RE Pulse Shapes for Selective Excitation in NMR Imaging

It is shown that the requirements of an RF pulse needed to produce a slice for use in NMR imaging approximate the requirements of the windows used for calculating the discrete Fourier transform (DFT). This approach gives an interesting insight into the physical background of pulse shape tailoring. One of the more successful DFT windows is the 3 term Blackman-Harris window, which is tailored to produce minimum sidelobes. The results of applying radio frequency (RF) pulses modulated to give this window shape is given. The pulse shape produces a uniform magnetization over a range of frequencies with a quasi-linear phase shift making it suitable for producing a slice for NMR imaging when an echo is produced via an inverse magnetic field gradient.