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Functional MRI of the brain

Published on Sunday 15 February 2009 by Denis Hoa

Contents

Functional MRI

  1. Introduction
  2. Physiological basis of brain activation and BOLD contrast
  3. Data acquisition in functional MRI
  4. Analysis of functional MRI data
  5. Applications of functional MRI

Learning objectives

After reading this chapter, you should be able:

  • Describe the cascade of phenomena linking neuronal activation and BOLD contrast
  • List the MRI sequences adapted to functional explorations
  • Present the basic steps of a functional MRI study: design of activation tasks, choice of paradigm, data acquisition, signal processing and statistical analysis of the results

Key points

  • Functional MRI will only detect brain activation very indirectly, as variations in the T2* signal, following changes in the oxyHb/deoxyHb ratio, after neurovascular coupling triggered by neuronal activity.
  • Data acquisition is carried out in T2*-weighted ultrafast sequences of the echo planar type, sensitive to BOLD contrast, during a succession of different repeated tasks following a paradigm.
  • The signal variations are very weak and their analysis is based on a statistical comparison between different states of activation.
  • The temporal resolution of fMRI, combined with the possibilities of morphological imaging, make MRI a modality of choice in the neurosciences.


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References

  1. Habas. . Journal de radiologie. 2002 Nov;83(11):1737-41.
  2. Le Bihan and Lehericy. . Journal of neuroradiology. 1999 Mar;26(1 Suppl):S54-8.
  3. Gore. Principles and practice of functional MRI of the human brain. The Journal of clinical investigation. 2003 Jul;112(1):4-9.
  4. Voss, Zevin. Functional MR imaging at 3.0 T versus 1.5 T: a practical review. Neuroimaging clinics of North America. 2006 May;16(2):285-97, x.
  5. Golay, de Zwart. Parallel imaging techniques in functional MRI. Top Magn Reson Imaging. 2004 Aug;15(4):255-65.
  6. Di Salle, Esposito. High field functional MRI. European journal of radiology. 2003 Nov;48(2):138-45.
  7. Delmaire, Krainik. . Journal de radiologie. 2007 Mar;88(3 Pt 2):497-509

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