JP5653860B2 - Method and apparatus for measuring hardness of tube wall - Google Patents

Description

  The present invention relates to a method for measuring the hardness of a vessel wall such as a blood vessel and an apparatus for carrying out the method.

  Conventionally, as shown in Patent Document 1 and Non-Patent Document 1, for example, a photoacoustic imaging apparatus that images the inside of a living body using a photoacoustic effect is known. In this photoacoustic imaging apparatus, a living body is irradiated with pulsed light such as pulsed laser light. Inside the living body that has been irradiated with the pulsed light, the living tissue that has absorbed the energy of the pulsed light undergoes volume expansion due to heat and generates acoustic waves. Therefore, it is possible to detect the acoustic wave with an ultrasonic probe or the like and visualize the inside of the living body based on the electrical signal (photoacoustic signal) obtained thereby. The photoacoustic imaging method is suitable for imaging a specific tissue in a living body, such as a blood vessel, since an image is constructed based only on an acoustic wave emitted from a specific light absorber.

  The photoacoustic image has an advantage that blood vessels and the like in the living body that are light absorbers can be extracted and displayed. For example, Patent Document 2 discloses a technique for displaying such extracted blood vessels.

  On the other hand, in clinical or medical research, there is a need to accurately measure the hardness of a blood vessel wall, particularly an arterial blood vessel wall, in order to grasp the risk of arteriosclerosis. Conventionally, the hardness of a blood vessel wall is mainly measured by a so-called PWV (Pulse Wave Velocity) test in which the transmission speed of a pulse wave from an arm to an ankle is measured.

  On the other hand, for example, the hardness of the lymph vessel wall has been examined in order to examine the presence or absence of cancer metastasis. Conventionally, the hardness is determined by palpation by a doctor or the like, or as shown in Patent Document 3, using a catheter. It is common to be examined.

JP 2005-21380 A Special table 2010-512929 JP 2008-142253 A

A High-Speed Photoacoustic Tomography System based on a Commercial Ultrasound and a Custom Transducer Array, Xueding Wang, Jonathan Cannata, Derek DeBusschere, Changhong Hu, J. Brian Fowlkes, and Paul Carson, Proc.SPIE Vol. 7564, 756424 (Feb. 23, 2010)

  However, the above-described PWV inspection has a problem in that it takes time for measurement. In addition, the method of examining the hardness of the lymphatic vessel wall by palpation or using a catheter has the disadvantage that it requires skill.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method capable of easily measuring the hardness of a vessel wall such as a blood vessel wall or a lymph vessel wall in a short time.

  Another object of the present invention is to provide an apparatus capable of performing such a method.

The method for measuring the hardness of a pipe wall according to the present invention comprises:
Irradiate pulsed light of a wavelength absorbed by the tubular subject from the light source,
Thereby, the acoustic wave emitted from the subject is detected by the acoustic wave detecting means,
Of the detected acoustic waves, the subject tube wall is generated based on the intensity of the acoustic wave which is generated by a subject tube wall portion and then reflected by another subject tube wall portion and detected by the acoustic wave detecting means. The hardness is measured.

  In the tube wall hardness measurement method according to the present invention, the detected acoustic wave is generated on the subject tube wall closest to the acoustic wave detecting means and then reflected on the subject tube wall farthest from the acoustic wave detecting means. It is desirable to measure the hardness of the subject tube wall based on the intensity of the acoustic wave detected by the acoustic wave detecting means.

  In such a case, out of the acoustic waves detected by the acoustic wave detecting means, the acoustic waves are reflected on the subject tube wall farthest from the acoustic wave detecting means after being generated on the tube wall closest to the acoustic wave detecting means. The hardness of the subject tube wall based on the intensity ratio between the acoustic wave detected by the wave detecting means and the acoustic wave generated at the subject tube wall closest to the acoustic wave detecting means and directly detected by the acoustic wave detecting means It is particularly desirable to measure

  Also, as described above, among the detected acoustic waves, after being generated on the subject tube wall closest to the acoustic wave detecting means, it is reflected on the subject tube wall farthest from the acoustic wave detecting means and detected by the acoustic wave detecting means When the hardness of the subject tube wall is measured based on the intensity of the acoustic wave that has been generated, it is generated on the subject tube wall closest to the acoustic wave detection means and then reflected on the subject tube wall farthest from the acoustic wave detection means It is preferable to determine the acoustic wave based on the elapsed time after the acoustic wave generated on the subject tube wall closest to the acoustic wave detecting means and directly detected by the acoustic wave detecting means is incident on the acoustic wave detecting means. .

