Diffusion Reflection

Abstract

Intraoperative detection of residual disease in oral cancer may reduce the high rate of recurrences. The aim of the present study was to evaluate the detection sensitivity of diffusion reflection (DR) measurements of bioconjugated gold nanorods (GNRs) to cancerous sites in a rat model of oral squamous cell carcinoma. We used hyperspectral spectroscopy and DR measurements of GNRs bioconjugated to slide specimens of rat tongues where squamous carcinoma was induced by 4NQO (4-nitroquinoline-N-oxide). Wistar-derived male rats were used: 6 were sacrificed at wk 32 to 37 following 4NQO administration (experimental rats), as were 2 control rats at wk 32 and 36. The detection results were compared with histopathology: 19 sites of cancerous changes were identified microscopically (11 invasive cancer and 8 carcinoma in situ [CIS]). The GNRs attached selectively to areas of carcinomatous changes with an intensity exceeding 17 intensity units at 780 nm (overall specificity, 97%; overall sensitivity, 87%) when the hyperspectral spectroscopy system was used. The resulting DR slopes of the reflected intensity showed an increase of >80% in areas of invasive cancer and an increase of >30% in the CIS sites. The resulting intensity units of the hyperspectral spectroscopy system in the invasive cancer significantly exceed those of the CIS ( t test, p = .0002; Mann-Whitney, p = .0024). The results demonstrate a great potential of the direct DR scanning as a new and simple tool for detecting residual disease intraoperatively.