Detection of inaccessible head and neck lesions using human saliva and fluorescence spectroscopy

Abstract

Head and neck cancer detection using fluorescence spectroscopy from human saliva is reported here. This study has been conducted on squamous cell carcinoma (SCC), and dysplastic (precancer) and control (normal) groups using an in-house developed compact set-up. Fluorescence set-up consists of a 375-nm laser diode and optical components. Spectral bands of flavin adenine dinucleotide (FAD), porphyrins, and Raman are observed in the spectral range of 400 to 800 nm. Presence of FAD and porphyrin bands in human saliva is confirmed by the liquid phantoms of FAD and porphyrin. Significant differences in fluorescence intensities among all the three groups are observed. Three spectral ranges from 455 to 600, 605 to 770, and 400 to 800 nm are selected for each group and area values under each spectral range are computed. To differentiate among the groups, receiver operating characteristic (ROC) analysis is employed on the area values. ROC differentiates among the groups with accuracies of 98%, 92.85%, and 81.13% respectively in the spectral ranges of 400 to 800 nm. However, in other two spectral ranges (455 to 600 and 605 to 770 nm), low accuracy values are found. Obtained accuracy values indicate that selection of human saliva for head and neck cancer detection may be a good alternative.

Keywords: Flavin adenine dinucleotide; Fluorescence; Head and neck cancer; Porphyrin; Receiver operating characteristic analysis; Saliva.

Fig. 1

Schematic diagram of in-house fabricated fluorescence system consisting a 375-nm laser diode, cuvette holder, collimating lens (CL), long pass filter (LPF), cuvette, spectrometer (SM), fibers, USB port, and laptop

Fig. 2

Fluorescence spectrum of FAD and porphyrin solutions in the scan range of 450 to 650 nm and 550 to 720 nm (a) FAD spectrum (b) porphyrin spectrum

Fig. 3

Fluorescence spectra of SCC, dysplastic, and normal saliva samples in the scan range of 400–800 nm taken in the interval of 0.46 nm (a) mean spectra (b) typical spectra

Fig. 4

Scatter data plots among SCC, dysplasia, and normal samples (a) SCC/normal (b) dysplasia/normal (c) SCC to dysplasia (d) ROC curve

Fig. 5

ROC curves among SCC, dysplasia, and normal groups for (a) area values in the spectral range 455–600 nm and (b) area values in the spectral range 605–770 nm