Simulation of effect of mechanical loading on dynamics of breast tissue optical properties

Considering enhanced angiogenesis in malignant tissues we propose in a new functional imaging technique. If proven in clinical trial, the technique may be useful for differentiating malignant tumors with enhanced vascularity from normal tissues and benign lesions. The technique is based on observing the dynamics of light attenuation in the breast tissue in response to an external pressure stimulus. The attenuation is related to blood flow and blood oxygenation. In the proposed technique the measurements are made in the red spectral wavelength region where hemoglobin serves as a natural contrast agent. In order to understand and interpret the temporal dynamic of attenuation or signatures, a model of blood circulation in zones of tumor and normal tissues is developed. The blood volume, blood flow, and oxygen saturation level are evaluated using a lumped fluid! flow model incorporating published hemodynamics data obtained from biopsy samples or in-situ chamber growth of human tumor. The hemodynamics properties are translated into temporal optical attenuation profiles. We compare the optical signatures in areas with active tumor growth and in normal tissues. The results suggest that the differences in the transient response may be used as a secondary diagnostic tool in breast imaging or as a monitoring tool in anti-angiogenesis drug therapy.