Electrical Properties Measurement And Preliminary Analysis Of Breast Cancer Development Process On Nude Mice

Objective:Electrical properties(EPs)of cancer tissues including electrical conductivity? and permittivity ? differ from normal tissues.These differences occur before the structural change of tissues.It is very important to establish a complete EPs database of biological tissues for early cancer diagnose.At present,the database of the electrical properties of biological tissue is based on the EPs of the ex-vivo tissues,and it cannot reflect the real electrical properties of the tissues inside the body.Therefore,it has great significance to study the EPs of normal biological tissues and cancer tissues.Frequency related electrical properties of biological tissues including electrical conductivity ? and permittivity ? have close connection to its physiological and pathological conditions.In this paper,the electrical properties of breast tumor tissues and normal biological tissues during the cancer development were studied.Meanwhile,the changes of the electrical properties of tumor tissue were also discussed.Mothed:This study developed a small size insertion-type probe to measure the electrical properties of biological tissues in-vivo and ex-vivo.A four-electrode method is used to design this microprobe and the effective contact volume between the probe and the tissue is only 0.25?mm3.Firstly,this paper used the probe to measure the EPs(?&?)of beef muscle tissues,pork muscle tissues and pork adipose tissues.And the influence of temperature on the measurement results was also studied.Then,the electrical properties of 40 nude mice with breast cancer at different growth periods(1-4 weeks)were studied by using this probe.Finally,this paper also analyzed the differences of the electric properties between in-vivo measurements and ex-vivo measurements,the relationship between tumor electrical properties and tumor size,and the relationship between the tumor EPs distribution and blood flow distribution.Results:There were statistically EPs(?&?)differences between fiber orientation and reverse fiber orientation of beef muscle tissues(P<0.05);there were also statistically EPs(?&?)differences between pork muscle tissues and pork adipose tissues(P<0.05).The EPs(?&?)of the breast tissue were gradually increasing during the tumor growth.And the EPs(?&?)of biological tissues decreased after excised.The EPs(?&?)of the tumor tissues were significantly greater than that of normal tissues(P<0.05).According to the analyzation of tumor size and EPs,it shows that they were moderate linear correlation(P<0.01).This result showed that the larger the tumor size was,the higher the EPs of the same frequency point were.And the correlation analyze results also shows that the EPs(?&?)of tumor tissues were significantly correlated with blood flow distribution(P<0.01).The large EPs occurred where the higher blood flow was.Conclusions:This study developed a small size insertion-type probe and obtained the ex-vivo EPs results of pork,beef.The electrical properties results of 40 nude mice with breast cancer at different growth periods showed the changes of electrical properties during the development of breast cancer.The study of this paper lays a data foundation of early cancer diagnosis based on the electrical properties of the body tissues for the future.