Magnetic-resonance-based electrical property mapping using Global Maxwell Tomography with an 8-channel head coil at 7 Tesla: a simulation study

Ilias Giannakopoulos, Jose EC Serralles, Luca Daniel, Daniel Sodickson, Athanasios Polimeridis, Jacob K. White, Riccardo Lattanzi

    Research output: Contribution to journalArticle

    Abstract

    Objective: Global Maxwell Tomography (GMT) is a recently introduced volumetric technique for noninvasive estimation of electrical properties (EP) from magnetic resonance measurements. Previous work evaluated GMT using ideal radiofrequency (RF) excitations. The aim of this simulation study was to assess GMT performance with a realistic RF coil. Methods: We designed a transmit-receive RF coil with 8 decoupled channels for 7T head imaging. We calculated the RF transmit field (B<formula><tex>$+1$</tex></formula><formula><tex>$_1$</tex></formula>) inside heterogeneous head models for different RF shimming approaches, and used them as input for GMT to reconstruct EP for all voxels. Results: Coil tuning/decoupling remained relatively stable when the coil was loaded with different head models. Mean error in EP estimation changed from 7.5% to 9.5% and from 4.8% to $7.2% for relative permittivity and conductivity, respectively, when changing head model without re-tuning the coil. Results slightly improved when an SVD-based RF shimming algorithm was applied, in place of excitation with one coil at a time. Despite errors in EP, RF transmit field (B<formula><tex>$+1$</tex></formula><formula><tex>$_1$</tex></formula>) and absorbed power could be predicted with less than 0.5% error over the entire head. GMT could accurately detect a numerically inserted tumor. Conclusion: This work demonstrates that GMT can reliably reconstruct EP in realistic simulated scenarios using a tailored 8-channel RF coil design at 7T. Future work will focus on construction of the coil and optimization of GMT&#x0027;s robustness to noise, to enable in vivo GMT experiments. Significance: GMT could provide accurate estimations of tissue EP, which could be used as biomarkers and could enable patient-specific estimation of RF power deposition, which is an unsolved problem for ultra-high-field magnetic resonance imaging.

    Original languageEnglish (US)
    JournalIEEE Transactions on Biomedical Engineering
    DOIs
    StateAccepted/In press - 2020

    Keywords

    • Contextualize Representation
    • Language Modeling
    • Lattice LSTM
    • NER

    ASJC Scopus subject areas

    • Biomedical Engineering

    Fingerprint Dive into the research topics of 'Magnetic-resonance-based electrical property mapping using Global Maxwell Tomography with an 8-channel head coil at 7 Tesla: a simulation study'. Together they form a unique fingerprint.

  • Cite this