Optimal excitation wavelengths for in vivo detection of oral neoplasia using fluorescence spectroscopy

There is no satisfactory mechanism to detect premalignant lesions in the up per aero-digestive tract. Fluorescence spectroscopy has potential to bridge the gap between clinical examination and invasive biopsy; however, optimal excitation wavelengths have not yet been determined. The goals of this stu dy were to determine optimal excitation-emission wavelength combinations to discriminate normal and precancerous/cancerous tissue, and estimate the pe rformance of algorithms based on fluorescence. Fluorescence excitation-emis sion matrices (EEM) were measured in vivo from 62 sites in nine normal volu nteers and 11 patients with a known or suspected premalignant or malignant oral cavity lesion. Using these data as a training set, algorithms were dev eloped based on combinations of emission spectra at various excitation wave lengths to determine which excitation wavelengths contained the most diagno stic information, A second validation set of fluorescence EEM was measured in vivo from 281 sites in 56 normal volunteers and three patients with a kn own or suspected premalignant or malignant oral cavity lesion. Algorithms d eveloped in the training set were applied without change to data from the v alidation set to obtain an unbiased estimate of algorithm performance, Opti mal excitation wavelengths for detection of oral neoplasia were 350, 380 an d 400 nm, Using only a single emission wavelength of 472 nm, and 350 and 40 0 nm excitation, algorithm performance in the training set was 90% sensitiv ity and 88% specificity and in the validation set was 100% sensitivity, 98% specificity. These results suggest that fluorescence spectroscopy can prov ide a simple, objective tool to improve in vivo identification of oral cavi ty neoplasia.