Atkinson D, Hill D L, Stoyle P N, Summers P E, Clare S, Bowtell R, Keevil S F
Division of Radiological Sciences and Medical Engineering, The Guy's, King's and St. Thomas' School of Medicine, London, United Kingdom.
Magn Reson Med. 1999 Jan;41(1):163-70. doi: 10.1002/(sici)1522-2594(199901)41:1<163::aid-mrm23>3.0.co;2-9.
Patient motion during the acquisition of a magnetic resonance image can cause blurring and ghosting artifacts in the image. This paper presents a new post-processing strategy that can reduce artifacts due to in-plane, rigid-body motion in times comparable to that required to re-scan a patient. The algorithm iteratively determines unknown patient motion such that corrections for this motion provide the best image quality, as measured by an entropy-related focus criterion. The new optimization strategy features a multi-resolution approach in the phase-encode direction, separate successive one-dimensional searches for rotations and translations, and a novel method requiring only one re-gridding calculation for each rotation angle considered. Applicability to general rigid-body in-plane rotational and translational motion and to a range of differently weighted images and k-space trajectories is demonstrated. Motion artifact reduction is observed for data from a phantom, volunteers, and patients.
