Bioimpedance spectroscopy can precisely discriminate human breast carcinoma from benign tumors

Abstract

Intraoperative frozen pathology is critical when a breast tumor is not diagnosed before surgery. However, frozen tumor tissues always present various microscopic morphologies, leading to a high misdiagnose rate from frozen section examination. Thus, we aimed to identify breast tumors using bioimpedance spectroscopy (BIS), a technology that measures the tissues' impedance. We collected and measured 976 specimens from breast patients during surgery, including 581 breast cancers, 190 benign tumors, and 205 normal mammary gland tissues. After measurement, Cole-Cole curves were generated by a bioimpedance analyzer and parameters R0/R∞, fc, and α were calculated from the curve. The Cole-Cole curves showed a trend to differentiate mammary gland, benign tumors, and cancer. However, there were some curves overlapped with other groups, showing that it is not an ideal model. Subsequent univariate analysis of R0/R∞, fc, and α showed significant differences between benign tumor and cancer. However, receiver operating characteristic (ROC) analysis indicated the diagnostic value of fc and R0/R∞ were not superior to frozen sections (area under curve [AUC] = 0.836 and 0.849, respectively), and α was useless in diagnosis (AUC = 0.596). After further research, we found a scatter diagram that showed a synergistic effect of the R0/R∞ and fc, in discriminating cancer from benign tumors. Thus, we used multivariate analysis, which revealed that these two parameters were independent predictors, to combine them. A simplified equation, RF = 0.2fc + 3.6R0/R∞, based on multivariate analysis was developed. The ROC curve for RF' showed an AUC = 0.939, and the sensitivity and specificity were 82.62% and 95.79%, respectively. To match a clinical setting, the diagnostic criteria were set at 6.91 and 12.9 for negative and positive diagnosis, respectively. In conclusion, RF' derived from BIS can discriminate benign tumor and cancers, and integrated criteria were developed for diagnosis.

Figure 1

(A) Typical Cole-Cole curves of mammary gland tissue, benign tumor, and breast carcinoma. (B) Some Cole-Cole curves of benign tumors and breast carcinomas overlapped. BT = benign tumor, Ca = carcinoma, MG = mammary gland.

Figure 2

The differences of parameters, including R₀/R_∞ (A), f_c (B), and α (C), in the three groups. BT = benign tumor, Ca = carcinoma, MG = mammary gland.

Figure 3

(A) Scatter diagram of R₀/R_∞ and f_c derived from breast tumors. (B) ROC curve for parameters R₀/R_∞, f_c, α, RF, RF′, and frozen section diagnosis. (C) The diagnostic criteria for RF′ in the clinical setting. RF = regression factor, ROC = receiver operating characteristic.