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

Area of Science:

• Biophysics
• Medical Imaging
• Electrical Engineering

Background:

• Electrical conductivity and permittivity are key diagnostic parameters for biological tissues.
• Water proton density is also clinically relevant for diagnosis.
• Electrical Properties Tomography (EPT) maps in vivo electrical properties using MRI but faces artifacts due to coupled proton density and B1 field signals.

Purpose of the Study:

• To develop a new method for simultaneously extracting quantitative conductivity, permittivity, and proton density from MRI data.
• To overcome the challenge of disentangling proton density and B1 field signals in EPT.
• To enable more accurate in vivo tissue property mapping.

Main Methods:

• Proposed a novel method using multi-channel radiofrequency (RF) coil MRI data.
• Utilized transmit B1 field magnitude, proton density-weighted receive B1 field, and transceiver phase.
• Evaluated the method's spatial resolution, sensitivity, and accuracy via numerical simulations (phantom and human head model).
• Experimentally validated the method ex vivo on pork tissue using a 7T MRI scanner.

Main Results:

• Successfully extracted quantitative conductivity, permittivity, and proton density simultaneously.
• Demonstrated the method's capability without specific assumptions for proton density distribution.
• Numerical simulations confirmed spatial resolution, sensitivity, and accuracy.
• Experimental validation on pork tissue showed successful ex vivo property acquisition.

Conclusions:

• The proposed MRI method effectively extracts simultaneous quantitative conductivity, permittivity, and proton density.
• This technique offers a potential advancement for artifact reduction and improved accuracy in EPT.
• The method holds promise for enhanced in vivo diagnostic capabilities using MRI.