JP3377882B2 - Osteoporosis diagnostic device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention diagnoses osteoporosis by applying ultrasonic impulses to the bone tissue of a predetermined part of the human body.
The present invention relates to an osteoporosis diagnostic device .

[0002]

2. Description of the Related Art Osteoporosis is a disease in which calcium in bones escapes to form squashes, which easily deforms or breaks with a small shock. As one of means for diagnosing osteoporosis, a device for diagnosing with ultrasonic waves as described in Japanese Patent Application Laid-Open No. 2-104337 is conventionally known. In this ultrasonic diagnostic apparatus, it can be considered that the speed of sound in the bone tissue is empirically proportional to the bone density, and an ultrasonic pulse is emitted from the skin of the subject toward the bone tissue at the measurement site and penetrates the bone tissue. The received ultrasonic pulse is measured and the speed of sound in the bone tissue is measured. Then, it is diagnosed that the osteoporosis is progressing as the speed of sound in the bone tissue is slower.

[0003]

Strictly speaking, the speed of sound in bone tissue is not proportional to bone density but is given by the square root of [bone elastic modulus / bone density]. Moreover, since the elastic modulus increases as the bone density increases, the sound velocity cannot respond sensitively to the increase in the bone density, and the correlation coefficient between the sound velocity and the bone density is never high. Therefore, it is difficult for the above-described conventional diagnostic device based on the sound velocity information to reliably judge the progress of osteoporosis. On the other hand, there is an opinion that osteoporosis can be diagnosed based on the condition of bone elasticity.

The present invention has been made under such a background, and an osteoporosis diagnostic apparatus capable of accurately estimating the states of bone density and bone elastic modulus and reliably diagnosing the progress of osteoporosis. It is intended to be provided.

[0005]

[0006]

[Means for Solving the Problems ] To solve the above problems
In the osteoporosis diagnostic device according to the first aspect of the present invention , the ultrasonic transducer is applied to the living body, the normal of the transmitting / receiving surface is directed to the bone, and within a predetermined angle range with respect to the normal of the bone. While swinging, ultrasonic impulses are emitted intermittently, echoes from the bone are sequentially received, and at least the bone density or the elastic modulus of the bone is estimated based on the echo information from the received bone. An osteoporosis diagnostic device for diagnosing osteoporosis, comprising: maximum echo level extraction means for extracting a maximum echo level by vertical reflection echo from echoes from the bone sequentially received by the ultrasonic transducer,
The output means outputs the maximum echo level extracted by the maximum echo level extraction means as an index for diagnosing osteoporosis.

In the invention according to claim 2 , the ultrasonic wave transmitter / receiver is applied to a living body, the normal line of its transmitting / receiving surface is directed to the bone, and the ultrasonic wave is shaken within a predetermined angle range with respect to the normal line of the bone. While intermittently emitting ultrasonic impulses, sequentially receive echoes from the bone, based on the echo information from the received bone, at least estimate the state of bone density or bone elastic modulus An osteoporosis diagnostic device for diagnosing osteoporosis, comprising: a maximum echo level extraction means for extracting a maximum echo level by a vertical reflection echo from echoes from the bone sequentially received by the ultrasonic transmitter / receiver; Based on the maximum echo level extracted by the echo level extraction means, a reflection coefficient calculation means for calculating a reflection coefficient at the interface between the soft tissue of the living body and the bone, and the reflection coefficient calculation means. The calculated reflection coefficient is characterized by comprising an output means for outputting as an indicator of osteoporosis diagnosis.

In the invention according to claim 3 , the ultrasonic wave transmitter / receiver is applied to the living body, the normal line of its transmitting / receiving surface is directed to the bone, and the ultrasonic wave is shaken within a predetermined angle range with respect to the normal line of the bone. While intermittently emitting ultrasonic impulses, sequentially receive echoes from the bone, based on the echo information from the received bone, at least estimate the state of bone density or bone elastic modulus An osteoporosis diagnostic device for diagnosing osteoporosis, comprising: a maximum echo level extraction means for extracting a maximum echo level by a vertical reflection echo from echoes from the bone sequentially received by the ultrasonic transmitter / receiver; Based on the maximum echo level extracted by the echo level extraction means, a reflection coefficient calculation means for calculating a reflection coefficient at the interface between the soft tissue of the living body and the bone, and the reflection coefficient calculation means. Based on the calculated reflection coefficient, an acoustic impedance calculating means for calculating the acoustic impedance of the bone, and an output means for outputting the acoustic impedance of the bone calculated by the acoustic impedance calculating means as an index of osteoporosis diagnosis It is characterized by becoming.

