An artifact on a MR image can appear when data read off an optical disc became corrupted. There two effects can be seen.
Firstly, Bands where the intensity has been incorrectly interpreted or secondly areas, where the horizontal position of the pixels has been incorrectly displayed. It is important to be able to differentiate between artifacts caused during a MRI scan, from those caused by the associated hardware of an imaging system.
Review the hardware and store the images on a new disc.