Central Point Artifact
The central point artifact is a focal dot of increased signal in the center
of an image. It is caused by a constant offset of the DC voltage in the receiver.
After fourier transformation, this constant offset gives the bright dot in
the center of the image as shown in the diagram below.
The following axial MRI image of the head shows a central point artifact
projecting in the pons (bright dot in the middle of the
image).