Nuclear magnetic resonance spectroscopy: a tool for skeletal muscle metabolic research.

Nuclear magnetic resonance spectroscopy provides non-invasive and non-destructive access to the chemistry of human tissue in situ. Two studies presented in this issue of the Journal [1, 2] apply this new technique on skeletal muscle metabolism in patients with chronic lung disease. In the 1940s, E. Purcell and F. Bloch discovered that electromagnetic radio-frequency energy could be used to interact with the magnetic fields of some atomic nuclei. The phenomenon was called nuclear magnetic resonance (NMR). For this discovery, Purcell and Block were awarded the Nobel Prize in 1952. In the 1950s, NMR was developed into NMR spectroscopy, as an instrument for analytical chemistry in vitro. The 1991 Nobel Prize in chemistry was awarded to R.R. Ernst for pioneering further development of the NMR technique, especially high resolution two dimensional spectroscopy. The NMR-principle also proved usable for producing two or three dimensional representations of the proton density in tissue, thereby adding a novel technique for medical imaging called magnetic resonance imaging, (MRI). Later, the principle was also developed for spectroscopy in vivo, magnetic resonance spectroscopy (MRS). MRS in particular requires magnets with large field strength. By development of the super-conducting principle, strong magnets large enough to accommodate the human body have been constructed.