The nutation spin echo and its use for localized NMR

A suitably matched combination of unidirectional gradient pulses of the radio frequency amplitude B-1 and of the main magnetic field B-0 produces an unconventional type of spin echo, the nutation echo. The echo signal becomes volume selective if the gradients to be matched are inhomogeneously distributed in space. An example is a combination of a constant B-0 gradient and the inhomogeneous B-1 gradient of a surface coil. We suggest a method for localized NMR on this basis. Nutation echoes can also be used to map the spatial distribution of B-1 gradients of an arbitrary radio frequency coil geometry with the aid of a small probe sample. (C) 2000 Academic Press.