Forward-scanning endoscopic optical coherence elastography for elasticity measurements of anisotropic tissues.

The elasticity of luminal tissues is closely associated with disease progression and functional status. Endoscopic optical coherence elastography (OCE) has emerged as a promising technique for assessing the mechanical properties of luminal tissues. However, previous endoscopic OCE approaches typically measure elasticity along only a single direction-either laterally or in depth-thereby potentially leading to an inaccurate estimation of anisotropic tissue mechanics. In this study, we propose a forward-scanning endoscopic OCE method that enables quantitative measurement of tissue elasticity in both the lateral and depth directions, allowing direct characterization of anisotropic mechanical properties in luminal tissues. An air-pulse excitation was applied to generate Rayleigh waves and longitudinal shear waves in agar phantoms and ex vivo gastric tissues. Elastic wave propagation was detected using phase-resolved Doppler optical coherence tomography. Experimental results demonstrate that the proposed method can quantitatively assess anisotropic elasticity with a forward-viewing configuration, highlighting its potential for clinical diagnosis and biomechanical characterization of luminal tissues.