Combined prospective and retrospective motion correction to relax navigator requirements

Prospective motion correction can prevent motion artifacts in magnetic resonance imaging of the brain. However, for high‐resolution imaging, the technique relies on precise tracking of head motion. This precision is often limited by tracking noise, which leads to residual errors in the prospectively‐corrected k‐space data and artifacts in the image. This work shows that it is possible to estimate these tracking errors, and hence the true k‐space sample locations, by applying a two‐sided filter to the tracking data after imaging. A conjugate gradient reconstruction is compared to gridding as a means of using this information to retrospectively correct for the effects of the residual errors. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.