Cross-excitation artifact (MRI)
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Title
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Cross-excitation artifact (MRI)
Body
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Cross-excitation artifact is a type of MRI artifact and refers to the loss of signal within a slice due to pre-excitation from RF pulse meant for an adjacent slice.
The frequency profile of the RF pulse is imperfect; this means that during slice selection there is some degree of excitation of the adjacent slices as well. If that adjacent slice is imaged during the same TR (i.e., multi-slice imaging) or soon after (i.e., imaging without leaving a gap), it will be partially saturated, to begin with, and the resulting signal will be reduced. This phenomenon is more conspicuous in inversion recovery (180°) sequences.
Remedy
- leaving a minimum gap of 1/3 slice thickness when imaging contiguous slices
- interleaving between slices
- employing 3D imaging if volume imaging is required
- using optimized pulse sequences that have a time penalty of a higher minimum TE and reduced number of slices for a given TR
See also
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cross-talk artifact
- similar in causation but it is due to angled images, e.g. lumbar spine imaging
-<p><strong>Cross-excitation artifact</strong> is a type of <a href="/articles/mri-artifacts">MRI artifact </a>and refers to loss of signal within a slice due to pre-excitation from RF pulse meant for an adjacent slice.</p><p>The frequency profile of the RF pulse is imperfect; this means that during slice selection there is some degree of excitation of the adjacent slices as well. If that adjacent slice is imaged during the same TR (i.e., multi-slice imaging) or soon after (i.e., imaging without leaving a gap), it will be partially saturated to begin with, and the resulting signal will be reduced. This phenomenon is more conspicuous in inversion recovery (180°) sequences</p><h5>Remedy</h5><ul>- +<p><strong>Cross-excitation artifact</strong> is a type of <a href="/articles/mri-artifacts-1">MRI artifact </a>and refers to the loss of signal within a slice due to pre-excitation from RF pulse meant for an adjacent slice.</p><p>The frequency profile of the RF pulse is imperfect; this means that during slice selection there is some degree of excitation of the adjacent slices as well. If that adjacent slice is imaged during the same TR (i.e., multi-slice imaging) or soon after (i.e., imaging without leaving a gap), it will be partially saturated, to begin with, and the resulting signal will be reduced. This phenomenon is more conspicuous in inversion recovery (180°) sequences.</p><h5>Remedy</h5><ul>
-<li>employing 3D imaging if volume imaging is required</li>- +<li>employing 3D imaging if volume imaging is required</li>
-<a title="Cross-talk artifact" href="/articles/slice-overlap-artifact-2">cross-talk artifact</a><ul><li>similar in causation but it is due to angled images, e.g. lumbar spine imaging</li></ul>- +<a href="/articles/slice-overlap-artifact-2">cross-talk artifact</a><ul><li>similar in causation but it is due to angled images, e.g. lumbar spine imaging</li></ul>
Images Changes:
Image ( update )
Caption
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Figure 1: cross-talk diagram
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