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.