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Configuration‐based electrical properties tomography
Author(s) -
Iyyakkunnel Santhosh,
Schäper Jessica,
Bieri Oliver
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.28542
Subject(s) - fourier transform , phase (matter) , aliasing , computer science , fourier analysis , sampling (signal processing) , monte carlo method , relaxometry , nuclear magnetic resonance , materials science , algorithm , undersampling , physics , magnetic resonance imaging , artificial intelligence , mathematics , computer vision , statistics , spin echo , medicine , quantum mechanics , radiology , filter (signal processing)
Purpose To introduce phase‐based conductivity mapping from a configuration space analysis. Methods The frequency response function of balanced SSFP (bSSFP) is used to perform a configuration space analysis. It is shown that the transceive phase for conductivity mapping can be directly obtained by a simple fast Fourier transform of a series of phase‐cycled bSSFP scans. For validation, transceive phase and off‐resonance mapping with fast Fourier transform is compared with phase estimation using a recently proposed method, termed PLANET. Experiments were performed in phantoms and for in vivo brain imaging at 3 T using a quadrature head coil. Results For fast Fourier transform, aliasing can lead to systematic phase errors. This bias, however, decreases rapidly with increasing sampling points. Interestingly, Monte Carlo simulations revealed a lower uncertainty for the transceive phase and the off‐resonance using fast Fourier transform as compared with PLANET. Both methods, however, essentially retrieve the same phase information from a set of phase‐cycled bSSFP scans. As a result, configuration‐based conductivity mapping was successfully performed using eight phase‐cycled bSSFP scans in the phantoms and for brain tissues. Overall, the retrieved values were in good agreement with expectations. Conductivity estimation and mapping of the field inhomogeneities can therefore be performed in conjunction with the estimation of other quantitative parameters, such as relaxation, using configuration theory. Conclusions Phase‐based conductivity mapping can be estimated directly from a simple Fourier analysis, such as in conjunction with relaxometry, using a series of phase‐cycled bSSFP scans.