WO2018235781A1 - Acoustic wave image generation device and optoacoustic image analysis method - Google Patents

Acoustic wave image generation device and optoacoustic image analysis method Download PDF

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Publication number
WO2018235781A1
WO2018235781A1 PCT/JP2018/023155 JP2018023155W WO2018235781A1 WO 2018235781 A1 WO2018235781 A1 WO 2018235781A1 JP 2018023155 W JP2018023155 W JP 2018023155W WO 2018235781 A1 WO2018235781 A1 WO 2018235781A1
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image
subject
acoustic wave
photoacoustic
region
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PCT/JP2018/023155
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French (fr)
Japanese (ja)
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村越　大
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富士フイルム株式会社
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/13—Tomography

Definitions

  • the present invention relates to an acoustic wave image generation device that generates a photoacoustic image, and a photoacoustic image analysis method that analyzes a photoacoustic image.
  • pulsed light having a certain appropriate wavelength for example, wavelength band of visible light, near infrared light or mid-infrared light
  • the photoacoustic wave which is an elastic wave generated as a result of absorption of light energy, is detected to quantitatively measure the concentration of the absorbing substance.
  • Absorbent substances in a subject are, for example, blood vessels, glucose and hemoglobin contained in blood, and the like.
  • a technology for detecting such photoacoustic waves and generating a photoacoustic image based on the detection signal is called photoacoustic imaging (PAI) or photoacoustic tomography (PAT). ing.
  • PAI photoacoustic imaging
  • PAT photoacoustic tomography
  • Patent Documents 1 and 2 show an apparatus for performing photoacoustic imaging to generate a photoacoustic image.
  • This type of photoacoustic image generating apparatus is often configured to be able to generate a so-called reflected ultrasonic image as shown in Patent Document 2 as well.
  • an apparatus for generating a reflected ultrasound image is a subject based on a signal obtained by detecting a reflected acoustic wave that an acoustic wave (mostly an ultrasonic wave) emitted toward a subject is reflected in the subject. Generate a tomographic image etc. inside the sample.
  • a photoacoustic image generation apparatus emits light such as laser light toward a subject, and a subject is obtained based on a signal obtained by detecting a photoacoustic wave generated from a portion that has absorbed the light.
  • the photoacoustic image which shows internal tissue etc. of is generated.
  • photoacoustic imaging can quantitatively measure the concentration of the absorbent contained in blood vessels and blood as described above, by measuring the state of peripheral blood vessel distribution by photoacoustic imaging, peripheral blood circulation disorders It is considered useful for the diagnosis of scleroderma, which is one of diabetes complications such as gangrene of the extremities and peripheral neuropathy, and collagen disease which causes Raynaud's symptom.
  • the present invention has been made in view of the above problems, and in an acoustic wave image generating device for generating a photoacoustic image, and a photoacoustic image analysis method for analyzing a photoacoustic image, in a region of a body surface of a subject It aims at eliminating the influence of the photoacoustic wave which arises and improving the measurement precision of the state of blood vessel distribution.
  • the photoacoustic wave generated from the inside of the subject by receiving the light emitted toward the subject is detected by the acoustic wave detection probe, and the photoacoustic wave is generated.
  • An acoustic wave image generating apparatus having an image generation unit for generating an image, excluding a body surface area detection unit for detecting an area of a body surface of a subject in a photoacoustic image and an area of a body surface of a subject in a photoacoustic image And a region of interest setting unit that sets a region of interest in the region.
  • the body surface area detection unit may detect an area of the body surface of the subject in the photoacoustic image based on the photoacoustic image.
  • the image generation unit generates an acoustic image based on a signal obtained by detecting a reflected acoustic wave reflected by transmission of an acoustic wave to a subject using an acoustic wave detection probe, and the body surface area detection unit The region of the body surface of the subject in the photoacoustic image may be detected based on the acoustic image.
  • the image generation unit may generate a three-dimensional image of only the region of interest based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe.
  • an evaluation value calculator may be provided to calculate an evaluation value of an image based on the luminance value of each pixel constituting the region of interest of the photoacoustic image.
  • an information output unit may be provided that outputs information indicating a disease state based on the evaluation value.
  • the information output unit may output information indicating a disease state based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
  • the photoacoustic image analysis method of the present invention is generated based on a signal obtained by detecting a photoacoustic wave generated from the inside of a subject by receiving light emitted toward the subject using an acoustic wave detection probe.
  • a photoacoustic image analysis method for analyzing a photoacoustic image a region of a body surface of a subject in the photoacoustic image is detected, and a region of interest is set in a region excluding a region of a body surface of a subject in the photoacoustic image. .
  • the region of the body surface of the subject in the photoacoustic image may be detected based on the photoacoustic image.
  • an acoustic image is generated based on a signal obtained by detecting a reflected acoustic wave reflected by transmission of an acoustic wave to an object by an acoustic wave detection probe, and an object in a photoacoustic image is generated based on the acoustic image.
  • the area of the body surface may be detected.
  • a three-dimensional image of only the region of interest may be generated based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe.
  • the evaluation value of the image may be calculated based on the luminance value of each pixel constituting the region of interest of the photoacoustic image.
  • information indicating a disease state may be output based on the evaluation value.
  • information indicating a disease state may be output based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
  • the “three-dimensional image” is not limited to a three-dimensional image having voxel information, but a projection obtained by projecting three-dimensional image information having a thickness in two dimensions. It also includes an image.
  • the area of the body surface of the subject in the photoacoustic image is detected, and the interest is in the area excluding the area of the body surface of the subject in the photoacoustic image.
  • generation apparatus which concerns on one Embodiment of this invention.
  • Schematic showing the measurement state of the subject in the above-mentioned acoustic wave image generating device The figure which shows an example of the photoacoustic image which shows the cross section of a finger part
  • the figure which shows an example of the projection image of the photoacoustic image of a finger part A diagram showing an example of an ultrasound image showing a cross section of a finger part
  • the figure which shows an example of the projection image of the photoacoustic image of a finger part Graph showing the relationship between the evaluation value of each pixel and the luminance when displaying an image in a single color
  • FIG. 1 is a schematic view showing an entire configuration of an acoustic wave image generating apparatus 10 according to an embodiment of the present invention.
  • the shape of an acoustic wave detection probe (hereinafter simply referred to as a probe) 11 is schematically shown.
  • the acoustic wave image generating apparatus 10 of this example has a function of generating a photoacoustic image based on a photoacoustic wave detection signal as one example, and as schematically shown in FIG.
  • a unit 12, a laser unit 13, an image display unit 14, an input unit 15, and the like are provided.
  • those components will be sequentially described.
  • the probe 11 has, for example, a function of emitting measurement light and an ultrasonic wave toward the subject M which is a living body, and a function of detecting an acoustic wave U propagating in the subject M. That is, the probe 11 performs emission (transmission) of ultrasonic waves (acoustic waves) to the subject M and detection (reception) of reflected ultrasonic waves (reflection acoustic waves) reflected back from the subject M. it can.
  • acoustic wave as used herein is a term including ultrasonic waves and photoacoustic waves.
  • ultrasonic wave means an elastic wave transmitted by the probe 11 and its reflected wave (reflected ultrasonic wave)
  • photoacoustic wave is an elasticity emitted by the absorber 65 absorbing the measurement light. Means a wave.
  • the acoustic wave emitted by the probe 11 is not limited to the ultrasonic wave, and the acoustic wave of the audio frequency may be used as long as an appropriate frequency is selected according to the test object, the measurement condition, etc. .
  • the absorber 65 in the subject M for example, blood vessels, glucose and hemoglobin contained in blood, and the like, and further metal members and the like can be mentioned.
  • probes 11 corresponding to sector scanning, linear scanning and convex scanning are prepared, and an appropriate probe is selected and used from among them depending on the imaging site.
  • an optical fiber 60 as a connection unit for guiding a laser beam L, which is measurement light emitted from a laser unit 13 described later, to the light emitting unit 40 is connected to the probe 11.
  • the probe 11 includes a transducer array 20 which is an acoustic wave detector, and a total of two light emitting portions 40 disposed one on each side of the transducer array 20 with the transducer array 20 interposed therebetween. And a case 50 in which the transducer array 20, the two light emitting units 40, and the like are accommodated.
  • the transducer array 20 also functions as an ultrasonic transmission element.
  • the transducer array 20 is connected to a circuit for transmitting an ultrasonic wave, a circuit for receiving an acoustic wave, and the like through a wire (not shown).
  • the transducer array 20 is formed by arranging a plurality of acoustic transducers (ultrasonic transducers), which are electroacoustic transducers, in one-dimensional direction.
  • the acoustic wave vibrator is a piezoelectric element made of, for example, piezoelectric ceramic.
  • the acoustic wave vibrator may be a piezoelectric element made of a polymer film such as polyvinylidene fluoride (PVDF).
  • PVDF polyvinylidene fluoride
  • the acoustic wave transducer has a function of converting the received acoustic wave U into an electrical signal.
  • the transducer array 20 may include an acoustic lens.
  • the transducer array 20 in the present embodiment is formed by arranging a plurality of acoustic wave transducers one-dimensionally in parallel, but a vibration in which a plurality of acoustic wave transducers are arranged two-dimensionally.
  • a child array may be used.
  • the acoustic wave transducer also has a function of transmitting an ultrasonic wave as described above. That is, when an alternating voltage is applied to the acoustic wave transducer, the acoustic wave transducer generates an ultrasonic wave of a frequency corresponding to the frequency of the alternating voltage.
  • the transmission and reception of ultrasonic waves may be separated from each other. That is, for example, ultrasonic waves may be transmitted from a position different from that of the probe 11, and the reflected ultrasonic waves to the transmitted ultrasonic waves may be received by the probe 11.
  • the light emitting unit 40 is a portion that emits the laser light L guided by the optical fiber 60 toward the subject M.
  • the light emitting unit 40 is constituted by the tip of the optical fiber 60, that is, the end farther from the laser unit 13 which is the light source of the measurement light.
  • two light emitting portions 40 are disposed on both sides, for example, in the elevation direction of the transducer array 20 with the transducer array 20 interposed therebetween.
  • the elevation direction is a direction parallel to the detection surface of the transducer array 20 at right angles to the alignment direction when a plurality of acoustic wave transducers are arranged in one dimension.
  • the light emitting portion may be configured of a light guide plate and a diffusion plate optically coupled to the tip of the optical fiber 60.
  • a light guide plate can be made of, for example, an acrylic plate or a quartz plate.
  • the diffusion plate a lens diffusion plate in which microlenses are randomly disposed on the substrate can be used.
  • a quartz plate in which diffusion particles are dispersed can be used.
  • a holographic diffusion plate may be used, or an engineering diffusion plate may be used.
  • the laser unit 13 shown in FIG. 1 includes, for example, a flash lamp excited Q-switched solid-state laser such as a Q-switched alexandrite laser, and emits laser light L as measurement light.
  • the laser unit 13 is configured to output a laser beam L in response to, for example, a trigger signal from the control unit 30 of the ultrasonic unit 12.
  • the laser unit 13 preferably outputs a pulsed laser beam L having a pulse width of 1 to 100 nsec (nanoseconds).
  • the wavelength of the laser beam L is appropriately selected according to the light absorption characteristic of the absorber 65 in the subject M to be measured.
  • the wavelength is preferably a wavelength belonging to the near infrared wavelength range.
  • the near infrared wavelength range means a wavelength range of approximately 700 to 2500 nm (nanometers).
  • the wavelength of the laser light L is of course not limited to this.
  • the laser light L may be of a single wavelength or may include multiple wavelengths such as 750 nm (nanometers) and 800 nm (nanometers). When the laser beam L includes a plurality of wavelengths, the light of these wavelengths may be emitted simultaneously or may be emitted while switching alternately.