  The method for measuring the hardness of the tube wall according to the present invention is particularly preferably carried out when the subject is a biological blood vessel or a biological lymphatic vessel. When a lymphatic vessel is used as a subject, it is desirable to detect acoustic waves with a contrast medium injected into the lymphatic vessel.

  In the tube wall hardness measurement method according to the present invention, it is desirable to display and / or record the measured hardness of the subject tube wall.

On the other hand, the pipe wall hardness measuring apparatus according to the present invention is:
A light source for irradiating a tubular specimen with pulsed light having a wavelength absorbed by the specimen;
An acoustic wave detecting means for detecting an acoustic wave emitted from the subject thereby from the pulsed light irradiation side,
Of the detected acoustic waves, the subject tube wall is generated based on the intensity of the acoustic wave which is generated by a subject tube wall portion and then reflected by another subject tube wall portion and detected by the acoustic wave detecting means. And an arithmetic unit for measuring the hardness of the steel.

  The calculation unit generates a sound wave on the subject tube wall closest to the acoustic wave detection unit from the detected acoustic waves, and then reflects the reflected wave on the subject tube wall farthest from the acoustic wave detection unit to the acoustic wave detection unit. It is desirable to measure the hardness of the subject tube wall based on the intensity of the detected acoustic wave.

  In the case where the calculation unit is configured as described above, it is more preferable that the calculation unit detect an acoustic wave after being generated on the tube wall closest to the acoustic wave detection unit among the acoustic waves detected by the acoustic wave detection unit. The acoustic wave reflected by the subject tube wall farthest from the means and detected by the acoustic wave detection means, and the acoustic wave generated by the subject tube wall closest to the acoustic wave detection means and directly detected by the acoustic wave detection means The hardness is measured based on the strength ratio.

  Then, as described above, the acoustic wave detected by the acoustic wave detecting means after being reflected by the subject tube wall farthest from the acoustic wave detecting means after being generated by the subject pipe wall closest to the acoustic wave detecting means. When the hardness of the subject tube wall is measured on the basis of the intensity of the object, the calculation unit is more preferably from the acoustic wave detecting means after being generated at the subject tube wall closest to the acoustic wave detecting means. Elapsed time after the acoustic wave reflected by the far subject tube wall is generated by the subject tube wall closest to the acoustic wave detecting unit and directly detected by the acoustic wave detecting unit is incident on the acoustic wave detecting unit It is determined based on the above.

  The tube wall hardness measuring apparatus according to the present invention preferably includes means for displaying and / or recording the measured hardness of the subject tube wall.

  After being generated at the tube wall portion, the acoustic wave detected by the acoustic wave detecting means after being reflected by the other tube wall portion is attenuated by reflection and is incident on the acoustic wave detecting means. The degree of attenuation becomes smaller as the tube wall hardness is higher. That is, the harder the tube wall, the higher the intensity of the detected reflected acoustic wave.

  In view of this knowledge, the method of measuring the hardness of a tube wall according to the present invention is based on the intensity of the acoustic wave detected by the acoustic wave detection means after being reflected at another subject tube wall portion after being generated at one subject tube wall portion. Since the hardness of the subject tube wall is measured based on this, according to this method, the hardness of the tube wall can be easily measured in a short time.

The block diagram which shows schematic structure of the hardness measuring apparatus of the pipe wall by one Embodiment of this invention. Schematic explaining the generation of photoacoustic signal in the blood vessel wall Schematic showing the waveform of the acoustic wave detected in the apparatus of FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a basic configuration of a photoacoustic imaging apparatus 10 according to an embodiment of the present invention. The photoacoustic imaging apparatus 10 can acquire both a photoacoustic image and an ultrasonic image, and in addition, has a function of measuring the hardness of a blood vessel wall. An ultrasonic probe (probe) 11, an ultrasonic unit 12, a laser light source unit 13, and an image display unit 14.

