title: On conductivity, permittivity, apparent diffusion coefficient, and their usefulness as cancer markers at MRI frequencies.
abstract: OBJECTIVE
  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.
  
  
  BACKGROUND
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: GE Global Research Center, Niskayuna, New York, USA.
authors.forename: Ileana
authors.initials: I
authors.lastname: Hancu
authors.forename: Jeannette Christine
authors.initials: JC
authors.lastname: Roberts
authors.forename: Selaka
authors.initials: S
authors.lastname: Bulumulla
authors.forename: Seung-Kyun
authors.initials: SK
authors.lastname: Lee
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis* / Q000473:pathology*; D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis*; D045744:Cell Line, Tumor; D058266:Dielectric Spectroscopy / Q000379:methods; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004195:Disease Models, Animal; D005260:Female; D007089:Image Enhancement / Q000379:methods*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008297:Male; D008325:Mammary Neoplasms, Experimental / Q000175:diagnosis* / Q000473:pathology*; D018482:Muscle, Skeletal / Q000473:pathology; D009368:Neoplasm Transplantation; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D051381:Rats; D011916:Rats, Inbred F344; D012680:Sensitivity and Specificity; D013223:Statistics as Topic
chemical_list: D014408:Biomarkers, Tumor
keywords: MRI; apparent diffusion coefficient; cancer; conductivity; permittivity; tumor