A Real-Time Electrical Impedance Sensing Biopsy Needle

Diagnostic confirmation of cancer in solid organs is based on biopsy findings. In a standard 12-core prostate biopsy protocol, conventional biopsy needles sample only 0.95% (~0.228 cm
³
) of a typical 24-cm
³
prostate gland. The primary objective of this study was to enhance the sensitivity of standard biopsy protocol by gauging electrical properties of tissue simultaneously with tissue extraction for histopathology analysis. A conventional biopsy (Bx) needle was instrumented with an electrical impedance spectroscopy (EIS) sensor to interrogate the tissue volume surrounding the needle tip. The EIS-Bx device was evaluated in a series of saline bath and ex vivo porcine experiments. It was found to sense a volume of 0.286 cm
³
of tissue around the needle tip. EIS measurements were recorded from three ex vivo human prostates using the device, and the extracted biopsy cores were histologically assessed. Prostate conductivity σ ranged from 0.179 to 0.3310S/m for benign tissues and 0.0746 to 0.0837 S/m for malignant tissues at frequencies ranging from 1 to 100 kHz. Relative permittivity ε
_r
ranged from 2.10 × 10
⁶
to 2.9 × 10
⁴
for benign and 6.63 × 10
⁵
to 5.3 × 10
³
for cancer tissues over the same frequency range. Both are found to be significantly higher in normal prostate tissues than in malignant tissue (
p
<; 0.00001).