Lymph node detecting apparatus

A sentinel lymph node detecting apparatus 1 includes: an excitation light source unit 2 that illuminates an excitation light 10 onto a living body observation portion 20 including a sentinel lymph node 21 near a tumor into which a fluorescent dye that emits fluorescence is injected; an optical filter 3 that transmits a fluorescence image 11; an image pickup device 4 that is integral with excitation light source unit 2 and picks up fluorescence image 11 transmitted through optical filter 3; an adjusting device 5 that adjusts the picked-up observation image; and an image displaying device 6 that displays the adjusted observation image. Adjusting device 5 adjusts at least one of a luminance and a contrast of the observation image. A lymph node detecting apparatus that is simple in apparatus arrangement, is easy to handle, and enables good images to be obtained is thereby realized.

TECHNICAL FIELD

This invention relates to a lymph node detecting apparatus for detecting a sentinel lymph node or other lymph node by use of a fluorescence image generated by a fluorescent dye.

BACKGROUND ART

A sentinel lymph node is a lymph node that is first reached by cancer cells from a tumor via lymph flow and is the lymph node with the highest possibility of metastasis by the cancer cells. Thus, if the sentinel lymph node is identified correctly and if metastasis by cancer cells is not found therein, it can be considered that there is no metastasis to other organs. Significant reductions in physical and psychological burdens placed on a patient, restraining of treatment costs by omission of ablative surgery, etc., are thus anticipated.

As methods of detecting the sentinel lymph node, dye methods and RI (radioisotope) methods are mainly known. With a dye method, for example, a blue dye, such as indigo carmine, is injected close to a tumor, the lymphatic duct that is dyed in blue is traced visually, and the lymph node that is reached first is detected as the sentinel lymph node. With the RI method, for example, a radioisotope that serves as a tracer is injected close to a tumor, a living body observation portion that is presumed to include the lymph node, at which the radioisotope first arrives and accumulates, is probed from above the skin by a gamma probe, and the living body observation portion at which gamma rays are sensed is detected as the sentinel lymph node.

Methods of identifying a sentinel lymph node using a fluorescent dye have also been proposed. With the sentinel lymph node detecting apparatus disclosed in Patent Document 1, a fluorescent dye is injected close to a tumor in advance, and light of a predetermined wavelength is illuminated as excitation light onto a living body observation portion that is presumed to include the sentinel lymph node in the periphery of the tumor. Identification of the sentinel lymph node is then carried out by converting and displaying a fluorescence image of the near-infrared wavelength band that is generated from the living body observation portion, to and as a visible image.Patent Document 1: Japanese Patent Application Laid-Open No. 2001-299676

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

However, with the above-described conventional dye method, abundant experience is required to visually trace the lymphatic duct that is dyed in blue, and once the position of the sentinel lymph node is lost track of, the dyeing must be repeated.

With the above-described conventional RI method, though the above-mentioned experience for visually tracing a lymphatic duct and repeating of dyeing are not required, there are such issues as the danger of exposing the surroundings to radiation due to use of a radionuclide, radioisotopes being expensive, etc.

With the above-described conventional sentinel lymph node detecting apparatus that uses a fluorescent dye, though there is no danger of exposure to radiation, the apparatus arrangement is complicated and difficult to handle in medical situations, and good images cannot be obtained necessarily.

The present invention has been made to resolve the above issues and an object thereof is to provide a lymph node detecting apparatus that is simple in apparatus arrangement, is easy to handle, and enables good images to be obtained.

Means for Solving the Problem

In order to achieve the above object, this invention provides a lymph node detecting apparatus that includes: an excitation light source, illuminating excitation light onto a living body observation portion that includes a lymph node near a tumor into which a fluorescent dye that emits fluorescence of a predetermined wavelength has been injected in advance; an optical filter, transmitting a fluorescence image generated from the living body observation portion; an image pickup means for picking up the fluorescence image transmitted through the optical filter; an adjusting means for adjusting at least one of a luminance and a contrast of an observation image output from the image pickup means; and an image displaying means for displaying the observation image, adjusted by the adjusting means, as an image for detecting the lymph node.

