Autofluorescence and Diagnostic Accuracy of Lesions of Oral Mucosa: A Pilot Study

Band-Selection of a Portal LED-Induced Autofluorescence Multispectral Imager to Improve Oral Cancer Detection

This aim of this study was to find effective spectral bands for the early detection of oral cancer. The spectral images in different bands were acquired using a self-made portable light-emitting diode (LED)-induced autofluorescence multispectral imager equipped with 365 and 405 nm excitation LEDs, emission filters with center wavelengths of 470, 505, 525, 532, 550, 595, 632, 635, and 695 nm, and a color image sensor. The spectral images of 218 healthy points in 62 healthy participants and 218 tumor points in 62 patients were collected in the ex vivo trials at China Medical University Hospital. These ex vivo trials were similar to in vivo because the spectral images of anatomical specimens were immediately acquired after the on-site tumor resection. The spectral images associated with red, blue, and green filters correlated with and without nine emission filters were quantized by four computing method, including summated intensity, the highest number of the intensity level, entropy, and fractional dimension. The combination of four computing methods, two excitation light sources with two intensities, and 30 spectral bands in three experiments formed 264 classifiers. The quantized data in each classifier was divided into two groups: one was the training group optimizing the threshold of the quantized data, and the other was validating group tested under this optimized threshold. The sensitivity, specificity, and accuracy of each classifier were derived from these tests. To identify the influential spectral bands based on the area under the region and the testing results, a single-layer network learning process was used. This was compared to conventional rules-based approaches to show its superior and faster performance. Consequently, four emission filters with the center wavelengths of 470, 505, 532, and 550 nm were selected by an AI-based method and verified using a rule-based approach. The sensitivities of six classifiers using these emission filters were more significant than 90%. The average sensitivity of these was about 96.15%, the average specificity was approximately 69.55%, and the average accuracy was about 82.85%.

Reproducibility of tissue autofluorescence for screening potentially malignant disorders

Introduction: Direct tissue autofluorescence (AF) visualization devices such as VELscope® are gaining interest to improve early detection of oral potentially malignant disorders (OPMD) and cancers. The main objective of this study was to assess inter-observer reproducibility of incandescent light (IL) and AF observations for OPMD and cancer. Materials and methods: High risk patients (exposed to alcohol or tobacco) were screened by two independent operators with a conventional oral examination (IL) followed by AF examination. The primary endpoint was the inter-observer agreement on the decision to biopsy assessed by kappa coefficients.Accuracy of IL and AF were estimated by the relative true positive rate (RTPR, increase of sensitivity), relative false positive rate (RFPR, loss of specificity) and their ratio. Results: 179 patients were included. 833 lesions were identified after IL and AF. Indication for biopsy was retrieved for 41 patients (61 lesions). Inter-observer agreement on the indications for biopsy was 93.3% after IL (Kappa coefficient 0.88 [0.80, 0.97]) and 96.1% after IL and AF (Kappa coefficient 0.78 [0.66, 0.90]). RTPR was 1.2, RFPR was 1 and their ratio was 1.2. Conclusion: IL and AF examination has shown good inter-observer reproducibility. Adjunction of AF allowed diagnosing more leukoplakia without dysplasia.

A Meta-analysis on efficacy of auto fluorescence in detecting the early dysplastic changes of oral cavity

Background

Light-based detection agents using autofluorescence may be helpful in the detection of early dysplasia, which would otherwise be misdiagnosed as nondysplastic by conventional oral examination (COE) with white light. Visually-enhanced lesion scope (VELscope) is one of such an aid used for the purpose. A meta-analysis was carried out on the sensitivity and specificity of VELscope that would enable in providing evidence of its usage in oral dysplasia.