  • the laser unit 13 can also output YAG (Yttrium Aluminum Garnet: Yttrium Aluminum Garnet) -SHG (Second Harmonic Generation), which can output laser light in the near-infrared wavelength region as well as the alexandrite laser described above.
  • Second harmonic generation)-OPO (Optical Parametric Osillation) laser or Ti-Sapphire (titanium-sapphire) laser can also be used.
  • the optical fiber 60 guides the laser light L emitted from the laser unit 13 to the two light emitting portions 40.
  • the optical fiber 60 is not particularly limited, and a known fiber such as a quartz fiber can be used.
  • a known fiber such as a quartz fiber can be used.
  • one thick optical fiber may be used, or a bundle fiber in which a plurality of optical fibers are bundled may be used.
  • the bundle fiber is disposed such that the laser beam L is incident from the light incident end face of the combined fiber portion, and the fiber portion branched into two of the bundle fiber Each tip constitutes the light emitting unit 40 as described above.
  • the ultrasound unit 12 includes a reception circuit 21, a reception memory 22, an image generation unit 26, an image output unit 27, a control unit 30, and a transmission control circuit 35.
  • the image generation unit 26 includes a data separation unit 23, a photoacoustic image generation unit 24, and an ultrasound image generation unit 25.
  • the control unit 30 also sets a region of interest in the body surface area detection unit 31 that detects the area of the body surface of the subject in the photoacoustic image, and the area excluding the body surface area of the subject in the photoacoustic image.
  • a function as the region of interest setting unit 32 is provided.
  • the ultrasound unit 12 typically includes a processor, a memory, a bus, and the like.
  • the ultrasound unit 12 includes a photoacoustic image generation process, an ultrasound image generation process, a process of detecting an area of the body surface of the subject in the photoacoustic image, and an area of the body surface of the subject in the photoacoustic image.
  • a program related to processing of setting a region of interest in a region is incorporated in the memory.
  • the program is operated by the control unit 30 configured of a processor, whereby the data separation unit 23, the photoacoustic image generation unit 24, the ultrasound image generation unit 25, the image output unit 27, the body surface area detection unit 31, and the interest
  • the function of the area setting unit 32 is realized. That is, these units are configured by a memory and a processor in which a program is incorporated.
  • the hardware configuration of the ultrasound unit 12 is not particularly limited, and a plurality of integrated circuits (ICs), processors, application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), memories, etc. It can be realized by appropriately combining
  • the receiving circuit 21 receives the detection signal output from the ultrasound probe 11 and stores the received detection signal in the reception memory 22.
  • the receiving circuit 21 typically includes a low noise amplifier, a variable gain amplifier, a low pass filter, and an analog to digital converter.
  • the detection signal of the ultrasonic probe 11 is amplified by a low noise amplifier, gain-adjusted according to the depth by a variable gain amplifier, high frequency components are cut by a low pass filter, and converted to a digital signal by an AD converter. It is converted and stored in the reception memory 22.
  • the receiving circuit 21 is configured of, for example, one IC.
  • the ultrasonic probe 11 outputs a detection signal of the photoacoustic wave and a detection signal of the reflected ultrasonic wave
  • the reception memory 22 detects detection signals of the photoacoustic wave and the reflected ultrasonic wave subjected to AD conversion (sampling data) Is stored.
  • the data separation unit 23 reads the detection signal of the photoacoustic wave from the reception memory 22 and transmits the detection signal to the photoacoustic image generation unit 24. Further, the detection signal of the reflected ultrasound is read from the reception memory 22 and transmitted to the ultrasound image generation unit 25.
  • the photoacoustic image generation unit 24 generates a photoacoustic image based on the detection signal of the photoacoustic wave detected by the ultrasonic probe 11.
  • the photoacoustic image generation process includes, for example, image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like.
  • the ultrasound image generation unit 25 generates an ultrasound image based on the detection signal of the reflected ultrasound detected by the ultrasound probe 11.
  • the ultrasonic image generation process also includes image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like.
  • the image output unit 27 outputs the photoacoustic image and / or the ultrasound image to an image display unit 14 such as a display device.
  • the control unit 30 controls each unit in the ultrasonic unit 12.
  • the control unit 30 transmits a trigger signal to the laser unit 13 and causes the laser unit 13 to emit laser light. Further, according to the emission of the laser light, the sampling trigger signal is transmitted to the receiving circuit 21 to control the sampling start timing of the photoacoustic wave and the like.
  • the sampling data received by the receiving circuit 21 is stored in the receiving memory 22.
  • the photoacoustic image generation unit 24 receives the sampling data of the detection signal of the photoacoustic wave via the data separation unit 23, and detects it at a predetermined detection frequency to generate a photoacoustic image.
  • the photoacoustic image generated by the photoacoustic image generation unit 24 is input to the image output unit 27.
  • the control unit 30 transmits an ultrasonic wave transmission trigger signal indicating that the ultrasonic wave transmission is instructed to the transmission control circuit 35.
  • the transmission control circuit 35 causes the ultrasonic probe 11 to transmit an ultrasonic wave when receiving the ultrasonic wave transmission trigger signal.
  • the ultrasonic probe 11 scans the receiving area of the piezoelectric element group while shifting the line by area, for example, under the control of the control unit 30, and detects a reflected ultrasonic wave.
  • the control unit 30 transmits a sampling trigger signal to the receiving circuit 21 in accordance with the timing of ultrasonic wave transmission, and starts sampling of reflected ultrasonic waves.
  • the sampling data received by the receiving circuit 21 is stored in the receiving memory 22.
  • the ultrasonic image generation unit 25 receives sampling data of a detection signal of ultrasonic waves through the data separation unit 23, detects the data at a predetermined detection frequency, and generates an ultrasonic image.
  • the ultrasound image generated by the ultrasound image generation unit 25 is input to the image output unit 27.
  • FIG. 2 is a schematic view showing a measurement state of a subject in the acoustic wave image generating apparatus of the present embodiment.
  • a photoacoustic image of the finger of the subject is acquired, and the progress of peripheral circulatory disorder is confirmed from the state of the blood vessel distribution of the finger of the subject.
  • the hand 73 of the subject is placed on the examination table 72 in the water tank 70 filled with the water 71, and the probe 74 is used to scan and move the probe 11. 11 is scanned to shoot the finger 73.
  • FIG. 3 is a view showing an example of a photoacoustic image showing a cross section of a finger part, and as shown in FIG. 3, the photoacoustic image is generated in blood vessels, glucose and hemoglobin contained in blood, etc. Not only the signal which detected the photoacoustic wave but also the signal which detected the photoacoustic wave which generate
  • FIG. 4 is a view showing an example of a projected image of a photoacoustic image based on three-dimensional image information obtained by scanning a finger part, and three-dimensional image information obtained by scanning a finger part Among them, only the projection area PJ in the cross-sectional view of FIG. 3 is a projection image, but as shown in FIG. 4, in this projection image, not only a signal indicating blood vessel distribution inside the finger but Since the signal generated in the region of the body surface of the subject and not related to the blood vessel distribution is also included, the signal generated on the body surface becomes an artifact and is superimposed on the image, preventing observation of blood vessels etc. to be actually observed. It had become.
  • the body surface area detection unit 31 detects the area of the body surface of the subject in the photoacoustic image, and the region of interest setting unit 32 The region of interest ROI is set in the region excluding the region of the body surface of the subject in the photoacoustic image.
  • imaging the finger 73 by scanning the probe 11 when imaging the finger 73 by scanning the probe 11, imaging of an ultrasonic image such as an example shown in FIG. 5 and photoacoustic such as an example shown in FIG. Take both of the images.
  • the photoacoustic image can selectively receive a signal indicating the presence of blood hemoglobin mainly, but it is difficult to grasp in detail the structure inside the finger, such as soft tissue such as muscle tendon and bone.
  • the body surface area detection unit 31 detects the body surface of the subject in the photoacoustic image based on the ultrasound image. It is preferred to detect the area.
  • the region of the body surface of the subject in the photoacoustic image based on the ultrasound image first, in the ultrasound image which can relatively grasp the structure inside the finger, The area of the body surface of the sample is detected.
  • FIG. 7 is an ultrasound image different from FIG.
  • the body surface P1, the blood vessel P2, the tendon P3, the muscle P4, and the bone P5 are shown as an example.
  • noise removal is first performed using a Median Filter or the like, and then the image is binarized to obtain an ultrasound binary image as shown in FIG.
  • the edge in the depth direction is extracted from this ultrasound binary image, the rising side edge in the same object is selected, the adjacent edges in the width direction are further connected, and the longest line is the body surface (in FIG. Set to line).
  • an area of a predetermined thickness from the body surface of the subject that is, an area which causes an artifact not related to the blood vessel distribution is set as an area of the body surface of the subject.
  • the region SF of the body surface of the subject is detected in the ultrasound image by the above-described method, and the region of interest setting unit 32 determines the region SF of the body surface of the subject in the photoacoustic image corresponding to the ultrasound image.
  • a region of a predetermined shape or a region of a predetermined thickness immediately below the region SF of the body surface of the subject may be automatically selected, or the region SF of the body surface of the subject may be selected.
  • the excluded area may be arbitrarily selected by the user.
  • the detection of the region SF of the body surface of the subject in the photoacoustic image may be directly detected from the photoacoustic image instead of the detection based on the ultrasonic image as described above.
  • the accuracy is lower than detection based on an ultrasound image
  • the number of imaging frames of a photoacoustic image can be increased instead of imaging an ultrasound image, thus contributing to a higher frame rate of the photoacoustic image.
  • It may also be detected based on both the photoacoustic image and the ultrasound image. In this way, for example, foreign substances such as air bubbles that are easily detected in an ultrasound image but not detected in a photoacoustic image can be distinguished from the body surface, so body surface SF can be detected with higher accuracy. It becomes.
  • control unit 30 functions as an evaluation value calculation unit 33 that calculates an evaluation value of an image based on the luminance value of each pixel that configures the region of interest of the photoacoustic image. To allow quantitative evaluation of the image.
  • FIG. 10 is a graph showing the relationship between the evaluation value of each pixel and the luminance when an image is displayed in a single color, and indicates that the evaluation value becomes higher as the luminance is higher.
  • the evaluation value of the image may be a sum value or an average value of the luminance values of the respective pixels in the region of interest excluding the region of the body surface of the subject in the case of the sectional view, and in the case of a projection image of the region of interest only
  • the sum of the luminance values of the respective pixels in the entire area of the image may be calculated as
  • FIG. 11 shows a projection image of only a region of interest of a patient with peripheral circulation disorder
  • FIG. 12 shows a projection image of only a region of interest of a healthy subject.
  • the projected image of a healthy person shown in FIG. 12 is generally higher in luminance than the projected image of a patient with peripheral circulatory disorder shown in FIG. 11, and blood vessels and their distribution can be clearly viewed. That is, it shows that healthy people have better blood circulation.
  • the evaluation value of the image is calculated for these projection images, it can be understood that the evaluation of the image can be quantitatively performed because the healthy person has a higher evaluation value.
  • FIG. 13 is a graph showing the relationship between the evaluation value of each pixel and the luminance when the image is displayed in two different colors across the threshold, and the evaluation value is higher as the luminance is higher for each color. Indicates that it will be higher.
  • the evaluation value of the image may be a sum value or an average value of the luminance values of the respective pixels in the region of interest excluding the region of the body surface of the subject in the case of the sectional view, and in the case of a projection image of the region of interest only
  • the sum of the luminance values of the respective pixels in the entire area of the image may be calculated as
  • FIG. 14 shows a projection image of only a region of interest of a patient with peripheral circulation disorder
  • FIG. 15 shows a projection image of only a region of interest of a healthy subject.
  • the projected image of a healthy person shown in FIG. 15 is generally higher in luminance than the projected image of a patient with peripheral circulatory disorder shown in FIG. 14, and blood vessels and their distribution can be clearly viewed. That is, it shows that healthy people have better blood circulation.