By arranging the above-described lymph node detecting apparatus to have the adjusting means that adjusts at least one of the luminance and the contrast of the observation image output from the image pickup means, display of good images is realized. A detecting apparatus that enables lymph nodes to be detected readily is thereby realized. Such a detecting apparatus is especially useful for detecting the above-mentioned sentinel lymph node.

Here, the image pickup means is preferably arranged as being integral with the excitation light source. By providing such an arrangement in which the excitation light source and the image pickup means are disposed integrally, an apparatus that is simple in apparatus arrangement and easy to handle is realized. Also, with such an arrangement, the device can be made compact and inexpensive.

The optical filter preferably transmits the fluorescence image and transmits, at a predetermined light intensity, a reflection image from the living body observation portion illuminated by the excitation light. An observation image, in which the fluorescence image and the reflection image are overlapped, can thereby be obtained and ascertainment of the position of the lymph node in the living body observation portion is facilitated.

The image displaying means is preferably mountable onto a head portion of an observer. The need to hold the lymph node detecting apparatus by a hand during observation is thereby eliminated and the degree of freedom of tasks besides observation can be increased.

An image recording means for recording the observation image adjusted by the adjusting means may furthermore be equipped. Observation images during observation can thereby be recorded.

The lymph node detecting apparatus may furthermore be equipped with a light guide means for guiding the excitation light from the excitation light source to the living body observation portion, and an image guide means for guiding the fluorescence image from the living body observation portion to the image pickup means. In this case, the lymph node detecting apparatus is arranged as an endoscopic apparatus. The portion of a living body that is to be incised can thereby be made small. Also, image pickup can be performed close to a lymph node to enable the lymph node to be detected at higher precision.

Effects of the Invention

By this invention, a lymph node detecting apparatus that is simple in apparatus arrangement, is easy to handle, and displays good images can be realized.

DESCRIPTION OF SYMBOLS

BEST MODES FOR CARRYING OUT THE INVENTION

Preferred embodiments of a lymph node detecting apparatus according to this invention shall now be described in detail along with the drawings. In the description of the drawings, elements that are the same are provided with the same symbol and overlapping description shall be omitted. The dimensional proportions in the drawings do not necessarily match those of the description.

FIG. 1is an arrangement diagram of a first embodiment of a sentinel lymph node detecting apparatus that is a lymph node detecting apparatus according to this invention.FIG. 2is a perspective view of an arrangement of an excitation light source unit and an image pickup device used in the detecting apparatus shown inFIG. 1. The arrangement of the sentinel lymph node detecting apparatus of the embodiment shall now be described with reference toFIGS. 1 and 2.

With this sentinel lymph node detecting apparatus1, an excitation light10of a predetermined wavelength is illuminated onto a living body observation portion20of a human body or other living body that includes a sentinel lymph node21, and the sentinel lymph node is detected by observation of an image (fluorescence image11) due to fluorescence emitted from living body observation portion20. In the detection of the sentinel lymph node using this detecting apparatus1, a fluorescent dye is injected close to a tumor inside living body observation portion20in advance. The fluorescence from the fluorescent dye that accumulates in the sentinel lymph node is then observed to detect the lymph node. The fluorescent dye used is selected suitably in consideration of the specific arrangement of detecting apparatus1, etc., and as an example of such a fluorescent dye, indocyanine green can be cited.

Detecting apparatus1, shown inFIG. 1, includes an excitation light source unit2, an optical filter3, an image pickup device4, an adjusting device5, and an image displaying device6. Excitation light source unit2has a plurality of excitation light sources2aand a supporting plate2b, on one surface of which excitation light sources2aare installed. Each of the plurality of excitation light sources2ais a light source that emits, as the excitation light, light of the same wavelength and is used to illuminate excitation light10onto living body observation portion20that includes sentinel lymph node21. Also, as shown inFIG. 2, excitation light sources2aare arrayed two-dimensionally with a central axis Ax of excitation light source unit2, which is an optical axis of detecting apparatus1, as a symmetry axis.

