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% (similar to 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 sigma ranged from 0.179 to 0.3310 S/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 epsilon(r) ranged from 2.10x10(6) to 2.9 x 10(4) for benign and 6.63x10(5) to 5.3 x 103 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).