Noninvasive imaging and analysis of biological tissue structure, function and abnormalities with optical coherence tomography

Optical coherence tomography (OCT) is a novel noninvasive optical imaging technique that enables cross-sectional imaging of highly scattering biological tissues at the axial resolution of 10 micrometers or less. Technological advances in our laboratory and others have permitted high-contrast and high-resolution OCT imaging of turbid biological tissues at depths of up to 2-3 mm, highly desirable for screening various kinds of superficial lesions and the invasion of these lesions. In this study, we will demonstrate the potential of OCT as a powerful tool of `optical biopsy' or `optical guided biopsy' for the purpose of noninvasive imaging diagnosis as well as the limitations of current OCT techniques in identifying and diagnosing malignancies in these tissues. We will present ex vivo OCT images of animal urinary bladders and lesions (including cancers) in these tissues in comparison with the corresponding histologic evaluations. Based on the comparative studies between OCT and histology, we will analyze the image contrast of OCT or the patterns in OCT images in relation to the micro morphologies in these tissues and their alternations or lesions at different stages of tumorigenesis. We will also analyze the image contrast of OCT related to the blood vessels as well as other tissue functions such as fluid penetration and buildup in these tissues. Our results demonstrate the utility of OCT in high-resolution imaging to delineate the micro morphology of highly scattering tissues such as urinary bladders and the clinical relevance of OCT in diagnosing alternations or tumor growth in these tissues. Because of limitations to specificity and resolution of current techniques, OCT is presently unable to provide distinctive diagnosis of malignancies that require subcellular imaging or identification of subtle changes in nuclear morphology. However, certain characteristics associated with malignancies in bladders such as heavy vascularization and proliferation within the urothelial tissue can be clearly demonstrated.