As excitation light source2a, a laser diode (LD) or a light emitting diode (LED) is preferably used. The wavelength of excitation light10supplied from excitation light source2ais selected, based on the light absorbing characteristics, etc., of the fluorescent dye used for observation, to be a wavelength that can excite the fluorescent dye. For example, if the above-mentioned indocyanine green is used as the fluorescent dye, the light absorption band thereof is in the near-infrared wavelength band, and thus, a wavelength (such as a wavelength of 730 nm) within this wavelength band is selected and used as suited.

Supporting plate2bis provided with an opening2cat a central position that includes central axis Ax. This opening2clets fluorescence image11, which is generated from living body observation portion20and enters from the front side of excitation light source unit2, to pass through to the rear. The above-mentioned plurality of excitation light sources2aare arrayed two-dimensionally so as to surround opening2c. With such an arrangement, to prevent the intensity distribution of excitation light10that is illuminated toward living body observation portion20from being weak at the center due to the influence of opening2c, the optical axes of excitation light sources2anear opening2care preferably inclined toward central axis Ax.

Inside opening2cof supporting plate2bis installed optical filter3, which, of the light from living body observation portion20that is to be the object of observation, transmits light of the wavelength band of fluorescence image11generated from living body observation portion20. As optical filter3, that having transmittance characteristics of cutting reflected light resulting from the reflection of excitation light10by living body observation portion20and other light of wavelengths besides fluorescence image11, is preferably used.

Image pickup device4is installed at the rear of excitation light source unit2. In the present embodiment, image pickup device4is disposed integrally with excitation light source unit2with optical axis Ax being matched. Fluorescence image11, generated from the fluorescent dye in living body observation portion20that is excited by excitation light10illuminated from excitation light source2a, thus reaches image pickup device4upon being transmitted through opening2cof supporting plate2band optical filter3. Image pickup device4picks up the incident fluorescence image11and outputs an obtained observation image as image data.

As image pickup device4, for example, a CCD camera that can acquire a two-dimensional image is used. In particular, an image pickup device that can pick up light of the wavelength band of fluorescence image11(normally a near-infrared wavelength band, since a fluorescence image of approximately 800 nm is subject to detection) at high sensitivity is preferably used as image pickup device4. To the plurality of excitation light sources2aand image pickup device4, an excitation light source power supply and an image pickup device power supply are respectively connected as necessary. However, the power supplies, etc., are omitted from illustration inFIG. 1. As these devices, those that are battery-driven may be used.

Adjusting device5is provided for the observation image output from image pickup device4. This adjusting device5is an adjusting means for automatically or manually adjusting the image data of the observation image output from image pickup device4. Adjusting device5in the present embodiment has a luminance adjusting part5band a contrast adjusting part5cthat perform adjustments of luminance and contrast, respectively, on the observation image from image pickup device4. The conditions of adjustment of the observation image in adjusting parts5band5care instructed from an adjustment instructing part5a. Adjustment instructing part5asets the adjustment conditions of the observation image automatically or according to inputs from an observer. However, if the adjustment conditions are fixed, such an adjustment instructing part5adoes not have to be provided. For transmission of the image data from image pickup device4to adjusting device5, a wired or a wireless transmission method may be used.

Image displaying device6and image recording device7are connected to adjusting device5. As an image for detecting sentinel lymph node21, image displaying device6displays observation image15, adjusted at adjusting device5, on a display part6athereof. As this image displaying device6, for example, a CRT monitor, a liquid crystal display mounted to the CCD camera that is image pickup device4, etc., may be used. Image recording device7is a recording means for recording the data of the observation image adjusted at adjusting device5. As this image recording device7, for example, a videotape recorder that records the observation image onto a videotape that is a recording medium may be used.

