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In our previous study, we reported on the development and preliminary testing of a prototype resonance
electrical impedance spectroscopy (REIS) system with a pair of probes. Although our pilot study on 150 young women
ranging from 30 to 50 years old indicated the feasibility of using REIS output sweep signals to classify between the
women who had negative examinations and those who would ultimately be recommended for biopsy, the detection
sensitivity was relatively low. To improve performance when using REIS technology, we recently developed a new
multi-probe based REIS system. The system consists of a sensor module box that can be easily lifted along a vertical
support device to fit women of different height. Two user selectable breast placement "cups" with different curvatures
are included in the system. Seven probes are mounted on each of the cups on opposing sides of the sensor box. By
rotating the sensor box, the technologist can select the detection sensor cup that better fits the breast size of the woman
being examined. One probe is mounted in the cup center for direct contact with the nipple and the other six probes are
uniformly distributed along an outside circle to enable contact with six points on the outer and inner breast skin surfaces.
The outer probes are located at a distance of 60mm away from the center (nipple) probe. The system automatically
monitors the quality of the contact between the breast surface and each of the seven probes and data acquisition can only
be initiated when adequate contact is confirmed. The measurement time for each breast is approximately 15 seconds
during which time the system records 121 REIS signal sweep outputs generated from 200 KHz to 800 KHz at 5 KHz
increments for all preselected probe pairs. Currently we are measuring 6 pairs between the center probe and each of six
probes located on the outer circle as well as two pairs between probe pairs on the outer circle. This new REIS system has
been installed in our clinical breast imaging facility. We are conducting a prospective study to assess performance when
using this REIS system under an approved IRB protocol. Over 200 examinations have been conducted to date. Our
experience showed that this new REIS system was easy to operate and the REIS examination was fast and considered
"comfortable" by examinees since the women presses her breast into the cup herself without any need for forced breast
compression, and all but a few highly sensitive women have any sensation of an electrical current during the
measurement.
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