Assessing Tissue Dielectric Constant Values in Tumor Bearing and Healthy Breasts.

Background: This study aimed to investigate, characterize, and provide quantitative reference data on tissue dielectric constant (TDC) values of female breasts when measurements were made to 5 mm depths and determine the utility of these measurements to differentiate between benign and malignant breast tumors. Methods and Results: Breast TDC was measured bilaterally in 82 women just prior to an ultrasound-guided diagnostic biopsy of one tumor in one breast. TDC was measured in triplicate over the tumor and the contralateral healthy breast. Considering all paired breasts, the average TDC (mean ± SD) for healthy breasts was less than for tumor-bearing breasts (26.7 ± 4.5 vs. 29.9 ± 8.5, p = 0.0003). Conclusions: Breast TDC values measured to 5 mm in 82 healthy nonedematous breasts provide a two-SD threshold reference value of 35.7. This represents a TDC value above which the presence of breast edema/lymphedema may be indicated based on the two-SD threshold criterion. For unilateral cases, an interbreast TDC ratio exceeding 1.275 may be considered a breast edema/lymphedema indicator also based on the two SD criteria used. These thresholds may have utility for early detection and to track breast edema/lymphedema changes. A comparison of these TDC values obtained from benign versus malignant tumors indicates no statistically significant difference between them. However, interbreast TDC ratios were statistically higher for breasts with malignant versus benign tumors. However, the large overlap of the ratio values renders this method of discrimination between benign vs. malignant tumors inadequate based on the present findings.