A method for detecting a sentinel lymph node using sentinel lymph node detecting apparatus1shown inFIG. 1shall now be described. First, the fluorescent dye, indocyanine green is injected close to a tumor. After the elapse of a predetermined time, the indocyanine green reaches sentinel lymph node21due to lymph flow. When excitation light10of the predetermined wavelength (for example, a wavelength of 730 nm) is then illuminated by excitation light source unit2onto living body observation portion20that includes sentinel lymph node21, fluorescence image11of the near-infrared wavelength band is generated from living body observation portion20by the indocyanine green. Here, fluorescence image11is transmitted through while the reflected light from living body observation portion20, illuminated by excitation light10, is cut by optical filter3.

Fluorescence image11, transmitted through optical filter3, is then picked up by the CCD camera that is image pickup device4and the data of the observation image is output from the CCD camera to adjusting device5. Adjusting device5performs luminance and contrast adjustments on the observation image from image pickup device4. Adjusted observation image15, used for detecting the sentinel lymph node, is thus generated. By this image15being displayed on display part6aof image displaying device6, easy detection of sentinel lymph node21is realized. Image15is also recorded as necessary into the recording medium at image recording device7.

The effects of sentinel lymph node detecting apparatus1according to the above-described embodiment shall now be described.

Detecting apparatus1, shown inFIG. 1, has the arrangement where excitation light source unit2, having excitation light sources2athat illuminate excitation light10onto living body observation portion20, and image pickup device4, that picks up fluorescence image11, are disposed integrally. Matching of the optical axes of excitation light source unit2and image pickup device4and other installation adjustment work are thus made unnecessary. Also, with this arrangement, there is no need to move excitation light source unit2and image pickup device4separately in moving detecting apparatus1. Detecting apparatus1of a simple apparatus arrangement and easy handling is thus realized.

Also, the observation image acquired at image pickup device4is not displayed as it is on image displaying device6, but the luminance and the contrast of the observation image are adjusted by means of adjusting device5and the adjusted observation image15is used as the image for detecting the sentinel lymph node. Display of a good image of living body observation portion20is thereby realized. By the above arrangement, detecting apparatus1that enables sentinel lymph node21to be detected readily is realized. Also, with this arrangement, the apparatus can be made compact and inexpensive. In regard to the positioning of adjusting device5, it is preferably disposed close to or inside image pickup device4.

Also, with excitation light source unit2, shown inFIGS. 1and2, by two-dimensional arraying of the plurality of excitation light sources2a, excitation light10can be illuminated uniformly across a predetermined range onto living body observation portion20. Excitation light source2apreferably has a function for adjusting the light intensity thereof. Also, optical filter3is preferably installed in front of a lens of image pickup device4or within image pickup device4.

Adjusting device5, image displaying device6, and image recording device7may be set up separately from or integrally with excitation light source unit2and image pickup device4. As image displaying device6, an arrangement (such as a goggle type or glasses type arrangement) that can be mounted onto a head portion of the observer as in the case of an image displaying device60shown inFIG. 3is preferably used. The need to move or hold image displaying device6, etc., with a hand during observation is thereby eliminated and the degree of freedom of work besides observation can be increased. In this case, the excitation light sources, the image pickup device, the adjusting device, and other components besides image displaying device6may be arranged to be integrally mounted along with the image displaying device.

Also, with the present embodiment, image recording device7is provided for the adjusted observation image from adjusting device5. The observation image during observation can thereby be recorded. However, such an image recording device7does not have to be provided if it is unnecessary.

Optical filter3, which selectively transmits fluorescence image11from among the light from living body observation portion20, may transmit, at a predetermined light intensity, a reflection image from living body observation portion20illuminated by excitation light10. As schematically shown inFIG. 4, an observation image, such as shown inFIG. 4(c), in which a fluorescence picture image, such as shown inFIG. 4(a) that corresponds to a fluorescence image, and a normal picture image, such as shown inFIG. 4(b) that corresponds to a reflection image, are overlapped, can thereby be obtained. The ascertainment of the position of sentinel lymph node21in living body observation portion20can thereby be facilitated.