[0009]

In the structure of the present invention, the ultrasonic wave transmitter / receiver is applied to the living body, the normal line of the wave transmission / reception surface is directed to the bone, and while being swung within a predetermined angle range with respect to the normal line of the bone, Ultrasonic impulses are emitted intermittently, echoes from bones are sequentially received, and echo information from the received bones is collected. Then, the maximum echo level is extracted from the collected echo information. The maximum echo level is received when the normal line of the bone and the normal line of the transmitting / receiving surface coincide with each other, and therefore, the echo of the vertical reflection from the bone enters the transmitting / receiving surface perpendicularly. When the echo from the bone is the vertical reflection, the level change of the echo from the bone becomes dull with respect to the displacement (vibration of the ultrasonic transducer), so that measurement data with good reproducibility can be obtained. Moreover, since the calculation formula of the acoustic impedance is a simple formula when the echo from the bone is vertical reflection, the acoustic impedance of the bone can be measured reliably and easily. Since the acoustic impedance of bone is expressed by the square root of [elastic modulus x density] of the bone, when the elastic modulus increases with the increase of bone density, these synergistic effects are received, resulting in a remarkable response. Increase to. Conversely, as bone density decreases and elastic modulus decreases, the acoustic impedance undergoes these synergistic effects and responds sensitively, significantly decreasing. Therefore, the acoustic impedance of bone is
It is a good index for judging bone density and elastic modulus. Therefore, the operator can reliably estimate the progress of osteoporosis from the value of the acoustic impedance of the bone output by the output means. For example, if the acoustic impedance is significantly smaller than the average value for that age group,
It can be seen that osteoporosis is getting worse.

Further, instead of using the acoustic impedance of the bone as an index of the bone density and the bone elastic modulus, the reflection coefficient at the interface between the soft tissue and the bone of the living body and the maximum echo level itself which are monotonically increasing functions of the acoustic impedance of the bone are used. The same effect as described above can be obtained as an index of bone density or bone elastic modulus.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a block diagram showing an electrical configuration of an osteoporosis diagnostic apparatus according to a first embodiment of the present invention, FIG. 2 is an external view of the apparatus, and FIG. 3 is a usage state of the apparatus. 4 is a diagram showing a state of osteoporosis diagnosis by the device, FIG. 5 is a flowchart showing an operation processing procedure of the device, and FIG. 6 is a diagram for explaining an operation of the device. As shown in FIGS. 1 to 4, the osteoporosis diagnosing device of this example emits an ultrasonic impulse Ai having good directivity toward the bone Mb, which is the measurement site of the subject M, and from the surface Y of the bone Mb. An ultrasonic transducer (hereinafter, simply referred to as a transducer) 1 that receives a returning echo (bone echo) Ae and converts it into a received signal (electrical signal), and an electric signal of a half-wave impulse is input to the transducer 1. In addition, the device main body 2 that processes the received signals (electrical signals) of various echoes supplied from the transducer 1 to provide the acoustic impedance information of the bone Mb that is an index for diagnosing osteoporosis, and the cable 3 that connects them. It is outlined from.

Although not shown, the transducer 1 is formed by laminating electrode layers on both sides of a disk-shaped thickness vibration type piezoelectric element made of lead titanium zirconate (PZT). Here, since it is preferable for the transducer (ultrasonic transducer) 1 to receive the bone echo Ae in the state of a plane wave in terms of measurement sensitivity, the emitted ultrasonic impulse A
It is preferable to use as large as possible a transmitting / receiving surface so that i can propagate toward the bone Mb in a state close to a plane wave.

