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Denoising of B 1 + field maps for noise‐robust image reconstruction in electrical properties tomography
Author(s) -
Michel Eric,
Hernandez Daniel,
Cho Min Hyoung,
Lee Soo Yeol
Publication year - 2014
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.4895987
Subject(s) - noise reduction , noise (video) , nonlinear system , iterative reconstruction , non local means , artificial intelligence , image quality , computer science , electrical impedance tomography , laplace operator , mathematics , tomography , pattern recognition (psychology) , algorithm , image (mathematics) , physics , optics , image denoising , mathematical analysis , quantum mechanics
Purpose: To validate the use of adaptive nonlinear filters in reconstructing conductivity and permittivity images from the noisyB 1 +maps in electrical properties tomography (EPT).Methods: In EPT, electrical property images are computed by taking Laplacian of theB 1 +maps. To mitigate the noise amplification in computing the Laplacian, the authors applied adaptive nonlinear denoising filters to the measured complexB 1 +maps. After the denoising process, they computed the Laplacian by central differences. They performed EPT experiments on phantoms and a human brain at 3 T along with corresponding EPT simulations on finite‐difference time‐domain models. They evaluated the EPT images comparing them with the ones obtained by previous EPT reconstruction methods.Results: In both the EPT simulations and experiments, the nonlinear filtering greatly improved the EPT image quality when evaluated in terms of the mean and standard deviation of the electrical property values at the regions of interest. The proposed method also improved the overall similarity between the reconstructed conductivity images and the true shapes of the conductivity distribution.Conclusions: The nonlinear denoising enabled us to obtain better‐quality EPT images of the phantoms and the human brain at 3 T.