Anderson, Ashley G.

PurposeTo 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.MethodsA novel spiral staircase trajectory is introduced. This trajectory is a modified stack of spirals, in which spiral arms are distributed between partitions along kz. The trajectory maintains the efficient separable reconstruction with a Cartesian fast Fourier transform along the kz 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.ResultsThe 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.ConclusionThe novel spiral staircase trajectory offers improved aliasing characteristics for through‐plane parallel imaging acceleration in 3D spiral acquisitions.