JP5415805B2 - Diagnosis support device - Google Patents

Description

  The present invention relates to a diagnosis support apparatus that calculates a lifetime of fluorescence from a subject and supports diagnosis.

Conventionally, endoscopes have been used to detect cancer, but overlooking cancers with little change in color tone or cancers that are nearly flat has become a problem. In recent years, fluorescent endoscopes utilizing living body autofluorescence have been put into practical use and are used for early detection of lesions.
Autofluorescence refers to fluorescence from a fluorescent substance that is naturally contained in a living body, and is a term used to distinguish it from drug fluorescence administered from outside the body. In the current autofluorescence endoscope, it is considered that fluorescence generated from collagen in the submucosal layer in the back of the mucous membrane is mainly observed by irradiating excitation light.
In neoplastic lesions such as cancer, the thickness of the mucosal layer covering the submucosal layer increases, and the fluorescence observed by absorption and scattering of the excitation light and fluorescence in the thickened mucosal layer is attenuated.
In addition, tumorous lesions generally have a large amount of blood contained in the tissue, and the fluorescence is attenuated by absorption of excitation light and fluorescence into hemoglobin.
However, since blood volume increases even in inflammatory diseases that are not tumors, there is a problem that it is difficult to distinguish tumors from inflammation under autofluorescence endoscope.

On the other hand, for example, Japanese translations of PCT publication No. 2003-535659 as a first conventional example moves a light guide together with a scanning actuator, scans a region of interest with light, detects light from the region of interest, and shows the characteristics of the light. Disclosed is a fluorescence lifetime analysis performed on the region of interest to generate a signal and determine the biophysical state of the region of interest.

However, although the first conventional example discloses analyzing the fluorescence lifetime, it does not disclose that it is easy to distinguish or discriminate between a neoplastic lesion and an inflammatory disease.

In addition, Japanese Patent Laid-Open No. 2005-283264 as a second conventional example irradiates a plurality of excitation light beams of different wavelength bands on the same material part, detects each fluorescence by a detection means, There is disclosed a fluorescence analysis apparatus provided with a calculation means for analyzing corresponding output signals based on comparison. In this case, the calculation means employs cross-correlation analysis or confocal coincidence analysis, and does not disclose that it is easy to distinguish or discriminate between tumor and inflammation as in the first conventional example.

For this reason, a device that assists diagnosis for an operator by making it easy to distinguish or discriminate between a neoplastic lesion and an inflammatory disease without being affected by fluorescence absorption of blood or the like is desired.
The present invention has been made in view of the above-described problems, and provides a diagnostic support device that can be used for lesion determination such as neoplastic lesions without being affected by a fluorescent absorbing material by using a fluorescence lifetime. Objective.

A diagnosis support apparatus according to one aspect of the present invention includes:
A light source unit that generates excitation light to irradiate the subject;
A detection unit for detecting fluorescence generated by irradiation of the excitation light;
A fluorescence lifetime calculation unit that calculates a first fluorescence lifetime and a second fluorescence lifetime based on the fluorescence detected by the detection unit;
A lesion determination unit that performs lesion determination based on the first fluorescence lifetime and the second fluorescence lifetime;
Have

A diagnosis support apparatus according to another aspect of the present invention provides:
A first light source that irradiates the subject and a light source unit that generates second excitation light having a wavelength different from that of the first excitation light;
A detection unit for detecting first fluorescence generated by irradiation of the first excitation light and second fluorescence generated by irradiation of the second excitation light;
A fluorescence lifetime calculation unit for calculating a first fluorescence lifetime related to the first fluorescence detected by the detection unit and a second fluorescence lifetime related to the second fluorescence detected by the detection unit;
A lesion determination unit that performs lesion determination based on the first fluorescence lifetime and the second fluorescence lifetime ;
Have

  According to the present invention, the fluorescence lifetime can be used to determine lesions such as neoplastic lesions without being affected by the fluorescent absorbing material.

FIG. 1 is a diagram showing a basic configuration of a diagnosis support apparatus of the present invention. FIG. 2 is a diagram showing an overall configuration of the diagnosis support apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram showing a state of time measurement in which fluorescence photons are detected from the irradiation timing of a laser pulse as excitation light generated by a laser light source. FIG. 4 is a diagram showing a schematic configuration of a time correlation single photon measurement system. FIG. 5 is a diagram showing an overall configuration of a diagnosis support apparatus according to the second embodiment of the present invention. FIG. 6 is an explanatory diagram of measuring the fluorescence intensity at two different times in order to calculate the fluorescence lifetime. FIG. 7 is a diagram showing an overall configuration of an endoscope apparatus according to the third embodiment of the present invention. FIG. 8 is an explanatory view of an operation of sequentially irradiating R, G, B light and a laser pulse and variably setting a gain of the photomultiplier. FIG. 9 is a diagram showing the arrangement of illumination fibers and detection fibers at the distal end of the endoscope. FIG. 10 is a diagram showing an overall configuration of a diagnosis support apparatus according to the fourth embodiment of the present invention.

As shown in FIG. 1, the diagnosis support apparatus 71 of the present invention includes a light source unit 72 that generates excitation light that irradiates a subject, and a detection unit 73 that detects fluorescence generated in the subject due to irradiation of the excitation light. Have.
In addition, the diagnosis support apparatus 71 includes a fluorescence lifetime calculation unit 74 that calculates a first fluorescence lifetime and a second fluorescence lifetime based on the fluorescence detected by the detection unit 73, and a first fluorescence lifetime and a second fluorescence lifetime. A lesion determination unit 75 that performs lesion determination based on the fluorescence lifetime.
The diagnosis support apparatus 71 corresponds to diagnosis support apparatuses 1A, 1B, and 1D of the first, second, and fourth embodiments described later, and an endoscope apparatus 1C of the third embodiment. The light source unit 72 corresponds to the laser light sources 2 of the first to third embodiments and the laser light sources 2A and 2B of the fourth embodiment. The laser light sources 2A and 2B generate a laser pulse as the first excitation light and a laser pulse as the second excitation light having a wavelength different from that of the first excitation light.

