Chapter

Ultra-fast fMRI

Richard A. Jones, Jason A. Brookes and Chrit T.W. Moonen

in Functional Magnetic Resonance Imaging

Published in print November 2001 | ISBN: 9780192630711
Published online March 2012 | e-ISBN: 9780191724770 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780192630711.003.0004
Ultra-fast fMRI

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Brain activation is known to lead to enhanced perfusion which, together with other physiological changes, results in a decreased deoxyhaemoglobin concentration in regions of neuronal activity. This effect is referred to as the blood oxygenation level dependent (BOLD) effect. The main purpose of this chapter is to outline the acquisition methods for ultra-fast BOLD functional magnetic resonance imaging (fMRI). It helps to explain the basics of echo planar imaging and alternative ultra-fast imaging techniques, discusses possible artefacts and pitfalls, and also studies the requirements for BOLD fMRI acquisition methods, focusing on echo planar imaging (EPI). The chapter discusses the two basic types of spin echo sequences that have been employed for fMRI studies, namely multiple echo sequences and spin echo EPI. The methods discussed traverse k-space in a rectilinear fashion. Moreover, the chapter also describes promising recent developments and mentions that ultra-fast 3D methods are under development which will potentially provide better signal-to-noise ratio and BOLD contrast per unit time than EPI, and which are also less sensitive to inflow effects.

Keywords: blood oxygenation level; ultra-fast fMRI; echo planar imaging; multiple echo sequences; spin echo sequences; signal to noise

Chapter.  9979 words.  Illustrated.

Subjects: Neuroscience

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