Improvement of the specificity of cancer detection by autofluorescence imaging in the tracheo-bronchial tree using backscattered violet light.
BACKGROUND
Autofluorescence bronchoscopy (AFB) is a highly sensitive tool for the detection of early bronchial cancers. However, its specificity remains limited due to primarily false positive results induced by hyperplasia, metaplasia and inflammation. We have investigated the potential of blue-violet backscattered light to eliminate false positive results during AFB in a clinical pilot study.


METHODS
The diagnostic autofluorescence endoscopy (DAFE) system was equipped with a variable band pass filter in the imaging detection path. The backscattering properties of normal and abnormal bronchial mucosae were assessed by computing the contrast between the two tissue types for blue-violet wavelengths ranging between 410 and 490 nm in 12 patients undergoing routine DAFE examination. In a second study including 6 patients we used a variable long pass (LP) filter to determine the spectral design of the emission filter dedicated to the detection of this blue-violet light with the DAFE system.


RESULTS
(Pre-)neoplastic mucosa showed a clear wavelength dependence of the backscattering properties of blue-violet light while the reflectivity of normal, metaplastic and hyperplastic autofluorescence positive mucosa was wavelength independent.


CONCLUSIONS
Our results showed that the detection of blue-violet light has the potential to reduce the number of false positive results in AFB. In addition we determined the spectral design of the emission filter dedicated to the detection of this blue-violet light with the DAFE system.
Swiss Federal Institute of Technology (EPFL), Laboratory for Air and Soil Pollution, Station 6, Building CH, 1015 Lausanne, Switzerland.
Tanja
T
Gabrecht
Alexandre
A
Radu
Pierre
P
Grosjean
Bernd
B
Weber
Günther
G
Reichle
Lutz
L
Freitag
Philippe
P
Monnier
Hubert
H
van den Bergh
Georges
G
Wagnières
D001980:Bronchi / Q000473:pathology*; D001984:Bronchial Neoplasms / Q000175:diagnosis*; D001999:Bronchoscopy / Q000379:methods*; D003116:Color; D005453:Fluorescence; D006801:Humans; D012542:Scattering, Radiation; D012680:Sensitivity and Specificity; D014132:Trachea / Q000473:pathology*; D014134:Tracheal Neoplasms / Q000175:diagnosis*