Self-refocusing 270 degrees Gaussian pulses for slice selection without gradient reversal in magnetic resonance imaging.

It is demonstrated, on the grounds of simulations, how 270 degrees Gaussian pulses can be used for slice selection in nuclear magnetic resonance imaging experiments. It is shown that the usual gradient reversal procedure can be omitted if the selective 90 degrees pulse normally used is replaced by a self-refocusing 270 degrees pulse with a Gaussian time-domain amplitude profile, and some of the properties which are specific to this type of pulse are explored.