  • the display color is changed with the threshold value of the evaluation value in between, blood vessels having different evaluation values and their distributions are distinguished and more visible.
  • the evaluation value of the image is calculated, it can be understood that the evaluation of the image can be quantitatively performed because the healthy person has a higher evaluation value.
  • the luminance of the photoacoustic image derives various evaluation values from the photoacoustic image signal in the region of interest using that it is derived from the property (concentration, oxygen saturation) of hemoglobin. It is also good.
  • FIG. 16 is a diagram showing the relationship between the blood vessel density and the photoacoustic image, and indicates that the higher the luminance, the higher the evaluation value.
  • Blood vessel distribution information can be obtained by binarizing the luminance information with a predetermined threshold.
  • the number of high-brightness pixels in the region of interest ROI after binarization may be normalized by the area of the region of interest ROI to be a unit of density. By using such an evaluation index, the degree of blood vessel or blood circulation can be quantitatively expressed.
  • blood vessel volume, hemoglobin concentration, blood vessel density, and oxygen saturation may be used as evaluation values based on the luminance of the photoacoustic image.
  • control unit 30 has a function as an information output unit 34 that outputs information indicating a disease state based on the evaluation value, and assists the user in disease judgment. It may be possible to
  • the evaluation value when the highest value is 100, it may be displayed in alphabets such as “C” for 0 or more and 40 or less, “B” for 40 or more and less than 80, and “A” for 80 or more.
  • 0 to less than 40 may be displayed as "1"
  • 40 to less than 80 may be displayed as "2”
  • 80 or more may be displayed as "3”.
  • 0 to less than 40 may be displayed as "defective", 40 to less than 80 as "careful", and 80 or more as "good” as character information.
  • the numerical value range of the evaluation value indicating each information is not limited to the above, and the display stage is not limited to the above, and any form may be used. Furthermore, the display content is not limited to the above, and may be in any form.
  • the information output unit 34 may output information indicating a disease state based on the temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
  • FIG. 17 shows how a projection image of only a region of interest of a patient with peripheral circulation disorder changes with the progress of treatment such as medication.
  • the evaluation value is calculated for the projection image of each stage, the change of the evaluation value due to the treatment progress is judged, and if the evaluation value is improved as shown in FIG. It can also be used to evaluate the efficacy of the treatment if it is displayed as "refractory" if it is not present or decreased.
  • measurement position 1 DIP joint (Distal Interphalangeal Joint: first joint of finger)
  • measurement position 3 PIP joint (Proximal Interphalangeal Joint: second joint of finger)
  • measurement position 2 DIP -By calculating the ratio of the evaluation value of the region of interest at three measurement positions in the middle of the PIP joint, it is possible to evaluate the blood circulation on the peripheral side with reference to the central side, and more accurate peripheral blood circulation. Evaluation can also be performed.
  • generation apparatus of this invention is not limited only to the said embodiment, Various corrections and changes are comprised from the structure of the said embodiment Also included in the scope of the present invention.

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Abstract

The present invention addresses the problem of, in an acoustic wave image generation device for generating an optoacoustic image and an optoacoustic image analysis method for analyzing an optoacoustic image, eliminating the influence of an optoacoustic wave generated in a body surface region of a subject, and improving the measurement accuracy of a blood vessel distribution state. An acoustic wave image generation device provided with an image generation unit which generates an optoacoustic image on the basis of a signal obtained by detecting, using an acoustic wave detection probe, an optoacoustic wave that has been generated from within the subject due to reception of light emitted toward the subject, is provided with: a body surface region detection unit which detects a body surface region of the subject in the optoacoustic image; and a region of interest setting unit which sets a region of interest in a region in the optoacoustic image other than the body surface region of the subject.

Description

音響波画像生成装置および光音響画像解析方法Acoustic wave image generating apparatus and photoacoustic image analysis method
　本発明は、光音響画像を生成する音響波画像生成装置、および光音響画像の解析を行う光音響画像解析方法に関する。 The present invention relates to an acoustic wave image generation device that generates a photoacoustic image, and a photoacoustic image analysis method that analyzes a photoacoustic image.
　近年、光音響効果を利用した非侵襲の計測法が注目されている。この計測法は、ある適宜の波長（例えば、可視光、近赤外光または中間赤外光の波長帯域）を有するパルス光を被検体に向けて出射し、被検体内の吸収物質がこのパルス光のエネルギーを吸収した結果生じる弾性波である光音響波を検出して、その吸収物質の濃度を定量的に計測するものである。被検体内の吸収物質とは、例えば血管や、血液中に含まれるグルコースおよびヘモグロビンなどである。また、このような光音響波を検出しその検出信号に基づいて光音響画像を生成する技術は、光音響イメージング（ＰＡＩ：Ｐｈｏｔｏ　Ａｃｏｕｓｔｉｃ　Ｉｍａｇｉｎｇ）あるいは光音響トモグラフィー（ＰＡＴ：Ｐｈｏｔｏ　Ａｃｏｕｓｔｉｃ　Ｔｏｍｏｇｒａｐｈｙ）と呼ばれている。 In recent years, non-invasive measurement methods using photoacoustic effects have attracted attention. In this measurement method, pulsed light having a certain appropriate wavelength (for example, wavelength band of visible light, near infrared light or mid-infrared light) is emitted toward the subject, and the absorbing material in the subject is the pulse. The photoacoustic wave, which is an elastic wave generated as a result of absorption of light energy, is detected to quantitatively measure the concentration of the absorbing substance. Absorbent substances in a subject are, for example, blood vessels, glucose and hemoglobin contained in blood, and the like. In addition, a technology for detecting such photoacoustic waves and generating a photoacoustic image based on the detection signal is called photoacoustic imaging (PAI) or photoacoustic tomography (PAT). ing.
　例えば特許文献１および２には、光音響イメージングを行って光音響画像を生成する装置が示されている。この種の光音響画像生成装置は、特許文献２にも示されているように、いわゆる反射超音波画像も生成可能に構成されることが多い。 For example, Patent Documents 1 and 2 show an apparatus for performing photoacoustic imaging to generate a photoacoustic image. This type of photoacoustic image generating apparatus is often configured to be able to generate a so-called reflected ultrasonic image as shown in Patent Document 2 as well.
　反射超音波画像を生成する装置は一般に、被検体に向けて出射された音響波（多くは超音波）が被検体内で反射した反射音響波を検出して得られた信号に基づいて、被検体の内部の断層画像などを生成する。 In general, an apparatus for generating a reflected ultrasound image is a subject based on a signal obtained by detecting a reflected acoustic wave that an acoustic wave (mostly an ultrasonic wave) emitted toward a subject is reflected in the subject. Generate a tomographic image etc. inside the sample.
　一方、光音響画像生成装置は一般に、被検体に向けてレーザ光などの光を出射し、この光を吸収した部位から発生した光音響波を検出して得られた信号に基づいて、被検体の内部組織などを示す光音響画像を生成する。 On the other hand, in general, a photoacoustic image generation apparatus emits light such as laser light toward a subject, and a subject is obtained based on a signal obtained by detecting a photoacoustic wave generated from a portion that has absorbed the light. The photoacoustic image which shows internal tissue etc. of is generated.
特開２０１３－１５８５３１号公報JP, 2013-158531, A 特開２０１５－１８１６６０号公報JP, 2015-181660, A
　光音響イメージングでは、上記のように血管や血液中に含まれる吸収物質の濃度を定量的に計測できるため、光音響イメージングにより末梢の血管分布の状態を測定することで、末梢の血液循環の不調に起因する、例えば四肢の壊疽や末梢神経障害といった糖尿病合併症やレイノー症状を呈する膠原病の一つである強皮症などの診断に有用と考えている。 Since photoacoustic imaging can quantitatively measure the concentration of the absorbent contained in blood vessels and blood as described above, by measuring the state of peripheral blood vessel distribution by photoacoustic imaging, peripheral blood circulation disorders It is considered useful for the diagnosis of scleroderma, which is one of diabetes complications such as gangrene of the extremities and peripheral neuropathy, and collagen disease which causes Raynaud's symptom.
　しかしながら、一般的に光音響イメージングでは、被検体の体表面の領域に存在するメラニンおよび毛根などの物質において発生する光音響波は、末梢の血管分布を観察する上での妨げとなる。特に３次元画像情報に基づいて投影画像を生成した場合には、体表面で発生した信号がアーチファクトとなって画像に重畳し、実際に観察したい血管などの観察の妨げになってしまうという問題があった。 However, in general, in photoacoustic imaging, photoacoustic waves generated in a substance such as melanin and hair roots present in the region of the body surface of a subject interfere with observation of peripheral blood vessel distribution. In particular, when a projection image is generated based on three-dimensional image information, the signal generated on the body surface becomes an artifact and is superimposed on the image, which causes a problem that it interferes with the observation of a blood vessel etc. to be actually observed. there were.
　本発明は上記の問題に鑑みてなされたものであり、光音響画像を生成する音響波画像生成装置、および光音響画像の解析を行う光音響画像解析方法において、被検体の体表面の領域で生じる光音響波の影響を無くし、血管分布の状態の測定精度を向上させることを目的とする。 The present invention has been made in view of the above problems, and in an acoustic wave image generating device for generating a photoacoustic image, and a photoacoustic image analysis method for analyzing a photoacoustic image, in a region of a body surface of a subject It aims at eliminating the influence of the photoacoustic wave which arises and improving the measurement precision of the state of blood vessel distribution.
　本発明の音響波画像生成装置は、被検体に向けて出射された光を受けることにより被検体内から発生した光音響波を音響波検出プローブにより検出して得られた信号に基づいて光音響画像を生成する画像生成部を有する音響波画像生成装置において、光音響画像における被検体の体表面の領域を検出する体表面領域検出部と、光音響画像における被検体の体表面の領域を除いた領域において関心領域を設定する関心領域設定部とを有する。 According to the acoustic wave image generating apparatus of the present invention, the photoacoustic wave generated from the inside of the subject by receiving the light emitted toward the subject is detected by the acoustic wave detection probe, and the photoacoustic wave is generated. An acoustic wave image generating apparatus having an image generation unit for generating an image, excluding a body surface area detection unit for detecting an area of a body surface of a subject in a photoacoustic image and an area of a body surface of a subject in a photoacoustic image And a region of interest setting unit that sets a region of interest in the region.
　本発明の音響波画像生成装置において、体表面領域検出部は、光音響画像に基づいて光音響画像における被検体の体表面の領域を検出するものとしてもよい。 In the acoustic wave image generation device of the present invention, the body surface area detection unit may detect an area of the body surface of the subject in the photoacoustic image based on the photoacoustic image.
　また、画像生成部は、被検体に対する音響波の送信によって反射された反射音響波を音響波検出プローブにより検出して得られた信号に基づいて音響画像を生成し、体表面領域検出部は、音響画像に基づいて光音響画像における被検体の体表面の領域を検出するものとしてもよい。 Further, the image generation unit generates an acoustic image based on a signal obtained by detecting a reflected acoustic wave reflected by transmission of an acoustic wave to a subject using an acoustic wave detection probe, and the body surface area detection unit The region of the body surface of the subject in the photoacoustic image may be detected based on the acoustic image.
　また、画像生成部は、音響波検出プローブにより被検体を走査することにより得られた複数の画像に基づいて、関心領域のみの３次元画像を生成するものとしてもよい。 The image generation unit may generate a three-dimensional image of only the region of interest based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe.
　また、光音響画像の関心領域を構成する各画素の輝度値に基づいて画像の評価値を算出する評価値算出部を有するものとしてもよい。 In addition, an evaluation value calculator may be provided to calculate an evaluation value of an image based on the luminance value of each pixel constituting the region of interest of the photoacoustic image.
　また、評価値に基づいて疾病の状態を示す情報を出力する情報出力部を有するものとしてもよい。 In addition, an information output unit may be provided that outputs information indicating a disease state based on the evaluation value.
