Three-dimensional triple-quantum-filtered Na-23 imaging of in vivo human brain

A scheme for the generation of three-dimensional, triple-quantum-filtered ( TQ) sodium images from normal human brain is presented. In this approach, a three-pulse, six-step, coherence transfer filter was used in conjunction w ith a fast twisted projection imaging sequence to generate spatial maps of the TQ signal across the entire brain. It is demonstrated, theoretically as well as experimentally, that the use of the three-pulse coherence filter l eads to TQ sodium images in which the dependence of the image intensity on the spatial variation of the flip angle is less pronounced than it is in th e "standard," four-pulse, TQ filter. Correction for the Variation of the TQ signal intensity across the field of view because of radio-frequency (RF) inhomogeneity is straightforward with this approach. This imaging scheme al lows the generation of RF inhomogeneity-corrected, Ta, sodium images from h uman brain at moderate field strength (3.0 T) in times acceptable for routi ne clinical examinations (20 minutes). (C) 1999 Wiley-Liss, Inc.