In vivo¹³C MRS

The application of ¹³C Magnetic Resonance Spectroscopy (MRS) for basic research/medical applications is challenging and, despite being available for more than 25 years, only a few groups have attempted ¹³C MRS in vivo. However, the few studies undertaken illustrate the great promise of in vivo ¹³C MRS. Interest in ¹³C MRS has grown considerably in recent years. The potential of ¹³C arises from its biggest handicap: Low natural abundance [and the compromised sensitivity (≈1/50 of ¹H)] renders ¹³C spectroscopy in vivo very difficulty due to the inherently very low signal-to-noise ratio (SNR). This low natural abundance, on the other hand, is the key to new, exciting applications of in vivo MRS: Investigation of metabolic pathways and the measurement of flux rates in vivo in animal and humans after ¹³C enriched substrate infusion. The interested reader is referred to a recent issue of NMR in Biomedicine [1] exclusively dedicated to the application of ¹³C MRS to study biological systems for a more detailed update on progress in ¹³C MRS than given below. Instead, in this chapter, basic experimental procedures of in vivo ¹³C MRS, with emphasis on experimental work in humans, are illustrated and discussed for the researcher interested in conducting similar experimental work in the future.