Feasibility study of tumor size classification via contrast-enhanced UWB breast imaging — A complex-domain analysis

Lesion classification using the tumor´s backscatter signature can be very challenging in microwave breast imaging due to the small intrinsic contrast between the dielectric properties of dysplastic and normal tissues. A possible solution to this problem is to use microwave contrast agents such as microbubbles, where the differential breast response before and after the administration of the agent to a dysplastic inclusion is used to classify various anomaly properties (size, depth, morphology, etc.). In this paper, we study the feasibility of contrast-agent-aided imaging for lesion size classification by studying received signals in the complex domain. A finite-difference time-domain (FDTD) numerical phantom is employed to simulate electromagnetic (EM) wave propagation inside the breast and extract the reflected waveforms with and without microbubbles in the tumor site. The complex-domain transfer function of differential response is then used to draw the poles-zero plots (PZPs) and Bode plots (BPs), which demonstrate the viability of the proposed method for lesion size categorization.