The detection unit 73 corresponds to the detection units 73A to 73D of the first to fourth embodiments. The detection unit 73D of the fourth embodiment detects the first fluorescence generated by the first excitation light and the second fluorescence generated by the second excitation light, respectively.
The fluorescence lifetime calculation unit 74 corresponds to the fluorescence lifetime calculation circuit 25 of the first to fourth embodiments. The lesion determination unit 75 corresponds to the determination circuit 27 of the first to fourth embodiments.

Here, the fluorescence lifetime used for lesion determination in the present invention will be described.
The fluorescent material absorbs light by excitation light irradiation and transitions to an excited state. However, since it is unstable, it emits fluorescence and returns to its original state. In this case, it generally takes a time on the order of picoseconds to nanoseconds to release the fluorescence from the excited state and return to the original state, and this time is called the fluorescence lifetime.
Specifically, the fluorescence lifetime is defined as the time required for the fluorescence intensity to drop to 1 / e. The fluorescence lifetime is not only different depending on the type of substance, but also changes depending on the state in which the substance is bound to other substances and the surrounding environment such as pH and temperature. However, this fluorescence lifetime is considered to be hardly affected by the absorption even when other absorbing materials that absorb fluorescence exist in the surroundings.
In other words, the method for discriminating tumorous lesions from the fluorescence lifetime absorbs fluorescence such as the mucosal layer thickness and blood volume, which is unavoidable when discriminating neoplastic lesions from the fluorescence intensity measurement results in the conventional example. It is considered that the disadvantage that the fluorescence intensity is affected by the substance can be solved.

On the other hand, various fluorescent substances such as NADH (nicotinamide adenine dinucleotide), FAD (flavin adenine dinucleotide), collagen, porphyrin, and the like exist in the living body. Among these, regarding NADH and FAD, those that exist as NADH or FAD alone and those that bind to proteins in the living body are mixed.
In this case, it is known that a fluorescent substance has a different fluorescence lifetime between a single substance and a substance bound to a protein. Since the binding state with this protein changes depending on the state of cell metabolism, there is a high possibility that even in a neoplastic lesion, the cell metabolism changes and the fluorescence lifetime changes.
The present inventor has compared the fluorescence lifetime of rat lesions and lesions in human colon tumors with normal regions. For example, the wavelength of the excitation light used for the rat was 450 nm for exciting FAD, and the fluorescence detection wavelength was 500 to 540 nm.

And the measurement result of the fluorescence lifetime of the tumor part and normal part of a colon tumor was obtained. This measurement result shows a tendency that the fluorescence attenuates sharply with time in the tumor part as compared with the normal part.
The fluorescence lifetime is calculated by curve-fitting these two measurement result curves with the sum of two exponential functions assuming that two fluorescent substances are present. That is,
I (t) = α ₁・ exp (-t / τ ₁ ) + α ₂・ exp (-t / τ ₂ ) (1)
I: Fluorescence intensity
t: time
α ₁ , α ₂ : fluorescence intensity of each component at t = 0
τ ₁ , τ ₂ : fluorescence lifetime of each component (τ ₁ <τ ₂ )
Using Equation 1, α ₁ , α ₂ , τ ₁ , and τ ₂ are calculated so that the fluorescence intensity I (t) is close to the actually measured curve.

Further, the contribution rate is defined using the fluorescence lifetime of each component. Contribution rate C ₁ of the first component (Write fluorescence lifetime is short), the
C ₁ = α ₁ · τ ₁ / (α ₁ · τ ₁ + α ₂ · τ ₂ ) (2)
Defined by
The average fluorescence lifetime (τ _AVE ) is
_{τ AVE = (α 1 · (} τ 1) 2 tens of ^{_{α 2 · (τ 2) 2}} ) / (α 1 · τ 1 tens of _{α 2 · τ 2) (3} )
As a result of the experiment, τ ₁ and τ ₂ tended to be shorter in the tumor part than in the normal part. Based on such measurement results, a neoplastic lesion is identified as a specific example of lesion determination using the fluorescence lifetime as described in the following embodiments.

(First embodiment)
The configuration and operation of the first embodiment of the present invention will be described below.
As shown in FIG. 2, the diagnosis support apparatus 1 </ b> A according to the first embodiment of the present invention generates a laser pulse as excitation light for irradiating a subject (as the light source unit 72), The endoscope 4 includes a light guide unit that guides the laser pulse from the laser light source 2 and irradiates the living tissue 3 in the body cavity as a subject.
In addition, the diagnosis support apparatus 1A is connected to an endoscope 4 that receives and guides autofluorescence (hereinafter simply abbreviated as fluorescence) from the living tissue 3, and detects the fluorescence from the guided light. The processor 5 having the unit 73A and the like, and the monitor 6 for displaying information of the determination result by the processor 5 are provided.

The laser light source 2 takes out the second harmonic with respect to the fundamental wavelength (800 nm) from a titanium sapphire laser, for example, by a second harmonic generation crystal (SHG crystal). Further, the laser light source 2 emits a laser pulse as an ultrashort pulse light having a wavelength of 400 nm, for example, at a repetition frequency of 10 MHz using a pulse picker or the like. FIG. 3 shows this laser pulse.
An incident end of a light guide fiber 8 serving as a light guide means inserted into the insertion portion 7 of the endoscope 4 is detachably connected to the emission end of the laser light source 2. The laser pulse incident on the incident end is guided to the emission end at the distal end of the light guide fiber 8.

This exit end is disposed at the distal end portion 9 of the insertion portion 7 to be inserted into the body cavity, and a dichroic mirror 11 is disposed opposite to the exit end. The dichroic mirror 11 is set to have a characteristic of reflecting light having a wavelength of 420 nm or less and transmitting light having a wavelength band of 450 nm or more.
The laser pulse reflected by the dichroic mirror 11 is reflected by a MEMS (Micro Electro Mechanical System) mirror 12.
The MEMS mirror 12 scans the laser pulse reflected by the dichroic mirror 11 two-dimensionally. The MEMS mirror 12 has a mirror surface whose angle is changed as indicated by an arrow by a drive signal generated in synchronization with a timing signal from a timing control circuit 13 in the processor 5, for example, and the mirror surface is reflected. The pulse is scanned two-dimensionally.

