One of the most promising modern methods of earlydiagnosis of oncological diseases is fluorescence endoscopy,which makes it possible to reveal malignant sections of tis-sue that are invisible to an ordinary endoscope examination.
The first studies in this area in this country were begunat S. I. Vavilov State Optical Institute �GOI� in the 1980s.This work was set up and carried out on the initiative andwith the support of the director of GOI, CorrespondingMember of the Russian Academy of Sciences, Professor M.M. Miroshnikov, in close collaboration with the staff of phy-sicians of the S. M. Kirov Military-Medical Academy,headed by Professor V. A. Lisovski�.
Using original devices developed at GOI, the lumines-cence was quantitatively estimated in tissues that were eitherextracted from the organism in the form of biopsies and op-eration material or were located in entire organs, access towhich was gained in the process of an endoscopic survey orduring a surgical operation. The studies were carried out inthe light of tetracycline-induced secondary fluorescence, aswell as in the light of intrinsic fluorescence.
In experiments on animals and under clinical conditions,a strengthening of the tetracycline luminescence was ob-served as the atrophic process progressed. The fluorescenceintensity increased by a factor of 2–3 when cancer waspresent. The opposite dependence was observed for intrinsicfluorescence in the blue and green regions. An effect inwhich the intensity of the intrinsic fluorescence decreased incancer tissue was detected and described in biopsies of thestomach, the rectum, and the body and neck of the uterus.1 Inlater papers by the staff indicated above, this effect was con-firmed by direct measurements of the fluorescence intensityduring endoscopic viewing and during operations.2,3 A simi-lar phenomenon, but now in bronchial tissue, was later de-scribed by the staff members of the Oncological ResearchCenter in Vancouver �Canada�.4 It formed the basis of workon commercially available devices from Xillix TechnologiesCorp.5
At present, the possibilities of fluorescence endoscopyhave expanded because of the appearance of new prepara-
739 J. Opt. Technol. 73 �10�, October 2006 1070-9762/2006/1
tions that possess greater selectivity to tumor tissue. A num-ber of these, for example, the domestically manufacturedpreparation Atasens �a derivative of 5-aminolevulinic acid�,which is produced at GNTs Scientific Research Institute ofOrganic Intermediate Products and Dyes �Moscow�, alreadyhas official permission for medical use.
The existing apparatus for fluorescence endoscopy oper-ates by two different methods—by recording spectra or byforming images in fluorescence light. In the former case, theemission spectra are recorded at individual points of the or-ganism by means of a fiber catheter introduced into the in-strumental channel of an endoscope, using laser excitationand a multichannel spectrometer �a laser-induced fluores-cence spectroscopy system�. In the latter case, a fluorescenceimage of the section of the organ is obtained by pre-equipping standard endoscopes with additional modules, in-tended to illuminate the entire field of the endoscope withexciting radiation and by recording its image in fluorescencelight �a fluorescence imaging system�.
There are commercial devices that implement both theformer method �LESA, ZAO Biospek, Russia; WavSTAT IIOptical Biopsy System, SpectraScience Inc., USA� and thelatter method �Onco-LIFE, Xillix Technologies Corp.,Canada; D-Light, Karl Stortz GmbH, Germany�.
We describe below an endoscopic system that providestelevision observation, recording, and photometry of imagesof the mucous membrane of the surface of the inner organsof the gastrointestinal tract in fluorescence light and in ordi-nary light.
THE DV-FENCY 1 SYSTEM
Fluorescence endoscopic studies have a number of fea-tures that must be taken into account when constructing thecorresponding apparatus.
A preparation labeled with a tumor marker in the idealcase gives luminescence only at the site where the tumoritself is located, leaving the sections of normal tissue invis-ible. The absence of an image in the nonfluorescent sectionsmakes it difficult and sometimes quite impossible for thephysician to orient himself in the organ being investigated.
Therefore, it is desirable to form an additional image in re-flected light at the same time with the fluorescence picture.This must be done in such a way that it does not interferewith the recording of the fluorescence image. Moreover, itmust remain possible to make observations in ordinary whitelight, which continue to play an important role in morpho-logical diagnosis. The transition from one method of obser-vation to another must occur efficiently, in order that thedoctor can compare the morphological pictures of the samesection in different lights.
The fluorescence image is much less bright than the or-dinary image. Optics with the minimum light losses and ahigh-sensitivity video camera are needed to record it.
Since diagnosis is based on different brightnesses of thediseased and healthy sections of tissue, it is desirable to pro-vide the possibility of a quantitative estimate of these differ-ences in the process of the studies.
