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 advantages 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 signal‐to‐noise ratio if an appropriate basis is used for encoding. With a unique design of excitation pulses, it also appears possible to significantly reduce in‐flow effects. An interleaved echo‐planar imaging (EPI) sequence was adapted for non‐Fourier encoding in the slice‐select direction and was implemented on a conventional 1.5‐Telsa system. The method was then used for functional mapping of the visual and motor areas where significant reduction of in‐flow effect was demonstrated. This approach can be adapted to other imaging sequences that are used for fMRI, such as single‐shot EPI. Magn Reson Med 41:759–766, 1999. © 1999 Wiley‐Liss, Inc.