Azimuthal Sorting in Tandem with Elliptical Reordering (ASTER): a new k-space reordering scheme for reduced motion sensitivity

Purpose: MRI is very sensitive to motion, particularly in 3D imaging where temporally localized motion can propagate across the whole reconstructed volume. In cardiac and abdominal imaging applications, subjects are required to suspend their respiration for a period of 15-25s to minimize ghosting and blurring artifacts. Breathholding poses difficulties in pediatric and elderly subjects and in patients with severe health conditions. Even in regions where breath-holding is not required (e.g. the brain, spine, and joints), involuntary motion is quite common especially towards the end of a long scan. We propose ASTER (Azimuthal Sorting in Tandem with Elliptical Reordering), a novel k-space reordering scheme that minimizes sensitivity to motion whilst permitting flexible combination with magnetization preparation schemes.