The apparatus main body 2 includes a pulse transmission section 4, a matching circuit 5, an amplifier 6, a waveform shaper 7, an A / D converter 8, a CPU (central processing unit) 9, a ROM 10, and a ROM 10.
It is composed of a RAM 11, a level meter 12, and a display 13. The pulse sending unit 4 is connected to the transducer 1 via the matching circuit 5 and has a center frequency of about 2.5.
An electric signal of a half-wave impulse of MHz is generated in a predetermined cycle and intermittently transmitted to the transducer 1. The matching circuit 5 is connected to the transducer 1 via a cable and exchanges signals between the transducer 1 and the apparatus main body 2 with maximum energy efficiency. The amplifier 6 amplifies the output signal of the matching circuit 5 with a predetermined amplification degree, and then inputs it to the waveform shaper 7. The waveform shaper 7 is composed of a detection circuit (not shown) and a low-pass filter (LPF). The output signal of the amplifier 6 (amplified received signal) is subjected to detection processing / filtering processing to shape the waveform, and then A Input to the / D converter 8. The A / D converter 8 includes a level detection circuit, a sample hold circuit, and the like (not shown), detects the level of the output signal of the waveform shaper 7, the arrival time, and the like to detect the bone echo Ae.
Are sequentially extracted. Then, the received signal of the extracted bone echo Ae is converted into a digital echo signal, and the digitally converted echo signal (hereinafter referred to as bone echo signal) is converted into C
Input to PU9 sequentially.

The CPU 9 executes the processing program stored in the ROM 10 using the RAM 11,
Bone Mb used as an index for diagnosing osteoporosis by controlling each part of the device
Acoustic impedance Za is calculated. That is, the CPU 9 sequentially takes the output signal (bone echo signal) of the A / D converter 8, extracts the maximum bone echo level from the fetched bone echo signal, and based on the extracted maximum bone echo level. , Acoustic impedance Za of bone Mb
To calculate. The ROM 10 stores various processing programs of the CPU 9 and a calculation subprogram for calculating the acoustic impedance Za of the bone Mb. RAM11 is C
It has a working area in which the work area of the PU 9 is set and a data area for temporarily storing various data. In this data area, there is a currently extracted data memory area for storing the bone echo level captured this time, and the data area previously fetched. A maximum value extraction data memory area for storing the maximum bone echo level extracted from the bone echo levels, a measurement continuation flag for storing information as to whether or not to continue the measurement, and the like are set. The level meter 12 is controlled by the CPU 9 and is stored in the currently extracted bone echo level (the current level 12a of the bone echo Ae) stored in the currently extracted data memory area of the RAM 11 and the maximum value extracted data memory area of the RAM 11. The maximum bone echo level (maximum level 12b of bone echo Ae) that is being displayed is simultaneously displayed by the liquid crystal pointer pattern. The display 13 is composed of a CRT display or a liquid crystal display, and displays the acoustic impedance Za of the bone Mb calculated by the CPU 9 and the result of the calculation.

Next, the operation processing procedure of this example will be described with reference to FIGS. In order to diagnose osteoporosis using the apparatus having the above-mentioned configuration, the bone Mb having a shape and site where a plane wave bone echo Ae is easily obtained is selected as a measurement target. For example, the heel and patella are less curved,
Since it is close to the skin and a plane wave bone echo Ae is easily obtained, it is suitable as a measurement target. When the power of the device is turned on after selecting the bone Mb to be measured, the CPU 9 first initializes each part of the device in step SP10 (FIG. 5). This initialization is for RAM1
This includes clearing the various data memory areas set to 1, resetting the measurement continuation flag, and initializing various variables that are the initial settings of the peripheral circuits. This allows RAM
The contents of this time extracted data memory area, maximum value extracted data memory area, measurement continuation flag, etc.
Each is initially set to the state of "0".

Here, as shown in FIG. 3, the operator places an ultrasonic coupling material 14 such as water or jelly on the surface (skin surface X) of the soft tissue Ma covering the bone Mb to be measured. After applying the ultrasonic wave so that the ultrasonic waves can be easily injected into the body of the subject M, the transducer 1 is brought into close contact with the skin surface X from above the ultrasonic coupling material 14, and the transmitting / receiving surface is directed to the bone Mb to be measured. In this condition, turn on the measurement start switch.

When the measurement start switch is turned on (step SP11), the CPU 9 rewrites the content of the measurement continuation flag to "1" (after setting the measurement continuation flag), and then
From this, the diagnostic operation is started according to the processing procedure shown in FIG. In step SP12, the CPU 9 controls the pulse sending unit 4 to send a half-wave impulse electric signal to the transducer 1. Transducer 1
When the electric signal of the half-wave impulse is received from the pulse sending unit 4, the ultrasonic impulse Ai having good directivity is emitted vertically from the transmitting / receiving surface toward the bone Mb of the subject M. The emitted ultrasonic impulse Ai is injected into the soft tissue Ma from the skin surface X and propagates toward the bone Mb to be measured, as shown in FIG. Then, a part is reflected on the bone surface Y to become a bone echo Ae, and the rest enters the bone Mb and is partially absorbed and partially penetrated. Of these, the bone echo Ae follows the opposite path and is received again by the transmitting / receiving surface of the transducer 1.

