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Accelerated five‐dimensional echo planar J‐resolved spectroscopic imaging: Implementation and pilot validation in human brain
Author(s) -
Wilson Neil E.,
Iqbal Zohaib,
Burns Brian L.,
Keller Margaret,
Thomas M. Albert
Publication year - 2016
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.25605
Subject(s) - undersampling , imaging phantom , sampling (signal processing) , planar , iterative reconstruction , computer science , image resolution , dimension (graph theory) , echo planar imaging , physics , nuclear medicine , nuclear magnetic resonance , artificial intelligence , optics , mathematics , magnetic resonance imaging , detector , medicine , radiology , computer graphics (images) , pure mathematics
Purpose To implement an accelerated five‐dimensional (5D) echo‐planar J‐resolved spectroscopic imaging sequence combining 3 spatial and 2 spectral encoding dimensions and to apply the sequence in human brain. Methods An echo planar readout was used to acquire a single spatial and a single spectral dimension during one readout. Nonuniform sampling was applied to the two phase‐encoded spatial directions and the indirect spectral dimension. Nonlinear reconstruction was used to minimize theℓ 1 ‐norm or the total variation and included a spectral mask to enhance sparsity. Retrospective reconstructions at multiple undersamplings were performed in phantom. Ten healthy volunteers were scanned with 8× undersampling and compared to a fully sampled single slice scan. Results Retrospective reconstruction of fully sampled phantom data showed excellent quality at 4×, 8×, 12×, and 16× undersampling using either reconstruction method. Reconstruction of prospectively acquired in vivo scans with 8× undersampling showed excellent quality in the occipito‐parietal lobes and good quality in the frontal lobe, consistent with the fully sampled single slice scan. Conclusion By utilizing nonuniform sampling with nonlinear reconstruction, 2D J ‐resolved spectra can be acquired over a 3D spatial volume with a total scan time of 20 min, which is reasonable for in vivo studies. Magn Reson Med 75:42–51, 2016. © 2015 Wiley Periodicals, Inc.