MRI slice selection with scaling functions

A new family of amplitude-only radiofrequency modulation waveforms for slice selection in Magnetic Resonance Imaging (MRI) is presented. Based on the scaling functions associated to different wavelet families, these new envelope waves provide higher slice selectivity than Gaussian or sine functions. They are also more compact on the time domain, since no truncation is needed, allowing to reduce the time required for the slice selection process. This feature is valuable on multislice-multiecho and fast acquisitions. Their performance has been evaluated both through simulations of the Bloch equations, and by measuring the slice width of real ramp phantoms images. The simulation results show that this amplitude modulation causes a phase behaviour of the resonant protons within the selected volume that is more coherent than with other techniques. This effect can be related to the higher intensity of the images acquired with this slice selection procedure.