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Abstract #4625

Variable Sampling Density Spherical Navigator Echoes (VSD SNAV) for Prospective 3D Alignment

Junmin Liu1,2, Maria Drangova1,2

1Imaging Research Laboratories, Robarts Research Institute, London, Ontario, Canada; 2Medical Biophysics, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario, Canada

An improved spherical navigator-based technique for prospective inter-scan realignment is presented. Instead of acquiring a set of orbital trajectories to cover the entire surface of a k-space sphere to determine rotation, combined with a linear navigator to determine translation, a two-shot variable density helical spiral spherical navigator (VSD SNAV) was adapted. Using the VSD-SNAV resulted in reduction of the navigator acquisition time from 19 s to 50 ms, while maintaining accuracy for translations up to 20 mm and rotations as large as 20 degrees. In vitro and in vivo results are presented.