Advanced Optical Endoscopes for Early Cancer Detection

Optical methods of investigating tissue have the advantages of high sensitivity, high resolution, relatively low cost, and ability to sense both structural and biochemical characteristics of tissue. Their limited penetration depth into the body can be mitigated by endoscopic methods. Optical techniques hold the promise of directing, minimizing, or perhaps even eliminating traditional destructive biopsy by providing diagnostic information in a harmless manner. Complimentary optical modalities hold excellent promise for early cancer detection: optical coherence tomography (OCT), fluorescence imaging (FI), and multiphoton microscopy (MPM). OCT provides micron-scale cross-sectional imaging up about 1 mm deep in scattering tissue, whereas FI and MPM provide information about the concentration and distribution of fluorescent and optically active biomolecules. When packaged into endoscopes ranging from 0.8 – 4 mm in diameter, the colon, ovary and fallopian tubes (among other organs) can be accessed. Intriguing images of early stage cancer have been obtained with OCT, while FI has provided information both on the metabolic activity of tissues and has resolved possible confounders in OCT. MPM is emerging in endoscopic form and holds promise for sub-cellular imaging.