When the transducer 1 sequentially receives the transmission reverberation An (FIG. 4) and the bone echo Ae, the transducer 1 converts the received wave (electrical signal) into a received signal (electrical signal), and the received signal generated by the conversion is transmitted via the cable 3. It is sent to the main body 2 (matching circuit 5).
The amplifier 6 amplifies the received signal output from the matching circuit 5 with a predetermined amplification degree and then inputs the amplified signal to the waveform shaper 7. The waveform shaper 7 detects and filters the output signal of the amplifier 6 to shape the waveform, and then inputs the signal to the A / D converter 8.

Here, the CPU 9 controls the A / D converter 8 to detect the level of the output signal of the waveform shaper 7, the arrival time, etc., removes the transmission reverberation An, and outputs only the bone echo Ae. Sequential extraction is performed, and the received signal of the bone echo Ae is converted into a digital bone echo signal (step SP13). C
The PU 9 takes in the bone echo signal from the A / D converter 8 and stores it in the currently extracted data memory area of the RAM 11 as the bone echo level of this time extraction (step SP
14), by controlling the level meter 12, the bone echo level extracted this time (the current level 12a of the bone echo Ae) and R
Maximum bone echo level stored in the maximum value extraction data memory area of AM11 (maximum level 1 of bone echo Ae
And 2b) are simultaneously displayed by the liquid crystal pointer pattern (step SP15).

Next, the CPU 9 proceeds to step SP16 to read the bone echo level of this time extraction from the currently extracted data memory area in the RAM 11 and the maximum bone echo level from the maximum value extracted data memory area to extract this time. It is judged whether the bone echo level of is larger than the maximum bone echo level. The result of this judgment is
If "YES", that is, if the bone echo level of this time extraction is higher than the maximum bone echo level, the process proceeds to step SP17, and the stored content (maximum bone echo level) of the maximum value extraction data memory area is set to the bone data of this time extraction. After rewriting with the stored contents of the memory area (bone echo level extracted this time), the process proceeds to step SP18. On the other hand, step S
When the result of determination in P16 is "NO", that is, when the bone echo level extracted this time is smaller than the maximum bone echo level, the process directly jumps to step SP18. In step SP18, the CPU 9 looks at the measurement continuation flag in the RAM 11 and determines whether or not to continue the measurement. If the measurement continuation flag is set (when the content of the measurement flag is "1"), the CPU 9 judges that the measurement is continued and step SP
Returning to step 12, the above-described processing (steps SP12 to SP1)
Repeat 8). The content of the measurement continuation flag is kept at "1" until the operator pushes the measurement end switch.

While the CPU 9 repeats the above-mentioned processing (steps SP12 to SP18), the operator applies the transducer 1 to the skin surface X as shown by an arrow R in FIG. While drawing a circle, sometimes like a precession motion of a top, sometimes like a seesaw, swinging back and forth diagonally to the left and right,
Aiming for the state where the LCD pointer pattern of wobbles to the maximum. When the liquid crystal pointer pattern of the level meter 12 swings to the maximum, as shown in FIG. 6A, when the normal line of the bone Mb, which is the measurement site, and the normal line of the transmitting / receiving surface of the transducer 1 match, that is, This is when the plane wave ultrasonic impulse Ai is vertically incident on the bone surface Y (when the wavefront of the ultrasonic impulse Ai is aligned substantially parallel to the bone surface Y).

