Dual-wavelength excitation of mucosal autofluorescence for precise detection of diminutive colonic adenomas.
BACKGROUND
The mucosal layer of the colon contains metabolism-related fluorophores, such as reduced nicotinamide adenine dinucleotide (NADH), which might have the potential to serve as biomarkers for detecting neoplasia.


OBJECTIVE
To examine NADH fluorescence in human colonic adenoma while eliminating the effect of hemoglobin absorption and to develop a novel imaging technique for precise detection of adenomas.


METHODS
Cross-sectional study.


METHODS
A total of 66 endoscopically resected colonic polyps were investigated. After serial acquisition of autofluorescence images between 450 and 490 nm illuminated with dual-wavelength excitation at 365 nm (F(365ex)) and 405 nm (F(405ex)) on cross sections of the samples, ratio images were created by dividing F(365ex) by F(405ex). The excitation-emission wavelength combinations in F(365ex) and F(405ex) were optimized for NADH fluorescence and reference fluorescence.


METHODS
The F(365ex)/F(405ex) ratio in the tumorous (T) and normal (N) mucosa.


RESULTS
F(365ex)/F(405ex) ratio images showed a 1.81- and 1.12-fold higher signal intensity in the adenomas and hyperplastic polyps, respectively, than in the adjacent normal mucosa. The ratio between signal intensities in tumorous mucosa and normal mucosa in F(365ex)/F(405ex) ratio images for tubular adenomas was significantly higher than that for hyperplastic polyps. The signal intensity in F(365ex)/F(405ex) ratio images was not correlated with the hemoglobin concentration index evaluated by reflection images at 550 nm and 610 nm. Diminutive adenomas (<5 mm) and large adenomas were well discriminated in F(365ex)/F(405ex) ratio images.


CONCLUSIONS
Ex vivo experiment.


CONCLUSIONS
These results suggest that the precise measurement of NADH fluorescence intensity together with eliminating the influence of blood hemoglobin concentration serves as a method for visualizing colonic adenomas and that the dual-wavelength excitation method is a promising technique applicable to endoscopic detection of early colonic adenomas.
Department of Pathology and Cell Regulation, Kyoto Prefectural University of Medicine Graduate School of Medical Science, Kyoto, Japan.
Katsuichi
K
Imaizumi
Yoshinori
Y
Harada
Naoki
N
Wakabayashi
Yoshihisa
Y
Yamaoka
Hideyuki
H
Konishi
Ping
P
Dai
Hideo
H
Tanaka
Tetsuro
T
Takamatsu
D000236:Adenoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000378:metabolism*; D003110:Colonic Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D003111:Colonic Polyps / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005453:Fluorescence; D006454:Hemoglobins; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009243:NAD / Q000378:metabolism*
D014408:Biomarkers, Tumor; D006454:Hemoglobins; D009243:NAD