　また、情報出力部は、同一被検体から得られた光音響画像の評価値の経時変化に基づいて疾病の状態を示す情報を出力するものとしてもよい。 In addition, the information output unit may output information indicating a disease state based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
　本発明の光音響画像解析方法は、被検体に向けて出射された光を受けることにより被検体内から発生した光音響波を音響波検出プローブにより検出して得られた信号に基づいて生成した光音響画像の解析を行う光音響画像解析方法において、光音響画像における被検体の体表面の領域を検出し、光音響画像における被検体の体表面の領域を除いた領域において関心領域を設定する。 The photoacoustic image analysis method of the present invention is generated based on a signal obtained by detecting a photoacoustic wave generated from the inside of a subject by receiving light emitted toward the subject using an acoustic wave detection probe. In a photoacoustic image analysis method for analyzing a photoacoustic image, a region of a body surface of a subject in the photoacoustic image is detected, and a region of interest is set in a region excluding a region of a body surface of a subject in the photoacoustic image. .
　本発明の光音響画像解析方法においては、光音響画像に基づいて光音響画像における被検体の体表面の領域を検出するようにしてもよい。 In the photoacoustic image analysis method of the present invention, the region of the body surface of the subject in the photoacoustic image may be detected based on the photoacoustic image.
　また、被検体に対する音響波の送信によって反射された反射音響波を音響波検出プローブにより検出して得られた信号に基づいて音響画像を生成し、音響画像に基づいて光音響画像における被検体の体表面の領域を検出するようにしてもよい。 Further, an acoustic image is generated based on a signal obtained by detecting a reflected acoustic wave reflected by transmission of an acoustic wave to an object by an acoustic wave detection probe, and an object in a photoacoustic image is generated based on the acoustic image. The area of the body surface may be detected.
　また、音響波検出プローブにより被検体を走査することにより得られた複数の画像に基づいて、関心領域のみの３次元画像を生成するようにしてもよい。 Alternatively, a three-dimensional image of only the region of interest may be generated based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe.
　また、光音響画像の関心領域を構成する各画素の輝度値に基づいて画像の評価値を算出するようにしてもよい。 Further, the evaluation value of the image may be calculated based on the luminance value of each pixel constituting the region of interest of the photoacoustic image.
　また、評価値に基づいて疾病の状態を示す情報を出力するようにしてもよい。 Further, information indicating a disease state may be output based on the evaluation value.
　また、同一被検体から得られた光音響画像の評価値の経時変化に基づいて疾病の状態を示す情報を出力するようにしてもよい。 Further, information indicating a disease state may be output based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
　本発明の音響波画像生成装置および光音響画像解析方法において、「３次元画像」とは、ボクセル情報を有する３次元画像に限らず、厚さを有する３次元画像情報を２次元に投影した投影画像も含むものである。 In the acoustic wave image generating apparatus and the photoacoustic image analysis method of the present invention, the “three-dimensional image” is not limited to a three-dimensional image having voxel information, but a projection obtained by projecting three-dimensional image information having a thickness in two dimensions. It also includes an image.
　本発明の音響波画像生成装置および光音響画像解析方法によれば、光音響画像における被検体の体表面の領域を検出し、光音響画像における被検体の体表面の領域を除いた領域において関心領域を設定することで、被検体の体表面の領域で生じる光音響波の影響を無くし、血管分布の状態の測定精度を向上させることができる。 According to the acoustic wave image generating apparatus and the photoacoustic image analysis method of the present invention, the area of the body surface of the subject in the photoacoustic image is detected, and the interest is in the area excluding the area of the body surface of the subject in the photoacoustic image. By setting the region, the influence of the photoacoustic wave generated in the region of the body surface of the subject can be eliminated, and the measurement accuracy of the state of blood vessel distribution can be improved.
本発明の一実施形態に係る音響波画像生成装置の全体構成を示す概略図Schematic which shows the whole structure of the acoustic wave image production | generation apparatus which concerns on one Embodiment of this invention. 上記音響波画像生成装置における被検体の測定状態を示す概略図Schematic showing the measurement state of the subject in the above-mentioned acoustic wave image generating device 手指部分の断面を示す光音響画像の一例を示す図The figure which shows an example of the photoacoustic image which shows the cross section of a finger part 手指部分の光音響画像の投影画像の一例を示す図The figure which shows an example of the projection image of the photoacoustic image of a finger part 手指部分の断面を示す超音波画像の一例を示す図A diagram showing an example of an ultrasound image showing a cross section of a finger part 手指部分の断面を示す光音響画像の一例を示す図The figure which shows an example of the photoacoustic image which shows the cross section of a finger part 被検体の体表面の領域の検出方法を説明するための図（１）Figure (1) for explaining the method of detecting the region of the body surface of the subject 被検体の体表面の領域の検出方法を説明するための図（２）Figure for explaining the detection method of the territory of the body surface of the subject (2) 手指部分の光音響画像の投影画像の一例を示す図The figure which shows an example of the projection image of the photoacoustic image of a finger part 画像を単色で表示した際の各画素の評価値と輝度の関係を示すグラフGraph showing the relationship between the evaluation value of each pixel and the luminance when displaying an image in a single color 末梢循環障害を伴う患者の関心領域のみの投影画像の一例を示す図A diagram showing an example of a projection image of only a region of interest of a patient with peripheral circulation disorder 健常者の関心領域のみの投影画像の一例を示す図A diagram showing an example of a projection image of only the region of interest of a normal subject 画像を２色で表示した際の各画素の評価値と輝度の関係を示すグラフGraph showing the relationship between the evaluation value of each pixel and the brightness when displaying an image in two colors 末梢循環障害を伴う患者の関心領域のみの投影画像の一例を示す図A diagram showing an example of a projection image of only a region of interest of a patient with peripheral circulation disorder 健常者の関心領域のみの投影画像の一例を示す図A diagram showing an example of a projection image of only the region of interest of a normal subject 血管密度と光音響画像との関係を示す図Diagram showing the relationship between blood vessel density and photoacoustic image 末梢循環障害を伴う患者の関心領域のみの投影画像の経時変化の様子を示す図The figure which shows a situation of the time-lapse change of the projection image of only a region of interest of the patient with peripheral circulation disorder 末梢循環評価を説明するための図Figure for explaining peripheral circulation evaluation
　以下、図面を参照して、本発明の実施形態について詳しく説明する。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
　図１は、本発明の一実施形態に係る音響波画像生成装置１０の全体構成を示す概略図である。なお図１において、音響波検出プローブ（以下、単にプローブという）１１の形状は概略的に示してある。本例の音響波画像生成装置１０は、一例として、光音響波検出信号に基づいて光音響画像を生成する機能を有するものであり、図１に概略的に示すように、プローブ１１、超音波ユニット１２、レーザユニット１３、画像表示部１４、および入力部１５などを備えている。以下、それらの構成要素について順次説明する。 FIG. 1 is a schematic view showing an entire configuration of an acoustic wave image generating apparatus 10 according to an embodiment of the present invention. In FIG. 1, the shape of an acoustic wave detection probe (hereinafter simply referred to as a probe) 11 is schematically shown. The acoustic wave image generating apparatus 10 of this example has a function of generating a photoacoustic image based on a photoacoustic wave detection signal as one example, and as schematically shown in FIG. A unit 12, a laser unit 13, an image display unit 14, an input unit 15, and the like are provided. Hereinafter, those components will be sequentially described.
　プローブ１１は、例えば生体である被検体Ｍに向けて測定光および超音波を出射する機能と、被検体Ｍ内を伝搬する音響波Ｕを検出する機能とを有する。すなわちプローブ１１は、被検体Ｍに対する超音波（音響波）の出射（送信）、および被検体Ｍで反射して戻って来た反射超音波（反射音響波）の検出（受信）を行うことができる。 The probe 11 has, for example, a function of emitting measurement light and an ultrasonic wave toward the subject M which is a living body, and a function of detecting an acoustic wave U propagating in the subject M. That is, the probe 11 performs emission (transmission) of ultrasonic waves (acoustic waves) to the subject M and detection (reception) of reflected ultrasonic waves (reflection acoustic waves) reflected back from the subject M. it can.
　本明細書において「音響波」とは、超音波および光音響波を含む用語である。ここで、「超音波」とはプローブ１１により送信された弾性波およびその反射波（反射超音波）を意味し、「光音響波」とは吸収体６５が測定光を吸収することにより発する弾性波を意味する。また、プローブ１１が発する音響波は超音波に限定されるものでは無く、被検対象や測定条件などに応じて適切な周波数を選択してさえいれば、可聴周波数の音響波を用いてもよい。なお被検体Ｍ内の吸収体６５としては、例えば血管や、血液中に含まれるグルコースおよびヘモグロビンなど、さらには金属部材などが挙げられる。 The term "acoustic wave" as used herein is a term including ultrasonic waves and photoacoustic waves. Here, "ultrasonic wave" means an elastic wave transmitted by the probe 11 and its reflected wave (reflected ultrasonic wave), and "photoacoustic wave" is an elasticity emitted by the absorber 65 absorbing the measurement light. Means a wave. Further, the acoustic wave emitted by the probe 11 is not limited to the ultrasonic wave, and the acoustic wave of the audio frequency may be used as long as an appropriate frequency is selected according to the test object, the measurement condition, etc. . As the absorber 65 in the subject M, for example, blood vessels, glucose and hemoglobin contained in blood, and the like, and further metal members and the like can be mentioned.
　プローブ１１は一般に、セクタ走査対応のもの、リニア走査対応のもの、コンベックス走査対応のものなどが用意され、それらの中から適宜のものが撮像部位に応じて選択使用される。またプローブ１１には、後述するレーザユニット１３から発せられた測定光であるレーザ光Ｌを、光出射部４０まで導光させる接続部としての光ファイバ６０が接続されている。 Generally, probes 11 corresponding to sector scanning, linear scanning and convex scanning are prepared, and an appropriate probe is selected and used from among them depending on the imaging site. In addition, an optical fiber 60 as a connection unit for guiding a laser beam L, which is measurement light emitted from a laser unit 13 described later, to the light emitting unit 40 is connected to the probe 11.
　プローブ１１は、音響波検出器である振動子アレイ２０と、この振動子アレイ２０を間に置いて、振動子アレイ２０の両側に各々１つずつ配設された合計２つの光出射部４０と、振動子アレイ２０および２つの光出射部４０などを内部に収容した筐体５０とを備えている。 The probe 11 includes a transducer array 20 which is an acoustic wave detector, and a total of two light emitting portions 40 disposed one on each side of the transducer array 20 with the transducer array 20 interposed therebetween. And a case 50 in which the transducer array 20, the two light emitting units 40, and the like are accommodated.
　本実施形態において振動子アレイ２０は、超音波送信素子としても機能する。振動子アレイ２０は、図示外の配線を介して、超音波送信用の回路および音響波受信用の回路などと接続されている。 In the present embodiment, the transducer array 20 also functions as an ultrasonic transmission element. The transducer array 20 is connected to a circuit for transmitting an ultrasonic wave, a circuit for receiving an acoustic wave, and the like through a wire (not shown).
　振動子アレイ２０は、電気音響変換素子である音響波振動子（超音波振動子）が複数、一次元方向に並設されてなるものである。音響波振動子は、例えば圧電セラミクスから構成された圧電素子である。また音響波振動子は、ポリフッ化ビニリデン（ＰＶＤＦ）のような高分子フィルムから構成された圧電素子であってもよい。音響波振動子は、受信した音響波Ｕを電気信号に変換する機能を有している。なお、振動子アレイ２０は音響レンズを含んでもよい。 The transducer array 20 is formed by arranging a plurality of acoustic transducers (ultrasonic transducers), which are electroacoustic transducers, in one-dimensional direction. The acoustic wave vibrator is a piezoelectric element made of, for example, piezoelectric ceramic. The acoustic wave vibrator may be a piezoelectric element made of a polymer film such as polyvinylidene fluoride (PVDF). The acoustic wave transducer has a function of converting the received acoustic wave U into an electrical signal. The transducer array 20 may include an acoustic lens.
