Time-Efficient Slab Selective Water Excitation

Introduction Spectral spatial (SPSP) RF pulses are simultaneously selective in both the spectral and spatial domains [1]. SPSP pulses consist of a train of slice selective RF subpulses applied simultaneously with an oscillating slice select gradient. When used for spatially selective water or fat excitation, the difference in frequency between water and fat, ∆ , limits the spacing between RF subpulses to 1 2∆ ⁄ [2]. At 3T and above, this leads to subpulse durations of less than 1 ms. This short subpulse duration limits the sharpness of the slab profile which can be achieved in 3D imaging applications. In the present work, time-efficient 3D slab-selective waterexcitation pulses with sharp spatial profiles are designed. These pulses are superior to separate fat saturation and water excitation in: overall duration, flexible choice of T2*-weighting, and level of fat suppression in the presence of B1 inhomogeneity.