Utility of proton magnetic resonance spectroscopy in the diagnosis of human brain tumors

Proton nuclear magnetic resonance spectroscopy (1H-MRS) was employed in vitro to obtain profiles of various metabolites contained in some of the representative human brain tumors. Extracted samples from each normal and tumoral tissue were used to obtain high-resolution spectra. While N-acetylaspartate was unequivocally demonstrated in normal brain tissues, it could not be detected in brain tumors. Creatine was variably reduced in brain tumors relative to that in normal brain tissue, and was undetectable in neurinomas and pituitary adenomas. Choline was present in all tumors and appeared as relatively prominent peaks in the spectra for meningiomas, pituitary adenomas and metastatic brain tumors. In contrast, levels of creatine and inositol in these tumors were low. Neurinoma showed the largest inositol peak among the tumors examined. Thus compared to normal brain tissue, creatine, choline and inositol in tumors exhibited various degrees of characteristic changes. Therefore we attempted to categorize the spectral pattern of normal and tumoral tissues based on creatine/inositol and/or choline/inositol ratios. There were statistically significant differences between either creatine/inositol ratios and choline/inositol ratios in the tumor groups and the ratios found in normal brain tissue. These ratios also varied relative to different tumor groups. These data suggested that nuclear magnetic resonance spectroscopy might yield clinically useful information which can not be provided by already widely used magnetic resonance imaging and might be applicable to the differential diagnosis of some brain tumors.