All these considerations were taken into account whencreating the DV-FENCY 1 �Dual Video Fluorescence Endo-scopy System�. It is based on two-channel recording of videofluxes—from a fluorescence channel and a reflected-lightchannel.6–8
The operating principle of the system is shown in thediagram in Fig. 1.
Combined illuminator unit 1, attached to illuminatorchannel 2 of endoscope 3, illuminates object 4 either withshort-wavelength exciting radiation for fluorescence studiesor with white light for ordinary observations. Since each ofthese regimes has its own requirements on the light source,two different lamps are mounted in the illuminator—for gen-erating white light 5 and for generating exciting radiation 6.The illumination regimes are switched by means of folding
FIG. 1. Schematic diagram of the DV-FENCY 1 system. 1—combined il-luminator, 2—illuminator braid, 3—endoscope, 4—object, 5—white-lightlamp, 6—lamp for exciting fluorescence, 7—folding mirror, 8—excitingfilter, 9—video head, 10—color TV camera, 11—high-sensitivity mono-chrome camera, 12—foldable dichroic mirror, 13� and 13�—projection ob-jectives, 14� and 14�—solenoids, 15—emission filter, 16—two-channelframegrabber, 17—computer, 18—monitor, 19—fluorescent comparisonsample.
740 J. Opt. Technol. 73 �10�, October 2006
mirror 7. The spectral region of excitation is separated out byfilter 8.
An image of the section of interest of object 4 is trans-mitted by the optical system of endoscope 3 into video head,9 in which two television cameras are mounted: color camera10, intended to receive an image in reflected light, and high-sensitivity monochrome camera 11, intended to receive im-ages in the light of the fluorescence emission. Besides thecameras, the video head contains folding dichroic mirror 12,two projection objectives 13� and 13�, emission filter 15, andsolenoid 14�.
The operating regimes of the device depend on the po-sitions of mirrors 7 and 12. When they are in position W,ordinary observation is carried out—the object is illuminatedwith white light, and a “full-color” image is recorded bymeans of a color television �TV� camera. Position F of themirrors corresponds to the regime of fluorescence studies. Inthis case, the object is illuminated with exciting radiation inthe blue-green region, and the exciting radiation reflectedfrom the object and the longer-wavelength fluorescence ra-diation generated by it are separated by a dichroic beamsplit-ter into two different TV channels: a color channel for ob-serving the object in reflected light and a monochromechannel for observing the object in fluorescence light. Emis-sion filter 15 is intended to transmit only the fluorescenceradiation to the TV receiver.
The signals from both TV cameras arrive at two-channelframegrabber 16, which digitizes them and introduces theminto the memory of computer 17. The computer processorcontrols the operation of the TV systems, processes and ana-lyzes the resulting frames, including measuring the signalintensities in real time, corrects the photometric data, recordsvideo clips, and displays the two TV images on the samemonitor 18. The system also includes comparison sample 19,intended for calibrating the system in the fluorescence re-gime.
THE DV-FENCY 1/GE DEVICE
The system described above is implemented in the DV-FENCY 1/GE device, intended for fluorescence studies ingastroenterology. An external view of the device is shown inFig. 2.
Illuminator 1 �Dual Lighter 1 /3� uses a short-arc DRSh-250-3M mercury lamp �NPP Razryad, Russia� for the fluo-rescence regime, while it uses a M50E011 metal-halide lamp�Welch Allyn, USA� for the white-light regime.
The DRSh-250-3M lamp possesses very bright lines inthe blue-violet region, and this is important for efficient ex-citation of porphyrin fluorescence. The exciting filter, madefrom SZS-22 blue-green glass, separates out a wider regionof short-wavelength radiation in the 370–535-nm region �atthe 50% level�, and this is needed not only for efficient ex-citation of the fluorescence, but also to create more favorableconditions when the object is observed in reflected light. TheM50E011 lamp has a continuous spectrum with a color tem-perature of 5700 K, corresponding to daytime illumination.The large working section of this lamp makes it possible toplace a folding mirror in front of it.
