The Use of a OCT Probe in Assessment of Endoscopic and Surgical Resection Specimen of Gastrointestinal Tract

Endoscopic treatment of early neoplasia in the gastrointestinal tract has been established as the standard therapy in the past decade. Various endoscopic resection techniques have been developed, such as endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD), to ensure complete removal of such lesions and avoid recurrence. Successful endoscopic resection of early gastrointestinal (GI) neoplasia relies on accurate pre-procedural prediction of the margin and depth of invasion of the corresponding lesions. Generally, GI neoplasia (even carcinoma) confined to the mucosa layer could be safely removed endoscopically with margin negative resection and minimal chance of lymph node involvement.

Image-enhanced endoscopy or endoscopic ultrasonography has been used as the modality of pre-resection assessment on the depth of invasion. Chromoendoscopy and digital enhancement such as magnifying Narrow Band Imaging (NBI) focus on characterization of the surface morphology and the vascular structures and predict the depth of invasion instead of direct depth measurement. Endoscopic ultrasonography allows good visualization of the different layers of GI tract, but the ability to differentiate early mucosal (T1a) or submucosal invasive (T1b) cancer remains limited owing to its low resolution (>100um). A small proportion of patients subjected for endoscopic resection had invasive cancer not curable by endoscopic means and require additional surgery afterwards. There is thus a potential role for further refinement of imaging technique to allow better prediction of tumor depth in early GI neoplasia.

Optical coherence tomography (OCT) is a novel high spatial-resolution, cross-sectional imaging technique that allows visualization of biological tissue at higher resolution (~10um). It has been used routinely in the field of ophthalmology for retinal assessment. Earlier studies have also confirmed the potential application in the gastrointestinal tract with a probe-based design to be placed within an endoscopy.

The Department of Mechanical and Automation Engineering from the Chinese University of Hong Kong have recently designed a novel OCT probe that could be placed within the working channel of an endoscope. In-vitro experiment with porcine intestinal model demonstrated its ability to provide high-resolution images with visualization of different layers of the GI tract. The investigators therefore design this pilot study to assess the application of the OCT probe in human resected tissue specimen to assess the ability in determining different layers of GI tract and depth of invasion of GI tumors.

The current pilot study is designed aiming to assess the ability of the novel OCT probe in visualization of the layers of the human GI tract and depth of invasion of GI neoplasia in resected surgical and endoscopic specimens. There would be two parts of the study:

1. To visualize normal gastrointestinal tract in a resected surgical specimen of esophageal, stomach, small bowel and colonic tissue.
2. To assess the depth of invasion of the neoplastic tissue in surgical specimens as well as endoscopic (ESD) specimens