Simultaneous Quantitative Imaging of Electrical Properties and Proton Density from B1 Maps Using MRI

Jiaen Liu, Pierre-Francois Van de Moortele, Xiaotong Zhang, Yicun Wang, Bin He

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI). The signal magnitude in MR images is locally proportional to both the proton density of tissue and the receive B1 field; this is a source of artifact in receive B1-based EPT reconstruction because these two quantities cannot easily be disentangled. In this study, a new method was proposed for simultaneously extracting quantitative conductivity, permittivity and proton density from the measured magnitude of transmit B1 field, proton density-weighted receive B1 field, and transceiver phase, in a multi-channel radiofrequency (RF) coil using MRI, without specific assumptions to derive the proton density distribution. We evaluated the spatial resolution, sensitivity to contrast, and accuracy of the method using numerical simulations of B1 field in a phantom and in a realistic human head model. Using the proposed method, conductivity, permittivity and proton density were then experimentally obtained ex vivo in a pork tissue sample on a 7T MRI scanner equipped with a 16-channel microstrip transceiver RF coil.

Original languageEnglish (US)
Article number7442843
Pages (from-to)2064-2073
Number of pages10
JournalIEEE Transactions on Medical Imaging
Volume35
Issue number9
DOIs
StatePublished - Sep 2016

Bibliographical note

Publisher Copyright:
© 1982-2012 IEEE.

Keywords

  • B -mapping
  • EPT
  • electrical properties
  • electrical properties tomography
  • magnetic resonance imaging (MRI)
  • proton density
  • proton density imaging
  • quantitative magnetic resonance imaging

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