The potential role of in vivo optical coherence tomography for evaluating oral soft tissue: A systematic review

Abstract

Although the OCT is an easy-to-perform test and it offers an attractive diagnostic and monitoring prospect for soft tissues of the oral cavity, further studies are needed to complete the current knowledge of this imaging technique.

In Vivo Endoscopic Optical Coherence Tomography of the Healthy Human Oral Mucosa: Qualitative and Quantitative Image Analysis

“…Although some volunteers reported an uncomfortable feeling during the examination process for measurement points within the posterior oral cavity and the oropharynx, at least 60% of the cases have been accessible and therefore image data were sufficient for a representative analysis. Previous studies concerning healthy oral soft tissue concentrated on the imaging of the anterior oral mucosa [ 17 , 25 , 26 , 27 ], so detailed information about the accessibility of the posterior areas have not been reported before. However, the presented data suggest that this aspect should be considered for the determination of the sample size.…”

“…By the implementation of adapted rigid or fiber optics, endoscopic OCT can be used for the non-invasive examination of human oral soft tissue [ 15 , 16 ]. As tissue elements of the mucosal sublayers result in various scattering behaviour, information about the appearance and geometry of the epithelium and the underlying lamina propria becomes accessible [ 14 , 17 ]. Ongoing research has occasionally proposed perspective measurement parameters, such as the mean epithelial thickness, the occurrence of a keratinized layer and the course of the basement membrane, for the detection of (pre-)malignant changes of the oral epithelium by means of OCT [ 14 , 17 ].…”

“…As tissue elements of the mucosal sublayers result in various scattering behaviour, information about the appearance and geometry of the epithelium and the underlying lamina propria becomes accessible [ 14 , 17 ]. Ongoing research has occasionally proposed perspective measurement parameters, such as the mean epithelial thickness, the occurrence of a keratinized layer and the course of the basement membrane, for the detection of (pre-)malignant changes of the oral epithelium by means of OCT [ 14 , 17 ]. Furthermore, OCT image scoring was performed using hamster cheek pouches, concentrating on the presence of irregular epithelial stratification in combination with broadened rete pegs and basal hyperplasia [ 18 ].…”

“…Beyond that, diagnostic scoring was done on human oral soft tissue in the context of preliminary studies [ 19 ]. Moreover, several ex vivo studies as well as an increasing amount of in vivo investigations have described key features of suspicious lesions and oral squamous cell carcinoma, such as the increase in epithelial thickness as well as the loss of the basement membrane during the progress of malignant transformation [ 17 , 20 ]. Regarding oral lesions alongside the upper aerodigestive tract, measurement of epithelial thickness provided large differences resulting in a moderate sensitivity and specificity in order to distinguish noninvasive from invasive proliferation [ 21 ].…”

“…Against this background, the demand for a comprehensive study with the aim of assessing the variance of appearance of the healthy oral mucosa, in dependence of the localization within the oral cavity, and with this the ground truth arises [ 17 , 26 ]. Moreover, systematic reviews suggest that the visual interpretation of OCT data sets is often strongly user-dependent due to a lack of established standards for the image analysis [ 17 ], which leads to the aim of defining qualitative and quantitative criteria for an improved optical biopsy by OCT. On the other hand, there are several studies dealing with an automatic evaluation of OCT images of oral pathologies [ 28 , 29 ]. Here, changes in the speckle pattern of the epithelium as well as in the signal intensity within the single A-scans offer the possibility to serve as indicators for the development of oral malignancy [ 28 ].…”