Application of MR spectroscopy to the study of tumor biology

Though MR spectroscopy has long been used to analyze the structure of organic compounds in solution, interest in applying it to the study of biologic systems has been slow in evolving because of past problems with spectral resolution in solids and gels. Renewed interest in this area has been stimulated both by the rapid growth of MR imaging as a clinical tool as well as by improvements in MR spectrometer design and use of sophisticated pulse sequences which have greatly improved the analysis of molecular composition. This review specifically focuses on the application of MR spectroscopy to studying the biology of malignant cells. The bulk of MR studies in this area to date have involved either 1H or 31P spectroscopy. Several investigators have now demonstrated that 1H spectra can be used to distinguish both animal and human tumors of differing metastatic properties. Preliminary data suggest that these spectral differences result in part from differences in cell surface glycoproteins and/or glycolipids between cells of low and high metastatic potential. Many of these molecules can absorb cell water potentially affecting T1 of cell water by their relative concentrations. Prolonged T2 relaxation times have been associated with some spectral peaks which distinguish cells of differing metastatic potential. The findings may partly explain why tumors have the prolonged T1 and T2 relaxation times seen in proton MR imaging. Other 1H MR spectroscopic studies suggest that there are detectable differences in plasma lipids in patients with a variety of malignancies compared to normal controls, suggesting possible utility as a screening test.(ABSTRACT TRUNCATED AT 250 WORDS)