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Accelerated three‐dimensional multispectral MRI with robust principal component analysis for separation of on‐ and off‐resonance signals
Author(s) -
Levine Evan,
Stevens Kathryn,
Beaulieu Christopher,
Hargreaves Brian
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.26819
Subject(s) - undersampling , multispectral image , principal component analysis , computer science , magnetic resonance imaging , artificial intelligence , pattern recognition (psychology) , compressed sensing , computer vision , algorithm , medicine , radiology
Purpose To enable highly accelerated distortion‐free MRI near metal by separating on‐ and off‐resonance to exploit the redundancy of slice‐phase encoding for the dominant on‐resonance component. Methods Multispectral MRI techniques resolve off‐resonance distortions by a combination of limited excitation bins and additional encoding. Inspired by robust principal component analysis, a novel compact representation of multispectral images as a sum of rank‐one and sparse matrices corresponding to on‐ and off‐resonance respectively is described. This representation is used in a calibration‐free and model‐free reconstruction for data with an undersampling pattern that varies between bins. Retrospective undersampling was used to compare the proposed reconstruction and bin‐by‐bin compressed sensing. Hip images were acquired in eight patients with standard and prospectively undersampled three‐dimensional multispectral imaging, and image quality was evaluated by two radiologists on a 5‐point scale. Results Experiments with retrospective undersampling showed that the enhanced sparsity afforded by the separation greatly reduces reconstruction errors and artifacts. Images from prospectively undersampled multispectral imaging offered 2.6–3.4‐fold (18–24‐fold overall) acceleration compared to standard multispectral imaging with parallel imaging and partial‐Fourier acceleration with equivalence in all qualitative assessments within a tolerance of one point ( P < 0.004). Conclusion Three‐dimensional multispectral imaging can be highly accelerated by varying undersampling between bins and separating on‐ and off‐resonance. Magn Reson Med 79:1495–1505, 2018. © 2017 International Society for Magnetic Resonance in Medicine.