740G. V. Papayan and Uk Kang
The single-array OTV S6 CCD camera �Olympus�, con-sisting of a miniature camera head and a control unit, is usedas a color TV camera, and a special high-sensitivity TVIST-4CCD camera9 is used as a monochromator. The resolution ofthe TVIST-4 CCD camera is 582�752 pixels, the array sizeis 0.5 in., the counting noise does not exceed 10 e−, and theoverall dimensions are 50�50�40 mm. The camera canoperate in the charge-integration regime, making it possibleto increase the sensitivity proportionally to the number ofaccumulated frames. Since a corresponding reduction of theframe frequency occurs in this case, an accumulation greaterthan 3–5 frames is not ordinarily used. Both cameras can beconnected to any standard endoscope via an optomechanicaladapter. Fibroscopes of the Olympus Corp. are used in theDV-FENCY 1/GE device: the GIF-XQ40 gastroscope andthe CF-30L colonoscope. An emission filter made fromKS-11 glass is mounted in the fluorescence channel to trans-mit the fluorescence radiation with ��630 nm and to blockthe exciting radiation.
The moiré effect that results from the beating of spatialfrequencies between the regular fiber braid of the endoscopeand the rasters of the CCD camera is eliminated by a spe-cially developed device, which serves the function of an op-tical filter of low spatial frequencies.
The video fluxes are recorded by means of a two-channel framegrabber, based on SAA7146 and SAA7111video processors �Philips�. This device digitizes the frames
FIG. 2. The DV-FENCY 1/GE device. 1—illuminator, 2—video head,3—system unit of personal computer, 4—main monitor of personal com-puter, 5—additional computer monitor, 6—endoscope, 7—controller ofcolor camera, 8—monitor of color camera, 9—pedal.
741 J. Opt. Technol. 73 �10�, October 2006
of both TV channels and then puts them out to a computer.The white-light-fluorescence operating regimes of the deviceare switched by means of a pedal, which controls the opera-tion of the two solenoids connected to the correspondingmirrors in the illuminator unit and the optical adapter via therelay plate of the framegrabber. For convenience of operationof the physician and his assistants, all the units of the deviceare placed in two racks.
SOFTWARE. OPERATING TECHNIQUE
Special program DUAL VIDEO was developed to supportthe DV-FENCY 1 system. This program monitors the re-gimes of the TVIST-4 camera, records and edits the digitalvideo files, and also measures the fluorescence signals. Itoperates under WINDOWS XP.
Data obtained from a histogram of the brightness distri-bution of the image field are used to estimate the fluores-cence intensity of the object. Such a method allows measure-ments of the brightest sections of the object to be made,regardless of their location in the field. Moreover, these dataare used to implement the “Auto Gain” function, which au-tomatically sets the magnification of the TVIST-4 camera.
Before beginning operation, the system is calibrated, forwhich the endoscope is introduced into an opening of theilluminator with a standard fluorescence sample installed init. All the measured data on the fluorescence brightness ofthe tissue are read in percent of the luminescence of theinternal standard, and this makes it possible to compare theresults obtained under different conditions with each other.
The studies are begun in white light. The images ob-tained from the color camera are displayed on a monitorconnected to the analog output of the controller of the colorTV system, as well as on the computer monitors—the mainone �for the physician� and a supplementary one �for theoperator�. When a suspicious section is detected, video re-cording is switched on, the data being recorded in avi format.When necessary, the physician’s voice is recorded, comment-
FIG. 3. View of the windows displayed by the DUAL VIDEO programduring operation. Top: program menu. Center: synchronously displayedvideo frames of the same object: in reflected blue-green exciting light �left�and in fluorescence light �right�. Below �left to right�: indicator with lumi-nescence intensities in relative units, control window of the TVIST-4 cam-era, window for setting the parameters of the measurements, and window forvideo editing.
741G. V. Papayan and Uk Kang
ing on the observed picture. The transition from one obser-vation regime to another is done by pressing the pedal.
In the regime of fluorescence studies, two images—inreflected blue-green light and in fluorescence light �Fig. 3�—are generated in adjacent windows on the monitor screen ofthe computer. In this case, the fluorescence brightness of theobject is displayed on a digital indicator. Since the brightnessdepends not only on the properties of the object, but also onthe distance between the distal end of the endoscope and thesurface of the object, the measurements are made from afixed distance. The correctness of the fixed distance is moni-tored by means of forceps introduced from the instrumentalchannel of the endoscope.
Even a very careful survey does not guarantee againstmissing some interesting detail; therefore, after the survey iscarried out, the video recording is viewed. A measurement ismade in the individual frames of the coefficient of fluores-cence contrast of the object, which is the ratio of the bright-ness at the focus of the disease to the brightness of a healthysection of tissue. The nonlinear editing functions built intothe program are used to edit the video images in order toeliminate noninformative segments and to compress the data.
