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Controlled aliasing for improved parallel imaging with a 3D spiral staircase trajectory
Author(s) -
Anderson Ashley G.,
Wang Dinghui,
Pipe James G.
Publication year - 2020
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.28154
Subject(s) - spiral (railway) , aliasing , undersampling , trajectory , plane (geometry) , acceleration , algorithm , mathematics , geometry , computer science , physics , mathematical analysis , computer vision , classical mechanics , astronomy
Purpose To introduce a modified 3D stack‐of‐spirals trajectory and efficient SENSE reconstruction for improved through‐plane undersampling, while maintaining SNR efficiency and other benefits of spiral acquisitions. Methods A novel spiral staircase trajectory is introduced. This trajectory is a modified stack of spirals, in which spiral arms are distributed between partitions along k z . The trajectory maintains the efficient separable reconstruction with a Cartesian fast Fourier transform along the k z direction, followed by a 2D slice‐by‐slice gridding reconstruction. An additional intermediate step introduces a phase correction to collapse the spiral arms into the prescribed slice planes. For data undersampled through plane, this produces aliasing with reduced coherence, controlled by the arm‐ordering. Undersampled data can then be reconstructed with reduced g‐factor using a conjugate gradient–based iterative SENSE algorithm. Results The trajectory significantly improves g‐factor for through‐plane accelerated acquisitions. Improvement manifests through both reduced overall g‐factor and reduced structure in the g‐factor maps. In the presented experiments, the mean g‐factor decreased from 1.26 to 0.93 and the maximum g‐factor decreased from 3.89 to 1.15 for R = 2 spiral staircase when compared with stack of spirals, and the mean g‐factor decreased from 2.51 to 0.94 and the maximum g‐factor decreased from 8.26 to 1.35 for R = 3 spiral staircase when compared with stack of spirals. Conclusion The novel spiral staircase trajectory offers improved aliasing characteristics for through‐plane parallel imaging acceleration in 3D spiral acquisitions.