fluorescence bronchoscopy

 Q; What purpose fluorescence bronchoscopy serves? 

 Answer: Biologically abnormal tissue such as precancerous lesions, particularly squamous cell dysplasias lose their fluorescent property. Auto-fluorescence bronchoscopy (AFB) is used to detect them. It can be used with a regular bronchoscope where a bronchoscope can switch fluorescent and white light modes.

 AFB scopes highlight differences in red and green fluorescence from the tissues. Squamous dysplasia, carcinoma in situ (CIS), and microinvasive carcinoma have much weaker green fluorescence and slightly weaker red fluorescence than normal tissues at a wavelength of 380 to 440 nm (blue spectrum). 

This decrease in florescence activity is probably due to increased epithelial thickness, and neovascularization. AFB is so far has been utilized to identify lesions at risk of progression to invasive squamous cell carcinoma only. Its utility is not much of value for metastatic or adeno carcinomas.  

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References:

1. Hung J, Lam S, LeRiche JC, Palcic B. Autofluorescence of normal and malignant bronchial tissue. Lasers Surg Med 1991; 11:99. 

2. Qu J, MacAulay C, Lam S, Palcic B. Mechanisms of ratio fluorescence imaging of diseased tissue. Society of Photo-optical Instrumentation Engineers 1995; 2387:71.