The timing control circuit 13 controls the emission timing of the laser pulse of the laser light source 2 and detectors 19a and 19b, which will be described later, and a time correlated single photon counting system (abbreviated as TCSPC). 21 controls the fluorescence lifetime calculating circuit 25, the image processing circuit 28, and the like.
The laser pulse that has passed through the MEMS mirror 12 is irradiated as an excitation light pulse through the condenser lens 14 while scanning the living tissue 3 two-dimensionally.
The light containing the fluorescence generated in the living tissue 3 by the laser pulse irradiated by the living tissue 3 is incident on the MEMS mirror 12 through the condenser lens 14.
The light reflected by the MEMS mirror 12 enters the dichroic mirror 11. As described above, the dichroic mirror 121 is set to have a characteristic of reflecting light of 420 nm or less and transmitting light of 450 nm or more. Therefore, the light transmitted through the dichroic mirror 11 contains a lot of fluorescence of 450 nm or more.

The light containing a large amount of fluorescence reflected by the mirror 15 is incident on the distal end of the light guide fiber 16 as the light guiding means, and is emitted from the proximal end by the light guide fiber 16 inserted through the insertion portion 7. The endoscope 4 includes an operation unit 10 on the proximal end side of the insertion unit 7. A configuration without the operation unit 10 may be used.
In the processor 5 to which the base end of the light guide fiber 16 is connected, a dichroic mirror 17 that constitutes the detection unit 73A is disposed facing the base end of the light guide fiber 16.
The dichroic mirror 17 is set to reflect light having a wavelength of 600 nm or more and transmit light having a wavelength of 600 nm or less.
The light transmitted through the dichroic mirror 17 passes through the excitation light cut filter 18a, is received by one detector 19a, and is detected by this detector 19a.
The light reflected by the dichroic mirror 17 passes through the excitation light cut filter 18b, is received by the detector 19b, and is detected by the detector 19b. For these two detectors 19a and 19b, for example, a highly sensitive APD (avalanche photodiode) is used. The detectors 19a and 19b are not limited to the APD, and may be photomultipliers (photomultiplier tubes). The detector 19a and the detector 19b have a function of detecting a single photon.
The excitation light cut filter 18a removes light having the wavelength of the excitation light and transmits a 480 nm to 540 nm light. The excitation light cut filter 18b removes light having the wavelength of the excitation light to obtain 620 nm to 650 nm. A band-pass filter that transmits light.

By the action of the dichroic mirror 17 and the excitation light cut filters 18a and 18b, the detector 19a detects fluorescence near the wavelength of 510 nm, and the detector 19b detects fluorescence near the wavelength of 635 nm. That is, the dichroic mirror 17, the excitation light cut filters 18a and 18b, and the detectors 19a and 19b are different in wavelength from the fluorescence in the first wavelength band as the specific wavelength region and the fluorescence in the first wavelength band. A detection unit 73A that detects fluorescence in the second wavelength band is formed.
The detection operation of the detectors 19 a and 19 b is controlled by the timing control circuit 13.
That is, the timing control circuit 13 stops the detection operation of the other detector 19b when one detector 19a is set to the operating state, and sets the other detector 19b to the operating state. Control is performed to stop the detection operation of one detector 19a.

The detection signals of the detector 19a and the detector 19b are alternately input to, for example, a time correlated single photon counting system (abbreviated as TCSPC) 21. The TCSPC 21 is configured as shown in FIG. 4, for example.
A laser pulse as a pumping light pulse generated by repetition shown in FIG. 3 is detected by a photodiode 22, and a detection signal of the photodiode 22 is input to a time / voltage converter (TAC) 23. Is done. In FIG. 2, the detection signal of the photodiode 22 is input from the laser light source 2 to the TCSPC 21 through a route via the timing control circuit 13.

The photodiode 22 detects a laser pulse branched by a half mirror or the like disposed in the optical path immediately before entering the light guide fiber 8 in the laser light source 2.
The time / voltage converter 23 uses the detection signal of the photodiode 22 as a start signal, and generates a voltage proportional to the time (elapsed time) from the start signal. Further, when a detection signal is input from the detector 19a (same as in the case of the detector 19b), the time / voltage converter 23 stops the change in voltage proportional to time using the detection signal as an end signal.

The time / voltage converter 23 supplies a voltage proportional to the time between the start signal and the end signal to the multichannel analyzer (MCA) 24. The MCA 24 converts this voltage into time and outputs it from the TCSPC 21 to the fluorescence lifetime calculation circuit 25 as the fluorescence lifetime calculation unit 94.
The fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetime as described below from the time information input from the MCA 24. In FIG. 4, the TCSPC 21 is illustrated as including the MCA 24, but the fluorescence lifetime calculating circuit 25 may include the MCA 24.
The fluorescence lifetime calculation circuit 25 accumulates (stores) information on photon detection timing obtained by repeated irradiation of laser pulses in the memory 26 for each scanning position (that is, scanning position).
The information on the scanning position stored in the memory 26 is acquired from the timing control circuit 13, for example.
FIG. 3 shows a state of time measurement from the emission timing of the laser pulse as the excitation light pulse in FIG. 4 to the detection timing at which the fluorescence photon is detected by the detector 19a or the detector 19b. In the example of FIG. 3, the times ta, tb, tc, and td are measured, respectively.
The fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetime from the histograms of the plurality of times measured a plurality of times for each scanning position.
In this way, after irradiation of a predetermined number of laser pulses, based on the information on the time at which the detectors 19a and 19b detected the fluorescence photons, the fluorescence fluorescence lifetime τ ₅₁₀ of the wavelength of 510 nm based on equation (1). And a fluorescence lifetime τ ₆₃₅ of fluorescence having a wavelength of 635 nm are calculated for each scanning position and output to the determination circuit 27 as the lesion determination unit 75.

