31 brain tumors in which the presence of lipids, lactate and additional intermediary metabolites had been detected, in vivo 1H-MR spectroscopy was performed. Metastasis (n=3), meningioma(n=7), astrocytic tumors of different grades(n=11), postop recurrent tumors(n=2) and other tumors(n=10) were examined using the stimulated echo(STEAM, TE=30ms) or double spin echo technique(PRESS, TE=272ms) with CHESS pulse for water suppression. The detection of lactate in astrocytic tumors correlated with a higher grade of malignancy, and lipid was observed in most glioblastomas. Elevated lactate levels in tumors do not simply originate in the necrotic region, but are related to the high glycolytic activity of adequately perfused, viable neoplastic cells. Lipid signals were detected in high grade, late stage brain tumors, indicating the need for enhanced phospholipid metabolism and membrane degradation, respectively. The absence of lactate and presence of alanine, glutamate/glutamine in most meningiomas distinguished them from schwannomas and other glial tumors. Observation of the spectral pattern of metabolites in brain tumors in which lipid and lactate has been detected might play an important prognostic role in the management and differentiation of metastasis, glial tumors, tumor recurrence, and other non-neoplastic diseases.