Fig. 1. H&E staining of colon tissue. (a) Normal colon tissue; (b) Dysplastic colonic tissue

Fig. 2. Path of scattered light. At shallow depths, photons are coherently reflected by a single scattering event (A), allowing the construction of images using this signal, such as in optical coherence tomography (OCT). At deeper depths, light undergoes multiple scattering, where it may be absorbed (B) or escape the tissue to be detected (C). Images can be constructed using this diffuse light, as in optical diffusion tomography^[14]

Fig. 3. Schematic of skin cancer detection system based on diffuse scattered light ^[15]

Fig. 4. Diffuse reflectance spectra of normal tissue and adenomatous polyps^[16]

Fig. 5. BDL framework for the nuclear size distribution inversion with the capability of uncertain estimation^[36]

Fig. 6. Overview of single scattering spectroscopy techniques

Fig. 7. (a) SOCT system schematic and (b) data processing flow^[37]

Fig. 8. Schematic of a/LCI system

Fig. 9. Physical depictions of the scanning a/LCI probe components. (a) A side profile of the actual probe with detachable probe tip; (b) A 3D transparent rendering of the ROTOR^[57]

Fig. 10. Schematic diagram of azimuthal LSS system^[59]

Fig. 11. Spatial gating^[62-63]. (a) Spatial gating probe; (b) Principle of spatial gating

Fig. 12. (a) In vivo spatial gating fiber optic probe for endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA); (b) Schematic diagram of pancreatic cyst detection by space gated probe^[64]

Fig. 13. In vivo clinical spectroscopic measurements in the bile duct during endoscopic retrograde cholangiopancreatography (ERCP) procedures ^[63]

Fig. 14. In vivo light scattering spectroscopic differentiation of bile duct malignancy in 29 subjects ^[63]

Fig. 15. Principle of polarization gating^[68]

Fig. 16. Schematic of the PLSS system^[60]

Fig. 17. Size distributions and refractive index distributions of epithelial cell nuclei obtained with PLSS for the (a) normal and (b) cancerous colon tissue samples

Fig. 18. Polarized light scattering spectroscopy imaging system^[69]

Fig. 19. System for simultaneous measurement of angular distribution and spectral properties of scattered light^[70]

Fig. 20. Fiber based PLSS system. (a) Diagram of the experimental setup; (b) Schematic of the PLSS probe^[71]

Fig. 21. Clinical EPSS instrument^[72]

Fig. 22. Pseudo-color maps highlighting areas suspicious for dysplasia^[72]

Fig. 23. (a) Endoscopic multispectral scanning imaging system; (b) Illustration of PLSS probe detecting the esophagus section^[74]

Fig. 24. Diagnostic flow chart of endoscopic multispectral scanning imaging system performance in BE patients^[74]

Fig. 25. Optical schema of the snapshot PLSS system

Fig. 26. Snapshot PLSS endoscopy. (a) Three fiber layout; (b) Two fiber layout; (c) Modulator. P: polarizer; R: delayer. (d) Snapshot polarization gating principle. I_in: the incident line-polarized light; S₁: the single scattered light; I_d: the diffusely scattered light. (e) Optical schema of snapshot PLSS endoscope; (f) Proof-of-concept system^[75]; (g) Spectral processing flow

Fig. 27. Differentiation of normal and cancerous samples using WSSL