Multiwavelength polarimetry of gastrointestinal ex vivo tissues for tumor diagnostic improvement

摘要

The implementation of tissue polarimetry in medicine arises mainly for the need of non-invasive and highly sensitive discrimination between healthy and tumor tissues. This fast, relatively cheap method may be useful for better histological diagnostics by the physicians. Although, the most challenging goal is to apply tissue polarimetric optical system for in vivo measurements, initially one have to optimize the optical system using ex vivo histological samples, phantoms and etc. This paper is focused on the polarimetric parameters from lower gastrointestinal tract histological samples, by using polarized light with several wavelengths, namely 444 nm, 488 nm, 514 nm, 594 nm and 635 nm, detected and processed by commercially available polarimeter. Our experimental results reveal the best wavelength choice in favor of 635 nm for all colon samples used. Light with circular polarization was used in the experiments, as found to survive more scattering events, compared to linearly polarized light. Furthermore, circularly polarized light carries additional information about the phase difference between the two orthogonal components of the electric field (E_x and E_y) and in the case of reflection, the incident state of polarization undergoes a ip of its helicity. By this way, a better detection of histological changes in tissues, related to abnormal tissue structure can be made. Furthermore, the multiwavelength, polarimetric analysis may provide better insight for future in vivo implementation and the results from the ex vivo biological samples presented in this study, contribute to better discrimination based on optical measurements, applicable for tumor detection.