Functional magnetic resonance imaging using non-Fourier, spatially selective radiofrequency encoding

A new method for functional magnetic resonance imaging (fMRI) employing non -fourier encoding using spatially selective radiofrequency (RF) excitation is presented, The method uses manipulation of spatially selective RF pulses to encode spins in the slice-select direction. The method has several adva ntages over standard multislice approaches. It provides a simple means for monitoring irregularly distributed sections throughout a volume without the need to encode the whole volume. It offers the potential for increased sig nal-to-noise ratio if an appropriate basis is used for encoding. With a uni que design of excitation pulses, it also appears possible to significantly reduce in-flow effects. An interleaved echo-planar imaging (EPI) sequence w as adapted for non-fourier encoding in the slice-select direction and was i mplemented on a conventional 1.5-Telsa system. The method was then used for functional mapping of the visual and motor areas where significant reducti on of in-flow effect was demonstrated. This approach can be adapted to othe r imaging sequences that are used for fMRI, such as single-shot EPI. (C) 19 99 Wiley-Liss, Inc.