CHOICE OF SOFT PULSE SHAPES FOR SIGNAL EXCITATION IN CHEMICAL-SHIFT SELECTIVE IMAGING

The choice of soft pulse shapes for chemical shift selective excitatio n in chemical shift imaging is discussed. In the presence of inhomogen eities in the static magnetic field resulting from susceptibility anom alies, it is important to optimise pulse bandshape and frequency offse t as well as bandwidth, in order to minimize artefacts arising from ex citation of unwanted resonances. A comparison of the use of Gaussian a nd sine shaped excitation pulses in the chemical shift micro-imaging o f grapes serves to illustrate some of the effects that may be observed .