Abstract: An MRI k-space data set is acquired using a series of shell k-space sampling trajectories of different radii. Off-resonance effects are reduced and fat-suppression can be improved by using a shorter TR for pulse sequences that sample at smaller radii. At larger radii sampling is repeated with the central axis of the shell sampling trajectory tilted such that the polar regions of shells acquired at the same radii are sampled by the other shell.

Abstract: An MRI k-space data set is acquired using a series of shell k-space sampling trajectories of different radii. Off-resonance effects are reduced and fat-suppression can be improved by using a shorter TR for pulse sequences that sample at smaller radii. At larger radii sampling is repeated with the central axis of the shell sampling trajectory tilted such that the polar regions of shells acquired at the same radii are sampled by the other shell.

Abstract: A 3D MRI image is acquired as a series of spherical shells of increasing radius. Each shell is sampled by one or more interleaved spiral sampling trajectories and to shorten the scan time one or more spiral sampling trajectories are skipped in the larger shells that sample the periphery of k-space. Motion correction of the acquired k-space data is accomplished by reconstructing tracking images from each of the shells and locating markers therein which indicate object movement from a reference position. The k-space data is corrected using this movement information.