Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1996-11-27
2001-02-20
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S431000
Reexamination Certificate
active
06192267
ABSTRACT:
The invention relates to endoscopic or fiberscopic imaging devices using infrared fluorescence.
More particularly, the present invention relates to an angiography device for inspecting a wall of a body cavity of a patient after the patient has been intravenously injected with a pharmaceutically acceptable fluorescent dye, the dye being capable of emitting light at “fluorescence” wavelengths when excited by light at “excitation” wavelengths, the device comprising:
a flexible duct of small section and having a free end which is designed to be inserted in said body cavity to inspect the wall thereof;
excitation means for emitting “excitation” light from said free end in a first range of wavelengths including at least a portion of the excitation wavelengths of the dye;
reception means for receiving, at said free end, an image of the observed wall in a second wavelength range which includes at least a portion of the fluorescence wavelengths of the dye and which has substantially no overlap with the first wavelength range; and
display means for displaying the received image.
Such a device has been disclosed in particular by T. Satoh et al. (“Use of fluorescent electronic endoscopy in evaluation of peptic ulcers”, Endoscopy 1991; 23: 313-316) and subsequently by U. K. Franzeck et al. (“Dynamic fluorescence video-endoscopy for intravital evaluation of gastrointestinal mucosa blood flow”, Gastrointest. Endosc. 1993; 39; 6: 806-809).
When that type of device is used, a fluorescent dye is injected intravenously into a patient. Under the effect of the excitation light, the dye emits fluoresced light making it possible to observe the vascular network in the wall of the body cavity under examination. Since the great majority of visceral lesions are accompanied by considerable vascular modifications, such lesions can thus be found.
The dye with which the above-mentioned known devices are designed to work is fluorescein which has very good fluorescing efficiency. Because fluorescein is excited by light in the visible range and because it fluoresces likewise in the visible range, the first and second wavelength ranges corresponding to the above-mentioned known devices both lie in the visible light spectrum.
Because visible light is absorbed to a great extent by the tissues forming the wall of the body cavity to be observed, those known devices are therefore capable of observing only the superficial vascular network, which is of little interest, clinically speaking.
Further, fluorescein also has the drawback of diffusing in the interstitial tissue that forms the wall to be observed. This generates background fluorescence that degrades the image.
It is therefore desirable to avoid using fluorescein as the dye, and more generally to avoid using a dye whose excitation and fluorescence wavelengths are situated in the visible range.
Elsewhere, G. Panzardi et al. (EP-A-0 554 643 and “Charoidial angiography with indocyanine green dye: absorption and fluorescence techniques”, European Journal of Ophthalmology, Volume 2, No. 2, 1992, pp. 83-85) have disclosed an angiography device enabling the vascular network of a patient's choroid to be observed using indocyanine green as the dye, which has the advantages firstly of making it possible to work in the infrared range, infrared rays being capable of penetrating relatively deeply into tissue, and secondly of not diffusing into tissue outside the vascular network. In addition, indocyanine green is particularly well tolerated by the body.
Unfortunately, indocyanine green fluoresces with very low efficiency, such that the light fluoresced by the wall under observation is likewise of very low level.
Consequently, although the device disclosed by G. Panzardi et al. is suitable for direct observation such as when observing the choroid, it is unsuitable for using fluorescence to observe the wall of a body cavity by means of a fiberscope or an endoscope insofar as a fiberscope gives rise to considerable light attenuation between its inlet and outlet ends, while an endoscope, gives rise to considerable attenuation of excitation light, and a miniature analog camera located at the free end of the endoscope runs the risk of generating considerable background noise because of its miniaturization, thereby degrading the quality of the image and preventing subsequent processing of the image.
An object of the present invention is thus to propose an endoscopic or fiberscopic angiography device using fluorescence that makes it possible to operate in the infrared range, in particular using indocyanine green or any other pharmaceutically acceptable dye that fluorescences in the infrared range, and enabling usable images to be obtained even if the dye used has poor fluorescencing efficiency.
To this end, according to the, invention, a device of the kind in question is essentially characterized in that each of said first and second wavelength ranges lies at least in part in the infrared range, and in that the reception means include a digital sensor for directly transforming the image as sensed into digital signals, and digital processing means for increasing definition, contrast, and brightness in the image as sensed.
Since the excitation light and the fluoresced light both belong to the infrared range, the device of the invention makes it possible to visualize the vascular network of the observed wall in depth.
Also, the image sensed by fluorescence provides an excellent signal
oise ratio because the second wavelength range has substantially no overlap with the first wavelength range, unlike the method of endoscopic angiography by infrared absorption disclosed, in particular, by Hidetoshi Ohta et al. in 1991 (“The near infrared electronic endoscope for diagnosis of esophageal varices”, Gastrointest. Endosc., 1992; 38: 330-335).
Because the light signals are transformed immediately into digital signals, this signal
oise ratio is conserved, thereby making it possible to process the image effectively to improve visibility therein.
In preferred embodiments of the invention, use is made of one or more of the following dispositions:
the first wavelength range lies, at least in part, between 766 nm and 815 nm, and the second wavelength range lies, at least in part, between 825 nm and 840 nm;
the excitation means include a high power polychromatic light source, means for sequentially interrupting emission from the light source, an “excitation” optical fiber for conveying the light emitted by the source to the free end of the flexible duct, and an excitation filter disposed to receive all of the light that also passes along the excitation optical fiber, said excitation filter allowing substantially all of the light in the first wavelength range to pass and absorbing substantially all of the light in the second wavelength range;
the means for sequentially interrupting the emission from the light source comprise a mask disposed upstream from the excitation filter;
the light source is a flash lamp;
the light source is of adjustable power;
the excitation filter is removable;
the device includes three color filters each having a separate passband in the visible range, and means for selectively or successively interposing each of said color filters between the light source and the excitation optical fiber;
the excitation means comprise a monochromatic laser source emitting infrared excitation light, and an “excitation” optical fiber for conveying the light emitted by the laser source to the free end of the flexible duct;
the excitation means apply a narrow excitation light beam on the wall to be observed, and include scanning means for moving the excitation light beam so as to cause it to scan the wall to be observed;
the scanning means comprise a mirror pivotable about two mutually perpendicular axes, and control means for controlling pivoting of the mirror about both of said axes, the excitation light beam reaching said mirror and being reflected thereby towards the wall to be observed;
the excitation light beam passes through a fixed semireflecting mirror before reaching the movin
Quentel Gabriel
Scherninski François
Henderson & Sturm LLP
Lateef Marvin M.
Shaw Shawna J
LandOfFree
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