Variation in the dielectric properties of freshly excised colorectal cancerous tissues at different tumor stages

Abstract

The study was designed to identify differences in the dielectric properties of ex vivo colorectal cancerous tissues at different tumor stages. To date, 130 freshly excised colorectal cancerous specimens underwent measurement of both relative permittivity and conductivity on the serosal and mucosal surfaces of the carcinoma nidus, and the mucosa of the surgical resection margin ranging from 50 to 500 MHz at the Larmor frequencies. Tumor node metastasis staging was determined according to pathological reports for each patient. There were statistically significant differences in the relative permittivity of both colorectal cancerous serosa and mucosa among stages ≤I, II, III, and IV and between stages ≤II and ≥III (P < 0.05) at most frequencies under 300 MHz; statistically significant differences in conductivity were also observed for most of the measured frequencies (P < 0.05). The significant differences in dielectric characteristics among tumor stages, especially between early and advanced stages, have value for selecting appropriate surgical strategies. The presented ex vivo data provide important information for magnetic resonance electrical properties tomography in vivo system because the frequencies of 64 MHz (1.5T) and 128 MHz (3T) are usually used in clinical settings. Bioelectromagnetics. 38:522-532, 2017. © 2017 Wiley Periodicals, Inc.

Electrical properties tomography: Available contrast and reconstruction capabilities

“…A few studies reported inter-and intraperson variability in normal tissue, indicating differences on the order of 7% to 20% that are unrelated to disease processes. 3,22,38 Moreover, it is found that conductivity contrast between normal and cancerous tissue remains roughly constant between 1.5 T and 7 T, whereas permittivity contrast decreases from 1.5 T to 7 T. 23,39 From the limited studies available on EP changes in cancer, many cancer types outside the brain and breast appear to exhibit less than 40% changes in EPs. This imposes a lower bound for the SNR (defined as r ∕Δ r or ∕Δ , where r is the relative permittivity and Δ denotes measurement uncertainty) of EPT for its clinical utilization.…”

Dielectric Properties of Normal and Metastatic Lymph Nodes Ex Vivo From Lung Cancer Surgeries

“…Biological tissues feature inherent dielectric properties, which are often expressed in terms of permittivity and conductivity, based on the interaction of an external field with the electric dipole moment of the samples [Volkov and Prokhorov, ]. Over the last few decades, the open‐ended coaxial probe method [Athey et al, ; Bobowski and Johnson, ] has been explored as a means to measure the dielectric properties of the tissues [Gabriel et al, ; Li et al, , ; Guardiola et al, ; Mirbeik et al, ]. The results indicated that the dielectric properties of human cancer tissues and the corresponding normal tissues are often quite different.…”

Boundary Value-Free Magnetic Resonance Electrical Properties Tomography Based on the Generalized Cauchy Formula With the Complex-Derivative Boundary Condition

“…Electrical properties (EPs), namely electric conductivity and dielectric permittivity, of biological tissues provide valuable information for clinical diagnoses of cancerous tissues [1][2][3]. Among several techniques to noninvasively image EPs, electrical impedance tomography (EIT) has been well studied in the past decades.…”

“…| when the body is excited using a quadrature birdcage coil (QBC), which is commonly used in modern MRI systems[18]. Hence, substituting Eqs (3). and(15) into Eq (13).…”