In vivo time-resolved spectroscopy of the human bronchial early cancer autofluorescence

Abstract

Time-resolved measurements of tissue autofluorescence (AF) excited at 405 nm were carried out with an optical-fiber-based spectrometer in the bronchi of 11 patients. The objectives consisted of assessing the lifetime as a new tumor/normal (T/N) tissue contrast parameter and trying to explain the origin of the contrasts observed when using AF-based cancer detection imaging systems. No significant change in the AF lifetimes was found. AF bronchoscopy performed in parallel with an imaging device revealed both intensity and spectral contrasts. Our results suggest that the spectral contrast might be due to an enhanced blood concentration just below the epithelial layers of the lesion. The intensity contrast probably results from the thickening of the epithelium in the lesions. The absence of T/N lifetime contrast indicates that the quenching is not at the origin of the fluorescence intensity and spectral contrasts. These lifetimes (6.9 ns, 2.0 ns, and 0.2 ns) were consistent for all the examined sites. The fact that these lifetimes are the same for different emission domains ranging between 430 and 680 nm indicates that there is probably only one dominant fluorophore involved. The measured lifetimes suggest that this fluorophore is elastin.

Fluorescence Lifetime Techniques in Medical Applications

“…The reported sensitivity of many of these devices for detecting specific diseases stages is high, but their specificity remains limited. 2,42,93 This is due to a number of factors emerging from the difficulty to conduct absolute emission intensity measurements in vivo . The fluorescence intensity measurements are affected by changes in light excitation-collection geometries due to tissue movement, presence and change in concentration of endogenous absorbers (e.g.…”

Rapid diagnosis and intraoperative margin assessment of human lung cancer with fluorescence lifetime imaging microscopy

“…which usually associates with changes of endogenous fluorophores and can be monitored by fluorescence. Recent studies have revealed the potential of autofluorescence imaging [9], [10], [11] and spectroscopy [12], [13] as diagnostic methods, including oral [8] cervical [14], [15] and breast [16] cancers. Since the irregular tissue surface or endogenous absorbers in tissues, the quantitatively measurement of fluorescence intensity remains a challenge [17].…”

Oncology applications: Brain

“…AF from the elastin network in the submucosa provided the major fluorescence signal following 405 nm excitation and was proposed to be used to distinguish tumoral tissue in the human bronchial early cancer (Uehlinger et al 2009); however, these authors did not identify changes in the fluorescence lifetimes in the diseased tissue.…”