  The laser light source unit 13 emits pulse laser light having a predetermined wavelength, and the pulse laser light emitted from the laser light source unit 13 is irradiated on the subject. The pulse laser beam is schematically shown in FIG. 1 with respect to the emission direction. For example, the pulse laser beam is guided to the probe 11 using light guide means such as a plurality of optical fibers, and directed from the probe 11 portion toward the subject. It is desirable to be irradiated.

  The probe 11 performs output (transmission) of ultrasonic waves to the subject and detection (reception) of reflected ultrasonic waves reflected back from the subject. For this purpose, the probe 11 has, for example, a plurality of ultrasonic transducers arranged one-dimensionally. The probe 11 detects ultrasonic waves (acoustic waves) generated by the observation target in the subject absorbing the laser light from the laser light source unit 13 by using a plurality of ultrasonic transducers. The probe 11 detects the acoustic wave and outputs an acoustic wave detection signal, and also detects the reflected ultrasonic wave and outputs an ultrasonic detection signal.

  When the above-described light guide means is coupled to the probe 11, the end portion of the light guide means, that is, the tip portions of the plurality of optical fibers are arranged in the direction in which the plurality of ultrasonic transducers are arranged (left and right in FIG. 1). The laser beam is emitted toward the subject from there. Hereinafter, the case where the light guide means is coupled to the probe 11 as described above will be described as an example.

  When acquiring a photoacoustic image or an ultrasonic image of a subject, the probe 11 is moved in a direction substantially perpendicular to a one-dimensional direction in which a plurality of ultrasonic transducers are arranged, whereby the subject is subjected to laser light and ultrasonic waves. Is two-dimensionally scanned. This scanning may be performed by an inspector moving the probe 11 manually, or a more precise two-dimensional scanning may be realized using a scanning mechanism.

  The ultrasonic unit 12 includes a reception circuit 21, AD conversion means 22, reception memory 23, data separation means 24, photoacoustic image reconstruction means 25, detection / logarithm conversion means 26, and photoacoustic image construction means 27. Yes.

  The receiving circuit 21 receives the acoustic wave detection signal and the ultrasonic wave detection signal output from the probe 11. The AD conversion means 22 is a sampling means, which samples the acoustic wave detection signal and the ultrasonic detection signal received by the receiving circuit 21 and converts them into photoacoustic data and ultrasonic data, which are digital signals, respectively. This sampling is performed at a predetermined sampling period in synchronization with, for example, an externally input AD clock signal.

  In addition to the ultrasonic image reconstruction means 40 that receives the output of the data separation means 24, the ultrasonic unit 12 detects, logarithmic conversion means 41, ultrasonic image construction means 42, the ultrasonic image construction means 42, and the aforementioned An image composition unit 43 that receives the output of the photoacoustic image construction unit 27 is included. The output of the image synthesizing unit 43 is input to the image display unit 14 including, for example, a CRT or a liquid crystal display device. Further, the ultrasonic unit 12 includes a transmission control circuit 30 and a control unit 31 that controls the operation of each unit in the ultrasonic unit 12.

  The photoacoustic data or ultrasonic data output from the AD converter 22 is temporarily stored in the reception memory and then input to the data separator 24. The data separation unit 24 separates the input photoacoustic data and the ultrasonic data from each other, the photoacoustic data is input to the photoacoustic image reconstruction unit 25, and the ultrasonic data is input to the ultrasonic image reconstruction unit 40. .

  The laser light source unit 13 is a solid-state laser unit including a Q-switch pulse laser 32 made of a Ti: Sapphire laser or the like and a flash lamp 33 as an excitation light source. In the following description, a case where a photoacoustic image showing a blood vessel is acquired will be described as an example. In this case, a laser light source unit 13 that emits pulsed laser light having a wavelength that is well absorbed in the blood vessel is selected. Used.

  When the laser light source unit 13 receives an optical trigger signal instructing light emission from the control means 31, the laser light source unit 13 turns on the flash lamp 33 to excite the Q switch pulse laser 32. For example, when the flash lamp 33 sufficiently excites the Q switch pulse laser 32, the control means 31 outputs a Q switch trigger signal. When the Q switch pulse laser 32 receives the Q switch trigger signal, the Q switch pulse laser 32 turns on the Q switch to emit pulsed laser light.

