Optical polarization response of collagen: role in clinical cancer diagnostics—part I

Optical polarimetry has increased interest in probing finer details of soft tissue components representing alterations during pathological tissue transformation. Stromal collagen, a potential candidate for optical polarimetry, plays a vital role during the developmental stages of cancer. This review presents an overview of the biology and optical response of stromal collagen followed by instrumentation and image analysis in various optical polarimetry configurations that help extract the relevant features for efficient tissue classification for diagnostic applications. Part 1 deals with the linear optical polarization properties of collagen, while Part 2 probes the extraction of finer structural details of collagen with the help of nonlinear optical polarimetry. Both in vivo and extracted tissue measurements are discussed, and directions for future research are recommended.