　本実施形態における振動子アレイ２０は、上述の通り、複数の音響波振動子が一次元に並設されてなるものであるが、複数の音響波振動子が二次元に並設されてなる振動子アレイが用いられてもよい。 As described above, the transducer array 20 in the present embodiment is formed by arranging a plurality of acoustic wave transducers one-dimensionally in parallel, but a vibration in which a plurality of acoustic wave transducers are arranged two-dimensionally. A child array may be used.
　上記音響波振動子は、上述した通り超音波を送信する機能も有する。すなわち、この音響波振動子に交番電圧が印加されると、音響波振動子は交番電圧の周波数に対応した周波数の超音波を発生させる。なお、超音波の送信と受信は互いに分離させてもよい。つまり、例えばプローブ１１とは異なる位置から超音波の送信を行い、その送信された超音波に対する反射超音波をプローブ１１で受信するようにしてもよい。 The acoustic wave transducer also has a function of transmitting an ultrasonic wave as described above. That is, when an alternating voltage is applied to the acoustic wave transducer, the acoustic wave transducer generates an ultrasonic wave of a frequency corresponding to the frequency of the alternating voltage. The transmission and reception of ultrasonic waves may be separated from each other. That is, for example, ultrasonic waves may be transmitted from a position different from that of the probe 11, and the reflected ultrasonic waves to the transmitted ultrasonic waves may be received by the probe 11.
　光出射部４０は、光ファイバ６０によって導光されたレーザ光Ｌを被検体Ｍに向けて出射させる部分である。本実施形態において光出射部４０は、光ファイバ６０の先端部、つまり測定光の光源であるレーザユニット１３から遠い方の端部によって構成されている。図１に示されるように、本実施形態では２つの光出射部４０が、振動子アレイ２０を間に置いて、振動子アレイ２０の例えばエレベーション方向の両側に配置されている。このエレベーション方向とは、複数の音響波振動子が一次元に並設された場合、その並び方向に対して直角で、振動子アレイ２０の検出面に平行な方向である。 The light emitting unit 40 is a portion that emits the laser light L guided by the optical fiber 60 toward the subject M. In the present embodiment, the light emitting unit 40 is constituted by the tip of the optical fiber 60, that is, the end farther from the laser unit 13 which is the light source of the measurement light. As shown in FIG. 1, in the present embodiment, two light emitting portions 40 are disposed on both sides, for example, in the elevation direction of the transducer array 20 with the transducer array 20 interposed therebetween. The elevation direction is a direction parallel to the detection surface of the transducer array 20 at right angles to the alignment direction when a plurality of acoustic wave transducers are arranged in one dimension.
　なお光出射部は、光ファイバ６０の先端に光学的に結合させた導光板および拡散板から構成されてもよい。そのような導光板は、例えばアクリル板や石英板から構成することができる。また拡散板としては、マイクロレンズが基板上にランダムに配置されているレンズ拡散板を使用することができる。また、例えば拡散微粒子が分散された石英板などを使用することができる。さらにレンズ拡散板としてはホログラフィカル拡散板を用いてもよいし、エンジニアリング拡散板を用いてもよい。 The light emitting portion may be configured of a light guide plate and a diffusion plate optically coupled to the tip of the optical fiber 60. Such a light guide plate can be made of, for example, an acrylic plate or a quartz plate. Further, as the diffusion plate, a lens diffusion plate in which microlenses are randomly disposed on the substrate can be used. Further, for example, a quartz plate in which diffusion particles are dispersed can be used. Furthermore, as the lens diffusion plate, a holographic diffusion plate may be used, or an engineering diffusion plate may be used.
　図１に示されるレーザユニット１３は、例えばＱスイッチアレキサンドライトレーザなどのフラッシュランプ励起Ｑスイッチ固体レーザを有し、測定光としてのレーザ光Ｌを発する。レーザユニット１３は、例えば超音波ユニット１２の制御部３０からのトリガ信号を受けてレーザ光Ｌを出力するように構成されている。レーザユニット１３は、１～１００ｎｓｅｃ（ナノ秒）のパルス幅を有するパルスレーザ光Ｌを出力するものであることが好ましい。 The laser unit 13 shown in FIG. 1 includes, for example, a flash lamp excited Q-switched solid-state laser such as a Q-switched alexandrite laser, and emits laser light L as measurement light. The laser unit 13 is configured to output a laser beam L in response to, for example, a trigger signal from the control unit 30 of the ultrasonic unit 12. The laser unit 13 preferably outputs a pulsed laser beam L having a pulse width of 1 to 100 nsec (nanoseconds).
　レーザ光Ｌの波長は、計測の対象となる被検体Ｍ内の吸収体６５の光吸収特性に応じて適宜選択される。例えば計測対象が生体内のヘモグロビンである場合、つまり血管を撮像する場合、一般的にその波長は、近赤外波長域に属する波長であることが好ましい。近赤外波長域とはおよそ７００～２５００ｎｍ（ナノメートル）の波長域を意味する。しかし、レーザ光Ｌの波長は当然これに限られるものではない。またレーザ光Ｌは、単波長のものでもよいし、例えば７５０ｎｍ（ナノメートル）および８００ｎｍ（ナノメートル）などの複数波長を含むものでもよい。レーザ光Ｌが複数の波長を含む場合、これらの波長の光は、同時に出射されてもよいし、交互に切り替えながら出射されてもよい。 The wavelength of the laser beam L is appropriately selected according to the light absorption characteristic of the absorber 65 in the subject M to be measured. For example, when the measurement target is hemoglobin in a living body, that is, when imaging a blood vessel, in general, the wavelength is preferably a wavelength belonging to the near infrared wavelength range. The near infrared wavelength range means a wavelength range of approximately 700 to 2500 nm (nanometers). However, the wavelength of the laser light L is of course not limited to this. The laser light L may be of a single wavelength or may include multiple wavelengths such as 750 nm (nanometers) and 800 nm (nanometers). When the laser beam L includes a plurality of wavelengths, the light of these wavelengths may be emitted simultaneously or may be emitted while switching alternately.
　なおレーザユニット１３は、上に述べたアレキサンドライトレーザの他、同様に近赤外波長域のレーザ光を出力可能なＹＡＧ（Ｙｔｔｒｉｕｍ　Ａｌｕｍｉｎｕｍ　Ｇａｒｎｅｔ：イットリウム・アルミニウム・ガーネット）－ＳＨＧ（Ｓｅｃｏｎｄ　Ｈａｒｍｏｎｉｃ　Ｇｅｎｅｒａｔｉｏｎ：第二次高調波発生）－ＯＰＯ（Ｏｐｔｉｃａｌ　Ｐａｒａｍｅｔｒｉｃ　Ｏｓｉｌｌａｔｉｏｎ：光パラメトリック発振）レーザ、あるいはＴｉ－Ｓａｐｐｈｉｒｅ（チタン－サファイア）レーザなどを用いて構成することもできる。 The laser unit 13 can also output YAG (Yttrium Aluminum Garnet: Yttrium Aluminum Garnet) -SHG (Second Harmonic Generation), which can output laser light in the near-infrared wavelength region as well as the alexandrite laser described above. Second harmonic generation)-OPO (Optical Parametric Osillation) laser or Ti-Sapphire (titanium-sapphire) laser can also be used.
　光ファイバ６０は、レーザユニット１３から出射されたレーザ光Ｌを、２つの光出射部４０まで導く。光ファイバ６０は特に限定されず、石英ファイバなどの公知のものを使用することができる。例えば１本の太い光ファイバが用いられてもよいし、あるいは複数の光ファイバが束ねられてなるバンドルファイバが用いられてもよい。一例としてバンドルファイバが用いられる場合、１つにまとめられたファイバ部分の光入射端面から上記レーザ光Ｌが入射するようにバンドルファイバが配置され、そしてバンドルファイバの２つに分岐されたファイバ部分の各先端部が前述した通り光出射部４０を構成する。 The optical fiber 60 guides the laser light L emitted from the laser unit 13 to the two light emitting portions 40. The optical fiber 60 is not particularly limited, and a known fiber such as a quartz fiber can be used. For example, one thick optical fiber may be used, or a bundle fiber in which a plurality of optical fibers are bundled may be used. When a bundle fiber is used as an example, the bundle fiber is disposed such that the laser beam L is incident from the light incident end face of the combined fiber portion, and the fiber portion branched into two of the bundle fiber Each tip constitutes the light emitting unit 40 as described above.
　超音波ユニット１２は、受信回路２１、受信メモリ２２、画像生成部２６、画像出力部２７、制御部３０、および送信制御回路３５を有する。画像生成部２６は、データ分離部２３、光音響画像生成部２４、および超音波画像生成部２５から構成される。また、制御部３０は、光音響画像における被検体の体表面の領域を検出する体表面領域検出部３１、および光音響画像における被検体の体表面の領域を除いた領域において関心領域を設定する関心領域設定部３２としての機能を備える。超音波ユニット１２は、典型的にはプロセッサ、メモリ、およびバスなどを有する。超音波ユニット１２には、光音響画像生成処理、超音波画像生成処理、光音響画像における被検体の体表面の領域を検出する処理、および光音響画像における被検体の体表面の領域を除いた領域において関心領域を設定する処理などに関するプログラムがメモリに組み込まれている。プロセッサによって構成される制御部３０によってそのプログラムが動作することで、データ分離部２３、光音響画像生成部２４、超音波画像生成部２５、画像出力部２７、体表面領域検出部３１、および関心領域設定部３２の機能が実現する。すなわち、これらの各部は、プログラムが組み込まれたメモリとプロセッサにより構成されている。 The ultrasound unit 12 includes a reception circuit 21, a reception memory 22, an image generation unit 26, an image output unit 27, a control unit 30, and a transmission control circuit 35. The image generation unit 26 includes a data separation unit 23, a photoacoustic image generation unit 24, and an ultrasound image generation unit 25. The control unit 30 also sets a region of interest in the body surface area detection unit 31 that detects the area of the body surface of the subject in the photoacoustic image, and the area excluding the body surface area of the subject in the photoacoustic image. A function as the region of interest setting unit 32 is provided. The ultrasound unit 12 typically includes a processor, a memory, a bus, and the like. The ultrasound unit 12 includes a photoacoustic image generation process, an ultrasound image generation process, a process of detecting an area of the body surface of the subject in the photoacoustic image, and an area of the body surface of the subject in the photoacoustic image. A program related to processing of setting a region of interest in a region is incorporated in the memory. The program is operated by the control unit 30 configured of a processor, whereby the data separation unit 23, the photoacoustic image generation unit 24, the ultrasound image generation unit 25, the image output unit 27, the body surface area detection unit 31, and the interest The function of the area setting unit 32 is realized. That is, these units are configured by a memory and a processor in which a program is incorporated.
