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Segmented K‐space blipped‐controlled aliasing in parallel imaging for high spatiotemporal resolution EPI
Author(s) -
Stirnberg Rüdiger,
Stöcker Tony
Publication year - 2021
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.28486
Subject(s) - aliasing , computer science , undersampling , sampling (signal processing) , image resolution , artificial intelligence , segmentation , computer vision , algorithm , pattern recognition (psychology) , filter (signal processing)
Purpose A segmented k‐space blipped‐controlled aliasing in parallel imaging (skipped‐CAIPI) sampling strategy for EPI is proposed, which allows for a flexible choice of EPI factor and phase encode bandwidth independent of the controlled aliasing in parallel imaging (CAIPI) sampling pattern. Theory and Methods With previously proposed approaches, exactly two EPI trajectories were possible given a specific CAIPI pattern, either with slice gradient blips (blipped‐CAIPI) or following a shot‐selective CAIPI approach (higher resolution). Recently, interleaved multi‐shot segmentation along shot‐selective CAIPI trajectories has been applied for high‐resolution anatomical imaging. For more flexibility and a broader range of applications, we propose segmentation along any blipped‐CAIPI trajectory. Thus, all EPI factors and phase encode bandwidths available with traditional segmented EPI can be combined with controlled aliasing. Results Temporal SNR maps of moderate‐to‐high‐resolution time series acquisitions at varying undersampling factors demonstrate beneficial sampling alternatives to blipped‐CAIPI or shot‐selective CAIPI. Rapid high‐resolution scans furthermore demonstrate SNR‐efficient and motion‐robust structural imaging with almost arbitrary EPI factor and minimal noise penalty. Conclusion Skipped‐CAIPI sampling increases protocol flexibility for high spatiotemporal resolution EPI. In terms of SNR and efficiency, high‐resolution functional or structural scans benefit vastly from a free choice of the CAIPI pattern. Even at moderate resolutions, the independence of sampling pattern, TE, and image matrix size is valuable for optimized functional protocol design. Although demonstrated with 3D‐EPI, skipped‐CAIPI is also applicable with simultaneous multislice EPI.