Cardiac magnetic resonance spectroscopy: a window for studying physiology.

Cardiac magnetic resonance spectroscopy (MRS) opens a window to the metabolism of the heart. Various intermediates of metabolic pathways can be observed and followed over time. Most applications of cardiac MRS have been performed with the 31P nuclei, which reflect the metabolites from the high-energy phosphate metabolism. Other nuclei, such as 1H or 13C, have also been investigated but less intensively, most likely because of either large background signals (e.g., water) or inherent low sensitivity of the method. MRS can be used for the examination of tissue extracts, isolated organs, whole animals in vivo, as well as healthy human subjects and patients. Although the primary motivation is to gain an understanding of metabolism using animal models, a potential for diagnostic applications in humans certainly exists.