Expanding Functionality of Commercial Optical Coherence Tomography Systems by Integrating a Custom Endoscope

Welge, Weston A.; Barton, Jennifer K.

doi:10.1371/journal.pone.0139396

Cited by 7 publications

(6 citation statements)

References 30 publications

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“…The current medical standard for the diagnosis of gastrointestinal disorders is based on white‐light endoscopy followed by histological analysis of biopsy samples taken during the procedure, while ongoing research is exploring the potential of alternative optical methods for cancer screening . These approaches, including Raman spectroscopy , confocal laser endoscopy , low‐coherence enhanced backscattering spectroscopy , optical coherence tomography or other quantitative phase methods , have been investigated as possible routes for improving the diagnostic and prognostic potential for the disease through clinical practice.…”

Section: Introductionmentioning

confidence: 99%

Complex refractive index of normal and malignant human colorectal tissue in the visible and near‐infrared

Giannios

Koutsoumpos

Toutouzas

et al. 2016

Journal of Biophotonics

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A multi-wavelength prism coupling refractometer is utilized to measure the angular reflectance of freshly excised human intestinal tissue specimens. Based on reflectance data, the real and imaginary part of the refractive index is calculated via Fresnel analysis for three visible (blue, green, red) and two near-infrared (963 nm and 1551 nm) wavelengths. Averaged values of the complex refractive index and corresponding Cauchy dispersion fits are given for the mucosa, submucosa and serosa layers of the colorectal wall at the normal state. The refractive constants of tumorous and normal mucosa are then cross-compared for the indicative cases of one patient diagnosed with a benign polyp and three patients diagnosed with adenocarcinomas of different phenotype. Significant index contrast exists between the normal and diseased states, indicating the potential use of refractive index as a marker of colorectal dysplasia.

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Section: Introductionmentioning

confidence: 99%

Complex refractive index of normal and malignant human colorectal tissue in the visible and near‐infrared

Giannios

Koutsoumpos

Toutouzas

et al. 2016

Journal of Biophotonics

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“…Although our endoscopic OCT system was successful in measuring tumor count and tumor burden in a useful fashion, future studies may be made more sensitive by using a spiral-scanning OCT system recently developed by the authors that can obtain three-dimensional images of the colon (26). Full rendering of the colon would allow more sensitive detection of adenoma, as well as a more accurate measurement of their size and shape.…”

Section: Discussionmentioning

confidence: 99%

Intermittent Dosing with Sulindac Provides Effective Colorectal Cancer Chemoprevention in the Azoxymethane-Treated Mouse Model

Chandra

Nymeyer

Rice

et al. 2017

Cancer Prevention Research

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Sulindac is a nonsteroidal anti-inflammatory drug that can provide effective chemoprevention for colorectal cancer. In this study, alternative dosing regimens of sulindac were evaluated for their chemoprevention effectiveness in the azoxymethane-treated A/J mouse model of colorectal cancer. High resolution endoscopic optical coherence tomography was utilized to time-serially measure tumor number and tumor burden in the distal colon as the biological endpoints. Four treatment groups were studied: 1) daily for 20 weeks (Sulindac-Daily), 2) for two weeks, then no sulindac for two weeks, cycle repeated 5 times (Sulindac-2), 3) for ten weeks (“on”), then no sulindac for 10 weeks (“off”) (Sulindac-10), 4) no sulindac (Sulindac-None). Sulindac-2 and Sulindac-Daily had statistically significantly lower final tumor counts and slopes (change in number of tumors per week) when compared with Sulindac-None (p < 0.0001). All of the treatment groups had statistically significantly lower final tumor burdens and slopes when compared with Sulindac-None (p < 0.001). There was a prolonged latency period in the Sulindac-10 group, with no significant difference between the “off” portion of this treatment and Sulindac-None. These results suggest that, while daily doses of sulindac provide the most optimal effects, intermittent doses of sulindac in a 50% duty cycle with an overall four-week period (Sulindac-2 model) can provide highly effective chemoprevention of colorectal cancer in this model. After cessation of sulindac treatment (Sulindac-10 “off”), there is not evidence of either a persistent chemopreventive effect nor a rebound effect.

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“…We previously integrated a lab‐built miniature endoscope for mouse colon imaging with a commercial swept‐source OCT system (OCS1050SS, Thorlabs, Newton, NJ) . The system layout and endoscope schematic are shown in Figure .…”

Section: Methodsmentioning

confidence: 99%

“…The raw data required numerical dispersion compensation due to an imbalance of dispersive media in the endoscope and the reference arm. We utilized a numerical method that determines the non‐linear dispersion by subtracting a linear fit to the phase data as a function of wavenumber . After numerical dispersion correction, the data were processed as described in the following subsections.…”

Section: Methodsmentioning

confidence: 99%

In vivo endoscopic Doppler optical coherence tomography imaging of the colon

Welge

Barton

2016

Lasers Surg Med

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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.

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Expanding Functionality of Commercial Optical Coherence Tomography Systems by Integrating a Custom Endoscope

Cited by 7 publications

References 30 publications

Complex refractive index of normal and malignant human colorectal tissue in the visible and near‐infrared

Complex refractive index of normal and malignant human colorectal tissue in the visible and near‐infrared

Intermittent Dosing with Sulindac Provides Effective Colorectal Cancer Chemoprevention in the Azoxymethane-Treated Mouse Model

In vivo endoscopic Doppler optical coherence tomography imaging of the colon

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