Magnetic-Resonance-Based Electrical Property Mapping Using Global Maxwell Tomography with an 8-Channel Head Coil at 7 Tesla: A Simulation Study

Ilias I. Giannakopoulos, Jose E.C. Serralles, Luca Daniel, Daniel K. Sodickson, Athanasios G. Polimeridis, Jacob K. White, Riccardo Lattanzi

Research output: Contribution to journalArticlepeer-review


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 (B1+) 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 (B1+) 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'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)
Article number9082887
Pages (from-to)236-246
Number of pages11
JournalIEEE Transactions on Biomedical Engineering
Issue number1
StatePublished - Jan 2021


  • Global Maxwell Tomography
  • MR-based electrical property mapping
  • RF shimming
  • integral equations
  • inverse scattering
  • ultra-high-field magnetic resonance imaging
  • Magnetic Resonance Spectroscopy
  • Humans
  • Radio Waves
  • Equipment Design
  • Magnetic Resonance Imaging
  • Tomography
  • Phantoms, Imaging

ASJC Scopus subject areas

  • Biomedical Engineering


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