Motion correction using an enhanced floating navigator and GRAPPA operations

Abstract

A method for motion correction in multicoil imaging applications, involving both data collection and reconstruction, is presented. The floating navigator method, which acquires a readout line off center in the phase-encoding direction, is expanded to detect translation/rotation and inconsistent motion. This is done by comparing floating navigator data with a reference k-space region surrounding the floating navigator line, using a correlation measure. The technique of generalized autocalibrating partially parallel acquisition is further developed to correct for a fully sampled, motion-corrupted dataset. The flexibility of generalized autocalibrating partially parallel acquisition kernels is exploited by extrapolating readout lines to fill in missing ''pie slices'' of k-space caused by rotational motion and regenerating full k-space data from multiple interleaved datasets, facilitating subsequent rigid-body motion correction or proper weighting of inconsistent data (e.g., with throughplane and nonrigid motion). Phantom and in vivo imaging experiments with turbo spin-echo sequence demonstrate the correction of severe motion artifacts. Magn Reson Med 63:339-348,

The l1 measure of image reconstruction subject to motion corrupted k-space data

“…The motion along each direction with respect to the frequency index is modeled as a random walk with each step independently distributed. Since we do not attempt to exploit the relationship among the motions at different frequencies, the optimization problems (6) and (7), respectively, can be equivalently written as The problems (9) and (10) are to solve the image s(m, n) from the magnitude of the k-space data setŜ(u, v) and are exactly the popularly known phase retrieval problem [7,10,11]. It is noted that the solution for the phase retrieval problem is ill-posed and subject to a global phase ambiguity.…”

“…It is noted that the solution for the phase retrieval problem is ill-posed and subject to a global phase ambiguity. Augmented Lagrangian alternating direction method (ADM) based algorithms are recently developed in [13] to solve (9) and (10), which are fast and accurate. In our simulations, a nonnegative satellite image shown in Fig.…”

“…The navigator based methods [8,9] have been popular in dealing with motions of rigid objects by acquiring extra k-space lines and detecting more motion information. The iterative projection algorithms [10] and the convex optimization method [11] are also popularly applicable to the motion correction problem.…”

High temporal resolution retrospective motion correction with radial parallel imaging

“…One of the most effective means for motion detection and compensation is the navigator echo technique and its variants (3)(4)(5)(6)(7)(8)(9). In these methods, a navigator signal is repetitively acquired and used either for respiratory gating or to detect motion for subsequent correction.…”

“…The coil sensitivity profiles offer additional information for the correction of artifacts either directly in the image domain (16)(17)(18), or in the k-space domain through estimating data points near the sampled trajectories (9,(19)(20)(21). In this work, a recently proposed parallel imaging method, GRAPPA operator for wider radial bands (GROWL) (22), is used to significantly improve the temporal resolution for motion correction in multicoil imaging applications.…”