Phase Dependence on Motion

Yu‐Chung Norman Cheng1, E. Mark Haacke1

1 The MRI Institute for Biomedical Research, St. Louis, Missouri
Publication Name:  Current Protocols in Magnetic Resonance Imaging
Unit Number:  Unit B7.1
DOI:  10.1002/0471142719.mib0701s13
Online Posting Date:  May, 2005
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Abstract

This unit introduces the sources of variable phase in the presence of motion. The sources of these phase changes can come from the read gradient, from the slice select gradient and from the phase encoding gradient. Motion during the gradient moves the spin from one location to another and, therefore, changes the effective field it sees. This field change leads to a frequency change in time during either the dephasing or rephasing gradient or both. As a result, the spins do not refocus at the expected time.

     
 
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Table of Contents

  • Overview
  • Technical Discussion
  • Key References
  • Figures
     
 
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Materials

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Figures

Videos

Literature Cited

Key References
   Haacke, E.M., Brown, R.W., Thompson, M.R., and Venkatesan, R. 1999. Magnetic Resonance Imaging: Physical Principles and Sequence Design. John Wiley & Sons, New York.
  This text covers the technical aspects presented here, but in more detail, and also discusses more advanced materials.
   Hahn, E.L. 1960. Detection of sea‐water motion by nuclear precession. Geophys. Res. 65: 776.
  This historical paper introduced phase changes for spins flowing along the direction of the applied magnetic field gradient.
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