At the wavelength of 510 nm, the fluorescence of FAD is mainly detected. However, in the case of neoplastic lesions, the fluorescence lifetime τ _510-1 (two components) of the fluorescence lifetime fluorescence lifetime τ ₅₁₀ of ₅₁₀ nm due to metabolic changes of FAD or the like. (When analyzed) shows a shortening characteristic (trend). At a wavelength of 635 nm, mainly porphyrin fluorescence is detected.
Since the fluorescence of porphyrin has a very long fluorescence lifetime as compared with fluorescent substances in other living organisms, the average fluorescence lifetime of a portion containing a large amount of porphyrin is increased.
Since the amount of porphyrin contained in tumor cells often increases, the average fluorescence lifetime at the fluorescence lifetime τ ₆₃₅ of ₆₃₅ nm is longer in the tumor portion (shows a tendency) than in the normal portion.

The determination circuit 27 determines whether or not there is a high possibility of a neoplastic lesion by calculating based on the fluorescence lifetimes τ ₅₁₀ and τ ₆₃₅ of both fluorescence having wavelengths of 510 nm and 635 nm.
As described above, when the fluorescence lifetime of the first component at ₅₁₀ nm is τ _510-1 and the average fluorescence lifetime at ₆₃₅ nm is τ _{635 -AVE} , the discrimination circuit 27 has two fluorescence lifetimes τ _{635 -AVE} and τ _510-1 . The fluorescence lifetime ratio τ _{635 -AVE} / τ _510-1 is calculated as a relative ratio.
Then, the determination circuit 27 determines whether or not it is a neoplastic lesion by comparing the fluorescence lifetime ratio τ _{635 -AVE} / τ _510-1 with the threshold value Vth. That means
τ _635-AVE / τ _510-1 > Vth (4)
If it is, it is determined that there is a high possibility of being a neoplastic lesion, and if Expression 4 is not satisfied, it is determined that there is a low possibility of being a neoplastic lesion.

The determination circuit 27 outputs information on the determination result to the image processing circuit 28 together with the scanning position. The image processing circuit 28 stores information on the determination result in the internal memory 29 together with the two-dimensional scanning position.
The image processing circuit 28 outputs information of the determination result for the living tissue 3 at the two-dimensional scanning position to the monitor 6 as a display device that displays the image information.
In this case, the display color is changed according to the determination result, and the display is performed on the monitor 6. Specifically, a pixel representing a discrimination result of a scanning position whose discrimination result does not satisfy Expression 4 is displayed in black and white (monochrome), for example, and when it satisfies Expression 4, it is displayed in red. Then, the operator is informed from the image displayed on the monitor 6 that the red display color portion has a high possibility of a neoplastic lesion.

Note that the determination result is not limited to Expression 4, and a plurality of levels of determination results may be calculated using a plurality of threshold values, and the display color may be changed according to the level size. For example, the threshold value Vth is set to two threshold values Vth1 and Vth2 (Vth1> Vth2), and the discrimination results in three stages, specifically, τ _635-AVE / τ _510-1 > Vth1, Vth1> τ _635-AVE / You may make it obtain (tau) _510-1 > Vth2, Vth2> (tau) _635-AVE / tau _510-1 .

In the display example on the monitor 6 shown in FIG. 2, when τ _{635 -AVE} / τ _510-1 > Vth 1, the first display color D 1, and when Vth 1> τ _{635 -AVE} / τ _510-1 > Vth 2 _Shows a state where the second display color D2 is displayed as the third display color D3 when Vth2> τ _{635 -AVE} / τ _510-1 . Note that the display is not limited to three stages, and color display may be performed in three or more stages.
As described above, in this embodiment, since the fluorescence lifetime is calculated to discriminate the neoplastic lesion, the neoplastic lesion is discriminated almost without being influenced by the amount of the substance that absorbs the fluorescence. Is possible. That is, the detected fluorescence intensity is affected by blood or the like that absorbs fluorescence, but the fluorescence lifetime value is not affected.
In addition, according to the present embodiment, not only single fluorescence lifetime information but also two different fluorescence lifetime information (characteristics that differ between a tumor lesion and a normal portion other than the tumor lesion, for example) Or the information having a tendency) is used to perform the neoplastic lesion, so that the neoplastic lesion can be discriminated with high accuracy.
The surgeon can smoothly diagnose the neoplastic lesion by referring to the display result on the monitor 6 for the discrimination result. For this reason, this embodiment can provide diagnosis support when the surgeon diagnoses a lesion, specifically, a neoplastic lesion.

(Second Embodiment)
Next, a diagnosis support apparatus 1B according to the second embodiment of the present invention will be described with reference to FIG. In the first embodiment, the MEMS mirror 12 is used to scan the living body tissue 3 as the subject with a laser pulse two-dimensionally.
On the other hand, in the present embodiment, a laser pulse (without using a scanning unit) is irradiated two-dimensionally on the living tissue 3 and the gate opens the two-dimensional fluorescence information acquired using the image light guiding unit. It is detected by a fluorescence image detecting means with a gate function that detects when the image is set to be activated.
A diagnosis support apparatus 1B shown in FIG. 5 includes a laser light source 2, an endoscope 4B, a processor 5B, and a monitor 6 as a display device.

The endoscope 4B guides the laser pulse emitted from the laser light source 2 to the emission end at the tip thereof by the light guide fiber 8 inserted into the insertion portion 7. The excitation light transmission filter 31 and the condenser lens 14 are disposed so as to face the emission end. The guided laser pulse passes through the excitation light transmitting filter 31 and is irradiated two-dimensionally to the living tissue 3 side through the condenser lens 14.
At the imaging position of the objective lens 32 disposed adjacent to the condenser lens 14 at the distal end portion 9, the distal end surface of the image guide fiber 33 as an image light guiding means is disposed, and the optical image formed on the distal end surface. The image is guided to the proximal end of the insertion portion 7.
The base end of the image guide fiber 33 is detachably connected to the processor 5B.

