[Progress of the application of optical coherence tomography in gastrointestinal tumor surgery]

Optical coherence tomography (OCT) is a real-time, cross-sectional optical imaging technology. It is analogous to ultrasonography, except that OCT uses light waves instead of sound waves, and can provide three-dimensional morphological images of living tissues with a micrometer resolution. Through the use of endoscopes, needles, catheters and laparoscopes, OCT has demonstrated tremendous imaging potential in tumor surgery. The current studies suggest that OCT has potential for clinical applications in the following fields of gastrointestinal tumor surgery: (1) Early tumor detection and diagnosis: OCT can distinguish differences between polyp tissue, normal tissue and malignant tissue. It could possibly identify premalignant lesions or conditions potentially predisposing to malignancy, such as gastric and intestinal metaplasia, gastritis associated with Helicobacter pylori, and early gastric cancer involving the mucosa or submucosa. In addition, OCT can differentiate between adenomatous polyps and hyperplastic polyps. (2) Optical biopsy of lymph nodes: As a high-resolution, near-IR imaging modality, OCT is capable of visualizing microscopic features within tissue, distinguishing lymph node tissue from surrounding adipose tissue, revealing nodal structures such as germinal centers and intra-nodal vessels. Consequently, OCT has the ability to show changes in node microarchitecture during metastatic tumor infiltration. (3) Intraoperative guidance for real-time determination of surgical margins: In other tumors such as oral squamous cell carcinoma and breast cancer, it has been demonstrated that OCT can be used to rapidly scan large areas of tissue, to guide at the cellular level the surgical resection of neoplastic disease, and to scan tumor margins for the presence of residual disease, tumor foci, and potentially even metastasizing tumor cells. It implies that colorectal neoplasms surgeons can possibly use the laparoscopic OCT to detect the intestinal tumor margin and lymph nodes during operation in the future, so as to determine the appropriate range of bowel resection and lymph node dissection. At present, there are few reports about the intra-operative application of OCT in the field of gastrointestinal tumor surgery. Thus there is a tremendous opportunity for further research in this field.