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

Magn Reson Med. 1999 Apr;41(4):759-66. doi: 10.1002/(sici)1522-2594(199904)41:4<759::aid-mrm15>3.0.co;2-k.

Abstract

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.

MeSH terms

  • Adult
  • Brain / anatomy & histology
  • Female
  • Humans
  • Magnetic Resonance Imaging / methods*
  • Male
  • Middle Aged