Materials and Methods

MeSH terms such as auto florescence in oral dysplasia, VELscope, Oral ID, Identifi, in a different medical database such as PubMed, Cochrane, EBSCO, and Google scholar was carried out by four research associates. The total articles available were 242, of which, 230 were excluded based on strict criteria of randomized control trials and proper design. Finally, only 12 studies were chosen for the present analysis. Of 1643 patients from 12 studies, 1264 patients had undergone the autofluorescence examination after the COE. Only 774 patients have shown the loss of fluorescence with VELScope examination and 487 had retained the fluorescence. Biopsy was performed on 1176 patients after the autofluorescence examination in the areas where there was the loss of fluorescence. The available data were subjected to software Review Manager for analysis.

Results and Discussion

Of the 11 studies analyzed, majority of them showed that the autofluorescence device were sensitive enough > 0.70; however, the values of sensitivity and specificities varied significantly. With the VELscope the diagnostic performance of the inexpert examiner was not improved, obtaining a sensitivity of 0.40 (95% of confidence interval [CI]: 0.406-0.773) and a specificity of 0.80 (95% CI: 0.614-0.923).

Conclusion

The new technique may help as an adjunct to histopathology in detecting the dysplasia initially and stop further progression to the carcinoma.

Early Diagnosis on Oral and Potentially Oral Malignant Lesions: A Systematic Review on the VELscope® Fluorescence Method

The fluorescence method is an innovative technique used by pathologists for examining body mucosa, and for the abnormalities tissue screening, potentially leading to the earlier discovery of pre-cancer, cancer or other disease processes. The early detection is one of the best mechanisms for enabling treatment success, increasing survival rates and maintaining a high quality of life. The purpose of this review is to evaluate the clinical efficiency of this diagnostic tool applied to the oral cavity (VELscope^®). A literature systematic review has been performed. The initial research provided 53 results after applying the inclusion and exclusion criteria, and after a manual screening of the abstracts by the authors, only 25 results were eligible for review. The results and data contained in all the researches, no older than 10 years, were manually evaluated, and provided useful information on this diagnostic method. The VELscope^® mean value about sensitivity and specificity resulted of 70.19% and 65.95%, respectively, by results analysis, but despite this some studies disagree about its clinical effectiveness, and this diagnostic method is still much debated in scientific and clinical medical literature. Surely being able to have efficient and effective tools from this point of view could help the clinician in the diagnosis, and also make timelier the pharmacological or surgical therapy, improving the quality of life of the patient, and in some cases guaranteeing a longer survival term.

Method for diagnosing neoplastic lesions by quantitative fluorescence value

Fluorescence visualization devices (FVs) are useful for detecting malignant lesions because of their simple and noninvasive application. However, their quantitative application has been challenging. This study aimed to quantitatively and statistically evaluate the change in fluorescence intensity (FI) during the progression from normal epithelium to squamous cell carcinoma using a reproducible animal tongue carcinogenesis model. To establish this model, rats were treated with 50 ppm 4-Nitroquinoline 1-oxide (4NQO) in their drinking water for 10, 15, and 20 weeks. After 4NQO administration, each rat tongue was evaluated by gross observation, histology, and FI measurements. Fluorescence images were captured by FV, and ImageJ was used to measure FI, which was analyzed quantitatively and statistically. The establishment of a reproducible tumor progression model was confirmed, showing precancerous lesions (low-grade dysplasia [LGD]), early cancers (high-grade dysplasia/carcinoma in situ [HGD/CIS]), and advanced cancers (Cancer). This carcinogenesis model was quantitatively evaluated by FI. The FI of LGD stage was 54.6, which was highest intensity of all groups. Subsequently, the HGD/CIS and Cancer stages showed decreased FI (HGD/CIS: 46.1, Cancer: 49.1) and manifested as dark spots. This result indicates that FI had more variation and a wider range with increasing tumor progression. We demonstrated that FI migration and an uneven distribution are consistent with tumor progression. Since each step of tumor progression occurs reproducibly in this animal model, statistical evaluation was possible. In addition, tumor progression can be monitored by this new FI analysis method in humans.

