Localized ³¹P magnetic resonance spectroscopy of large pediatric brain tumors

Fourteen children aged 1 week to 16 years, with a variety of large or superficial brain tumors, underwent localized in vivo ³¹P magnetic resonance spectroscopy of their tumor. Quantitative spectral analysis was performed by measuring the area under individual peaks using a computer algorithm. In eight patients with histologically benign tumors the spectra were considered to be qualitatively indistinguishable from normal brain. The phosphocreatine/inorganic phosphate ratio (PCr/Pi) averaged 2.0. Five patients had histologically malignant tumors; qualitatively, four of these were considered to have abnormal spectra, showing a decrease in the PCr peak. The PCr/Pi ratio for this group averaged 0.85, which was significantly lower than that seen in the benign tumor group (p < 0.05). No difference between the two groups was seen in adenosine triphosphate or phosphomonoesters. It is concluded that a specific metabolic 'fingerprint' for childhood brain tumors may not exist, but that some malignant tumors show a pattern suggestive of ischemia.