A general approach to selection of multiple cubic volume elements using the ISIS technique

The ISIS method is used regularly for the selection of a single cubic volume of tissue for in vivo investigation by high‐resolution NMR spectroscopy. This technique has been extended on a theoretical basis to include the simultaneous selection of a number of cubes, the signals from which can be either assessed individually or in certain circumstances coadded to produce improvement in signal‐to‐noise ratio. The modification requires additional selective RF pulses in the spatial encoding prepulse period, and spatially localized spectra are produced by addition and subtraction of NMR signals in a manner similar to the original ISIS technique.