The investigation of experimental brain tumours using 31P-MRS and 1H-MRI

In vivo 31P-magnetic resonance spectra (MRS) were obtained by the surface coil method from rat glioma, human glioblastoma, and human neuroblastoma inoculated subcutaneously in CD Fisher rats and hamsters, and the effects of chemotherapy, photoradiation therapy, and radiofrequency hyperthermia as well as 60Co-irradiation were evaluated by sequentially observing spectral changes. In the 31P-spectra of tumour tissue, the nucleoside triphosphate (NTP), phosphomonoesters (PME) peaks were high and the phosphocreatine peak was low compared to those of normal brain. When the antitumour agents were given and were effective, NTP peaks decreased, and inorganic phosphate increased remarkably within several hours after the treatment. 1H-magnetic resonance imaging (MRI) were also obtained in some cases. Necrotic regions was detected by the 1H-MRI as image changes which appeared later than those detected by MRS. It proved practical to monitor the effect of therapy by employing either 31P-MRS or 1H-MRI. However, the image changes which demonstrated the effect of the therapy used closely resembled those changes which occurred with the onset of necrosis in tumour tissue during tumour growth. Several problems for future application of these techniques to human brain tumours are also mentioned.