Day13: Yolk! Yolk! Yolk!
The correct answer is "c".
Here is an explanation
from our imaging expert, Carl Gregory:
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
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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