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Day13: Yolk! Yolk! Yolk!

MRI Answers

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The correct answer is "c".

Here is an explanation from our imaging expert, Carl Gregory:

Motion Artifact 1 Motion Artifact 2

The sample in the left image was jostled with a stick during the acquisition. Virtually any instability or fluctuations in the system will cause artifacts of this type, of greater or lesser intensity. This includes power supply problems, mechanical vibrations, cryogen boiling, large iron objects moving in the fringe field, loose connections anywhere, or pulse timing variations, as well as sample motion. The displacement need not be very much, as can be seen from the absence of any shift along the frequency axis. Raw data here.

A much more extreme example is shown on the right, where one of the shim currents was changed drastically several times during the acquisition. This results in a frequency shift, as well. This particular case is much less common, but motion along the frequency axis can look similar.

For more information on artifacts, visit the MRI Artifact Gallery in Carl's Roost.

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EGG BIOLOGICAL IMAGING DATABASE EGG MATH EMBRYOLOGY NIH Image HOME Copyright (C) 1998 University of Illinois at Urbana-Champaign