Multinuclear NMR studies of naturally occurring nuclei.

The ability to obtain nuclear magnetic resonance spectra from spatially localized regions of living animals and patients has led to the possibility of measuring biochemical processes in vivo. Localization is generally achieved through the use of surface coils. Using this technique, intracellular pH, and concentrations of high-energy phosphates and "abnormal" marker compounds have been measured in animal organs (both in vitro and in vivo) and in human brain and muscle (in vivo). The majority of studies have used the P-31 nucleus, but carbon (C-13) and hydrogen (H-1) have also been studied. However, both C-13 and H-1 experiments have technical difficulties. Carbon-13 has a low natural abundance, and H-1-containing metabolites may have their signals obscured by the large water peak. The phosphorus studies have been largely preclinical, but diagnostic possibilities are appearing from the many research problems now under investigation.