Diffuse Terahertz Spectroscopic and Polarimetric Imaging Mediated by Mie Scattering: Potential Biomedical Diagnostic Signal Contrast Mechanism

Biomedical applications of terahertz imaging have primarily focused on the water content of tissue as a signal contrast mechanism, but many disease processes, including cancerous tumors and burn injuries, can induce changes in the structure of tissue, resulting in Mie scattering patterns and polarization changes. Polarimetric terahertz measurements have the potential to provide new diagnostic markers. In this work, we present Monte Carlo simulation of Mie scattering of polarized terahertz light for cancerous tumor budding and compare the results to experimental phantom measurements, showing contrast between different sizes of polypropylene particles within a gelatin medium in diffuse (off-specular) intensity and degree of polarization uniformity. Additionally, we present a polarimetric scan of an ex vivo porcine burn injury, demonstrating a similar signal contrast between injured and healthy regions at off-specular angles. These results open a new avenue in using the polarimetric signal contrast in tissue diagnosis using terahertz imaging.