title: Electrical impedance spectroscopy of benign and malignant prostatic tissues.
abstract: OBJECTIVE
  The specificity of current screening methods for prostate cancer is limited and it results in approximately 75% to 80% of patients who undergo biopsy having findings negative for cancer. We used electrical impedance spectroscopy to evaluate how significantly the electrical properties of benign and malignant prostatic tissues differ with the goal of providing clinicians with a new biomarker to aid in diagnosis.
  
  
  METHODS
  We collected freshly excised prostates from 14 men immediately following radical prostatectomy. The prostates were sectioned into 3 mm slices. Electrical property measurements of conductivity and relative permittivity were recorded from each slice using a coaxially configured probe over the frequency range of 1 kHz to 1 MHz. The area probed was marked so that following tissue fixation and slide preparation histological assessment could be correlated directly with the recorded electrical impedance spectroscopy spectra.
  
  
  RESULTS
  Prostatic adenocarcinoma, benign prostatic hyperplasia, nonhyperplastic glandular tissue and stroma were the primary tissue types probed with electrical impedance spectroscopy. Conductivity ranged from 0.093 S/m at 1 kHz to 0.277 S/m at 1 MHz. Relative permittivity ranged from 8.5 x 10(5) at 1 kHz down to 1.3 x 10(3) at 1 MHz. There were significant conductivity differences between cancer and stroma at all frequencies (p <0.01). There were significant permittivity differences between cancer and benign prostatic hyperplasia at frequencies greater that 92 kHz (p <0.01). Significant correlations were observed between electrical properties, and the concentration of stromal and glandular tissues present in the tissue area histologically assessed.
  
  
  CONCLUSIONS
  The electrical properties of benign and malignant prostate tissues differ significantly. This should be considered for use as a diagnostic tool. The differences observed between cancer and benign prostatic hyperplasia are especially important since current screening methods do not reliably differentiate between the 2 conditions.
authors.affiliation: Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA. ryan.halter@dartmouth.edu
authors.forename: Ryan J
authors.initials: RJ
authors.lastname: Halter
authors.forename: Alan
authors.initials: A
authors.lastname: Schned
authors.forename: John
authors.initials: J
authors.lastname: Heaney
authors.forename: Alex
authors.initials: A
authors.lastname: Hartov
authors.forename: Shannon
authors.initials: S
authors.lastname: Schutz
authors.forename: Keith D
authors.initials: KD
authors.lastname: Paulsen
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis; D017097:Electric Impedance; D004568:Electrodiagnosis; D006801:Humans; D008297:Male; D015233:Models, Statistical; D011467:Prostate / Q000502:physiology; D011469:Prostatic Diseases / Q000175:diagnosis* / Q000473:pathology; D011471:Prostatic Neoplasms / Q000175:diagnosis / Q000473:pathology; D012815:Signal Processing, Computer-Assisted; D013057:Spectrum Analysis