Autofluorescence bronchoscopy: The d-light system

Early malignant changes are difficult to detect by conventional white light bronchoscopy (WLB). These lesions are only a few cell layers thick and som e millimeters in surface diameter. Therefore, the endoscopic changes are ve ry subtle and can be missed even by experienced bronchoscopists. On the oth er hand, dysplasia and carcinoma in situ occur in up to 10% of high risk pa tients. New methods can help to improve the detection rate of these finding s. The most promising technique for this purpose is based on the detection of autofluorescence phenomena. Up to now, several different systems have be en developed, some of them being in the state of clinical evaluation. All f luorescence bronchoscopy systems depend on the individual, subjective exper ience of the investigator. The technical and scientific effort aims firstly to simplify the technical procedure, secondly to objectify the endoscopic findings, and thirdly to increase sensitivity and specificity further on. S ome possibilities to obtain these targets are: (1) Replacement of lasers by conventional white light sources with the advantage of using WLB and autof luorescence bronchoscopy (AFB) in one diagnostic procedure. (2) Development of appropriate image processing routines and implementation of wavelength- resolving spectral analysis. (3) Integration of various filters for emissio n of specific wavelength is necessary to stimulate exogenous fluorescence s ensitizers (e.g. aminolevulinic acid). (4) Combination of various detection methods in one technical system. Some of the above-mentioned targets have been implemented in a newly developed diagnostic system described in detail in this paper. Preliminary results of this system show a more than twofold increase of the sensitivity for early stages by the use of additional AFB in comparison to WLB. Future research should be focused on the use of autof luorescence phenomena on a cellular level too. The diagnosis of early malig nancy should include newly developed cytological methods to preselect patie nts with clinically occult malignancies within a screening program. Finally , these highly selected patients should be investigated by highly efficient interventional fluorescence bronchoscopy methods to localize and to charac terize the malignancy. This will offer the chance for endoscopic therapeuti c procedures and might help to significantly reduce mortality for patients with lung cancer.