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Single acquisition electrical property mapping based on relative coil sensitivities: A proof‐of‐concept demonstration
Author(s) -
Marques José P.,
Sodickson Daniel K.,
Ipek Ozlem,
Collins Christopher M.,
Gruetter Rolf
Publication year - 2015
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.25399
Subject(s) - electromagnetic coil , imaging phantom , sensitivity (control systems) , computer science , noise (video) , permittivity , signal (programming language) , acoustics , channel (broadcasting) , data acquisition , nuclear magnetic resonance , algorithm , physics , materials science , dielectric , electronic engineering , optics , artificial intelligence , telecommunications , image (mathematics) , programming language , optoelectronics , quantum mechanics , engineering , operating system
Purpose All methods presented to date to map both conductivity and permittivity rely on multiple acquisitions to compute quantitatively the magnitude of radiofrequency transmit fields,B 1 + . In this work, we propose a method to compute both conductivity and permittivity based solely on relative receive coil sensitivities ( B 1 − ) that can be obtained in one single measurement without the need to neither explicitly perform transmit/receive phase separation nor make assumptions regarding those phases. Theory and Methods To demonstrate the validity and the noise sensitivity of our method we used electromagnetic finite differences simulations of a 16‐channel transceiver array. To experimentally validate our methodology at 7 Tesla, multi compartment phantom data was acquired using a standard 32‐channel receive coil system and two‐dimensional (2D) and 3D gradient echo acquisition. The reconstructed electric properties were correlated to those measured using dielectric probes. Results The method was demonstrated both in simulations and in phantom data with correlations to both the modeled and bench measurements being close to identity. The noise properties were modeled and understood. Conclusion The proposed methodology allows to quantitatively determine the electrical properties of a sample using any MR contrast, with the only constraint being the need to have 4 or more receive coils and high SNR. Magn Reson Med 74:185–195, 2015. © 2014 Wiley Periodicals, Inc.