Bioimpedance Could Offer "Virtual” Biopsies

A new diagnostic technique using bioimpedance spectroscopy is being explored to diagnose quickly and accurately cervical and skin cancers.

Researchers at the Queensland University of Technology (QUT, Brisbane, Australia) developed the new diagnostic technique using a tetrapolar electrode configuration, which has been shown to distinguish between normal squamous epithelium and cervical intra-epithelial neoplasia. Exploring a possible solution to anomalous results of the tetrapolar configuration--manifested in an increase in measured impedance when a low impedance lesion is located between a drive and measurement electrode--the researchers employed bioimpedance mapping using an array of 25 (5x5) electrodes. This array allows 64 individual tetrapolar measurements to be taken on 16 locations giving an impedance map of 49 mm2 on the surface of a tissue sample. Multiple measurements at each location reduce the chance of anomalous results since these can later be identified and excluded.

The researchers found that the technique detected changes inside the cells, changes in cells' membranes, and changes in the space between cells. By putting all the information together, the researchers say it may be possible to diagnose different types of cancer, along with their boundaries. The procedure does not necessitate an anesthetic, and has the potential to be as accurate as other, more time-consuming, expensive techniques. The technique was presented at the 13th International Conference on Electrical Bioimpedance and the 8th Conference on Electrical Impedance Tomography, held during September 2007 in Graz (Austria).

"If a cell's structure has changed, the impedance characteristics change and clinicians can use the changes to diagnose the type of lesion,” said lead investigator Jye Smith, Ph.D., a researcher at the school of physical and chemical sciences. "It offers the possibility of a simple device that can be run over the surface of the skin or internal organ that can quickly, cheaply, and accurately record changes in cellular structure that point to cancerous changes.”

Bioimpedance (or bioelectrical impedance) is a measure of the resistance to the flow of electric current through the tissues. The measurement of the bioimpedance in humans and animals has proved useful as a non-invasive method for measuring such things as blood flow (bioimpedance plethysmography) and body composition (bioelectrical impedance analysis (BIA)).


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Queensland University of Technology