Detection of squamous cell carcinomas and pre-cancerous lesions in the oral cavity by quantification of 5-aminolevulinic acid induced fluorescence endoscopic images

Background and Objectives: Studies of 5-aminolevulinic acid-induced protoporphyrin IX fluorescence have shown a sensitivity of 95-100% for oral cancer diagnosis, but the specificity is only about 50-60%. Here, we explore the applicability of quantifying PPIX fluorescence images to improve the diagnostic specificity and detect early oral lesions. Study Design/Materials and Methods: PPIX Fluorescence endoscopy and imaging were performed on 28 patients with a known or suspected premalignant or malignant oral cavity lesion. A total of 70 biopsies were taken from the tissue sites imaged for histological analysis. The red-to-blue and red-to-green intensity ratios were calculated from the fluorescence images to correlate with histology. Results: Suspicious lesions display bright reddish fluorescence, while normal mucosas exhibit blue color background in the fluorescence images. The red-to-blue and red-to-green intensity ratios of malignant tissues are larger than those of benign tissues. Combining the two ratio diagnostic algorithms yields a sensitivity and specificity of 95% and 97%, respectively, exceeding each diagnostic algorithm alone for discriminating malignant tissue from benign tissue. Conclusions: Quantifying PPIX fluorescence endoscopic images combined with the ratio diagnostic algorithms developed in this study has the potential to significantly improve the noninvasive diagnosis of oral cavity lesions in vivo.