Opposite to the base end of the image guide fiber 33, an imaging lens 34 and a dichroic mirror 17 constituting a detection unit 73B are disposed.
In addition, an excitation light cut filter 18a and an image intensifier (II in FIG. 5) 35a with a high-speed gate are disposed at the imaging position of the imaging lens 34 on the optical path side that has passed through the dichroic mirror 17. A CCD 36a is disposed on the exit surface of the tensiifier 35a.
In addition, an excitation light cut filter 18b and an image intensifier 35b with a high-speed gate are disposed at the imaging position of the imaging lens 34 on the optical path side reflected by the dichroic mirror 17, and the exit surface of the image intensifier 35b. The CCD 36b is disposed on the side.

The image intensifiers 35a and 35b are opened at a predetermined timing by the timing control circuit 13 every time a laser pulse is irradiated.
Then, the image intensifiers 35a and 35b amplify only the incident image light (image light) that is opened at this predetermined timing and emits the light to the CCDs 36a and 36b, respectively. The CCDs 36a and 36b are amplified. Detect image light.
The detection unit 73B having the function of a fluorescent image detection unit includes an imaging lens 34, a dichroic mirror 17, excitation light cut filters 18a and 18b, image intensifiers 35a and 35b, and CCDs 36a and 36b.

The CCD drive signals are also applied to the CCDs 36 a and 36 b by the timing control circuit 13, and the fluorescence image signals detected by the CCDs 36 a and 36 b are input to the fluorescence lifetime calculation circuit 25.
The fluorescence lifetime calculation circuit 25 in this embodiment calculates the fluorescence lifetime of one component by simplifying the calculation of the fluorescence lifetime.
Each image intensifier 35i (i = a or b) is amplified by a predetermined number of pulses by opening the gate in a short period W at time t1 after the emission timing of the laser pulse as shown in FIG. The CCD 36i repeats the exposure. Thereafter, the fluorescence image signal stored in the CCD 36 i is read out by the CCD drive signal from the timing control circuit 13.

That is, since the exposure amount of the CCD 36i is small in one exposure, the CCD 36i is exposed a plurality of times through the image intensifier 35i at the same time t1, and then photoelectrically converted and accumulated from the CCD 36i. The fluorescent image is read out by applying a CCD drive signal.
Next, the fluorescence in the short period W at time t2 is similarly amplified by the image intensifier 35i, the fluorescent image exposed in the period W at time t2 is accumulated in the CCD 36i, and then the fluorescence image signal accumulated from the CCD 36i is stored. Is read.
The fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetime by the following calculation.

When the fluorescence intensity in the period W at time t1 is I1, the fluorescence intensity in the period W at time t2 is I2, and the time interval between times t1 and t2 is to, the fluorescence lifetime is τ = to / ln (I1 / I2) (5)
It is represented by
The fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetimes τ ₅₁₀ and τ ₆₃₅ of the wavelength bands of 510 nm and 635 nm for each pixel position of the CCD 36 i according to Equation 5, and stores them in the memory 26.
The fluorescence lifetimes τ ₅₁₀ and τ ₆₃₅ stored in the memory 26 are output to the determination circuit 27. By appropriately setting the times t1 and t2, the discriminating circuit 27 uses the fluorescence lifetimes τ ₅₁₀ and τ ₆₃₅ of ₅₁₀ nm and 635 nm to discriminate the neoplastic lesion based on the value of the fluorescence lifetime ratio τ ₆₃₅ / τ _510. .

Similar to the first embodiment, the determination circuit 27 determines whether or not the possibility of a neoplastic lesion is high based on the determination result of whether or not the fluorescence lifetime ratio τ ₆₃₅ / τ ₅₁₀ is greater than a threshold value. The determination circuit 27 outputs the determination result to the image processing circuit 28.
The image processing circuit 28 stores the determination result in the memory 29 in association with information on the two-dimensional position where the fluorescence in which the determination is performed in the living tissue 3 is generated.
The monitor 6 displays an image of the discrimination result at the two-dimensional position of the living body. It is possible to change the times t1 and t2 for opening the gate from the emission timing of the laser pulse so as to cope with various fluorescent materials.
According to this embodiment, it is possible to determine a neoplastic lesion without being affected by the amount of a substance that absorbs fluorescence, as in the first embodiment.

Further, according to the present embodiment, since the tumorous lesion is determined based on a plurality of fluorescence lifetimes as in the first embodiment, it is possible to perform highly accurate determination.
Further, according to the present embodiment, it is possible to calculate the fluorescence lifetime with respect to the two-dimensional position of the living tissue 3 without using a scanning unit, and obtain the determination result. For this reason, desired information can be acquired in a short time. In addition, the fluorescence lifetime can be easily calculated by calculating the fluorescence lifetime from the fluorescence intensity obtained by changing the gate application time from the emission timing of the excitation light pulse (laser pulse).
Moreover, this embodiment can respond to various fluorescent substances by making the time for applying the gate changeable (adjustable). And this embodiment can perform support when an operator performs a lesion diagnosis.

(Third embodiment)
Next, an endoscope apparatus 1C as a diagnosis support apparatus according to a third embodiment of the present invention will be described with reference to FIG. The endoscope apparatus 1C includes a laser light source 2, an endoscope 4C, a processor 5C, and a monitor 6. In the present embodiment, the excitation light applied to the living tissue 3 is two-dimensionally scanned by a scanning unit different from that of the first embodiment. Further, the present embodiment has a normal endoscope function for acquiring a reflected light image in the visible region.
The endoscope 4C according to the present embodiment includes light guide fibers 41a, 41b, 41c, and 41d that are branched into four in the operation unit 10 on the proximal end side of the insertion unit 7, for example. These four light guide fibers 41 a, 41 b, 41 c, 41 d are made into one illumination fiber 43 in the fiber coupler 42.
Opposing to the base end that is the incident end of the light guide fibers 41a, 41b, 41c, an illumination lens 44, 44, 44 and a light emitting diode portion (abbreviated as LED portion) 45 as a visible light source portion are configured. LEDs 45R, 45G, and 45B are respectively disposed.

