Echoplanar chemical shift imaging.

A novel method of chemical shift imaging utilizing echoplanar imaging (EPI) has been developed for the purpose of improving the spatial resolution of metabolite images for the specific goal of high spatial resolution mapping of neuronal content. An EPI sequence was modified to allow temporal offsets of the 180 degree refocusing pulse that encode the chemical shift information into the phase of the signal. Implementation of this method on 1.5 and 3 T human imagers has resulted in images of N-acetyl aspartate in humans with spatial resolution of 360 microl and signal-to-noise ratio approximately 7:1 in less than 13 min.