　なお、超音波ユニット１２のハードウェアの構成は特に限定されるものではなく、複数のＩＣ（Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）、プロセッサ、ＡＳＩＣ（Ａｐｐｌｉｃａｔｉｏｎ　Ｓｐｅｃｉｆｉｃ　Ｉｎｔｅｇｒａｔｅｄ　Ｃｉｒｃｕｉｔ）、ＦＰＧＡ（Ｆｉｅｌｄ－Ｐｒｏｇｒａｍｍａｂｌｅ　Ｇａｔｅ　Ａｒｒａｙ）、およびメモリなどを適宜組み合わせることによって実現することができる。 The hardware configuration of the ultrasound unit 12 is not particularly limited, and a plurality of integrated circuits (ICs), processors, application specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), memories, etc. It can be realized by appropriately combining
　受信回路２１は、超音波探触子１１が出力する検出信号を受信し、受信した検出信号を受信メモリ２２に格納する。受信回路２１は、典型的には、低ノイズアンプ、可変ゲインアンプ、ローパスフィルタ、およびＡＤ変換器（Ａｎａｌｏｇ　ｔｏ　Ｄｉｇｉｔａｌ　Ｃｏｎｖｅｒｔｏｒ）を含む。超音波探触子１１の検出信号は、低ノイズアンプで増幅された後に、可変ゲインアンプで深度に応じたゲイン調整がなされ、ローパスフィルタで高周波成分がカットされた後にＡＤ変換器でデジタル信号に変換され、受信メモリ２２に格納される。受信回路２１は、例えば１つのＩＣで構成される。 The receiving circuit 21 receives the detection signal output from the ultrasound probe 11 and stores the received detection signal in the reception memory 22. The receiving circuit 21 typically includes a low noise amplifier, a variable gain amplifier, a low pass filter, and an analog to digital converter. The detection signal of the ultrasonic probe 11 is amplified by a low noise amplifier, gain-adjusted according to the depth by a variable gain amplifier, high frequency components are cut by a low pass filter, and converted to a digital signal by an AD converter. It is converted and stored in the reception memory 22. The receiving circuit 21 is configured of, for example, one IC.
　超音波探触子１１は、光音響波の検出信号と反射超音波の検出信号とを出力し、受信メモリ２２には、ＡＤ変換された光音響波および反射超音波の検出信号（サンプリングデータ）が格納される。データ分離部２３は、受信メモリ２２から光音響波の検出信号を読み出し、光音響画像生成部２４に送信する。また、受信メモリ２２から反射超音波の検出信号を読み出し、超音波画像生成部２５に送信する。 The ultrasonic probe 11 outputs a detection signal of the photoacoustic wave and a detection signal of the reflected ultrasonic wave, and the reception memory 22 detects detection signals of the photoacoustic wave and the reflected ultrasonic wave subjected to AD conversion (sampling data) Is stored. The data separation unit 23 reads the detection signal of the photoacoustic wave from the reception memory 22 and transmits the detection signal to the photoacoustic image generation unit 24. Further, the detection signal of the reflected ultrasound is read from the reception memory 22 and transmitted to the ultrasound image generation unit 25.
　光音響画像生成部２４は、超音波探触子１１で検出された光音響波の検出信号に基づいて光音響画像を生成する。光音響画像の生成処理は、例えば位相整合加算などの画像再構成、検波および対数変換などを含む。超音波画像生成部２５は、超音波探触子１１で検出された反射超音波の検出信号に基づいて超音波画像を生成する。超音波画像の生成処理も、位相整合加算などの画像再構成、検波および対数変換などを含む。画像出力部２７は、光音響画像および／または超音波画像を、ディスプレイ装置などの画像表示部１４に出力する。 The photoacoustic image generation unit 24 generates a photoacoustic image based on the detection signal of the photoacoustic wave detected by the ultrasonic probe 11. The photoacoustic image generation process includes, for example, image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like. The ultrasound image generation unit 25 generates an ultrasound image based on the detection signal of the reflected ultrasound detected by the ultrasound probe 11. The ultrasonic image generation process also includes image reconstruction such as phase matching addition, detection, logarithmic conversion, and the like. The image output unit 27 outputs the photoacoustic image and / or the ultrasound image to an image display unit 14 such as a display device.
　制御部３０は、超音波ユニット１２内の各部を制御する。制御部３０は、光音響画像を取得する場合は、レーザユニット１３にトリガ信号を送信し、レーザユニット１３からレーザ光を出射させる。また、レーザ光の出射に合わせて、受信回路２１にサンプリングトリガ信号を送信し、光音響波のサンプリング開始タイミングなどを制御する。受信回路２１によって受信されたサンプリングデータは、受信メモリ２２に格納される。 The control unit 30 controls each unit in the ultrasonic unit 12. When acquiring the photoacoustic image, the control unit 30 transmits a trigger signal to the laser unit 13 and causes the laser unit 13 to emit laser light. Further, according to the emission of the laser light, the sampling trigger signal is transmitted to the receiving circuit 21 to control the sampling start timing of the photoacoustic wave and the like. The sampling data received by the receiving circuit 21 is stored in the receiving memory 22.
　光音響画像生成部２４は、データ分離部２３を介して光音響波の検出信号のサンプリングデータを受信し、所定の検波周波数で検波して光音響画像を生成する。光音響画像生成部２４が生成した光音響画像は、画像出力部２７に入力される。 The photoacoustic image generation unit 24 receives the sampling data of the detection signal of the photoacoustic wave via the data separation unit 23, and detects it at a predetermined detection frequency to generate a photoacoustic image. The photoacoustic image generated by the photoacoustic image generation unit 24 is input to the image output unit 27.
　また、制御部３０は、超音波画像を取得する場合は、送信制御回路３５に超音波送信を指示する旨の超音波送信トリガ信号を送信する。送信制御回路３５は、超音波送信トリガ信号を受けると、超音波探触子１１から超音波を送信させる。超音波探触子１１は、超音波画像を取得する場合には、制御部３０による制御によって、例えば圧電素子群の受信領域を一ラインずつずらしながら走査して反射超音波の検出を行う。制御部３０は、超音波送信のタイミングに合わせて受信回路２１にサンプリングトリガ信号を送信し、反射超音波のサンプリングを開始させる。受信回路２１によって受信されたサンプリングデータは、受信メモリ２２に格納される。 In addition, when acquiring an ultrasonic image, the control unit 30 transmits an ultrasonic wave transmission trigger signal indicating that the ultrasonic wave transmission is instructed to the transmission control circuit 35. The transmission control circuit 35 causes the ultrasonic probe 11 to transmit an ultrasonic wave when receiving the ultrasonic wave transmission trigger signal. When acquiring an ultrasonic image, the ultrasonic probe 11 scans the receiving area of the piezoelectric element group while shifting the line by area, for example, under the control of the control unit 30, and detects a reflected ultrasonic wave. The control unit 30 transmits a sampling trigger signal to the receiving circuit 21 in accordance with the timing of ultrasonic wave transmission, and starts sampling of reflected ultrasonic waves. The sampling data received by the receiving circuit 21 is stored in the receiving memory 22.
　超音波画像生成部２５は、データ分離部２３を介して超音波の検出信号のサンプリングデータを受信し、所定の検波周波数で検波して超音波画像を生成する。超音波画像生成部２５が生成した超音波画像は、画像出力部２７に入力される。 The ultrasonic image generation unit 25 receives sampling data of a detection signal of ultrasonic waves through the data separation unit 23, detects the data at a predetermined detection frequency, and generates an ultrasonic image. The ultrasound image generated by the ultrasound image generation unit 25 is input to the image output unit 27.
　ここで、本実施形態の音響波画像生成装置１０における画像解析方法について詳細に説明する。図２は、本実施形態の音響波画像生成装置における被検体の測定状態を示す概略図である。ここでは一例として、被検体の手指の光音響画像を取得し、被検体の手指の血管分布の状態から、末梢循環障害の進行状態を確認する場合を例に説明する。 Here, the image analysis method in the acoustic wave image generation apparatus 10 of the present embodiment will be described in detail. FIG. 2 is a schematic view showing a measurement state of a subject in the acoustic wave image generating apparatus of the present embodiment. Here, as an example, a photoacoustic image of the finger of the subject is acquired, and the progress of peripheral circulatory disorder is confirmed from the state of the blood vessel distribution of the finger of the subject.
　図２に示すように、水７１が満たされた水槽７０内の診察台７２上に被検体の手指７３を乗せて、プローブ１１を走査移動させるスキャナ７４を用いて、診察台７２と平行にプローブ１１を走査させて手指７３の撮影を行う。 As shown in FIG. 2, the hand 73 of the subject is placed on the examination table 72 in the water tank 70 filled with the water 71, and the probe 74 is used to scan and move the probe 11. 11 is scanned to shoot the finger 73.
　図３は、手指部分の断面を示す光音響画像の一例を示す図であり、図３に示すように、光音響画像中には、血管や、血液中に含まれるグルコースおよびヘモグロビンなどにおいて発生した光音響波を検出した信号だけでなく、被検体の体表面の領域に存在するメラニンおよび毛根などの物質において発生した光音響波を検出した信号も含まれる。すなわち、手指内部の血管分布を示す信号だけでなく、被検体の体表面の領域で発生した、血管分布とは無関係の信号も含まれるため、光音響画像中の各画素の輝度値に基づいて疾病の状態を判断しようとした場合に、正確に疾病の状態を判断することができないおそれがある。 FIG. 3 is a view showing an example of a photoacoustic image showing a cross section of a finger part, and as shown in FIG. 3, the photoacoustic image is generated in blood vessels, glucose and hemoglobin contained in blood, etc. Not only the signal which detected the photoacoustic wave but also the signal which detected the photoacoustic wave which generate | occur | produced in substances, such as melanin which exists in the area | region of the body surface of a subject, and a hair root, are included. That is, not only a signal indicating blood vessel distribution inside the finger, but also a signal unrelated to the blood vessel distribution generated in the region of the body surface of the subject is included, so based on the luminance value of each pixel in the photoacoustic image. When trying to determine the condition of a disease, it may not be possible to accurately determine the condition of the disease.
　また、図４は、手指部分を走査することにより得られた３次元画像情報に基づく光音響画像の投影画像の一例を示す図であり、手指部分を走査することにより得られた３次元画像情報のうち、図３の断面図中の投影領域ＰＪについてのみ投影画像としたものであるが、図４に示すように、この投影画像中には、手指内部の血管分布を示す信号だけでなく、被検体の体表面の領域で発生した、血管分布とは無関係の信号も含まれるため、体表面で発生した信号がアーチファクトとなって画像に重畳し、実際に観察したい血管などの観察の妨げになってしまっていた。 FIG. 4 is a view showing an example of a projected image of a photoacoustic image based on three-dimensional image information obtained by scanning a finger part, and three-dimensional image information obtained by scanning a finger part Among them, only the projection area PJ in the cross-sectional view of FIG. 3 is a projection image, but as shown in FIG. 4, in this projection image, not only a signal indicating blood vessel distribution inside the finger but Since the signal generated in the region of the body surface of the subject and not related to the blood vessel distribution is also included, the signal generated on the body surface becomes an artifact and is superimposed on the image, preventing observation of blood vessels etc. to be actually observed. It had become.
　このような問題を解消するために、本実施形態の音響波画像生成装置１０では、体表面領域検出部３１において光音響画像における被検体の体表面の領域を検出し、関心領域設定部３２において光音響画像における被検体の体表面の領域を除いた領域において関心領域ＲＯＩを設定するように構成されている。 In order to solve such a problem, in the acoustic wave image generation device 10 of the present embodiment, the body surface area detection unit 31 detects the area of the body surface of the subject in the photoacoustic image, and the region of interest setting unit 32 The region of interest ROI is set in the region excluding the region of the body surface of the subject in the photoacoustic image.
　具体的には、プローブ１１を走査させて手指７３の撮影を行う際に、同一撮影箇所において、図５に一例を示すような超音波画像の撮影と、図６に一例を示すような光音響画像の撮影の両方を行う。 Specifically, when imaging the finger 73 by scanning the probe 11, imaging of an ultrasonic image such as an example shown in FIG. 5 and photoacoustic such as an example shown in FIG. Take both of the images.
　光音響画像は主として血液ヘモグロビンの存在を示す信号を選択的に受信できる代わりに、筋腱などの軟部組織や骨等、手指内部の構造を詳細に把握することが難しい。これに対して、超音波画像は、手指内部の構造を比較的詳細に把握することができるため、体表面領域検出部３１は、超音波画像に基づいて光音響画像における被検体の体表面の領域を検出することが好ましい。 The photoacoustic image can selectively receive a signal indicating the presence of blood hemoglobin mainly, but it is difficult to grasp in detail the structure inside the finger, such as soft tissue such as muscle tendon and bone. On the other hand, since the ultrasound image can grasp the structure inside the finger in a relatively detailed manner, the body surface area detection unit 31 detects the body surface of the subject in the photoacoustic image based on the ultrasound image. It is preferred to detect the area.
