Optical spectroscopy may be used for in vivo, noninvasive distinction of malignant from normal tissue. The aim of our study was to analyze the accuracy of various optical spectroscopic techniques for the classification of cancerous lesions of the bronchial tree. We developed a fiberoptic instrument allowing the measurement of autofluorescence spectroscopy (AFS), diffuse reflectance spectroscopy (DRS), and differential path length spectroscopy (DPS) during bronchoscopy. Spectroscopic measurements were obtained from 191 different endobronchial lesions (63 malignant and 128 nonmalignant) in 107 patients. AFS, DRS, and DPS sensitivity/specificity for the distinction between malignant and nonmalignant bronchial lesions were 73%/82%, 86%/81%, and 81%/88%, respectively. All three optical spectroscopic modalities facilitate an increase of the positive predictive value of autofluorescence bronchoscopy for the detection of endobronchial tumors. Even better results were obtained when the three spectroscopic techniques were combined. Key Words: autofluorescence bronchoscopy ¿ lung cancer ¿ optical spectroscopy@en

Detection of malignancies of the bronchial tree in an early stage, such as carcinoma in situ (CIS), augments the cure rate considerably. It has been shown that the sensitivity of autofluorescence bronchoscopy is better than white light bronchoscopy for the detection of CIS and dysplastic lesions. Autofluorescence bronchoscopy is, however, characterized by a low specificity with a high rate of false positive findings. In the present paper we propose to combine autofluorescence bronchoscopy with optical spectroscopy to improve the specificity of autofluorescence imaging, while maintaining the high sensitivity. Standard autofluorescence bronchoscopy was used to find suspect lesions in the upper bronchial tree, and these lesions were subsequently characterized spectroscopically using a custom made fiberoptic probe. Autofluorescence spectra of the lesions as well as reflectance spectra were measured. We will show in this preliminary report that the addition of either of these spectroscopic techniques decreases the rate of false positives findings, with the best results obtained when both spectroscopic modalities are combined. Keywords: Autofluorescence spectroscopy; Reflectance spectroscopy; Lung cancer; Bronchoscopy@en