Retrospective intra-scan motion correction.
This paper analyzes the effects of intra-scan motion and demonstrates the possibility of correcting them directly in k-space with a new automatic retrospective method. The method is presented for series of 2D acquisitions with Cartesian sampling. Using a reference k-space acquisition (corrected for translations) within the series, intra-scan motion parameters are accurately estimated for each trajectory in k-space of each data set in the series resulting in pseudo-random sample positions. The images are reconstructed with a Bayesian estimator that can handle sparse arbitrary sampling in k-space and reduces intra-scan rotation artefacts to the noise level. The method has been assessed by means of a Monte Carlo study on axial brain images for different signal-to-noise ratios. The accuracy of motion estimates is better than 0.1 degrees for rotation, and 0.1 and 0.05 pixel, respectively, for translation along the read and phase directions for signal-to-noise ratios higher than 6 of the signals on each trajectory. An example of reconstruction from experimental data corrupted by head motion is also given.
Bourgeois
Marc E
ME
Laboratoire de RMN, CNRS UMR 5012, Université Claude Bernard LYON I, CPE, Domaine scientifique de la Doua, 3 rue Victor Grignard, F-69616 Villeurbanne, France.
Wajer
Frank T A W
FT
Roth
Muriel
M
Briguet
André
A
Décorps
Michel
M
van Ormondt
Dirk
D
Segebarth
Christoph
C
Graveron-Demilly
Danielle
D
D000465:Algorithms; D000818:Animals; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008954:Models, Biological; D015233:Models, Statistical; D009038:Motion; D011786:Quality Control; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity