BackgroundStrong proof-of-principle for utilisation of diffuse reflectance spectroscopy, a non-invasive tool for early detection of malignant changes, has emerged recently. The potential of this technique in distinguishing normal tissue from hyperplastic and dysplastic tissues was explored.MethodsDiffuse reflectance (DR) spectra in the 400–700 nm region were obtained from the buccal mucosa of 96 patients and 34 healthy volunteers. The DR spectral data were compared against the gold standard biopsy and histopathology results. A principal-component analysis was performed for dimensional reduction in the normalised spectral data with linear discriminant analysis as the classifying technique. The receiver operator characteristic curve technique was employed for evaluating the performance of the diagnostic test.ResultsDR spectral features for different lesions, such as normal/healthy, hyperplastic, dysplastic and squamous cell carcinoma (SCC), varied significantly according to the intensity of oxygenated haemoglobin absorption. While the classification based on discriminant scores provided an overall sensitivity of 98.5% and specificity of 96.0% for distinguishing SCC from dysplasia, they were 100.0% and 95.0%, respectively, for distinguishing dysplasia from hyperplasia. Similarly, the analysis yielded a sensitivity of 95.0% and specificity of 100.0% for distinguishing hyperplasia from healthy tissue. The areas under the receiver operator characteristic curves were 0.98 (95% CI 0.95 to 1.00) and 0.95 (95% CI 0.90 to 1.00) for distinguishing dysplasia from SCC and hyperplasia from dysplasia, respectively.ConclusionDR spectral data efficiently discriminate healthy tissue from oral malignant lesions. Diagnostic accuracies obtained in this study highlight the potential use of this method for routine clinical practice.

The application of LDA-LOO method on the autofluorescence spectra recorded during a clinical trial in patients was found suitable to discriminate oral mucosal alterations during tissue transformation towards malignancy with improved diagnostic accuracies.

BackgroundDiffusely reflected light is influenced by cytologic and morphologic changes that take place during tissue transformation, such as, nuclear changes, extracellular matrix structure and composition as well as blood flow. Albeit with varying degree of sensitivity and specificity, the properties of diffusely reflected light in discriminating a variety of oral lesions have been demonstrated by our group in multiple studies using point monitoring systems. However, the point monitoring system could not identify the region with the most malignant potential in a single sitting.MethodsIn order to scan the entire lesion, we developed a multi-spectral imaging camera system that records diffuse reflectance (DR) images of the oral lesion at 545 and 575 nm with white light illumination. The diagnostic accuracy of the system for 2-dimensional DR imaging of pre-malignant and malignant changes in the oral cavity was evaluated through a clinical study in 55 patients and 23 healthy volunteers. The DR imaging data were compared with gold standard tissue biopsy and histopathology results.ResultsIn total 106- normal/clinically healthy sites, 20- pre-malignant and 29- malignant (SCC) sites were compared. While the median pixel value of the R545/R575 image ratio for normal/clinically healthy tissue was 0.87 (IQR = 0.82-0.94), they were 1.35 (IQR = 1.13-1.67) and 2.44 (IQR = 1.78-3.80) for pre-malignant and malignant lesions, respectively. Area under the ROC curve to differentiate malignant from normal/clinically healthy [AUC = 0.99 (95% CI: 0.99-1.00)], pre-malignant from normal/clinically healthy [AUC = 0.94 (95% CI: 0.86-1.00)], malignant from pre-malignant [AUC = 0.84 (95% CI: 0.73-0.95)] and pre-malignant and malignant from normal/clinically healthy [AUC = 0.97 (95% CI: 0.94-1.00)] lesions were desirable.ConclusionWe find DR imaging to be very effective as a screening tool in locating the potentially malignant areas of oral lesions with relatively good diagnostic accuracy while comparing it to the gold standard histopathology.

Autofluorescence (AF) and diffuse reflectance (DR) spectroscopic techniques have shown good diagnostic accuracies for noninvasive detection of oral cavity cancer. In the present study, AF and DR spectra recorded in vivo from the same set of sites in 65 patients were analyzed using Principal component analysis (PCA) and linear discriminant analysis (LDA). The effectiveness of these two techniques was assessed by comparison with gold standard and their discrimination efficiency was determined from the area under the receiver operator characteristic (AUC-ROC) curve. Analysis using a DR technique shows a higher AUC-ROC of 0.991 as against 0.987 for AF spectral data.