  Here, the time required from when the flash lamp 33 is turned on until the Q-switch pulse laser 33 is sufficiently excited can be estimated from the characteristics of the Q-switch pulse laser 33 and the like. In place of controlling the Q switch from the control means 31 as described above, the Q switch may be turned on after the Q switch pulse laser 32 is sufficiently excited in the laser light source unit 13. In that case, a signal indicating that the Q switch is turned on may be notified to the ultrasonic unit 12 side.

  The control unit 31 inputs an ultrasonic trigger signal for instructing ultrasonic transmission to the transmission control circuit 30. When receiving the ultrasonic trigger signal, the transmission control circuit 30 transmits an ultrasonic wave from the probe 11. The control means 31 outputs the optical trigger signal first, and then outputs an ultrasonic trigger signal. The light trigger signal is output to irradiate the subject with laser light and the acoustic wave is detected, and then the ultrasonic trigger signal is output to transmit the ultrasonic wave to the subject and the reflected ultrasonic wave. Is detected.

  The control means 31 further outputs a sampling trigger signal that instructs the AD conversion means 22 to start sampling. The sampling trigger signal is output after the optical trigger signal is output and before the ultrasonic trigger signal is output, more preferably at the timing when the subject is actually irradiated with the laser light. Therefore, the sampling trigger signal is output in synchronization with the timing at which the control means 31 outputs the Q switch trigger signal, for example. When receiving the sampling trigger signal, the AD conversion means 22 starts sampling the acoustic wave detection signal output from the probe 11 and received by the receiving circuit 21.

  After outputting the optical trigger signal, the control means 31 outputs the ultrasonic trigger signal at the timing when the detection of the acoustic wave is finished. At this time, the AD conversion means 22 continues the sampling without interrupting the sampling of the acoustic wave detection signal. In other words, the control unit 31 outputs the ultrasonic trigger signal in a state where the AD conversion unit 22 continues sampling the acoustic wave detection signal. When the probe 11 transmits ultrasonic waves in response to the ultrasonic trigger signal, the detection target of the probe 11 changes from acoustic waves to reflected ultrasonic waves. The AD conversion means 22 continuously samples the acoustic wave detection signal and the ultrasonic wave detection signal by continuously sampling the detected ultrasonic wave detection signal.

  The AD conversion unit 22 stores photoacoustic data and ultrasonic data obtained by sampling in a common reception memory 23. The sampling data stored in the reception memory 23 is photoacoustic data up to a certain point, and becomes ultrasonic data from a certain point. The data separation unit 24 separates the photoacoustic data and the ultrasonic data stored in the reception memory 23, inputs the photoacoustic data to the photoacoustic image reconstruction unit 25, and converts the ultrasonic data into the ultrasonic image reconstruction unit. 40.

  Hereinafter, generation and display of an ultrasonic image and a photoacoustic image will be described. The ultrasound image reconstruction means 40 adds the ultrasound data that is data for each of the plurality of ultrasound transducers included in the probe 11 to generate ultrasound tomographic image data for one line. The detection / logarithmic conversion means 41 generates an envelope of the ultrasonic tomographic image data, and then logarithmically converts the envelope to widen the dynamic range, and then inputs this data to the ultrasonic image construction means 42. The ultrasonic image construction unit 42 generates an ultrasonic tomographic image (ultrasonic echo image) based on the data of each line output from the detection / logarithm conversion unit 41. That is, the ultrasonic image construction unit 42 generates an ultrasonic tomographic image such that, for example, the position of the peak portion of the ultrasonic detection signal described above in the time axis direction is converted into a position in the depth direction of the tomographic image. .

  The above processing is sequentially performed with the scanning movement of the probe 11, thereby generating ultrasonic tomographic images regarding a plurality of locations in the scanning direction of the subject. The image data carrying these ultrasonic tomographic images is input to the image composition means 43. If it is desired to display only the ultrasonic tomographic image alone, the image data carrying the ultrasonic tomographic image is sent through the image synthesizing unit 43 to the image display unit 14, and the image display unit 14 receives the ultrasonic wave. A tomographic image is displayed.

