Distinguishing Colon Pathologies by Optical and Mechanical Contrast using Optical Coherence Elastography and Optical Coherence Tomography

Colon pathologies including colorectal cancer (CRC) and ulcerative colitis (UC) affect nearly 200,000 people per year. Early detection of these pathologies is crucial for positive prognoses. However, screening of CRC and UC by existing diagnostic tools such as white light endoscopy and sonography is limited due to their poor resolution, depth penetration, and contrast. Hence, additional contrast, such as biomechanical properties, may be necessary for accurate early detection. Existing techniques to evaluate tissue mechanical properties lack the resolution to distinguish CRC and UC in the early disease state. Optical coherence elastography (OCE) is a functional extension of optical coherence tomography (OCT) and is capable of micrometer-scale spatial resolution and nanometer-scale displacement sensitivity, making it an effective tool to distinguish small structural and mechanical changes in healthy tissue due to disease. In this work, murine colon samples from three distinct groups: healthy, CRC, and UC were tested to assess optical and elastic properties. An OCE system was used to image elastic waves that were induced by focused air-pulses in the samples. The elastic wave group velocity and dispersion of the elastic wave were translated to the viscoelastic properties of each sample. Additionally, the structural OCT image was analyzed as another method to differentiate between healthy and diseased samples. The result showed a significant difference in elasticity between CRC and UC as compared to healthy tissue and a significant difference in optical properties (p<<.05 in two-sample T-test).