When such an optical filter that transmits the reflection image (normal image) of the excitation light from living body observation portion20at a predetermined intensity is used, the reflection image is preferably transmitted at a light intensity no more than the fluorescence intensity of the fluorescence image, and especially in order to clearly distinguish fluorescence image11, the reflection image is preferably transmitted at an intensity of no more than 10% and preferably approximately 10% of the fluorescence image.

The arrangement of adjusting device5and the adjustments of the luminance and the contrast of the observation image shall now be described with a specific example.FIG. 5is a block diagram of an arrangement example of the adjusting device used in the detecting apparatus shown inFIG. 1.

With this example, adjusting device5has, in addition to adjustment instructing part5a, luminance adjusting part5b, and contrast adjusting part5cmentioned above withFIG. 1, a signal separating circuit5dand a signal synthesizing circuit5e. Normally, a composite video signal, made up of a video signal and a synchronizing signal, is output as the image data from image pickup device4that acquires the two-dimensional image. The composite video signal of the observation image that is input into adjusting device5from image pickup device4is separated into the synchronizing signal and the video signal at signal separating circuit5d, and of these signals, the video signal is input into luminance adjusting part5band contrast adjusting part5c. Adjusting parts5band5cperform luminance and contrast (gain and offset) adjustments on the video signal according to adjustment conditions instructed from adjustment instructing part5a. The video signal adjusted at adjusting parts5band5cand the synchronizing signal are then synthesized again by signal synthesizing circuit5eand output as the composite video signal of the adjusted observation image to image displaying device6.

Such adjustments of the observation image are especially useful in the case where the optical filter, which transmits, in addition to the fluorescence image (fluorescence picture image), the reflection image (normal picture image) from the living body observation portion at the predetermined intensity, is used as described above.FIG. 6shows graphs relating to luminance and contrast adjustments of an observation image by the adjusting device.FIG. 7shows photographs of examples of luminance and contrast adjustments of an observation image by the adjusting device.

When the optical filter, which transmits a portion of the reflection image, is used as described above, the normal picture image and the fluorescence picture image are mixed in the video signal as shown inFIG. 6(a). By performing an adjustment of enhancing the contrast on this video signal as shown inFIGS. 6(b) and7(a), an image in which the lymph node appears clearly can be obtained. Also, by performing an adjustment of enhancing the luminance as shown inFIGS. 6(c) and7(b), the position of the lymph node in the living body observation portion can be ascertained clearly from the image in which the normal picture image and the fluorescence picture image are overlapped. By thus performing luminance and contrast adjustments on an observation image, a good observation image can be obtained. As the specific adjusting method, suitable settings may be made according to the purpose as in the examples of adjusting the luminance or contrast. In general, adjusting device5is arranged to adjust at least one of the luminance and the contrast of the observation image.

The lymph node detecting apparatus according to this invention shall now be described further.

FIG. 8is an arrangement diagram of an endoscopic apparatus that is a second embodiment of the lymph node detecting apparatus according to this invention.

With this endoscopic apparatus100, an excitation light110of a predetermined wavelength is illuminated onto a living body observation portion120of a living body that includes a sentinel lymph node or other lymph node121, and the lymph node is detected by observation of an image (fluorescence image111) due to fluorescence emitted from living body observation portion120.

Endoscopic apparatus100, shown inFIG. 8, includes an excitation light source unit102, an optical filter103, an image pickup device unit104, an adjusting device105, an image displaying device106, and a fiberscope150. Fiberscope150includes a long, thin, flexible inserted portion150athat is inserted into a body and used to observe living body observation portion120, and a manipulating portion150bthat is disposed at a base portion with respect to inserted portion150a.