  Next, generation and display of a photoacoustic image will be described. In the photoacoustic image reconstruction means 25, photoacoustic data obtained by irradiating the subject with photoacoustic data separated from the ultrasonic data by the data separation means 24, that is, pulse laser light having a wavelength absorbed by the blood vessel. Data is entered. The photoacoustic image reconstruction means 25 adds the photoacoustic data, which is data for each of the plurality of ultrasonic transducers included in the probe 11, to generate photoacoustic image data for one line. The detection / logarithm conversion means 26 generates an envelope of the photoacoustic image data, and then logarithmically converts the envelope to widen the dynamic range, and then inputs this data to the photoacoustic image construction means 27. The photoacoustic image construction unit 27 generates a photoacoustic image based on the photoacoustic image data for each line. That is, the photoacoustic image construction unit 27 generates a photoacoustic image such that, for example, the position of the peak portion of the photoacoustic image data in the time axis direction is converted into the position in the depth direction of the tomographic image.

  The above processing is sequentially performed with the scanning movement of the probe 11, thereby generating photoacoustic images regarding a plurality of locations in the scanning direction of the subject. The image data carrying these photoacoustic images is input to the image synthesizing means 43, where it is synthesized with the image data carrying the above-mentioned ultrasonic tomographic image, and the image carried by the synthesized data is input to the image display means 14. Is displayed. The image displayed based on the synthesized data is a blood vessel image that is a photoacoustic image in the ultrasonic tomographic image. The blood vessel image may be colored with a predetermined color so as to be clearly distinguished from other portions.

  Next, the point of measuring the hardness of the blood vessel wall will be described. FIG. 2 schematically shows how an acoustic wave is generated from a blood vessel wall. Here, as described above, it is assumed that the light guide means 15 including the tip portions of a plurality of optical fibers is coupled to the probe 11 and the pulsed laser light L is emitted toward the blood vessel therefrom. In the figure, the portion of the blood vessel wall is shown as BV. When the pulse laser beam L is irradiated in this way, blood in the blood vessel absorbs it and expands, thereby vibrating the portion of the blood vessel wall BV and generating an acoustic wave.

  At this time, the acoustic wave directly detected by the probe 11 after irradiation with the pulsed laser light L, that is, the acoustic wave Sf generated in the blood vessel wall portion closest to the acoustic wave detecting means side (probe 11), and the acoustic wave detecting means FIG. 3 shows the detection timing of the acoustic wave Sr generated at the blood vessel wall portion farthest from the side (probe 11) and directly detected by the probe 11 latest. In the figure, the horizontal axis represents time, and the vertical axis represents the intensity of the acoustic wave, that is, the sound pressure (this corresponds to the voltage of the acoustic wave detection signal output from the probe 11). As shown here, the acoustic wave Sr is directly detected after the time T has elapsed since the probe 11 directly detected the acoustic wave Sf. This time T is the time required for the acoustic wave Sr to travel the diameter of the blood vessel, that is, T = sound speed / blood vessel diameter.

  In addition to being directly detected by the probe 11, the acoustic wave Sf travels in the opposite direction to the probe 11 and may be detected by the probe 11 after being reflected by the blood vessel wall portion farthest from the probe 11. This reflected acoustic wave is shown as Sf ′ in FIG. Since this acoustic wave Sf ′ reaches the probe 11 after reciprocating once through the blood vessel, it is detected by the probe 11 with a delay of 2T compared to the acoustic wave Sf. The phase is reversed when the acoustic wave Sf is reflected. For example, when the blood vessel wall BV expands, the blood vessel wall portion farthest from the probe 11 moves to the probe 11 side, and the blood vessel wall portion farthest from the probe 11 moves to the opposite side of the probe 11, so that the acoustic wave Sf and the acoustic wave The phases of Sr are also opposite to each other.

  On the other hand, the acoustic wave Sr is also detected directly by the probe 11, travels toward the probe 11, is reflected by the blood vessel wall portion closest to the probe 11, and is further reflected by the blood vessel wall portion farthest from the probe 11. It may be detected by the probe 11. This reflected acoustic wave is shown as Sr 'in FIG. Compared with the acoustic wave Sr directly incident on the probe 11, this acoustic wave Sr ′ reaches the probe 11 after traveling a long distance corresponding to one round trip of the blood vessel diameter. It is detected by the probe 11 with a delay.