An Overview on Current Non-invasive Diagnostic Devices in Oral Oncology

Oral squamous cell carcinoma (OSCC) is the most common head and neck malignancy, and despite advances in cancer therapies, the overall 5-year survival rate has remained below 50% over the past decades. OSCC is typically preceded by potentially malignant disorders (PMD), but distinguishing high-risk from low-risk PMD is challenging. In the last years, several diagnostic methods as light-based detection systems (LBDS) have been proposed to facilitate the detection of OSCC and PMD. Furthermore, the recent evolution of nanotechnology may provide new opportunities to detect PMD and OSCC at an early stage. Indeed, several preclinical studies showed the potential of nanotechnology to enhance diagnostic accuracy. For these reasons, it is fundamental to conduct studies to evaluate the efficacy of nanotechnology implementation in LBDS. The aim of this article is to review the current literature on LBDS and to provide a summary of the sensitivity and specificity of each technique, and possible future applications of nanotechnologies. The LBDS showed great potential for screening and monitoring oral lesions, but there are several factors that hinder an extensive use of these devices. These devices seem to be useful in assessing lesion margins that must be biopsied. However, to date, conventional oral examination, and tissue biopsy remain the gold standard for OSCC diagnosis. The use of nanotechnologies could be the next step in the evolution of LBDS, thus providing devices that can help clinicians to detect and better monitor oral lesions.

Evaluation of the diagnostic efficacy and spectrum of autofluorescence of benign, dysplastic and malignant lesions of the oral cavity using VELscope

OBJECTIVES

Conventional oral examination and biopsy are the only reliable methods for the early detection of oral cancer at present. Autofluorescence examination of oral tissues using the VELscope has been suggested as an adjunctive tool for cancer detection and diagnosis. The aim of our study was to evaluate the efficacy of the VELscope in recognizing dysplastic and/or neoplastic changes in oral mucosal lesions that were identified on conventional oral examination.

MATERIALS AND METHODS

Two hundred patients with oral mucosal lesions were subjected to conventional oral examination followed by VELscope examination and their autofluorescence characteristics were compared with the histopathological diagnosis. The sensitivity, specificity, positive and negative predictive values of the VELscope examination was calculated.

RESULTS

The VELscope examination showed sensitivity and specificity values of 76% (95% CI: 54.87-90.64%) and 66.29% (95% CI: 58.76-73.24%) respectively while the positive and negative predictive values were 24.36% (95% CI: 19.22-30.36%) and 95.08% (95% CI: 90.52-97.51%) respectively.

CONCLUSION

The VELscope examination alone cannot provide a definitive diagnosis as to the presence of dysplastic tissue change. In spite of having a reasonable sensitivity, the high number of false-positive results limits its efficiency as an adjunct. However, a high negative predictive value can serve to alleviate patient anxiety regarding suspicious mucosal lesions in a general practice setting.

Portable LED-induced autofluorescence spectroscopy for oral cancer diagnosis

Oral cancer is a serious and growing problem in many developing and developed countries. To improve the cancer screening procedure, we developed a portable light-emitting-diode (LED)-induced autofluorescence (LIAF) imager that contains two wavelength LED excitation light sources and multiple filters to capture ex vivo oral tissue autofluorescence images. Compared with conventional means of oral cancer diagnosis, the LIAF imager is a handier, faster, and more highly reliable solution. The compact design with a tiny probe allows clinicians to easily observe autofluorescence images of hidden areas located in concave deep oral cavities. The ex vivo trials conducted in Taiwan present the design and prototype of the portable LIAF imager used for analyzing 31 patients with 221 measurement points. Using the normalized factor of normal tissues under the excitation source with 365 nm of the central wavelength and without the bandpass filter, the results revealed that the sensitivity was larger than 84%, the specificity was not smaller than over 76%, the accuracy was about 80%, and the area under curve of the receiver operating characteristic (ROC) was achieved at about 87%, respectively. The fact shows the LIAF spectroscopy has the possibilities of ex vivo diagnosis and noninvasive examinations for oral cancer.