Feasibility of a Video‐Mosaicking Approach to Extend the Field‐of‐View For Reflectance Confocal Microscopy in the Oral Cavity In Vivo

Abstract

Background Reflectance confocal microscopy (RCM) is a developing approach for noninvasive detection of oral lesions with label‐free contrast and cellular‐level resolution. For access into the oral cavity, confocal microscopes are being configured with small‐diameter telescopic probes and small objective lenses. However, a small probe and objective lens allows for a rather small field‐of‐view relative to the large areas of tissue that must be examined for diagnosis. To extend the field‐of‐view for intraoral RCM imaging, we are investigating a video‐mosaicking approach. Methods A relay telescope and objective lens were adapted to an existing confocal microscope for access into the oral cavity. Imaging was performed using metal three‐dimensional‐printed objective lens front‐end caps with coverslip windows to contact and stabilize the tissue and set depth. Four healthy volunteers (normal oral mucosa), one patient (with an amalgam tattoo) in a clinical setting, and 20 anesthetized patients (with oral squamous cell carcinoma [OSCC]) in a surgical setting were imaged. Instead of the usual still RCM images, videos were recorded and then processed into video‐mosaics. Thirty video‐mosaics were read and qualitatively assessed by an expert reader of RCM images of the oral mucosa. Results Whereas the objective lens’ native field‐of‐view is 0.75 mm × 0.75 mm, the video‐mosaics display larger areas, ranging from 2 mm × 2 mm to 4 mm × 2 mm, with resolution, morphologic detail, and image quality that is preserved relative to that observed in the original videos (individual images). Video‐mosaics in healthy volunteers’ and the patients’ images showed cellular morphologic patterns in the lower epithelium and at the epithelial junction, and connective tissue along with capillary loops and blood flow in the deeper lamina propria. In OSCC, tumor nests could be observed along with normal looking mucosa in margin areas. Conclusions Video‐mosaicking is a reasonably quick and efficient approach for extending the field‐of‐view of RCM imaging, which can, to some extent, overcome the inherent limitation of an intraoral probe's small field‐of‐view. Reading video‐mosaics can mimic the procedure for examining pathology: initial visualization of the spatial cellular and morphologic patterns of the tumor and the spread of tumor margins over larger areas of the lesion, followed by digitally zooming (magnifying) for closer inspection of suspicious areas. However, faster processing of videos into video‐mosaics will be necessary, to allow examination of video‐mosaics in real‐time at the bedside. Lasers Surg. Med. 51:439–451, 2019. © 2019 Wiley Periodicals, Inc.

Reflectance confocal microscopy characteristics of oral lichen planus: An analysis of 47 cases in a Chinese cohort

“…Furthermore, a more portable device would be helpful during manipulation (31). Recently a new video-mosaicking approach was reported for intraoral imaging, meaning this technique may be able to overcome the limitation of original confocal microscopy (32).…”

Changes in the tarsal conjunctiva viewed by in vivo confocal microscopy are associated with ocular symptoms and contact lens wear

“…18,19 In mucosal tissues, the equivalent union that joins the epithelium and lamina propria is commonly known as the epithelial-lamina propria junction. [20][21][22] Thus, the hyporeflective interior of the oval structures observed with confocal microscopy corresponds with the papilla lumen of the dermis or lamina propria, the hyperreflective border with the basal membrane of the epidermis or epithelium, and the area surrounding the papillae with the rete ridges of the epidermis or epithelium. 17 This particular architecture of the skin and mucosal tissues enlarges the contact area between the dermis and epidermis as well as between the epithelium and lamina propria enhancing the metabolic exchange and reinforcing the adhesion between these two layers, among other functions.…”

“…Rete ridges are downward invaginations of the epidermis into the dermis between papillae, which are the analogous upward projections of the dermis into the epidermis, whose union in the skin is called the dermal‐epidermal junction . In mucosal tissues, the equivalent union that joins the epithelium and lamina propria is commonly known as the epithelial‐lamina propria junction . Thus, the hyporeflective interior of the oval structures observed with confocal microscopy corresponds with the papilla lumen of the dermis or lamina propria, the hyperreflective border with the basal membrane of the epidermis or epithelium, and the area surrounding the papillae with the rete ridges of the epidermis or epithelium …”

Real‐time video mosaicking to guide handheld in vivo microscopy

“…For certain point-of-care clinical applications, the ability to obtain noninvasive real-time pathology data could have significant advantages compared to traditional histopathology [3][4][5][6]. For example, noninvasive real-time pathology could be of value for disease screening in situations where invasive biopsy is not justified in terms of cost and risk [2,7]. For surgical guidance, the time and cost of rapid frozensection analysis prevents surgeons from examining more than a trace amount of tissue during surgery, and rapid in vivo microscopy could allow for much larger amounts of tissue to be interrogated [8][9][10][11].…”

“…For example, in the case of oral cancer detection, dentists and physicians often can visually identify suspicious lesions, but are hesitant to biopsy them since the majority of such lesions are benign. A noninvasive handheld microscope would allow for "image-guided biopsy" by providing images that approximate the gold standard of invasive histopathology [2,7]. However, due to the small field of view (FOV) of most handheld and endoscopic microscopes, it is difficult for users to know if they have adequately sampled/imaged the lesion.…”