Electrical impedance spectroscopy for prostate cancer diagnosis.

Electrical impedance was recorded at 21 discrete frequencies (1 to 100 kHz) from 27 ex vivo human prostates. These electrical properties were measured by using custom designed Electrical Impedance Spectroscopy (EIS) sensing biopsy (Bx) needles. EIS-Bx needles gauge the electrical properties of tissue in tandem with the tissue extraction (used for histopathological assessment). The EIS-Bx probe has a signal-to-noise ratio (SNR) of 65 dB across the frequency range (1 kHz to 100 kHz). A total of 36 cancers and 288 benign regions were sampled from 27 human prostates. Mean resistance (R) of prostate decreased from 537.27 Ω to 126.74 Ω for benign tissues and 999.52 Ω to 340.67 Ω for malignant tissues across the 1 kHz - 100 kHz spectral range. Likewise, mean reactance (X) ranged from -391.41 Ω to -62.6 Ω for benign and -675.09 Ω to -162.28 Ω for cancer tissues over the same frequency range. Both R and X values are found to be significantly lower in normal prostate tissues than in malignant tissue (p<0.001). Further testing to evaluate the clinical efficacy of this coupled device is underway.