An endoscopic fluorescence imaging system for simultaneous visual examination and photodetection of cancers

Abstract

We describe the design and performance tested during six years of clinical trials of a fluorescence endoscope for the detection and delineation of cancers in several hollow organs. The apparatus is based on the imaging of the laser-induced fluorescence that differs between a tumor and its surrounding normal tissue. The tests are carried out in the upper aerodigestive tract, the tracheobronchial tree, the esophagus, and the colon. In the three former cases an exogenous dye is used (Photofrin II), whereas in the latter case fluorescein molecules conjugated with monoclonal antibodies directed against carcinoembryonic antigen are injected. The decrease of native tissue autofluorescence observed in early cancers is also used for detecting lesions in the tracheobronchial tree. The fluorescence contrast between the tumor and surrounding normal tissue is enhanced by real time image processing. This is done by simultaneously recording the fluorescence image in two spectral domains, after which these two images are digitized and manipulated with a mathematical operator (look-up table) at video frequency. Moreover, the device that is described below allows for an immediate observation of the endoscopic area under white light illumination during fluorescence detection in order to localize the origin of the “positive” fluorescence signals. Typical results obtained in the tracheobronchial tree and in the colon are presented and the sources of false positives and false negatives are evaluated in terms of the fluorescent dye, tissue optical properties, and illumination optics.

In Vivo Fluorescence Spectroscopy and Imaging for Oncological Applications

“…Specialized instrumentation is required for each type of clinical application: lesion detection (14,115,(192)(193)(194), localization and evaluation of the extent of lesions for surgical or biopsy guidance (7), and optimizatiodmonitoring of therapies such as PDT (21,107), laser photocoagulation (4,195) or photorefractive keratectomy (196). The fundamental principle is to exploit the optical contrast, either intrinsic (autofluorescence) or induced (exogenous fluorophorelprecursor), between the lesion and its surrounding normal tissue.…”

“…Illumination of the tissue surface may be done in two distinct ways. In the first, the excitation light delivery fiber is placed in direct contact with the tissue (7), while in the second, essentially used for imaging, a larger surface area of the tissue is illuminated (12,(192)(193)(194). Each approach has advantages and limitations.…”

“…For low signal strength (<-lo0 photons per image element [pixel] per frame), an intensified charge-coupled device (CCD) camera is required. The low fluorescence intensity from the tissue, low collection efficiency and throughput of the imaging system optics, particularly with endoscopes, often limit the image quality (193). Selection of specific fluorescence emission wavelength bands is most commonly done either by a switchable filter in front of a single CCD (197) or by several filter-CCD sets in parallel (18,192,194).…”

Selective noise removal method in low frequency region for fiber bundle-based endoscopy

“…These days it expands other sections; prevention, early detection, diagnosis, staging, and treatment of cancer [1,2]. Various Endoscopic microscopy techniques have been developed for pathology and visual examinations [3]. As a novel noninvasive imaging technique, optical coherence tomography (OCT) provides high-resolution morphological, structural and functional information through the tissues using an endoscope [4].…”

<title>Light-induced autofluorescence for detection of nasopharyngeal carcinoma in vivo</title>

“…[5][6][7][8] Different organ sites in human using various spectral classification algorithms have been summarized in the recent reviews 2-3 , in which multivariate statistical algorithms were common classification strategies with high sensitivity and specificity. [5][6][7][8] Different organ sites in human using various spectral classification algorithms have been summarized in the recent reviews 2-3 , in which multivariate statistical algorithms were common classification strategies with high sensitivity and specificity.…”