The electrical properties of leg skin in normal individuals and in patients with ischemia

Two-dimensional dielectric imaging for dermatologic screening: a feasibility study

BACKGROUND/PURPOSE

The diagnosis of skin neoplasia can be very challenging, given the low sensitivity and specificity of traditional methods of diagnosis which are based on visual appearance. Techniques which are based on the dielectric properties of cells can improve the diagnostic accuracy of screening techniques; as an example, point-contact coaxial probes for dielectric measurement can improve diagnostic accuracy. Unfortunately, these probes are not well suited for two-dimensional spatial imaging of the skin surface, given that they must be manually scanned over the skin surface.

METHODS/RESULTS

An electronic scanning probe was developed and fabricated to simulate an open-ended coaxial probe suitable for two-dimensional dielectric imaging of human skin in real time. A clinical study was undertaken to demonstrate proof-of-concept for the instrumentation. A select group of normal healthy subjects as well as a subject with diagnosed squamous cell carcinoma participated in this study. The electronic scanning probe was found to be a potentially useful tool for providing two-dimensional images from diseased skin.

CONCLUSION

The electronic scanning probe used for the present study addresses existing limitations with current coaxial probes. Measurements of healthy and diseased areas of skin are provided to illustrate the feasibility of the approach.

Dielectric relaxation of a protein–water system in atherosclerotic artery wall

Measurements of the dielectric properties of healthy and atherosclerotic human artery tissues were made in the frequency range of 100 Hz-100 kHz and temperatures from 22 to 260 degrees C. The temperature dependencies of the dielectric parameters for healthy tissues reveal distinctively the temperature ranges corresponding to the release of water up to 200 degrees C and the decomposition processes of elastin and collagen, above this temperature. The influence of atherosclerosis on the dielectric properties of artery tissues is significant in the whole temperature range. The relative permittivity for atherosclerotic tissues at the same temperature is much lower than for the healthy tissues. This suggests, that the polarization in atherosclerotic tissues due to protons hopping between a smaller number of sites than in healthy tissues, as a results of the thermal degradation of collagen-water. The data obtained above 200 degrees C indicate that the atherosclerosis induces the higher physico-chemical changes in the collagen when compared to elastin.