Imaging of human airways by endoscope-compatible dynamic microscopic optical coherence tomography

With the improvement of chest CT and the implementation of lung cancer screening, there will be an increasing demand for biopsy work-up of detected lung lesions. Many new navigation devices with or without endobronchial ultrasound have been developed to facilitate localization and subsequent sampling by bronchoscopy. Nevertheless, in several trials the diagnostic yield remained limited. Subsurface real-time imaging at cellular level is needed. We hypothesize that optical coherence tomography (OCT), which is based on the backscattering of light, can fulfil those demands. OCT has a high penetration depth compared to other optical methods and reaches microscopic resolution (mOCT). It allows direct capture of cross-sectional images without contrast agent. By analysing the dynamic changes of cells a high cell-specific contrast is achieved (dmOCT). The usability of dmOCT for diagnostics was tested with an endoscope-compatible setup on freshly excised human lung tissue. The setup provided high-resolution images, enabled us to identify the organ-specific architecture of the airways, to picture epithelium, connective tissue, vessels, smooth muscles, bronchial glands and to discriminate cells, such as ciliated epithelial cells, goblet cells, and immune cells. In samples of squamous cell carcinomas we could capture the altered tissue architecture and growth pattern of the neoplasia comprised of irregular nests set in a desmoplastic stroma. Furthermore, inflammation was identified by the presence of sub- and intraepithelial immune cells. The dmOCT could complement bronchoscopy and, with further advancements, such as automatic focus shift or motion correction, might reduce the need for biopsies.