Combination of structural and vascular optical coherence tomography for differentiating oral lesions of mice in different carcinogenesis stages

Abstract

Differentiating between early malignancy and benign lesions in oral cavities is difficult using current optical tools. As has been shown in previous studies, microvascular changes in squamous epithelium can be regarded as a key marker for diagnosis. We propose the combination of structural and vascular optical coherence tomography (OCT) imaging for the investigation of disease related changes. Progressive thickness changes of epithelium and the destruction of underlying lamina propria was observed during cancer development in a 4- nitroquinoline-1-oxide (4NQO) mouse model. At the same time, microvascular changes in hyperplasia, dysplasia, carcinoma in situ and advanced cancer were observed. Findings from OCT imaging were compared with histology.

Keywords: (110.4500) Optical coherence tomography; (170.0170) Medical optics and biotechnology.

Fig. 1

Imaging protocol. (A) OCT imaging schedule and time of mouse sacrifice for histology. (B) Fluorescent image of the tongue: the green spot indicated the potential tumor location on the dorsal surface of the tongue and was fixed by two plastic slides with a 2mm diameter hole before OCT imaging.

Fig. 2

In vivo structural and vascular imaging of the anterior, dorsal tongue of control mouse. (A) 3D rendered OCT structural image. (B) Cross-sectional OCT image at the location of the green dotted line in (A). (C) Histological image of approximately the same location as displayed in (B). (D) Corresponding vascular image from the orange rectangle in (B) (orange arrow: IPCL in the junction of EP and LP; green arrow: branching vessels in the LP). (E) 2D en-face vascular image of superficial mucosal layer showing IPCL. (F) Magnified image of region indicated with orange rectangle in (E) showing small and narrow IPCL. (G) 2D en-face vascular image in deep mucosal layer showing branching vessels in LP. (H) Magnified image of branching vessels indicated with orange rectangle in (G). IPCL: intraepithelial papillary capillary loops; KL: keratinized layer; FiPa: filiform papilla; EP: epithelial layer; LP: lamina propria.

Fig. 3

In vivo Structural and Vascular imaging of the dorsal tongue with hyperplasia to LGD of 4NQO mouse. (A) Cross-sectional OCT image at the location of the green dotted line in (C) shows increased thickness of the EP (orange double-sided arrow) with the preserved boundary of EP and LP. (B) Corresponding histology image obtained at a similar location as displayed in (A) which shows increased thickness of EP with basal cell hyperplasia. (C) 2D en-face vascular image of superficial mucosal layer showing IPCL. (D) Magnified image of region indicated with orange rectangle in (C). IPCL presents as elongated and closed loops. (E) 2D en-face vascular image of deep mucosal layer showing branching vessels in LP. (F) Magnified image of region indicated with orange rectangle in (E). IPCL: intraepithelial papillary capillary loop; EP: epithelial layer; LP: lamina propria; LGD: low grade dysplasia.

Fig. 4

In vivo structural and vascular imaging of the dorsal tongue with HGD to CIS of 4NQO mouse (A) Cross-sectional OCT image at the location of the green dotted line in (C) shows increased thickness of the EP (orange double-sided arrow) with the preserved boundary of EP and LP. (B) Corresponding histology image obtained at a similar location as displayed in (A) which shows full thickness of dysplastic changes of the lining epithelium. (C) 2D en-face vascular image of superficial mucosal layer showing IPCL. (D) Magnified image of region indicated with orange rectangle in (C). IPCL presents as open, dilated, meandering, and non-uniform loops. (E) 2D en-face vascular image of deep mucosal layer showing branching vessels in LP. (F) Magnified image of region indicated with orange rectangle in (E). IPCL: intraepithelial papillary capillary loop; EP: epithelial layer; LP: lamina propria; HGD: high grade dysplasia; CIS: carcinoma in situ.

Fig. 5

Comparing IPCL between hyperplasia to LGD and HGD to CIS. (A) 2D en-face vascular image of superficial mucosal layer showing IPCL. (B) Cross-sectional OCT image at the location of the blue dot line in (A) shows increased thickness of the EP (orange double-sided arrow) with the preserved boundary of EP and LP. (C) Corresponding histology image obtained at a similar location as displayed in (B) which indicates hyperplasia to LGD. (D) Magnified image of IPCL indicated with the blue rectangle in (A). It presents IPCL with elongated and closed loop, favor hyperplasia to LGD change. (E) Cross-sectional OCT image at the location of the orange dot line in (A) shows focal thickness of the EP (orange double-sided arrow) with the preserved boundary of EP and LP layer. (F) Corresponding histology image obtained at a similar location as displayed in (E) which indicates HGD to CIS change. (G) Magnified image of IPCL indicated with the orange rectangle in (A). It presents IPCL with opened, dilated, meandering, and non-uniform loop, favor HGD to CIS change. IPCL: intraepithelial papillary capillary loop; EP: epithelial layer; LP: lamina propria; LGD: low grade dysplasia; HGD: high grade dysplasia; CIS: carcinoma in situ

Fig. 6

Comparing IPCL between HGD to CIS and SCC (A) 2D en-face vascular image of superficial mucosal layer showing IPCL. (B) Cross-sectional OCT image at the location of the blue dot line in (A) shows increased thickness of the EP with the preserved boundary of EP and LP layer (orange double-sided arrow). (C) Corresponding histology image obtained at a similar location as displayed in (B) which indicates HGD to CIS change. (D) Magnified image of IPCL indicated with the blue rectangle in (A). It presented IPCL with open, dilated, meandering, and non-uniform loop, favor HGD to CIS change. (E) Cross-sectional OCT image at the location of the orange dot line in (A) shows polypoid tumor with LP layer invasion (orange arrow). (F) Corresponding histology image obtained at a similar location as displayed in (E) which indicates SCC with muscular layer invasion. (G) Magnified image of IPCL indicated with the orange rectangle in (A). It presented large branching type neovascular tumor vessels, favor advanced SCC change. IPCL: intraepithelial papillary capillary loop; EP: epithelial layer; LP: lamina propria; HGD: high grade dysplasia; CIS: carcinoma in situ; SCC: squamous cell carcinoma.

Fig. 7

Change of structure and vasculature in different pathological stages of disease progression. (A) normal histology: normal structural image (left part) with small and closed IPCL (right part). (B) hyperplasia to LGD: focal thickness of EP layer (left part) with elongated and closed IPCL (right part). (C) HGD to CIS: focal thickness of EP layer (left part) with open, dilated and meandering IPCL (right part). (D) SCC: polypoid tumor with LP invasion (left part) with large and branching IPCL (right part). IPCL: intraepithelial papillary capillary loop; EP: epithelial layer; LP: lamina propria; LGH: low grade dysplasia; HGD: high grade dysplasia; CIS: carcinoma in situ; SCC: squamous cell carcinoma.