Effect of Amplitude Modulation on Selective Excitation in NMR Imaging

If NMR imaging uses selective excitation, then it has to do it correctly as it affects the image resolution. We have related the properties of the selected slice, such as its width, its rate of attenuation, and its side lobes to the amplitude modulation of the radio frequency pulse. An interesting observation was that multiplying sinc(t) function by a triangle can give better results than multiplying it with a Gauss function. We have used computer simulation and tried to emphasize the qualitative relationship between the properties. We conclude with some practical requirements and show the need of a numerical design procedure if the slice properties have to be optimized.