Rigid-body motion correction with self-navigation MRI.

The use of phase correlation to detect rigid-body translational motion is reviewed and applied to individual echotrains in turbo-spin-echo data acquisition. It is shown that when the same echotrain is acquired twice, the subsampled correlation provides an array of delta-functions, from which the motion that occurred between the acquisitions of the two echotrains can be measured. It is shown further that a similar correlation can be found between two sets of equally spaced measurements that are adjacent in k-space. By measuring the motion between all adjacent pairs of k-space subgroups, the complete motion history of a subject can be determined and the motion artifacts in the image can be corrected. Some of the limiting factors in using this technique are investigated with turbo-spin-echo head and hand images.