Broadband nuclear magnetic resonance pulses with two‐dimensional spatial selectivity

Two‐dimensional spatial localization can be achieved using a single nuclear magnetic resonance (NMR) pulse if the pulse is applied in the presence of a magnetic field gradient which is reorienting through two dimensions. The application of these pulses to whole‐body NMR imaging systems is hampered, however, by amplitude and slew‐rate constraints on the magnetic field gradients, resulting in longer pulses with relatively limited bandwidth. We describe here a variable rate method for shortening these pulses by as much as 36% for pulses limited by slew rate and 55% for pulses limited by gradient amplitude, without changing their spatial excitation profiles on resonance.