Development of a dual-modality gastrointestinal imaging capsule for optical coherence tomography (OCT) and near-infrared fluorescence (NIRF) imaging

Barrett’s esophagus (BE) is a precursor lesion to esophageal adenocarcinoma. Early detection of BE with dysplasia allows for effective and minimally invasive therapeutic prevention of esophageal adenocarcinoma. The Tearney lab has developed a swallowable tethered capsule that can be used to conduct esophageal OCT imaging. Capsule OCT can be conducted in unsedated patients, only takes about 5 minutes, and is inexpensive. These features make capsule OCT an ideal screening tool for BE. In addition to identifying BE, it would be desirable for capsule OCT to be capable of further stratifying risk in patients by detecting dysplasia. While standard OCT has been demonstrated to detect dysplastic BE, it is limited by its use of only architectural morphologic information. As a result, it may be necessary to improve accuracy in order to comply with gastroenterological society guidelines for use of new BE diagnostic tools.

Previous studies have shown that the lectin, wheat germ agglutinin (WGA), binds less to BE dysplasia compared to non dysplastic BE due to changes in cell surface glycans. Visualization of this binding change could enable a new mode of negative contrast that could be used to discriminate dysplastic BE. Capsule-based OCT-NIRF of WGA binding has the potential to significantly increase accuracy and therefore could become an important advance for screening for BE with improved risk stratification by detection of dysplasia.

I built a near-infrared module and imaging capsule with fluorescent capabilities that is compatible with the current OCT system. I measured the sensitivity of the system and detected fluorescence intensity on ex vivo swine esophageal tissue before and after topical application of conjugated WGA-AlexaFluor680 dye. Laser excitation of 10 mW and WGA binding at 10 mM application concentration generated signal intensities of high contrast. I will continue further testing of this technology in swine and in human patients in vivo during the next year. Once validated, this technology has the potential to become a powerful tool for accurately diagnosing dysplastic BE during TCE-based esophageal cancer screening

Details

Project duration: June 3, 2017 –  August 3, 2017

Weekly hours: 40

Total hours completed: 360

Supervisors: Dr. Gary Tearney (gtearney@partners.org)