In‐vivo measurements of the dielectric properties of breast carcinoma xenografted on nude mice

Abstract

A developing method of cancer detection is to use electromagnetic waves to compare the dielectric properties of normal and cancerous tissue. Because most of the previous studies consisted of dielectric measurements taken ex-vivo, this study investigated the advantages of in-vivo measurements, obtained using the newly developed insertion-type planar probe, through the measurements of cancer (MDA MB 231), which was cultivated and implanted into the mammary fat pad of nude mice. Reflection coefficients were obtained in the broadband frequency range from 0.5 to 30 GHz, from which broadband complex permittivity data was extracted. Complex permittivity, in addition to other parameters such as conductivity and characteristic frequency, were used to make comparisons between cancerous tissue, normal muscle tissue and fat tissue, as well as comparisons between in-vivo and ex-vivo measurements. This study investigated the suitability of in-vivo cancer detection using microwaves with the newly developed insertion-type planar probe. Results showed that both sensitivity and specificity of the current method was 97%. In addition, predictive values were 99% for the positive and 94% for the negative, thus greatly enhancing the practicality of this method. In conclusion, it was demonstrated that in-vivo measurements are highly beneficial in studying the potential of microwaves as a diagnostic tool of breast cancer, especially in combination with the newly developed insertion-type planar probe.

High‐frequency microwave ablation method for enhanced cancer treatment with minimized collateral damage

“…Among these, the difference in the dielectric losses between tumor and normal tissues is most important because of the well-known fact that the temperature rise by microwave ablation is a function of the dielectric loss of the material. 19 As shown in Figure 6, the large difference of dielectric loss is observed in the low-frequency band (<1 GHz) as well as in the high-frequency band (15)(16)(17)(18)(19)(20)(21)(22)(23)(24), which may suggest that the low-frequency microwave ($ 0.9 GHz) can also be a good candidate for efficient heat generation (Fig. 6).…”

“…Also, the heat applicator of our work could be used to verify the dielectric properties of a target region before and after the ablation. 15 When used for the ablation, the applicator of our work allows highly efficient ablation using high-frequency microwaves. For example, with the use of 18-GHz microwave, the applicator raises the temperature of the in vivo cancer xenografted on nude mice up to 55 C at 6 mm away from the aperture within 5 min using only 1-W input power.…”

“…The details of the probe design have been presented in our previous work. 15,16 In our work, the planar applicator was further optimized for efficient heat generation, which required larger coaxial aperture diameter. The outer conductor diameter of the coaxial aperture was limited to 4 mm for easy insertion for interstitial applications.…”

Microwave active integrated probes for biomedical applications

“…The microwave methods are based on the fact that cancerous and normal tissues have an obvious difference in their electromagnetic properties [3]. It has been shown by the authors that the complex permittivity at multiple frequency bands can be successfully applied to detect breast cancer [1], [4]. In addition, microwave can offer efficient and material-specific heating and ablation with minimal collateral damage to normal tissue [5].…”

A K-Band Low-Power Miniaturized Hyperthermia System

“…The hyperthermia frequency choice in this work can be explained with the frequency-dependent permittivity plot of Fig. 2, which shows the measured complex permittivity of fat and human breast cancer xenografted onto the nude mice at up to 40 GHz [11], [12] . Also, it can be seen from Fig.…”