Because, when both normals coincide with each other, the bone echo Ae reflected vertically on the bone surface Y returns perpendicularly to the transmitting / receiving surface of the transducer 1 as shown in FIG. The wave front of the echo Ae is also aligned substantially parallel to the transmission / reception surface, and therefore, the phase shift of the bone echo Ae due to the difference in the reception position is minimized, so that the reception signal has a cancellation of peaks and troughs. This is because the number of bone echoes Ae is small and therefore the maximum level of bone echo Ae is received. On the other hand, when the normals do not match, the wavefront of the bone echo Ae is not uniform on the transmitting / receiving surface as shown in (b) of the figure, so that the received signal has peaks and troughs that cancel each other. Get smaller. Here, what is important is that, of the bone echoes Ae, what is desired to be extracted is the bone echoes Ae returning by vertical reflection. This is because the mathematical formula applied to the algorithm described later is a formula that holds when the bone echo Ae is substantially vertical reflection for the sake of accuracy and simplification of calculation. However, the bone echo Ae reflected vertically on the bone surface Y has the maximum level of the received signal as described above, and therefore the level meter 1 is used to extract the bone echo Ae reflected vertically.
The maximum level of bone echo Ae is extracted with reference to step 2. The liquid crystal pointer pattern of the level meter 12 changes sensitively when the normal line of the bone Mb and the normal line of the transmitting / receiving surface are not significant, but changes slowly when both normal lines are substantially the same. Therefore, the bone echo Ae of vertical reflection can be extracted easily and with good reproducibility.

When the operator determines that the maximum level of bone echo Ae can be extracted by looking at the fluctuation of the liquid crystal pointer pattern of the level meter 12, the operator presses the measurement end switch. When the measurement end switch is pressed, the CPU 9 rewrites the content of the measurement continuation flag to "0" by the interrupt processing and lowers the measurement continuation flag. When the measurement continuation flag is cleared, the CPU 9 determines that the measurement is completed (step SP18), controls the pulse sending unit 4, and stops the transmission of the half-wave impulse (electrical signal) to the transducer 1. Then, from the maximum value extraction data memory area,
The stored contents (maximum bone echo level) are read out and displayed on the display 13 (step SP19).

Thereafter, the CPU 9 uses the maximum echo level V1 obtained by the above-described processing and the complete echo level V0 stored in the ROM 10 in advance to determine the soft tissue Ma.
-Calculate the reflection coefficient R at the interface of the bone Mb (step SP
20), display the calculation result on the display 13 (step S
P21). Here, the reflection coefficient R is derived from the ratio [R = V1 / V0] of the perfect echo level V0 and the maximum echo level V1 at the time of perfect vertical reflection, and the perfect echo level V0 should be theoretically calculated. However, it can be obtained by preparing a plastic dummy block and measuring the echo level.

Next, the CPU 9 proceeds to step SP22, and acoustic impedance Za (Ns / m ³ ) of the bone Mb.
Is calculated using equation (1), and the calculation result is displayed on the display 13 (step SP21).

[0026]

[Equation 1]

Here, Za (w): acoustic impedance of soft tissue R: reflection coefficient equation (1) at the time of vertical reflection at the interface between soft tissue Ma and bone Mb is derived as follows. The reflection coefficient R at the time of vertical reflection at the interface between the soft tissue Ma and the bone Mb is given by the equation (2). Therefore, by rearranging equation (2), equation (1) is obtained.

[0028]

[Equation 2]

According to the above configuration, since the bone echo Ae of vertical reflection in which the level change of the echo from the bone is dull with respect to the displacement (vibration of the transducer 1) is used, the measurement data can be easily extracted and reproduced. It can be extracted easily. In addition, the current level 12a of the bone echo Ae is displayed on the level meter 12 every moment, and the maximum level 12b of the bone echo Ae is also fixedly displayed, so that the maximum level can be easily searched. Therefore, the acoustic impedance Za of the bone Mb can be reliably measured.

The acoustic impedance Za of the bone Mb is
Since it is represented by the square root of [elastic modulus × density] of b, when the elastic modulus increases with the increase of bone density, these synergistic effects cause a significant response and a significant increase. On the contrary, when the density of the bone Mb decreases and the elastic modulus decreases, the acoustic impedance Za receives these synergistic effects,
Responsive sensitively and significantly reduced. Therefore, the acoustic impedance Za of the bone Mb is a good index for determining the bone density. Therefore, from the value of the acoustic impedance Za of the bone Mb displayed on the display 13, the operator
It is possible to reliably estimate the progress of osteoporosis. For example, when the acoustic impedance is significantly smaller than the average value of that age group, it is understood that the osteoporosis of the bone Mb is aggravated. In addition, since the RAM 11 is set with a currently extracted data memory area that stores only the currently extracted data and a maximum value extracted data memory area that stores only the maximum bone echo level and related data, it is inexpensive and has a small storage capacity. RAM can be used.

