NUCLEAR-MAGNETIC-RESONANCE SPECTROSCOPY - BIOCHEMICAL EVALUATION OF BRAIN-FUNCTION IN-VIVO AND IN-VITRO

Nuclear magnetic resonance spectroscopy (MRS) offers a unique opportun ity to monitor mmolar concentrations of high energy phosphates, glucos e, lactate and amino acids. The possibility oi obtaining information a bout chemical constituents noninvasively is of great importance. MRS a nd chemical shift imaging (CSI) are emerging as tools for tumor gradin g, monitoring of treatment, ischemia research, in pediatric research f or follow-up of children with borderline mental retardation, for defin ing brain death and to define epileptic foci. It is important to know which cell type (neuronal or glial) shows changes as a result of exter nal manipulations (e.g. excitotoxins) or intern al changes (brain path ology). Metabolic studies have been carried out on brain cell cultures . By using C-13 labeled glucose and acetate in combination with C-13 M RS it Was shown that astrocytes release lactate, glutamine, citrate an d alanine and that cerebral cortical neurons use glutamine released fr om astrocytes as a precursor for GABA synthesis. An important feature in MRS is the localization of N-acetyl aspartate in neurons, since thi s enables monitoring of neuronal reactions, such as survival after neu rotoxic insults. Recent advances have yielded high speed functional ec ho planar imaging (EPI) techniques that are sensitive to changes in ce rebral blood volume, blood flow and blood oxygenation (Functional MRI) . During cognitive cask performance, local alterations in neuronal act ivity induce local changes in cerebral metabolism and cerebral perfusi on, which can now be detected with MRI. (C) 1994 Intox Press, Inc.