Morphological features of the human lingual mucosa assessed by line-field confocal optical coherence tomography

Line-field confocal optical coherence tomography (LC-OCT) is an emerging optical imaging technique combining vertical OCT-like sections with confocal en face imaging at micrometer-scale resolution. The present study aimed to evaluate the ability of LC-OCT to depict the morphological features of healthy human lingual mucosa, including both the mobile tongue and the base of the tongue, under cadaveric and ex vivo conditions.

A two-phase prospective morphological study was conducted. In the cadaveric phase, two human tongues donated to science were examined after fixation. In the ex vivo phase, twenty-four histologically normal mucosal specimens were obtained from tumor-free surgical margins in fourteen patients undergoing surgery for base-of-tongue squamous cell carcinoma. Vertical and en face LC-OCT images were qualitatively compared with corresponding hematoxylin-eosin-stained histological sections. Epithelial thickness was measured on LC-OCT images by two independent observers, and interobserver agreement was assessed.

Line-field confocal OCT enabled visualization of epithelial stratification, basement membrane delineation, and lamina propria architecture in both lingual regions. Three epithelial layers, superficial, intermediate, and basal, were consistently identified based on reproducible optical patterns. Mean epithelial thickness was significantly greater in the mobile tongue than in the base of the tongue (270.4 ± 16.4 μm vs 182.7 ± 14.9 μm; p < 0.001). Interobserver agreement for epithelial thickness measurements was excellent (Pearson's r = 0.993).

Under cadaveric and ex vivo conditions, LC-OCT provides high-resolution morphological imaging of healthy lingual mucosa with close correspondence to histological architecture. These findings support the value of LC-OCT as a morphological imaging tool for anatomical research of the oral cavity.