　超音波画像に基づいて光音響画像における被検体の体表面の領域を検出する具体的な手法としては、まず、手指内部の構造を比較的詳細に把握することが可能な超音波画像において、被検体の体表面の領域を検出する。 As a specific method of detecting the region of the body surface of the subject in the photoacoustic image based on the ultrasound image, first, in the ultrasound image which can relatively grasp the structure inside the finger, The area of the body surface of the sample is detected.
　ここでは、分かりやすくするために、図５とは別の超音波画像である図７を用いて説明する。図７では、一例として、体表面Ｐ１、血管Ｐ２、腱Ｐ３、筋Ｐ４、骨Ｐ５が映っている。図７に示すような超音波画像において、まずＭｅｄｉａｎ　Ｆｉｌｔｅｒなどを用いてノイズ除去を行った後、画像の２値化を行い、図８に示すような超音波２値画像を取得する。そしてこの超音波２値画像において深さ方向のエッジを抽出し、同一オブジェクトにおける上昇側エッジを選択し、さらに幅方向の隣接エッジをつなぎ、最長線を体表面（図７では体表面Ｐ１を示す線）に設定する。そして被検体の体表面から所定の厚さの領域、すなわち血管分布と関係がないアーチファクトを生じさせてしまう領域を、被検体の体表面の領域として設定する。 Here, in order to make it intelligible, it demonstrates using FIG. 7 which is an ultrasound image different from FIG. In FIG. 7, the body surface P1, the blood vessel P2, the tendon P3, the muscle P4, and the bone P5 are shown as an example. In an ultrasound image as shown in FIG. 7, noise removal is first performed using a Median Filter or the like, and then the image is binarized to obtain an ultrasound binary image as shown in FIG. Then, the edge in the depth direction is extracted from this ultrasound binary image, the rising side edge in the same object is selected, the adjacent edges in the width direction are further connected, and the longest line is the body surface (in FIG. Set to line). Then, an area of a predetermined thickness from the body surface of the subject, that is, an area which causes an artifact not related to the blood vessel distribution is set as an area of the body surface of the subject.
　図５に戻り、上記手法により超音波画像において被検体の体表面の領域ＳＦを検出し、関心領域設定部３２において、この超音波画像に対応する光音響画像における被検体の体表面の領域ＳＦを除いた領域において関心領域ＲＯＩを設定することで、血管分布とは無関係の体表面で発生した信号を除き、手指内部の血管分布を示す信号だけに着目することができるため、正確に疾病の状態を判断することが可能となる。 Referring back to FIG. 5, the region SF of the body surface of the subject is detected in the ultrasound image by the above-described method, and the region of interest setting unit 32 determines the region SF of the body surface of the subject in the photoacoustic image corresponding to the ultrasound image. By setting the region of interest ROI in the region except for excluding the signal generated on the body surface unrelated to the blood vessel distribution, it is possible to focus only on the signal indicating the blood vessel distribution inside the finger, so that the disease It is possible to determine the state.
　関心領域ＲＯＩについては、被検体の体表面の領域ＳＦ直下における所定の形状の領域または所定の厚さの領域を自動的に選択するようにしてもよいし、被検体の体表面の領域ＳＦを除いた領域をユーザーが任意に選択できるようにしてもよい。 For the region of interest ROI, a region of a predetermined shape or a region of a predetermined thickness immediately below the region SF of the body surface of the subject may be automatically selected, or the region SF of the body surface of the subject may be selected. The excluded area may be arbitrarily selected by the user.
　また、図９に示すように、手指部分を走査することにより得られた３次元画像情報のうち、図６の断面図中の関心領域ＲＯＩについてのみ投影画像とすることで、手指内部の血流を示す信号だけを投影画像に反映させることができるため、実際に観察したい血管分布の状態をより鮮明に把握できるようになる。 Further, as shown in FIG. 9, by making only the region of interest ROI in the cross-sectional view of FIG. 6 among the three-dimensional image information obtained by scanning the finger part into a projected image, the blood flow inside the finger. Since it is possible to reflect only the signal representing in the projection image, it is possible to grasp the state of the blood vessel distribution to be actually observed more clearly.
　なお、光音響画像における被検体の体表面の領域ＳＦの検出については、上記のように超音波画像に基づいて検出するのではなく、光音響画像から直接検出するようにしてもよい。この場合、超音波画像に基づいて検出するよりも精度は落ちるが、超音波画像を撮影する代わりに光音響画像の撮影フレーム数を増やすことができるため、光音響画像の高フレームレート化に寄与する。また、光音響画像および超音波画像の両方に基づいて検出されてもよい。このようにすることで、たとえば超音波画像には容易に検出されるが、光音響画像には検出されない気泡などの異物を体表面と区別可能なため、体表面ＳＦをより高精度に検出可能となる。 The detection of the region SF of the body surface of the subject in the photoacoustic image may be directly detected from the photoacoustic image instead of the detection based on the ultrasonic image as described above. In this case, although the accuracy is lower than detection based on an ultrasound image, the number of imaging frames of a photoacoustic image can be increased instead of imaging an ultrasound image, thus contributing to a higher frame rate of the photoacoustic image. Do. It may also be detected based on both the photoacoustic image and the ultrasound image. In this way, for example, foreign substances such as air bubbles that are easily detected in an ultrasound image but not detected in a photoacoustic image can be distinguished from the body surface, so body surface SF can be detected with higher accuracy. It becomes.
　本実施形態の音響波画像生成装置１０においては、制御部３０に、光音響画像の関心領域を構成する各画素の輝度値に基づいて画像の評価値を算出する評価値算出部３３としての機能を備え、画像の評価を定量的に行えるようにしてもよい。 In the acoustic wave image generating apparatus 10 of the present embodiment, the control unit 30 functions as an evaluation value calculation unit 33 that calculates an evaluation value of an image based on the luminance value of each pixel that configures the region of interest of the photoacoustic image. To allow quantitative evaluation of the image.
　図１０は、画像を単色で表示した際の各画素の評価値と輝度の関係を示すグラフであり、輝度が高いほど評価値が高くなることを示している。 FIG. 10 is a graph showing the relationship between the evaluation value of each pixel and the luminance when an image is displayed in a single color, and indicates that the evaluation value becomes higher as the luminance is higher.
　画像の評価値については、断面図の場合には被検体の体表面の領域を除いた関心領域における各画素の輝度値の合計値または平均値とすればよく、関心領域のみの投影画像の場合には画像全域の各画素の輝度値の合計値または平均値とすればよい。 The evaluation value of the image may be a sum value or an average value of the luminance values of the respective pixels in the region of interest excluding the region of the body surface of the subject in the case of the sectional view, and in the case of a projection image of the region of interest only The sum of the luminance values of the respective pixels in the entire area of the image may be calculated as
　例として、図１１に末梢循環障害を伴う患者の関心領域のみの投影画像を示し、図１２に健常者の関心領域のみの投影画像を示す。 As an example, FIG. 11 shows a projection image of only a region of interest of a patient with peripheral circulation disorder, and FIG. 12 shows a projection image of only a region of interest of a healthy subject.
　図１１に示す末梢循環障害を伴う患者の投影画像よりも、図１２に示す健常者の投影画像の方が全体的に輝度が高く、血管およびその分布が明瞭に視認できる。すなわち、健常者の方が血液循環の状態が良いことを示している。これらの投影画像について、画像の評価値を算出した場合、健常者の方が高い評価値となるため、画像の評価を定量的に行えることが分かる。 The projected image of a healthy person shown in FIG. 12 is generally higher in luminance than the projected image of a patient with peripheral circulatory disorder shown in FIG. 11, and blood vessels and their distribution can be clearly viewed. That is, it shows that healthy people have better blood circulation. When the evaluation value of the image is calculated for these projection images, it can be understood that the evaluation of the image can be quantitatively performed because the healthy person has a higher evaluation value.
　また、上記の変形例として、図１３は、画像を閾値を挟んで異なる２色で表示した際の各画素の評価値と輝度の関係を示すグラフであり、色毎に輝度が高いほど評価値が高くなることを示している。 Further, as a modification, FIG. 13 is a graph showing the relationship between the evaluation value of each pixel and the luminance when the image is displayed in two different colors across the threshold, and the evaluation value is higher as the luminance is higher for each color. Indicates that it will be higher.
　画像の評価値については、断面図の場合には被検体の体表面の領域を除いた関心領域における各画素の輝度値の合計値または平均値とすればよく、関心領域のみの投影画像の場合には画像全域の各画素の輝度値の合計値または平均値とすればよい。 The evaluation value of the image may be a sum value or an average value of the luminance values of the respective pixels in the region of interest excluding the region of the body surface of the subject in the case of the sectional view, and in the case of a projection image of the region of interest only The sum of the luminance values of the respective pixels in the entire area of the image may be calculated as
　例として、図１４に末梢循環障害を伴う患者の関心領域のみの投影画像を示し、図１５に健常者の関心領域のみの投影画像を示す。 As an example, FIG. 14 shows a projection image of only a region of interest of a patient with peripheral circulation disorder, and FIG. 15 shows a projection image of only a region of interest of a healthy subject.
　図１４に示す末梢循環障害を伴う患者の投影画像よりも、図１５に示す健常者の投影画像の方が全体的に輝度が高く、血管およびその分布が明瞭に視認できる。すなわち、健常者の方が血液循環の状態が良いことを示している。また、評価値の閾値を挟んで表示色を変えているため、評価値の異なる血管およびその分布を区別して、より視認し易くなっている。これらの投影画像についても、画像の評価値を算出した場合、健常者の方が高い評価値となるため、画像の評価を定量的に行えることが分かる。 The projected image of a healthy person shown in FIG. 15 is generally higher in luminance than the projected image of a patient with peripheral circulatory disorder shown in FIG. 14, and blood vessels and their distribution can be clearly viewed. That is, it shows that healthy people have better blood circulation. In addition, since the display color is changed with the threshold value of the evaluation value in between, blood vessels having different evaluation values and their distributions are distinguished and more visible. Also for these projection images, when the evaluation value of the image is calculated, it can be understood that the evaluation of the image can be quantitatively performed because the healthy person has a higher evaluation value.
　また、上記の変形例として、光音響画像の輝度は、ヘモグロビンの性状（濃度、酸素飽和度）に由来することを利用して、関心領域内の光音響画像信号から各種の評価値を導いてもよい。例えば、図１６は、血管密度と光音響画像との関係を示す図であり、輝度が高いほど評価値が高くなることを示している。輝度情報を所定の閾値で２値化することで血管分布情報を得ることができる。さらに、２値化後の関心領域ＲＯＩ内の高輝度画素数を関心領域ＲＯＩの面積で規格化することで密度の単位とすることもできる。このような評価指標を用いることで、血管または血液循環の充実度を定量的に表すことができる。 In addition, as the above-mentioned modification, the luminance of the photoacoustic image derives various evaluation values from the photoacoustic image signal in the region of interest using that it is derived from the property (concentration, oxygen saturation) of hemoglobin. It is also good. For example, FIG. 16 is a diagram showing the relationship between the blood vessel density and the photoacoustic image, and indicates that the higher the luminance, the higher the evaluation value. Blood vessel distribution information can be obtained by binarizing the luminance information with a predetermined threshold. Furthermore, the number of high-brightness pixels in the region of interest ROI after binarization may be normalized by the area of the region of interest ROI to be a unit of density. By using such an evaluation index, the degree of blood vessel or blood circulation can be quantitatively expressed.
