Quantitative analysis of near infrared optical signal in fluorescence molecular navigation surgery for oral squamous cell carcinoma

Abstract

Objective: To evaluate the effect of quantitative analysis of optical signal in the near infrared fluorescence molecular navigation surgery for oral squamous cell carcinoma (OSCC). Methods: SCC9, HSC3 and epithelial cell lines (Leuk-1) were co-cultured with indocyanine green (ICG) for 6 hours in vitro in order to verify whether the quantitative analysis of near infrared optical signal could distinguish tumor cells from normal cells. A total of 16 BALB/c male mice (5-6 weeks, 20-25 g) were selected and fed in clean grade equipment and were equally divided into two groups. SCC9 and HSC3 cells were inoculated into the back of each mouse at a concentration of 1×106 cells/ml to establish a subcutaneous graft tumor model. The 5 mg/kg ICG was injected into the caudal vein to each of the tumor bearing mouse and the difference between OSCC and normal tissues was then analyzed by near infrared optical signal quantitative analysis (Paired t test). Ten patients with OSCC were enrolled in the Department of Stomatology of the First Affiliated Hospital of Bengbu Medical College from November 2019 to July 2020, including 6 patients with tongue squamous cell carcinoma and 4 patients with buccal squamous cell carcinoma.The patients were 6 males and 4 females and the range of age was from 46 to 71 years with an average age of 58.6 years. These patients were injected ICG (0.75 mg/kg) via the cubital vein at 6-8 h before surgery. Intraoperatively, the fluorescence intensities (FI) of near infrared signal were measured at tumor, peritumor tissues (2.0 cm beyond the tumor boundary) and normal tongue or buccal mucosa respectively. The signal background ratios (SBR) from the three site groups were assessed using one-way ANOVA followed by the Tukey post hoc test for multiple comparisons. Results: In vitro, the levels of near infrared FI in HSC3 and SCC9 groups were higher than that in Leuk-1group (P<0.01). In vivo, the result showed that the SBR of OSCC and normal tissues was 8.67±0.35. Clinical studies showed that the intensity of tumor [(408.23±101.51) arbitrary units (AU)] was significantly higher than those of peritumoral [(253.12±64.89) AU] and normal tissues [(261.50±80.47) AU] respectively. The SBRs of near infrared FI of tumor and peritumoral tissues, tumor and normal tissues were 1.61±0.53 and 1.56±0.48 respectively, while that of peritumoral and normal tissues was 0.96±0.17. Conclusions: The quantitative analysis of near infrared optical signal could distinguish OSCC from normal cells and could locate the OSCC tissue intraoperatively. Optical signal quantification and ICG near infrared fluorescence molecular technology possessed the feasibility in primary OSCC resection.