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Spatial encoding using the nonlinear field perturbations from magnetic materials
Author(s) -
Karimi Hirad,
DominguezViqueira William,
Cunningham Charles H.
Publication year - 2014
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.24950
Subject(s) - encoding (memory) , nonlinear system , magnetic field , signal (programming language) , computer science , field (mathematics) , proof of concept , algorithm , biological system , computer vision , physics , artificial intelligence , mathematics , quantum mechanics , pure mathematics , biology , programming language , operating system
Purpose A proof‐of‐concept study was performed to assess the technical feasibility of using magnetic materials to generate spatial encoding fields. Theory and Methods Spatially varying magnetic fields were generated by the placement of markers with different volume susceptibilities within the imaging volume. No linear gradients were used for spatial encoding during the signal acquisition. A signal‐encoding model is described for reconstructing the images encoded with these field perturbations. Simulation and proof‐of‐concept experimental results are presented. Experiments were performed using field perturbations from a cylindrical marker as an example of the new encoding fields. Based on this experimental setup, annular rings were reconstructed from signals encoded with the new fields. Results Simulation results were presented for different acquisition parameters. Proof‐of‐concept was supported by the correspondence of regions in an image reconstructed from experimental data compared to those in a conventional gradient‐echo image. Experimental results showed that inclusions of dimensions 1.5 mm in size could be resolved with the experimental setup. Conclusion This study shows the technical feasibility of using magnetic markers to produce encoding fields. Magnetic materials will allow generating spatial encoding fields, which can be tailored to an imaging application with less complexity and at lower cost compared to the use of gradient inserts. Magn Reson Med 72:399–408, 2014. © 2013 Wiley Periodicals, Inc.