　このほかにも、光音響画像の輝度に基づいて、血管容積、ヘモグロビン濃度、血管密度、酸素飽和度を評価値としてもよい。 In addition, blood vessel volume, hemoglobin concentration, blood vessel density, and oxygen saturation may be used as evaluation values based on the luminance of the photoacoustic image.
　また、本実施形態の音響波画像生成装置１０においては、制御部３０に、評価値に基づいて疾病の状態を示す情報を出力する情報出力部３４としての機能を備え、ユーザーによる疾病判断の補助を行えるようにしてもよい。 Further, in the acoustic wave image generating apparatus 10 of the present embodiment, the control unit 30 has a function as an information output unit 34 that outputs information indicating a disease state based on the evaluation value, and assists the user in disease judgment. It may be possible to
　例えば、評価値について、最高値を１００としたとき、０以上４０未満を「Ｃ」、４０以上８０未満を「Ｂ」、８０以上を「Ａ」というように、アルファベットで表示してもよいし、０以上４０未満を「１」、４０以上８０未満を「２」、８０以上を「３」というように、数字で表示してもよい。また、０以上４０未満を「不良」、４０以上８０未満を「要注意」、８０以上を「良好」というように、文字情報で表示してもよい。 For example, regarding the evaluation value, when the highest value is 100, it may be displayed in alphabets such as “C” for 0 or more and 40 or less, “B” for 40 or more and less than 80, and “A” for 80 or more. , 0 to less than 40 may be displayed as "1", 40 to less than 80 may be displayed as "2", and 80 or more may be displayed as "3". In addition, 0 to less than 40 may be displayed as "defective", 40 to less than 80 as "careful", and 80 or more as "good" as character information.
　なお、上記はあくまでも表示例であり、各情報を示す評価値の数値範囲は上記に限られるものではなく、また表示の段階についても上記に限られるものではなく、どのような態様としてもよい。さらに表示内容についても、上記に限らず、どのような態様としてもよい。 The above is only a display example, the numerical value range of the evaluation value indicating each information is not limited to the above, and the display stage is not limited to the above, and any form may be used. Furthermore, the display content is not limited to the above, and may be in any form.
　また、情報出力部３４は、同一被検体から得られた光音響画像の評価値の経時変化に基づいて疾病の状態を示す情報を出力するようにしてもよい。 In addition, the information output unit 34 may output information indicating a disease state based on the temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
　例として、図１７に末梢循環障害を伴う患者の関心領域のみの投影画像が、投薬等の治療の経過によりに変化していく様子を示す。各段階の投影画像について評価値を算出し、評価値の治療経過による変化を判断し、図１７に示すように評価値が向上していれば「良好」と表示し、評価値が変化していない、または低下していれば「不応」と表示するようにすれば、治療の有効性評価に用いることもできる。 As an example, FIG. 17 shows how a projection image of only a region of interest of a patient with peripheral circulation disorder changes with the progress of treatment such as medication. The evaluation value is calculated for the projection image of each stage, the change of the evaluation value due to the treatment progress is judged, and if the evaluation value is improved as shown in FIG. It can also be used to evaluate the efficacy of the treatment if it is displayed as "refractory" if it is not present or decreased.
　また、図１８に示すように、測定位置１：ＤＩＰ関節（Ｄｉｓｔａｌ　Ｉｎｔｅｒｐｈａｌａｎｇｅａｌ　Ｊｏｉｎｔ：手指の第１関節）、測定位置３：ＰＩＰ関節（Ｐｒｏｘｉｍａｌ　Ｉｎｔｅｒｐｈａｌａｎｇｅａｌ　Ｊｏｉｎｔ：手指の第２関節）、測定位置２：ＤＩＰ－ＰＩＰ関節の中間の３つの測定位置における関心領域の評価値の比を求めるようにすれば、中枢側を基準として末梢側の血液循環を評価することができ、より精度の高い末梢血液循環の評価を行うこともできる。 Also, as shown in FIG. 18, measurement position 1: DIP joint (Distal Interphalangeal Joint: first joint of finger), measurement position 3: PIP joint (Proximal Interphalangeal Joint: second joint of finger), measurement position 2: DIP -By calculating the ratio of the evaluation value of the region of interest at three measurement positions in the middle of the PIP joint, it is possible to evaluate the blood circulation on the peripheral side with reference to the central side, and more accurate peripheral blood circulation. Evaluation can also be performed.
　以上、本発明をその好適な実施形態に基づいて説明したが、本発明の音響波画像生成装置は、上記実施形態にのみ限定されるものではなく、上記実施形態の構成から種々の修正及び変更を施したものも、本発明の範囲に含まれる。 As mentioned above, although this invention was demonstrated based on the suitable embodiment, the acoustic wave image production | generation apparatus of this invention is not limited only to the said embodiment, Various corrections and changes are comprised from the structure of the said embodiment Also included in the scope of the present invention.

Claims (14)

  1. 　被検体に向けて出射された光を受けることにより該被検体内から発生した光音響波を音響波検出プローブにより検出して得られた信号に基づいて光音響画像を生成する画像生成部を有する音響波画像生成装置において、
    　前記光音響画像における前記被検体の体表面の領域を検出する体表面領域検出部と、
    　前記光音響画像における前記被検体の体表面の領域を除いた領域において関心領域を設定する関心領域設定部とを有する音響波画像生成装置。     It has an image generation unit that generates a photoacoustic image based on a signal obtained by detecting a photoacoustic wave generated from inside the subject by receiving light emitted toward the subject using an acoustic wave detection probe. In the acoustic wave image generating apparatus,
    A body surface area detection unit that detects an area of a body surface of the subject in the photoacoustic image;
    An acoustic wave image generating apparatus comprising: a region of interest setting unit configured to set a region of interest in a region excluding a region of a body surface of the subject in the photoacoustic image;
  2. 　前記体表面領域検出部は、前記光音響画像に基づいて前記光音響画像における前記被検体の体表面の領域を検出する
    　請求項１記載の音響波画像生成装置。     The acoustic wave image generation device according to claim 1, wherein the body surface area detection unit detects an area of a body surface of the subject in the photoacoustic image based on the photoacoustic image.
  3. 　前記画像生成部は、前記被検体に対する音響波の送信によって反射された反射音響波を前記音響波検出プローブにより検出して得られた信号に基づいて音響画像を生成し、
    　前記体表面領域検出部は、前記音響画像に基づいて前記光音響画像における前記被検体の体表面の領域を検出する
    　請求項１記載の音響波画像生成装置。     The image generation unit generates an acoustic image based on a signal obtained by detecting the reflected acoustic wave reflected by transmission of the acoustic wave to the subject by the acoustic wave detection probe,
    The acoustic wave image generation device according to claim 1, wherein the body surface area detection unit detects an area of a body surface of the subject in the photoacoustic image based on the acoustic image.
  4. 　前記画像生成部は、前記音響波検出プローブにより前記被検体を走査することにより得られた複数の画像に基づいて、前記関心領域のみの３次元画像を生成する
    　請求項１から３のいずれか１項記載の音響波画像生成装置。     The image generation unit generates a three-dimensional image of only the region of interest based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe. The acoustic wave image production | generation apparatus of description.
  5. 　前記光音響画像の前記関心領域を構成する各画素の輝度値に基づいて画像の評価値を算出する評価値算出部を有する
    　請求項１から４のいずれか１項記載の音響波画像生成装置。     The acoustic wave image generation apparatus according to any one of claims 1 to 4, further comprising: an evaluation value calculation unit that calculates an evaluation value of an image based on a luminance value of each pixel constituting the region of interest of the photoacoustic image.
  6. 　前記評価値に基づいて疾病の状態を示す情報を出力する情報出力部を有する
    　請求項５記載の音響波画像生成装置。     The acoustic wave image generation apparatus according to claim 5, further comprising an information output unit that outputs information indicating a disease state based on the evaluation value.
  7. 　前記情報出力部は、同一被検体から得られた前記光音響画像の前記評価値の経時変化に基づいて疾病の状態を示す情報を出力する
    　請求項６記載の音響波画像生成装置。     The acoustic wave image generation device according to claim 6, wherein the information output unit outputs information indicating a disease state based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
  8. 　被検体に向けて出射された光を受けることにより該被検体内から発生した光音響波を音響波検出プローブにより検出して得られた信号に基づいて生成した光音響画像の解析を行う光音響画像解析方法において、
    　前記光音響画像における前記被検体の体表面の領域を検出し、
    　前記光音響画像における前記被検体の体表面の領域を除いた領域において関心領域を設定する光音響画像解析方法。     A photoacoustic that analyzes a photoacoustic image generated based on a signal obtained by detecting a photoacoustic wave generated from inside the subject by receiving light emitted toward the subject using an acoustic wave detection probe In the image analysis method,
    Detecting an area of a body surface of the subject in the photoacoustic image;
    The photoacoustic image analysis method which sets a region of interest in the area | region except the area | region of the body surface of the said object in the said photoacoustic image.
  9. 　前記光音響画像に基づいて前記光音響画像における前記被検体の体表面の領域を検出する
    　請求項８記載の光音響画像解析方法。     The photoacoustic image analysis method according to claim 8, wherein a region of a body surface of the subject in the photoacoustic image is detected based on the photoacoustic image.
  10. 　前記被検体に対する音響波の送信によって反射された反射音響波を前記音響波検出プローブにより検出して得られた信号に基づいて音響画像を生成し、
    　前記音響画像に基づいて前記光音響画像における前記被検体の体表面の領域を検出する
    　請求項８記載の光音響画像解析方法。     An acoustic image is generated based on a signal obtained by detecting, with the acoustic wave detection probe, a reflected acoustic wave reflected by transmission of the acoustic wave to the subject,
    The photoacoustic image analysis method according to claim 8, wherein a region of a body surface of the subject in the photoacoustic image is detected based on the acoustic image.
  11. 　前記音響波検出プローブにより前記被検体を走査することにより得られた複数の画像に基づいて、前記関心領域のみの３次元画像を生成する
    　請求項８から１０のいずれか１項記載の光音響画像解析方法。     The photoacoustic image according to any one of claims 8 to 10, wherein a three-dimensional image of only the region of interest is generated based on a plurality of images obtained by scanning the subject with the acoustic wave detection probe. analysis method.
  12. 　前記光音響画像の前記関心領域を構成する各画素の輝度値に基づいて画像の評価値を算出する
    　請求項８から１１のいずれか１項記載の光音響画像解析方法。     The photoacoustic image analysis method according to any one of claims 8 to 11, wherein an evaluation value of an image is calculated based on a luminance value of each pixel constituting the region of interest of the photoacoustic image.
  13. 　前記評価値に基づいて疾病の状態を示す情報を出力する
    　請求項１２記載の光音響画像解析方法。     The photoacoustic image analysis method according to claim 12, wherein information indicating a disease state is output based on the evaluation value.
  14. 　同一被検体から得られた前記光音響画像の前記評価値の経時変化に基づいて疾病の状態を示す情報を出力する
    　請求項１３記載の光音響画像解析方法。     The photoacoustic image analysis method according to claim 13, wherein information indicating a disease state is output based on a temporal change of the evaluation value of the photoacoustic image obtained from the same subject.
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Citations (3)

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JP2013188461A (en) * 2012-02-13 2013-09-26 Fujifilm Corp Photoacoustic visualization method and device
JP2016053482A (en) * 2014-09-02 2016-04-14 キヤノン株式会社 Photoacoustic wave measuring apparatus and photoacoustic wave measuring method
WO2016111105A1 (en) * 2015-01-08 2016-07-14 富士フイルム株式会社 Photoacoustic measuring device and photoacoustic measuring system

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* Cited by examiner, † Cited by third party
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JP2013188461A (en) * 2012-02-13 2013-09-26 Fujifilm Corp Photoacoustic visualization method and device
JP2016053482A (en) * 2014-09-02 2016-04-14 キヤノン株式会社 Photoacoustic wave measuring apparatus and photoacoustic wave measuring method
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