Further, a laser pulse from the laser light source 2 is incident on the incident end of the light guide fiber 41d. The laser light source 2 in the present embodiment is set to emit a 440 nm laser pulse that excites the FAD more efficiently as its excitation wavelength.
The LEDs 45R, 45G, and 45B sequentially emit R (red 610 nm), G (green 550 nm), B (blue 460 nm), and laser pulses together with the laser light source 2 under timing control by the timing control circuit 13 (FIG. 9). See below).
The light guide fibers 41 a, 41 b, 41 c, 44 d guide light incident from the respective incident ends to the distal end surface of the illumination fiber 43.
The distal end surface of the illumination fiber 43 is disposed at the distal end portion 9 of the insertion portion 7, and for example, a piezoelectric element 46 constituting a scanning unit is attached near the distal end of the illumination fiber 43.

The piezoelectric element 46 is driven two-dimensionally by a drive signal from a drive circuit inside the timing control circuit 13.
The piezoelectric element 46 drives the tip of the illumination fiber 43 two-dimensionally by applying a drive signal. Therefore, R, G, B light and a laser pulse are irradiated from the front end surface of the illumination fiber 43 through the condenser lens 14 toward the living tissue 3 while scanning in a two-dimensional manner.
A condensing lens 47 for detection is disposed adjacent to the condensing lens 14, and condenses fluorescence and the like from the living tissue 3 to enter the distal end surface of the detection fiber 48.
FIG. 8 shows the timing of irradiation light. As shown in FIG. 8, in order to acquire information for one pixel, the living tissue 3 is sequentially irradiated with R, G, B light and a plurality of repeated laser pulses.

The reflected light from the living tissue 3, the fluorescence and the laser pulse are sequentially incident on the distal end surface of the detection fiber 48. The laser pulse is interrupted by thinning-out processing by a pulse picker (not shown) inside the laser light source 2 during the illumination period of R, G, B light. FIG. 9 shows an arrangement example of the illumination fiber 43 and the detection fiber 48 in the vicinity of the distal end surface. As shown in FIG. 9, an illumination fiber 43 is disposed in the vicinity of the center of the illumination window 50 provided in the center of the distal end portion 9. A detection fiber 48 is disposed concentrically outside the illumination window 50.
The illumination fiber 43 is driven two-dimensionally by the piezoelectric element 46 (for example, two orthogonal arrow directions shown in FIG. 9).
Although not shown in FIG. 9, condensing lenses 14 and 47 are arranged to face the end surfaces of the illumination fiber 43 and the detection fiber 48, respectively.

The light incident on the detection fiber 48 is guided to the proximal end of the detection fiber 48. This base end is detachably connected to the processor 5C. In the processor 5C, an excitation light cut filter 52 and a photomultiplier 53 constituting the detection unit 73C are arranged on the optical path opposite to the base end.
The light emitted from the base end of the detection fiber 48 is cut by the pumping light cut filter 52 with the laser pulse having a wavelength of 440 nm as pumping light.
The excitation light cut filter 52 is a band-pass filter that further transmits light having a wavelength of 450 nm to 620 nm. Accordingly, light having a wavelength of 450 nm to 620 nm that has passed through the excitation light cut filter 52 is incident on the photomultiplier 53.

  The light incident by the photomultiplier 53 becomes an amplified detection signal, and this detection signal is input to the TCSPC 21.

An output signal of the photomultiplier 53 during the laser pulse irradiation period is input to the TCSPC 21.
The TCSPC 21 uses the output signal of the photomultiplier 53 as an end signal, performs time measurement from the laser pulse irradiation timing, and outputs information on the measured time to the fluorescence lifetime calculation circuit 25.
On the other hand, the image processing circuit 28 corresponds to a reflected light signal (referred to as R, G, B signal) of R, G, B light from an output signal from the photomultiplier 53 during the illumination period of R, G, B light. Color R, G, B images are generated. In this case, the image processing circuit 28 receives information on the scanning position by the piezoelectric element 46 via the timing control circuit 13, and stores the information on the scanning position in association with the R, G, B signals in the memory 29. Then, the image processing circuit 28 generates R, G, and B images and outputs them to the monitor 6.
The image processing circuit 28 detects the intensity of the G signal corresponding to the reflected light intensity of the G light, and outputs a laser pulse intensity control signal (abbreviated as laser intensity control signal) for controlling the intensity of the laser pulse to the laser light source 2. Output to.

The intensity of the laser pulse emitted from the laser light source 2 is adjusted by this laser intensity control signal.
Specifically, the laser intensity control signal controls the laser light source 2 to emit a laser pulse having an increased intensity when the intensity of reflected light from the living tissue 3 irradiated with G light is small (dark). To do.
On the other hand, the laser intensity control signal controls the laser light source 2 to emit a laser pulse having a reduced intensity when the intensity of reflected light from the living tissue 3 irradiated with the G light is large (bright). To do.

By performing such control, S / N is ensured even in a portion where an image becomes dark due to fluorescence absorption by blood and the influence of distance, so that a highly accurate fluorescence lifetime can be obtained.
Further, since the fluorescence intensity is weaker than the reflected light intensity, the amplification factor of the photomultiplier 53 is adjusted as shown in FIG. As shown in FIG. 8, the amplification factor of the photomultiplier 53 is adjusted by a control signal from the timing control circuit 13. That is, the amplification factor of the photomultiplier 53 is small during the R, G, and B light illumination periods, and the amplification factor is set sufficiently high during the laser pulse irradiation (illumination) period (in FIG. The pliers are abbreviated as PMT).
The fluorescence lifetime calculation circuit 25 operates in the single photon detection mode in order to measure the fluorescence lifetime.
In the present embodiment, the shorter fluorescence lifetime of the two-component analysis is output to the discrimination circuit 27 as τ _1a and the longer fluorescence lifetime τ _2a .
The discriminating circuit 27 discriminates a neoplastic lesion, for example, depending on whether the integrated value τ _1a × τ _{2a of the} two fluorescence lifetimes τ _1a and τ _2a is higher or lower than a threshold value. That is, when the integrated value τ _1a × τ _2a is smaller than the threshold value, it is determined that there is a high possibility of a neoplastic lesion. Then, the determination result is output to the image processing circuit 28.