Fiberscope150is provided with a light guide optical fiber151, which is a light guide means that guides excitation light110from excitation light source unit102to living body observation portion120, and an image guide optical fiber152, which is an image guide means that guides the fluorescence image from living body observation portion120to image pickup device unit104. Also, lenses151aand152aare disposed at respective end portions at the inserted portion150aside of optical fibers151and152.

Excitation light source unit102is connected to an end portion at the manipulating portion150bside of light guide optical fiber151. This excitation light source unit102has a single excitation light source102aand an excitation light source power supply102b. Excitation light source102ais arranged from a light source that emits light of the predetermined wavelength as the excitation light, and is used to illuminate excitation light110onto living body observation portion120that includes lymph node121. The same description as that provided in relation toFIG. 1applies in regard to the wavelength, etc., of excitation light110.

Image pickup device unit104is connected to an end portion at the manipulating portion150bside of image guide optical fiber152. This image pickup device unit104has optical filter103that transmits light of the wavelength band of fluorescence image111generated from living body observation portion120, and an image pickup device104athat picks up fluorescence image111that has been transmitted through optical filter103. Also, an image forming optical system104b, including an image forming lens104c, is disposed between optical fiber152and image pickup device unit104.

Adjusting device105is provided for an observation image output from image pickup device104a. As with adjusting device5shown inFIG. 1, adjusting device105of the present embodiment has a luminance adjusting part105band a contrast adjusting part105cthat respectively perform luminance adjustment and contrast adjustment on the observation image from image pickup device104a. The conditions of the adjustments of the observation image at adjusting parts105band105care instructed from an adjustment instructing part105a.

Image displaying device106and an image recording device107are connected to adjusting device105. Image displaying device106displays observation image115, adjusted at adjusting device105, on a display part106aas an image for detecting sentinel lymph node121. Image recording device107is a recording means for recording the data of the observation image adjusted at adjusting device105.

As with detecting apparatus1, shown inFIG. 1, with endoscopic apparatus100that is the lymph node detecting apparatus shown inFIG. 8, the observation image acquired by image pickup device104ais not displayed as it is on image displaying device106but the luminance and the contrast of the observation image are adjusted by means of adjusting device105, and the adjusted observation image115is used as the image for detecting the lymph node. The display of a good image of living body observation portion120is thereby realized. By the above arrangement, endoscopic apparatus100that enables lymph node121to be detected readily is realized.

Also, by applying the above arrangement to an endoscopic apparatus, the portion of a living body that is to be incised can be made small. Also, image pickup can be performed close to a lymph node to enable the lymph node to be detected at higher precision.

The sentinel lymph node detecting apparatus according to this invention is not restricted to the above-described embodiments and arrangement examples, and various modifications are possible. For example, though in regard to the excitation light source that illuminates excitation light onto a living body observation portion, excitation light source unit2, having a plurality of excitation light sources2a, was used in the above-described embodiment, a single excitation light source may be used instead as in the embodiment shown inFIG. 8. In regard to the image data output from the image pickup device, if noise in the image data is a problem in the case of a live moving image (30 Hz), etc., a recursive filter or other filtering method may be employed to reduce the noise and obtain a clearer fluorescence image. Also, the detecting apparatus of the above arrangement is not restricted to a sentinel lymph node detecting apparatus and can be applied generally as a lymph node detecting apparatus.

In regard to the fluorescent dye used to observe the sentinel lymph node, though a water-soluble fluorescent dye is generally used, since a fluorescent dye, with which a fluorescent dye is dissolved in physiological saline, etc., is generally small in molecular weight, it may not stay in the lymph node that is reached first and may reach a second or a third lymph node. In this case, by using a quantum dot of a diameter of several dozen nm that emits near-infrared fluorescence or a fluorescent tracer, in which a fluorescent reagent is bound to a metal colloid or to latex beads, improvement of the precision of identification of the sentinel lymph node position can be anticipated.

INDUSTRIAL APPLICABILITY

This invention can be used as a lymph node detecting apparatus that is simple in apparatus arrangement, is easy to handle, and enables good images to be displayed.