A Differential Approach for Estimating Microwave Propagation Speed in Breast Tissue Without Breast Compression or Contrast Agents

This work investigates using differential transmission coefficient measurements to estimate the propagation speed in the breast without contact or matching liquid. Transmission measurements of the breast in air often include undesired contributions from leaky waves, and existing systems for estimating the dielectric permittivity of breast tissues require direct contact. Leaky waves propagate along the surface of the breast but lose energy by radiating into air. The differential method eliminates the need for breast contact by assuming that the leaky waves are identical for both the left and right breasts of an individual. The results demonstrate that sufficient contribution of the signal transmitted through the breast tissue could be extracted to estimate the signal propagation speed. Estimating the average speed through the breast using transmission measurements improves the performance of beamforming algorithms.