Application Of Optical Coherence Tomography In The Diagnosis Of Oral Squamous Cell Carcinoma

Background: Oral cancer is a unique type of cancer that develops in the tissues of the mouth,tongue,and lips,and has been identified as one of the most common malignancy worldwide.! Oral squamous cell carcinoma(OSCC)is the most common oral cancer type and accounts for >90% of human oral malignancy types.OSCC mortality is high,with a 5-year survival of under 60%.! The treatment of oral cancer is mainly surgical therapy,and the complete resection of the primary focus is very important to the treatment of the tumor.At present,surgeons mainly evaluate the scope of resection of the primary focus according to the visual examination and palpation of the tumor during the operation.Although the intraoperative frozen pathology of the incisal margin can be used to evaluate the cutting edge,the intraoperative frozen pathology can only study a small part of the cutting edge,which is easy to cause false negative.Therefore,it is necessary to find a new technique to determine the tumor boundary conveniently,accurately and quickly,and to guide tumor resection during operation.Optical coherence tomography is a non-invasive and real-time imaging method with rapid development in recent years,and it has been used in clinical ophthalmology.Because cancerous tissues have different spectral characteristics and structure from healthy tissues,coupled with the fact that OCT can provide high resolution(10-20μm)detection images and sufficient tissue penetration depth,OCT has a considerable prospect in early cancer diagnosis and tumor treatment detection.Objective: In the surgical resection of OSCC,the evaluation of the resection range of the primary focus mainly depends on the vision and palpation of surgeons,which is easy to cause positive margin.In this study,OCT imaging and HE pathological staining were performed on normal tissues and oral cancer tissues to explore the difference between oral cancer and normal tissues under OCT,and to explore whether OCT can assist tumor margin evaluation.Establish an animal model of squamous cell carcinoma of the tongue in situ for follow-up study.Through animal model study,to evaluate the ability of OCT to distinguish oral cancer from normal tissue,and to explore the possibility of tumor resection under the guidance of OCT.Methods: 3 cases of oral carcinoma,3 cases of Cancerous boundary tissue and 3 cases of normal tissue(9 cases)were collected and stained with HE after imaging by OCT,the OCT images were compared with HE images,and the OCT images were quantitatively analyzed.CAL-27 tongue squamous cell carcinoma cell line was cultured and in situ injected into BALB/c nude mice to establish an animal model of tongue squamous cell carcinoma in situ.A total of 36 tongue tissues of nude mice were collected and stained with HE after imaging by OCT.The ability of OCT to distinguish oral cancer from normal tissue was evaluated by single sample t test,scatter plot and ROC curve.Results: OCT images were highly similar to HE images,and the signal intensity of oral cancer was significantly higher than that of normal tissues in OCT images.The animal model of tongue squamous cell carcinoma in situ was successfully constructed,the average tumor formation time was 3 days,and the tumor success rate was 100%.HE images of tongue squamous cell carcinoma in nude mice showed a large number of tumor cells in the muscular layer,local tumor cell necrosis,nuclear fragmentation or dissolution.A total of 108 HE images were obtained in nude mice,including 40 OSCC images,50 normal tissue images and 18 paracancerous tissue images.there were also 108 OCT images.The grey value of tumor tissue in OCT image was significantly different from that of normal tissue(P < 0.0001).When OCT mean gray value 48 was used as a tumor marker for OSCC diagnosis,the sensitivity was 98.6% and the specificity was 80.1%.Conclusion: As a non-invasive,real-time imaging method,OCT shows a good correlation with HE pathological images.It can effectively distinguish squamous cell carcinoma from normal tissues,and has high sensitivity and specificity,which is expected to assist and guide tumor margin evaluation.