  Focusing on the intensity of the acoustic wave Sf detected directly and the acoustic wave Sf ′ detected after reflection, that is, the sound pressure, as described above, the acoustic wave Sf ′ attenuates when reflected, and thus is detected directly. The sound pressure is lower than the acoustic wave Sf. Since the acoustic wave Sf ′ is reflected better as the hardness of the blood vessel wall BV is higher, the hardness of the blood vessel wall BV can be measured based on the sound pressure of the acoustic wave Sf ′ detected by the probe 11. become.

  Therefore, in the present embodiment, as shown in FIG. 1, the photoacoustic data output from the data separation unit 24 is input to the calculation unit 44, and the calculation unit 44 indicates the peak values of the acoustic waves Sf and Sf ′. Based on the photoacoustic data, the hardness of the blood vessel wall BV is calculated from the value of sound pressure ratio = (sound pressure of the detected acoustic wave Sf ′) / (sound pressure of the detected acoustic wave Sf). The photoacoustic data indicating the peak value of the acoustic wave Sf corresponds to the signal having the peak value first among the acoustic wave detection signals output from the probe 11, and the peak value of the acoustic wave Sf ′. Photoacoustic data corresponding to the signal corresponding to the signal indicating the peak value output by the probe 11 with a delay of 2T from the signal indicating the peak value first. The calculating means 44 discriminates photoacoustic data indicating each peak value of the acoustic waves Sf and Sf ′ based on the time 2T.

  Information indicating the hardness of the blood vessel wall BV measured as described above is input to the image synthesizing means 43 as an example, where image data carrying a photoacoustic image and image data carrying an ultrasonic tomographic image Synthesized. Thereby, in the image displayed on the image display means 14, the measured hardness of the blood vessel wall is displayed as a numerical value or the like. This hardness can be expressed in terms of an index that has been conventionally used, such as PWV (Pulse Wave Velocity), but is not limited thereto, and may be indicated by a specific hardness index. Good.

  As is apparent from the above description, in the present embodiment, the laser light source unit 13 and the light guide means 15 constitute a light source that irradiates the subject with pulsed light, and the probe 11 emits an acoustic wave emitted from the subject. It constitutes a means for detection.

  In the above embodiment, the blood vessel wall hardness is measured based on the value of sound pressure ratio = (sound pressure of the detected acoustic wave Sf ′) / (sound pressure of the detected acoustic wave Sf). When the measurement conditions such as the distance from the measurement target blood vessel wall BV and the intensity of the pulsed laser beam L are always kept constant, the blood vessel wall is determined based only on the sound pressure of the detected acoustic wave Sf ′. It is also possible to measure the hardness. However, if the measurement is performed based on the above sound pressure ratio, it can be said that it is more preferable because the blood vessel wall hardness can be accurately measured even when measurement conditions are varied.

  As described above, also when the hardness of the blood vessel wall is measured based only on the sound pressure of the detected acoustic wave Sf ′, as described above, only the time 2T from the output signal of the probe 11 that first showed the peak value. It can be determined that the signal indicating the peak value output from the probe 11 with a delay indicates the peak value of the acoustic wave Sf ′.

  It is also possible to measure the vessel wall hardness using the acoustic wave Sr generated at the vessel wall portion farthest from the probe 11. Also in this case, based on the value of the sound pressure ratio = (sound pressure of the detected acoustic wave Sr ′) / (sound pressure of the detected acoustic wave Sr) or the value of the sound pressure of the detected acoustic wave Sr ′. Blood vessel wall hardness can be measured.

  Further, in addition to using the acoustic wave Sf generated in the blood vessel wall portion closest to the probe 11 and the acoustic wave Sr generated in the blood vessel wall portion farthest from the probe 11, another blood vessel is generated after being generated in other blood vessel wall portions. It is also possible to measure the blood vessel wall hardness using acoustic waves reflected from the wall portion.

  Although one embodiment of the present invention has been described above, the photoacoustic imaging apparatus and method of the present invention are not limited to the above embodiment, and various modifications and changes are made to the configuration of the above embodiment. What has been done is also included in the scope of the present invention.

