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

Detection of oral mucosal lesions by the fluorescence spectroscopy and classification of cancerous stages by support vector machine

Detection of oral mucosal lesions has been performed by an in-house developed fluorescence-based portable device in the present study. A laser diode of 405 nm wavelength and a UV-visible spectrometer are utilized in the portable device as excitation and detection sources. At the 405 nm excitation wavelength, the flavin adenine dinucleotide (FAD) band at 500 nm and three porphyrin bands at 634, 676, and 703 nm are observed in the fluorescence spectrum of the oral cavity tissue. We have conducted this clinical study on a total of 189 tissue sites of 36 oral squamous cell carcinoma (OSCC) patients, 18 dysplastic (precancerous) patients, and 34 volunteers. Analysis of the fluorescence data has been performed by using the principal component analysis (PCA) method and support vector machine (SVM) classifier. PCA is applied first in the spectral data to reduce the dimension, and then classification among the three groups has been executed by employing the SVM. The SVM classifier includes linear, radial basis function (RBF), polynomial, and sigmoid kernels, and their classification efficacies are computed. Linear and RBF kernels on the testing data sets differentiated OSCC and dysplasia to normal with an accuracy of 100% and OSCC to dysplasia with an accuracy of 95% and 97%, respectively. Polynomial and sigmoid kernels showed less accuracy values among the groups ranging from 48 to 88% and 51 to 100%, respectively. The result indicates that fluorescence spectroscopy and the SVM classifier can help to identify early oral mucosal lesions with significant high accuracy.

Human Saliva as a Substitute Diagnostic Medium for the Detection of Oral Lesions Using the Stokes Shift Spectroscopy: Discrimination among the Groups by Multivariate Analysis Methods

OBJECTIVE

Our objective in the present study is to detect oral mucosal lesions non-invasively by probing two solutions with reference to diagnostic technique and non-invasive media. In the diagnostic technique, Stokes shift (SS) spectroscopy (SSS) has been utilized for the detection of oral lesions. In the diagnostic media, human oral tissue and saliva are included.

METHODS

SS measurements are carried out on oral squamous cell carcinoma (OSCC), dysplastic (precancer), and normal/control tissue and saliva samples. Measurements are performed on 86 tissue and 86 saliva samples using the commercially available spectrofluorometer. Offset wavelength of 120 nm, which is the Stoke shift of nicotinamide adenine dinucleotide (NADH) has been selected over the other offsets (i.e., 20, 40, 70 and 90 nm).

RESULT

Presence of tryptophan, collagen, NADH, and flavin adenine dinucleotide (FAD) bands were noticed in the SS spectra of tissue. Like the tissue spectra, presence of these bands was also found in the SS spectra of saliva except the collagen band. Classification among the samples accomplished by the make use of multivariate analysis methods. In the multivariate analysis methods, principal component analysis (PCA) is applied first on SS data of tissue and saliva and then Mahalanobis distance (MD) model and receiver operating characteristic (ROC) analysis employed successively. Overall accuracy values of 94.91 %, 84.61 %, and 85.24 % were obtained among OSCC to normal, dysplasia to normal, and OSCC to dysplasia for tissue samples and 88.46 %, 90.16 % and 94.91 % accuracy values were obtained for saliva using the SS spectroscopy.

CONCLUSION

Obtained results of human saliva are equivalent to human oral tissue using the SS spectroscopy. It indicates that saliva may be utilized as a substitute diagnostic medium and SS spectroscopy as a diagnostic technique for non-invasive detection of oral lesions at the primarily stage.

Label-Free Optical Spectroscopy for Early Detection of Oral Cancer

Oral cancer is the 16th most common cancer worldwide. It commonly arises from painless white or red plaques within the oral cavity. Clinical outcome is highly related to the stage when diagnosed. However, early diagnosis is complex owing to the impracticality of biopsying every potentially premalignant intraoral lesion. Therefore, there is a need to develop a non-invasive cost-effective diagnostic technique to differentiate non-malignant and early-stage malignant lesions. Optical spectroscopy may provide an appropriate solution to facilitate early detection of these lesions. It has many advantages over traditional approaches including cost, speed, objectivity, sensitivity, painlessness, and ease-of use in clinical setting for real-time diagnosis. This review consists of a comprehensive overview of optical spectroscopy for oral cancer diagnosis, epidemiology, and recent improvements in this field for diagnostic purposes. It summarizes major developments in label-free optical spectroscopy, including Raman, fluorescence, and diffuse reflectance spectroscopy during recent years. Among the wide range of optical techniques available, we chose these three for this review because they have the ability to provide biochemical information and show great potential for real-time deep-tissue point-based in vivo analysis. This review also highlights the importance of saliva-based potential biomarkers for non-invasive early-stage diagnosis. It concludes with the discussion on the scope of development and future demands from a clinical point of view.