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Partial Fourier techniques in single‐shot cross‐term spatiotemporal encoded MRI
Author(s) -
Zhang Zhiyong,
Frydman Lucio
Publication year - 2018
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.26824
Subject(s) - fourier transform , computer science , bandwidth (computing) , k space , fourier analysis , a priori and a posteriori , algorithm , single shot , dimension (graph theory) , nuclear magnetic resonance , optics , physics , mathematics , telecommunications , mathematical analysis , philosophy , epistemology , pure mathematics
Purpose Cross‐term spatiotemporal encoding (xSPEN) is a single‐shot approach with exceptional immunity to field heterogeneities, the images of which faithfully deliver 2D spatial distributions without requiring a priori information or using postacquisition corrections. xSPEN, however, suffers from signal‐to‐noise ratio penalties due to its non‐Fourier nature and due to diffusion losses—especially when seeking high resolution. This study explores partial Fourier transform approaches that, acting along either the readout or the spatiotemporally encoded dimensions, reduce these penalties. Methods xSPEN uses an orthogonal (e.g., z ) gradient to read, in direct space, the low‐bandwidth (e.g., y ) dimension. This substantially changes the nature of partial Fourier acquisitions vis‐à‐vis conventional imaging counterparts. A suitable theoretical analysis is derived to implement these procedures, along either the spatiotemporally or readout axes. Results Partial Fourier single‐shot xSPEN images were recorded on preclinical and human scanners. Owing to their reduction in the experiments’ acquisition times, this approach provided substantial sensitivity gains vis‐à‐vis previous implementations for a given targeted in‐plane resolution. The physical origins of these gains are explained. Conclusion Partial Fourier approaches, particularly when implemented along the low‐bandwidth spatiotemporal dimension, provide several‐fold sensitivity advantages at minimal costs to the execution and processing of the single‐shot experiments. Magn Reson Med 79:1506–1514, 2018. © 2017 International Society for Magnetic Resonance in Medicine.