Magnetic Resonance Spectroscopy in Clinical Oncology

The combination of magnetic resonance spectroscopy (MRS) and imaging (MRI) has led to mapping metabolites from normal and neoplastic tissue within the time limits of a routine study. MRSI (magnetic resonance spectroscopy imaging) detects metabolites that contain protons, phosphorus, fluorine, or other nuclei. The uniqueness of the information available in vivo and in a non-invasive manner encouraged radiologists and oncologists to apply MRSI in research and clinical practice. Both (1)H- and (31)P-MRS have revealed significant disturbances in amino acids, lipids, and phosphorus-containing metabolites within tumors. Phosphocreatine is often diminished in neoplasms compared to their primary host or surrounding tissues. However, the reduction of the compound does not appear to be closely correlated to the degree of malignancy. Moreover, abnormalities in (31)P spectra from neoplasms are shared by other disorders. Changes in high-energy phosphate levels almost invariably occur with radio- and chemotherapy of tumors. The spectroscopic alterations are often seen before any variations in tumor size and shape can be detected. However, opposite responses can be associated with the same clinical outcome. (1)H-MRS has been successfully used to quantify the extent of neuronal cell loss imposed on the brain during radiotherapy. Recently, MRSI was successfully integrated into radiotherapy planning in prostate cancer patients. (19)F-MRS opens access to artificially induced fluorocompounds such as 5-fluorouracil and its metabolites.