Quick measurement of nuclear magnetic resonance coil sensitivity with a single-loop probe

The coil sensitivity for nuclear magnetic resonance (NMR) signal detection can be defined as B-1/root P, which represents the magnetic field that the coil induces per unit supplied power. An inductive probe was previously proposed to quickly evaluate the sensitivity of a tuned NMR coil. As this probe uses two loops, decoupled by means of a slight overlapping, it is not applicable to small NMR coils since the decoupling efficiency is limited by the loop dimensions. We present a new method, derived from the former, which uses a single-loop probe and allows accurate sensitivity mapping even for very small NMR coils. This new method proves to be in good agreement with both the theoretical formula and a reference method for assessing a simple coil's sensitivity. We conclude that it is both reliable and particularly convenient for development and optimization of small coils for surface MR imaging. (C) 1999 American Institute of Physics. [S0034-6748(99)04012-5].