USING THE DEVICE IN GASTROENTEROLOGY
The device has undergone medical testing at the clinic ofthe All-Russia Center for Ecological and Radiation Medi-cine, Ministry of the Russian Federation for Civil Defense,Emergencies, and the Elimination of the Consequences of
FIG. 4. Examples of images obtained in fluorescence light on the DV-FENCof the esophagus �AF�, �b� callous ulcer of the stomach �ALA-IF�, �c� malignof the stomach �ALA-IF�, �e� early cancer of the sigmoid intestine �ALA-IF�ALA-IF�.
742 J. Opt. Technol. 73 �10�, October 2006
Natural Disasters. Honored Physician of the Russian Federa-tion A. S. Kondrashin performed the studies. The studieswere carried out both by the technique of ALA-induced fluo-rescence �ALA-IF� using preparation Alasens, and by thetechnique of autofluorescence �AF�.
The operating mechanism of preparation Alasens isbased on the capacity of tumor cells for increased accumu-lation of protoporphyrin IX in the presence of exogenous5-aminolevulinic acid. The intrinsic fluorescence of the cellsin the spectral region ��630 nm is caused by the lumines-cence of endogenous porphyrins. According to the literaturedata, an increase of this substance can also serve as a basisfor diagnosing diseases.
The dosage of preparation Alasens for peroral usage was5–10 mg/kg when studying the stomach and 10–15 mg/kgwhen studying the large intestine. The lifetimes of ALA-IFafter reception of the preparation varied within 2–6 h.
Studies of the dynamics of the fluorescence variation invarious sections of the skin and the mucous membranes ofthe lip and the stomach were also carried out after prepara-tion Alasens was taken. These studies showed that the curvesof the growth of the fluorescence signal in regions of the lipsand temple that are easily accessible for monitoring are simi-lar to the curves that characterize the behavior of the mucousmembrane inside the organism, and it is proposed to use thisfor individual monitoring of the operating efficiency of thepreparation and to choose the optimum time to begin theexamination.
GE device for various diseases of the gastrointestinal tract: �a� Candidiasisolyp of the stomach-early cancer �ALA-IF�, �d� cancer of the output sectionearly cancer on a background of severe dysplasia of the prepyloric section
Y 1/ant p�, �f�
742G. V. Papayan and Uk Kang
In all, 128 fluorescence-endoscopic studies of 111 pa-tients with various disturbances of the gastrointestinal tractwere carried out. Examples of the resulting images areshown in Fig. 4. The sensitivity and specificity of theALA-IF was 96 and 92.1%, respectively. The diagnostic pos-sibilities of AF endoscopy are significantly inferior to thoseof ALA-IF. The fluorescence contrast of malignant tumorswas on the average almost a factor of 3 lower for AF than theanalogous index for ALA-IF. Moreover, the brightness of theAF image was a factor of 6–10 lower than for ALA-IF. Nev-ertheless, AF studies give useful information in a number ofcases—for example, for detecting candidiasis.
CONCLUSION
The DV-FENCY 1 fluorescence endoscopic video sys-tem that has been developed makes it possible to see anobject simultaneously in fluorescence light and in reflectedexciting light, and this allows a physician to easily orienthimself inside the organ. At the same time, it remains pos-sible to carry out high-quality observation in ordinary light.The transition from one observation regime to another ismade efficiently, using a pedal. By using a television mea-surement system, special image-processing algorithms, andthe presence of an internal standard, a quantitative estimatecan be made of the fluorescence brightness. Computer pro-cessing and the recording of video tapes are also possible.The high sensitivity of the system, achieved by optimizingall the elements of the fluorescence-recording tract �a brightlight source, optics with small light losses, a high-sensitivitytelevision camera� makes it possible to record not only thesecondary fluorescence, but also the substantially weaker in-trinsic fluorescence. The possibility of using diverse standardendoscopes of flexible and rigid type allows the system to be
used for studying various internal organs.
743 J. Opt. Technol. 73 �10�, October 2006
Tests of the device under clinical conditions when dis-eases of the gastrointestinal tract were being investigatedshowed that the resulting images had high information con-tent and that it was convenient for the physician-endoscopistto work with.
The authors are grateful to Corresponding Member ofthe Russian Academy of Sciences, Professor M. M. Mirosh-nikov for constant attention and support of the work on fluo-rescence endoscopy, as well as to Honored Physician of theRussian Federation, A. S. Kondrashin, for careful and thor-ough medical testing of the device.
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