  For example, the tube wall of the object whose hardness is to be measured is not limited to the blood vessel wall, and according to the method of the present invention, it is possible to measure the hardness of the lymph vessel wall in order to examine the presence or absence of cancer metastasis. is there. In that case, it is desirable to inject a contrast medium into the lymphatic vessel so that the pulsed light is well absorbed.

  Further, the measured hardness of the blood vessel wall such as a blood vessel wall may be recorded on a sheet by using a recording means in addition to being displayed on the display means with a predetermined numerical value, or may be directly displayed with a numerical value. Alternatively, instead of recording, “normal”, “abnormal”, “necessary observation”, “necessary inspection”, etc. corresponding to hardness may be displayed or recorded.

DESCRIPTION OF SYMBOLS 10 Photoacoustic imaging apparatus 11 Probe 12 Ultrasonic unit 13 Laser light source unit 14 Image display means 15 Light guide means 21 Reception circuit 22 AD conversion means 23 Reception memory 24 Data separation means 25 Photoacoustic image reconstruction means 26, 41 Logarithmic conversion means 27 Photoacoustic image construction means 30 Transmission control circuit 31 Control means 32 Q-switched laser 33 Flash lamp 40 Ultrasound image reconstruction means 42 Ultrasound image construction means 43 Image composition means 44 Calculation means

Claims (8)

The acoustic wave emitted from the subject by being irradiated with the pulsed light having a wavelength that is absorbed by the tubular subject is detected by the acoustic wave detecting means,
Among the detected acoustic waves , an acoustic wave that is generated on the tube wall closest to the acoustic wave detection unit and then reflected on the subject tube wall farthest from the acoustic wave detection unit and detected by the acoustic wave detection unit, and an acoustic wave Hardness of a tube wall characterized in that the hardness of the tube wall is measured based on an intensity ratio with an acoustic wave that is generated at the subject tube wall closest to the wave detection means and directly detected by the acoustic wave detection means Measuring method. The acoustic wave generated on the subject tube wall closest to the acoustic wave detecting means and then reflected on the subject tube wall farthest from the acoustic wave detecting means is generated directly on the subject tube wall closest to the acoustic wave detecting means. hardness measurement method according to claim 1, wherein the tube wall, characterized in that the acoustic wave detected in the acoustic wave detection means is determined based on the elapsed time after entering the acoustic wave detection means. 3. The method for measuring the hardness of a tube wall according to claim 1, wherein the tubular subject is a blood vessel of a living body. 3. The method for measuring the hardness of a tube wall according to claim 1, wherein the tubular object is a lymphatic vessel of a living body, and the acoustic wave is detected in a state in which a contrast medium is injected into the lymphatic vessel. Hardness measurement method of the display the hardness of the measured object pipe wall and / or recording the tube wall of claims 1 to 4 any one of claims, characterized in that the. A light source for irradiating a tubular specimen with pulsed light having a wavelength absorbed by the specimen;
An acoustic wave detecting means for detecting an acoustic wave emitted from the subject thereby from the pulsed light irradiation side,
Among the detected acoustic waves , an acoustic wave that is generated on the tube wall closest to the acoustic wave detection unit and then reflected on the subject tube wall farthest from the acoustic wave detection unit and detected by the acoustic wave detection unit, and an acoustic wave A tube wall comprising: an arithmetic unit that measures the hardness of the subject tube wall based on an intensity ratio with an acoustic wave that is generated at the subject tube wall closest to the wave detecting unit and directly detected by the acoustic wave detecting unit Hardness measuring device. The calculation unit generates an acoustic wave that has been generated on the subject tube wall closest to the acoustic wave detection unit and then reflected on the subject tube wall farthest from the acoustic wave detection unit, on the subject tube wall closest to the acoustic wave detection unit. 7. The tube wall hardness measuring apparatus according to claim 6, wherein the acoustic wave generated and directly detected by the acoustic wave detecting means is discriminated based on an elapsed time after entering the acoustic wave detecting means. . 8. The tube wall hardness measuring apparatus according to claim 6, further comprising means for displaying and / or recording the measured hardness of the subject tube wall.

Images