The image processing circuit 28 generates a color image based on the reflected light intensity in the visible region, and blinks a portion of the color image that has a high possibility of a neoplastic lesion based on the determination result signal from the determination circuit 27 (brightness). The image signal that has been changed is output to the monitor 6.
At this time, the degree of intensity of brightness is determined by the image processing circuit 28 so that the higher the possibility of a neoplastic lesion, the greater the rate of change in brightness according to the integrated value τ _1a × τ _2a. Control.
Further, in this embodiment, in order to confirm the accuracy of the calculated fluorescence lifetime, the fluorescence lifetime calculation circuit 25 has an actually measured curve and a curve composed of the calculated fluorescence lifetimes τ _1a , τ _2a and α. An index value (for example, a Kini power value) that represents a deviation from is calculated. Then, the fluorescence lifetime calculation circuit 25 outputs the calculated index value to the image processing circuit 28, and the image processing circuit 28 also displays the index value on the monitor 6.

According to the present embodiment, as in the first embodiment, the fluorescence lifetime is calculated and the tumorous lesion is discriminated, so that the tumor is hardly affected by the amount of the substance that absorbs fluorescence. It becomes possible to discriminate sex lesions.
In addition, according to the present embodiment, not only single fluorescence lifetime information but also two different fluorescence lifetime information (characteristics or trends that differ between a neoplastic lesion and, for example, a normal portion other than the neoplastic lesion) Therefore, it is possible to discriminate the neoplastic lesion with high accuracy.
In addition, a color image by reflected light in the visible region is displayed, and the discrimination result based on the corresponding fluorescence lifetime is displayed on the color image so that it can be easily confirmed by the operator. Is easy to identify the part with high possibility of neoplastic lesions.
Moreover, this embodiment can be used also as an endoscope apparatus which inserts the insertion part 7 in a body cavity and performs endoscopic observation or endoscopic examination in a normal visible region. In addition, tumorous lesions can be identified by the fluorescence lifetime during endoscopy.
In addition, since this embodiment also displays an index value, the surgeon can use the determination result more appropriately by referring to this index value (in consideration of its reliability). The illumination fiber 43 and the detection fiber 48 may be formed separately for the excitation light and the reflected light. Further, for example, the reflected light side may be formed like a normal fiberscope.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. In the first embodiment, the two fluorescence wavelengths are separated and detected on the detection unit 73A side, but in the present embodiment, the first excitation light on the light source unit side that generates excitation light, Second excitation light having a wavelength different from that of the first excitation light is sequentially generated.
Further, in the present embodiment, the detection unit 73D is configured as one detection unit, and the first fluorescence corresponding to the case of the first excitation light and the second fluorescence corresponding to the case of the second excitation light. Are detected at different times.
A diagnosis support apparatus 1D according to the fourth embodiment of the present invention shown in FIG. 10 includes two laser light sources 2A and 2B, an endoscope 4D, a processor 5D, and a monitor 6.

The laser light sources 2A and 2B sequentially generate laser pulses having wavelengths of 405 nm and 370 nm, respectively, under the control of the timing control circuit 13. In this case, a laser pulse with a wavelength of 405 nm is mainly used to excite FAD, and a laser pulse with a wavelength of 370 nm is mainly used to excite NADH.
Two laser pulses having wavelengths of 405 nm and 370 nm are sequentially incident on the two branched incident ends 61a and 61b of the light guide fiber 61 of the endoscope 4D. The branched light guide fiber 61 becomes one halfway and guides the incident laser pulse to the tip.
This endoscope 4D has the same configuration as the endoscope 4 of the first embodiment except that the light guide fiber 61 is different.

Two laser pulses having wavelengths of 405 nm and 370 nm are reflected from the tip of the light guide fiber 61 by the dichroic mirror 11, and then irradiated to the living tissue 3 through the MEMS mirror 12 and the condenser lens 14. The dichroic mirror 11 reflects light having a wavelength of 420 nm or less and transmits light having a wavelength of 430 nm or more.
Light including fluorescence from the living tissue 3 is incident on the dichroic mirror 11 via the condenser lens 14 and the MEMS mirror 12. Light containing fluorescence of 430 nm or more passes through the dichroic mirror 11, is reflected by the mirror 15, and enters the tip of the light guide fiber 16. The laser pulse as excitation light is reflected by the dichroic mirror 11.

The light including the fluorescence incident on the distal end of the light guide fiber 16 is guided to the proximal end of the light guide fiber 16 and incident on the excitation light cut filter 18 constituting the detection unit 73D facing the proximal end. Is done. The excitation light cut filter 18 is set to cut the wavelength band of the excitation light and transmit light having a wavelength of 450 nm to 490 nm.
The excitation light cut filter 18 transmits fluorescence having a wavelength of 450 nm to 490 nm and is detected by the detector 19.
The detection signal of the detector 19 is input to the TCSPC 21. Similar to the first embodiment, the TCSPC 21 measures the time at which the photon is detected by the detector 19 from the irradiation (emission) timing of the laser pulse.

In this case, the TCSPC 21 measures the time for calculating the fluorescence lifetime of the first fluorescence under the excitation light of 405 nm and calculates the fluorescence lifetime of the second fluorescence under the excitation light of 370 nm. The measurement of the time for this is performed using the detection signal of the detector 19.
The TCSPC 21 outputs information on the measured time to the fluorescence lifetime calculation circuit 25. The fluorescence lifetime calculation circuit 25 calculates a first fluorescence lifetime τ _1b in the case of 405 nm excitation light and a second fluorescence lifetime τ _2b in the case of 370 nm excitation light, and outputs them to the discrimination circuit 27.
Specifically, the fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetime of the first component in the fluorescence in the case of 405 nm excitation light (the shorter fluorescence lifetime of the two-component analysis) τ ₄₀₅ ex−1 as the fluorescence lifetime τ _1b. To do.

