Ultrahigh-resolution optical coherence elastography through a micro-endoscope: towards in vivo imaging of cellular-scale mechanics
Quantitative detection of mechanical properties of the living tissue is of great importance in clinical imaging as it promises to improve our understanding of disease processes and provides advanced diagnostic capabilities in detecting onset and progression of many diseases, including cancers. Over the last 10 years, several optical elastography techniques have been developed to open a window into probing microscopic mechanical properties of tissue. One of these techniques, optical coherence elastography (OCE), was the most promising for future in vivo imaging of depth-resolved tissue mechanics. The paper by Qi Fang et al. presents the latest advances in miniaturization of Ultrahigh-Resolution Optical Coherence Elastography (UHROCE), showing the clear path to finally achieving in vivo cellular-scale imaging of tissue mechanical properties. By incorporating a gradient-index (GRIN)-lens microendoscope into an UHROCE system with Bessel beam illumination and Gaussian mode detection, the authors developed an OCE imaging probe that can finally provide access to sub-surface tissue structure. The system performance has been tested on a silicone phantom with a rigid inclusion and on tissue excised from a murine model of pancreatic cancer. Additionally, the authors demonstrated the feasibility of this system directly on a murine sample in situ by measuring strain micro-elastograms of muscle 200 µm below the tissue surface. These very encouraging results combined with the list of potential improvements of the current UHROCE system prove that we are on the clear path to achieving in vivo UHROCE in the near future.