Optical coherence tomography and elastography for the visualization of architecture and stiffness differences in gastric cancer and dysplasia.

Abstract

382 Background: Individuals at high risk for gastric cancer may be recommended to undergo risk-reducing gastrectomy, which leads to life-long morbidity. Surveillance with endoscopy can be an appropriate and effective option for avoiding unnecessary surgery. Gastric cancer is commonly characterized by changes in tissue architecture and increased tissue stiffness, but visualization of these alterations is challenging for white light endoscopy methods. We utilized optical coherence tomography (OCT), a non-destructive imaging modality that uses reflected near-infrared light to generate cross-sectional images of tissue, to visualize microstructure and relative tissue stiffness. Methods: We utilized two modes of OCT for visualization of ex vivo tissue samples collected from patients undergoing gastrectomy for gastric cancer, endoscopic mucosal resection, or endoscopic biopsy. Images were collected with a benchtop OCT system (Thorlabs Telesto TEL221). Structural OCT was used to visualize changes in tissue architecture including thickened mucosa and irregular put structure of the mucosa. Optical coherence elastography (OCE) was used to extract relative measures of tissue stiffness using an optical palpation method. A phantom of known mechanical properties was placed on the tissue and an axial force was applied. The resulting deformation (strain) of the phantom provided relative measurements of tissue stiffness. Classification of normal and cancerous tissue was confirmed by histology. Results: Structural OCT imaged architectural features of tissue with high resolution (<10 um) and depth of imaging up to 1.5 mm. Strain maps generated with OCE data showed that normal gastric tissue had relatively consistent stiffness, whereas stomach cancer and dysplasia exhibited increased tissue stiffness compared to normal. Conclusions: Structural OCT and OCE captured changes in tissue architecture and increased stiffness in patient samples of gastric cancer and dysplasia. These tissue features are classic characteristics of cancer, making this technique a useful screening tool for several cancer types. Future work aims to implement endoscopic OCT and OCE to detect cancer at early stages in vivo .