In vivo endoscopic Doppler optical coherence tomography imaging of the colon

Abstract

Background and Objective Colorectal cancer remains the second deadliest cancer in the United States. Several screening methods exist, however detection of small polyps remains a challenge. Optical coherence tomography has been demonstrated to be capable of detecting lesions as small as 1 mm in the mouse colon, but detection is based on measuring a doubling of the mucosa thickness. The colon microvasculature may be an attractive biomarker of early tumor development because tumor vessels are characterized by irregular structure and dysfunction. Our goal was to develop an endoscopic method of detecting and segmenting colon vessels using Doppler optical coherence tomography to enable future studies for improving early detection and development of novel chemopreventive agents. Method We conducted in vivo colon imaging in an azoxymethane (AOM)-treated mouse model of colorectal cancer using a miniature endoscope and a swept-source OCT system at 1040 nm with a 16 kHz sweep rate. We applied the Kasai autocorrelation algorithm to laterally oversampled OCT B-scans to resolve vascular flow in the mucosa and submucosa. Vessels were segmented by applying a series of image processing steps: (1) intensity thresholding, (2) two-dimensional matched filtering, and (3) histogram segmentation. Results We observed differences in the vessels sizes and spatial distribution in a mature adenoma compared to surrounding undiseased tissue and compared the results with histology. We also imaged flow in four young mice (2 AOM-treated and 2 control) showing no significant differences, which is expected so early after carcinogen exposure. We also present flow images of adenoma in a living mouse and a euthanized mouse to demonstrate that no flow is detected after euthanasia. Conclusion We present, to the best of our knowledge, the first Doppler OCT images of in vivo mouse colon collected with a fiber-based endoscope. We also describe a fast and robust image processing method for segmenting vessels in the colon. These results suggest that Doppler OCT is a promising imaging modality for vascular imaging in the colon that requires no exogenous contrast agents.

Colposcopic imaging using visible-light optical coherence tomography

“…In addition to ultrahigh-resolution morphology, we will also explore the possibilities to quantify hemodynamics-related parameters using our vis-OCT colposcopic imaging. 17,30,37,43 Disclosures Hao F. Zhang, Cheng Sun, and Wenzhong Liu have financial interests in Opticent Health, which, however, did not support this work.…”

The clinical usefulness of optical coherence tomography during cancer interventions

“…Hariri et al showed that Polarization Sensitive OCT (PS-OCT) has a potential to help in differentiation between lung tumor and fibrosis and Kiseleva et al used PS-OCT to diagnose mucosal pathologies in in-vivo human bladders (Hariri et al 2013 ; Kiseleva et al 2015 ). In addition, other functional OCT variants, such as Doppler-OCT that visualizes tissue vasculature and spectroscopic OCT that differentiates tissue types based on signal attenuation, as well as multimodality approaches are currently a topic of research (Barwari et al 2011 , 2012 ; Mavadia et al 2012 ; Welge and Barton 2017 ).…”

Real-time colorectal cancer diagnosis using PR-OCT with deep learning

“…In prior work, several research groups have demonstrated promising results that suggest OCT, an established high resolution imaging modality [9][10][11][12][13], may address the shortcomings of traditional camera endoscopy in the upper gastrointestinal tract [14][15][16] or large intestine [17][18][19]. OCT has been shown to accurately differentiate abnormal from normal tissue in multiple organs as an "optical biopsy" tool [20][21][22][23] in both murine and human colorectal models [24][25][26][27].…”