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. 2015 May;73(5):2025-9.
doi: 10.1002/mrm.25309. Epub 2014 Jun 19.

On conductivity, permittivity, apparent diffusion coefficient, and their usefulness as cancer markers at MRI frequencies

Ileana Hancu  1 , Jeannette Christine Roberts, Selaka Bulumulla, Seung-Kyun Lee
Affiliations

On conductivity, permittivity, apparent diffusion coefficient, and their usefulness as cancer markers at MRI frequencies

Ileana Hancu et al. Magn Reson Med. 2015 May.

Abstract

Purpose: To investigate the permittivity and conductivity of cancerous and normal tissues, their correlation to the apparent diffusion coefficient (ADC), and the specificity that they could add to cancer detection.

Theory: Breast and prostate carcinomas were induced in rats. Conductivity and permittivity measurements were performed in the anesthetized animals using a dielectric probe and an impedance analyzer between 50 and 270 MHz. The correlations between ADCs (measured at 128 MHz) and conductivity values were investigated. Frequency-dependent discriminant functions were computed to assess the value that each parameter adds to cancer detection.

Methods: Tumors exhibited higher permittivity than muscle tissue by 27%/12%/5% at 64/128/270MHz. Frequency independent, 15-20% higher conductivity was also noted in tumors compared to muscle tissue over the same frequency range. Strong negative correlation was observed between tissue conductivity and ADC. Whereas permittivity had the strongest discriminatory power at 64 MHz, it became comparable to ADC at 128 MHz and less important than ADC at 270 MHz.

Conclusion: Conductivity measurements offered limited advantages in separating cancer from normal tissue beyond what ADC already provided; conversely, permittivity added separation power when added to the discriminant function. The moderately high cancerous tissue permittivity and conductivity impose strong constraints on the capability of MRI-based tissue electrical property measurements.

Keywords: MRI; apparent diffusion coefficient; cancer; conductivity; permittivity; tumor.

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Figures

Figure 1
Figure 1
Example of the overlay between the ADC map and the anatomical image. Dielectric probe placement, following the imaging experiment, is highlighted here in white
Figure 2
Figure 2
Tumor-muscle TEP differences for the MATBIII (top) and MATLyLu (bottom) strains as a function of frequency.
Figure 3
Figure 3
Correlation between ADC and conductivity at 128MHz.
See this image and copyright information in PMC

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