Surface (Local) Coils as NMR Receivers

The advent of “wide bore,” high‐field, high‐homogeneity magnets in the 1970s provided the opportunity to use nuclear magnetic resonance spectroscopy for nondestructive chemical analysis of intact biological systems. Surface or local coils, when used as NMR receivers, provide the NMR experiment with both high signal‐to‐noise sensitivity and a good degree of spatial discrimination. Such attributes are critical to the examination of biological processes in laboratory animals and human patients when concentrations of the metabolites of interest are low and when the sample is characterized by large‐scale heterogeneity, i.e., there are different tissues and organs of interest. The high signal sensitivity also provides for very high spatial resolution when such receivers are used in magnetic resonance imaging of regions such as the spine. This article describes the basic principles of surface coil NMR with the aim of illuminating the concepts underlying its widespread application for in vivo systems.