The Dialog window that appears will offer a variety of parameters to control artifact detection. The various classes are discussed below.
Displacement refers to displacement of the image within the imaging plane, measured in pixels.
If the subject moves, we would expect the number of pixels increasing and decreasing in intensity to be roughly the same, which will make this ratio large. Thus, sudden increases in this ratio can indicate subject movement. However, spike artifacts or other scanner problems will cause the number of pixels increasing to rise much faster than the number of pixels decreasing, which will not cause as large a change in this ratio. This ratio, therefore, can help distinguish between motion and scanner artifacts. Use the Show Artifact Data Graph selection on the Display menu to show a graph describing the artifacts.