The power of the proton

Magnetic resonance spectroscopy (MRS) is used to determine the biochemical structure of human body tissue. It relies on signals emitted by the hydrogen atom, abundant in the human body. MRS studies have demonstrated tissue metabolism in both animals and human subjects. Until recently, most MRS studies showed how muscle activity works by measuring alterations in adenosine triphosphate (ATP). Traditionally, new magnetic resonance (MR) techniques have been applied to brain studies. MRS, which is a specialized application of the principles of MR technology, can be used to investigate how the brain works with respect to edema, oxygen depletion or hypoxia, and carbohydrate metabolism. Preliminary studies on brain activity, using MRS, suggest that different types of brain tumors exhibit different ways of using hydrogen. Widespread studies are currently underway to improve the diagnostic reliability of hydrogen MRS. It will be important to compare the accuracy of these findings with computed tomography (CT) studies, since CT evaluation of the brain has been used for some time. It is expected that spectroscopic imaging studies of brain tumors and other abnormalities will be used to obtain added metabolic information for tissue characterization. Although MR imaging is a powerful tool for the study of anatomy, function, blood flow, and perhaps even perfusion, it has not yet allowed direct detection of biochemical changes. MRS may be the improvement that will make MR a powerful tool for the evaluation of these biochemical aspects of brain activity.