Ultrahigh-resolution in-vivo versus ex-vivo OCT imaging and tissue preservation

Many studies have been performed which compare ex-vivo OCT imaging to histopathology in a wide range of tissues and organ systems. While some tissues, such as arterial pathology or cartilage, are relatively stable post mortem, others, such as epithelial tissues, exhibit rapid degradation. It is important to preserve these tissues with minimal changes in morphology relative to their in vivo state in order to enable meaningful ex vivo OCT imaging studies. In this paper, we investigate the differences between in vivo and ex vivo OCT imaging and the effect of different tissue preservation solutions on tissue degradation and image quality. Ultrahigh resolution OCT imaging was preformed using a Ti:Al2O3 light source with 2 micrometers axial and 5 micrometers transverse resolution, using the hamster cheek pouch as a model for epithelial tissue. Tissue preservation solutions examined included: low temperature saline, room temperature saline, phosphate buffered sucrose, University of Wisconsin solution, and 10% formalin. Results of in vivo versus ex vivo ultrahigh resolution OCT imaging indicate that changes in optical properties and image degradation occur on a rapid time scale (in minutes) for all preservation solutions except formalin.