Editing and Other Adventures in Measuring Neurochemicals by MRS
The measurement of metabolites in the human brain by 1H MRS is a well established technique which has been in the literature for over 30 years and most modern scanners operating at 3T or above are capable of acquiring good quality spectra. Much of the initial research concentrated on metabolites such as NAA, creatine/phosphocreatine and choline-containing compounds which are relatively easy to measure and quantify. However, other neurochemicals, such as the neurotransmitters glutamate and GABA and the anti-oxidant glutathione are of great interest to neuroscientists because of their importance in normal brain function and their potential disturbance in disease. This talk will concentrate on these metabolites and demonstrate that spectral editing is the most reliable way to measure them in the human brain in vivo. Finally, the use of 13C MRS in vivo, combined with infusion of 13C-enriched glucose, will be described as a way of accessing neurotransmitter turnover (rather than steady state levels as measured by 1H MRS) in vivo.