In addition, the fluorescence lifetime calculation circuit 25 calculates the fluorescence lifetime of the second component in fluorescence in the case of excitation light of 370 nm (the longer fluorescence lifetime of the two-component analysis) τ ₃₇₀ ex-2 as the fluorescence lifetime τ _2b .
Then, the fluorescence lifetime calculation circuit 25 outputs the calculated fluorescence lifetime to the discrimination circuit 27.
Discriminating circuit 27, the two fluorescence lifetime τ ₄₀₅ ex-1, τ ₃₇₀ when ex-2 is a tumor section, when a tendency to become shorter, respectively, compared to the normal part, the two fluorescence lifetime tau ₄₀₅ ex For example, an integrated value τ ₄₀₅ ex-1 × τ ₃₇₀ ex-2 at −1, τ ₃₇₀ ex-2 is calculated. The discrimination circuit 27, two fluorescent lifetime τ ₄₀₅ ex-1, possible neoplastic lesions when the integrated value _{τ 405 ex-1 × τ 370} ex-2 of tau ₃₇₀ ex-2 is smaller than the threshold value It is determined that the property is high.
On the other hand, when the integrated value τ ₄₀₅ ex-1 × τ ₃₇₀ ex-2 is larger than the threshold value, it is determined that the possibility of a neoplastic lesion is low.

  Information about the determination result is sent to the image processing circuit 28. Information on the scanning position by the MEMS mirror 12 is input to the image processing circuit 28 via the timing control circuit 13. The image processing circuit 28 stores the information of the determination result in the memory 29 in association with the scanning position (that is, the fluorescence generation position) where the determination result is obtained.

The image processing circuit 28 outputs information on the determination result to the monitor 6. The monitor 6 displays the position of the biological tissue 3 determined to have a high possibility of a neoplastic lesion, for example, in a different color from the position determined to have a low possibility of a neoplastic lesion.
According to the present embodiment, lesion determination is performed using two fluorescence lifetimes as in the case of the first embodiment, so that highly accurate determination can be performed.
In the above-described embodiment, the method for obtaining the fluorescence lifetime by the time resolution method is described. However, the present invention can also be applied to the case of obtaining the fluorescence lifetime by the phase modulation method.
In addition, embodiments configured by partially combining the above-described examples and the like also belong to the present invention.

DESCRIPTION OF SYMBOLS 1A, 1B, 1D, 71 ... Diagnosis support apparatus, 1C ... Endoscope apparatus, 2A, 2B ... Laser light source, 3 ... Living tissue, 4A-4D ... Endoscope, 5A-5D ... Processor, 6 ... Monitor, 8 Light guide fiber 11, 17 ... Dichroic mirror, 18a, 18b ... Excitation light cut filter, 19a, 19b ... Detector, 21 ... TCSPC, 25 ... Fluorescence lifetime calculation circuit, 27 ... Discrimination circuit, 28 ... Image processing circuit, 72 ... light source unit, 73, 73A ... detection unit, 74 ... fluorescence lifetime calculation unit, 74 ... lesion determination unit

Special table 2003-535659 gazette JP 2005-283264 A

Claims (9)

A light source unit that generates excitation light to irradiate the subject;
A detection unit for detecting fluorescence generated by irradiation of the excitation light;
A fluorescence lifetime calculation unit that calculates a first fluorescence lifetime and a second fluorescence lifetime based on the fluorescence detected by the detection unit;
A diagnosis support apparatus comprising: a lesion determination unit that performs lesion determination based on the first fluorescence lifetime and the second fluorescence lifetime. A first light source that irradiates the subject and a light source unit that generates second excitation light having a wavelength different from that of the first excitation light;
A detection unit for detecting first fluorescence generated by irradiation of the first excitation light and second fluorescence generated by irradiation of the second excitation light;
A fluorescence lifetime calculation unit for calculating a first fluorescence lifetime related to the first fluorescence detected by the detection unit and a second fluorescence lifetime related to the second fluorescence detected by the detection unit ;
A lesion determination unit that performs lesion determination based on the first fluorescence lifetime and the second fluorescence lifetime ;
A diagnosis support apparatus having The detection unit detects fluorescence in a first wavelength band generated by irradiation of the excitation light and fluorescence in a second wavelength band having a wavelength different from the first wavelength band;
The fluorescence lifetime calculation unit calculates the first fluorescence lifetime based on the fluorescence in the first wavelength band detected by the detection unit and the second fluorescence lifetime based on the fluorescence in the second wavelength band. The diagnosis support apparatus according to claim 1, wherein the diagnosis support apparatus is calculated.   The diagnosis according to claim 1 or 3, wherein the lesion determination unit performs lesion determination by comparing a relative ratio or an integrated value of the first fluorescence lifetime and the second fluorescence lifetime with a threshold value. Support device.   5. The display device according to claim 1, further comprising: a display device that displays information on a lesion determination result by the lesion determination unit as image information associated with a position of a subject that generates the fluorescence whose lesion is determined. The diagnosis support apparatus according to any one of claims.   The diagnosis support apparatus according to claim 1, wherein the detection unit detects, as the fluorescence, fluorescence in a specific wavelength band showing a characteristic in which a fluorescence lifetime value differs between a tumor part and a normal part.   The endoscope device including an endoscope in which the light source unit and the detection unit are detachably connected and a light guide unit for guiding the excitation light and the fluorescence is inserted. The diagnosis support apparatus according to any one of claims 1 to 6.   The diagnosis support apparatus according to any one of claims 1 to 6, wherein the detection unit detects fluorescence from FAD (flavin adenine dinucleotide) or porphyrin in the subject.   The fluorescence lifetime calculation unit measures the time from the emission timing of the laser pulse as the excitation light emitted from the light source unit to the detection timing of the fluorescence detected by the detection unit a plurality of times, and The diagnosis support apparatus according to claim 1, wherein a fluorescence lifetime and the second fluorescence lifetime are calculated.

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