Rationale and objectives: Phosphorus magnetic resonance spectroscopy has been used noninvasively to determine characteristic spectral parameters for untreated human brain tumors as a prelude to its use in clinical diagnosis.
Methods: The spectra, which reflect the relative amounts of phosphorus-containing compounds, and the pH within and surrounding the tumors, were obtained in vivo using the localization technique of one-dimensional chemical shift imaging applied with a surface coil. Phosphorus-31 chemical shift imaging was performed successfully in vivo on 9 volunteers and 27 patients with untreated brain tumors, including 7 with astrocytoma, 4 with glioblastoma, 3 with meningioma, and 11 with metastases. This study provides spectra from within and surrounding the brain tumors, and allows accountability for the heterogeneity of brain tumors by the selection of the maximum data point for each parameter.
Results: The ratios of resonance areas, phosphodiesters over nucleoside triphosphate (NTP), and phosphomonoesters over NTP, were found to be higher in glioblastomas (2.55 +/- 0.22, 1.06 +/- 0.09) and astrocytomas (3.04 +/- 0.36, 1.28 +/- 0.36) than in normal brain (2.00 +/- 0.32, 0.79 +/- 0.22). The ratios of areas due to inorganic phosphate and NTP, and phosphocreatine and NTP, also were higher in astrocytomas (1.16 +/- 0.40, 1.17 +/- 0.41) compared with glioblastomas (0.68 +/- 0.01, 0.88 +/- 0.19) and normal brain (0.61 +/- 0.03, 0.77 +/- 0.03). The pH of brain tumors ranged from alkaline to neutral, with meningiomas consistently having alkaline pH.
Conclusions: These data show that there are statistically significant differences in the magnetic resonance parameters of the affected brain hemispheres of patients with astrocytomas, glioblastomas, meningiomas, and normal brain tissue, and underline the need for a multisite clinical trial to establish clinical criteria for diagnosis.