Electrical Impedance Scanning (EIS)


Electrical Impedance Scanning (EIS) is a diagnostic test that measures how electricity travels through tissue in the body. Some types of tissue have high electrical impedance, or resistance to conducting electricity, while others have lower electrical impedance. As cancerous breast tissue has a lower level of impedance, EIS is helpful in locating these breast abnormalities. EIS is also known as Transscan or T-Scan.


EIS is commonly used in conjunction with mammography to detect breast cancer. EIS can also be used to reduce the number of biopsies required when ascertaining if a particular mass is cancerous.


The device consists of a hand-held scanning probe and a computer screen that displays two-dimensional images of the breast. Although radiation-free, the device does emit a very small amount of electric current that is transmitted into the body to measure the level of impedance in the tissue. During the procedure, an electrode patch is placed on the patient’s arm. As current travels from the patch through the breast, the impedance level is measured by the scanning probe. When the device detects low levels of impedance (an indication of abnormalities in breast tissue), these areas show up as bright white spots on the computer screen.


What are the advantages of this device?

The EIS can help confirm the location of abnormalities in breast tissues detected by a mammogram. As the image appears directly on a computer screen, a radiologist is able to move the probe around the abnormal area for the best views and thus reduce the total number of biopsies needed for an accurate result. It may also help identify women who require a biopsy.

Can this procedure be used to identify breast cancer?

EIS is not currently approved as a screening device for breast cancer. It is used as an adjunct to mammography.