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While white light laparoscopy (WLL) has been established as a method that yields improved detection of peritoneal metastatic lesions over radiographic imaging, its sensitivity and specificity remain sub-optimal, leading to thousands of cancer patients that are over- or under- treated every year. We present studies that establish the sensitivity of polarization enhanced (PEL) laparoscopy to changes in the cross-section and alignment of scattering centers using phantoms and report on our initial in vivo human feasibility trial. The design of our PEL probe is simple and highly compatible with current laparoscopes, the standard of patient care and the established procedure flow for WLL. It comprises of a sheath inserted on the WLL laparoscope to provide linearly polarized illumination and a modified detection optical path that allows for recording of co- and cross-polarized images relative to the incident illumination. The sum of these images is equivalent to WLL, while their difference corresponds to PEL. Using PDMS phantoms with features that contain either TiO2 and ZnO2 particles, we demonstrate the enhanced sensitivity of PEL to scattering cross-section differences. Measurements performed with collagen gels that are being stretched reveal improved sensitivity of PEL (over WLL) to collagen fiber alignment. Our initial feasibility study results support the improved diagnostic potential of PEL. In fact, a Monte Carlo-based analysis approach that utilizes the color content of the PEL images indicates that PEL yields improved contrast for detection and differentiation of benign and malignant metastatic lesions. These studies provide strong motivation for further development of PEL imaging as an approach that may improve significantly the detection of peritoneal metastatic lesions.
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