Spatially encoded spin echoes, J imaging

Recently various methods of chemical-shift imaging were developed (I-5), in which the NMR spectra of different substances are obtained together with their spatial location. Unfortunately, due to the crude magnetic fields produced by whole-body magnets, a very poor resolution is obtained, and the fine details that make NMR spectroscopy so useful for chemical analysis are lost. Moreover, chemical-shift imaging experiments are usually performed only with high-field whole-body magnets, which are very expensive.
We suggest an alternative experiment which may overcome these problems. In this experiment, which we call J imaging, the spectral information is given in the form of
J spectra. The basic pulse sequence is seen in Fig. 1.