Second Embodiment Next, a second embodiment of the present invention will be described. In the second embodiment, a reflection coefficient calculation algorithm different from that in the first embodiment is adopted. Otherwise, the first
The configuration is substantially the same as that of the embodiment. In the second embodiment, the reflection coefficient R at the interface between the soft tissue Ma and the bone Mb is such that the ultrasonic impulse Ai and the bone echo Ae can be regarded as sufficiently plane waves, and the attenuation of the ultrasonic wave in the soft tissue Ma can be ignored. It is given by the equation (3).

[0032]

[Equation 3]

Here, P: When a unit electric signal (voltage, current, scattering parameter, etc.) is applied to the transducer 1, the sound pressure of the ultrasonic impulse Ai output from the transducer 1 in the vertical direction Q: The sound pressure of the transducer 1 Amplitude B of the received signal (electrical signal) output from the transducer 1 when the bone echo Ae of unit sound pressure is vertically incident on the transmitting / receiving surface: the amplitude amplification degree of the amplifier 6 and the amplitude amplification degree of the waveform shaper 7. Product Vi: amplitude of electric signal applied to the transducer 1 from the pulse sending unit 4 when the device is used Ve: maximum bone echo level (maximum electric signal of bone echo signal detected by the A / D converter 8) P, Q, B, and Vi are all functions of frequency, but here, the component at the center frequency (for example, 2.5 MHz) is used. Regarding P, Q, B and Vi,
These measured values and setting values are written and stored in the ROM 10.

Equation (3) is derived as follows. First, the amplitude Vi from the pulse sending unit 4 to the transducer 1
Is applied, an ultrasonic impulse Ai of sound pressure PVi is output from the transmitting / receiving surface of the transducer 1 toward the bone Mb. Therefore, the bone echo Ae of the sound pressure RPVi returns perpendicularly to the transmitting / receiving surface of the transducer 1. Therefore, the maximum echo level Ve is given by the equation (4).

[0035]

[Equation 4]       Ve = Q / R / P / B / Vi (4) From equation (4), equation (3) is obtained.

As described above, also in the second embodiment, the reflection coefficient R at the interface between the soft tissue Ma and the bone Mb and the acoustic impedance Za of the bone Mb are calculated by the CPU 9, so that they are substantially the same as in the first embodiment. The effect can be obtained.

The embodiment of the present invention has been described in detail above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and there are design changes and the like within a range not departing from the gist of the present invention. Also included in the present invention. For example, bones are not limited to humans. Similarly, the measurement site is not limited to the heel or the patella. Further, the ultrasonic transducer forming the transducer is not limited to the thickness vibration type, but may be the bending vibration type. The wave transmission / reception surface of the ultrasonic transducer is not limited to a large one. The center frequency used is 2.5M.
Not limited to Hz. Further, since the acoustic impedance of the soft tissue Ma is close to the acoustic impedance of water, the acoustic impedance of water may be used instead of the acoustic impedance of the soft tissue Ma when applying the formula (1). Further, the output device for outputting the index (acoustic impedance) of the osteoporosis diagnosis is not limited to the display device, and a printer may be used. A time waveform display device (eg, digital oscilloscope) may be provided to observe the echo waveform. Further, since the acoustic impedance of the soft tissue Ma is close to the acoustic impedance of water, the acoustic impedance of water may be used instead of the acoustic impedance of the soft tissue Ma when applying the formula (1). Also,
Although there is an opinion that osteoporosis can be diagnosed from the situation of the bone elastic modulus, the acoustic impedance of the bone is expressed by the square root of [elastic modulus × density] of the bone, and thus can be an index of the bone elastic modulus. Further, instead of using the acoustic impedance of bone as an index of bone density or bone elastic modulus, the reflection coefficient at the interface of soft tissue Ma / bone Mb, which is a monotonically increasing function of the acoustic impedance of bone, or the maximum bone echo level itself is used as the bone density. The same effect as described above can be obtained as an index of bone elasticity.

[0038]

As described above, according to the configuration of the present invention, the vertical reflection bone echo in which the level change of the echo from the bone is blunted with respect to the displacement (vibration of the ultrasonic transducer) is utilized. The measurement data can be extracted easily and with good reproducibility. Therefore, the acoustic impedance of bone can be reliably measured. Since the acoustic impedance of bone is expressed by the square root of [elastic modulus x density] of the bone, when the elastic modulus increases with the increase of bone density, these synergistic effects are received, resulting in a remarkable response. Increase to. Conversely, as bone density decreases and elastic modulus decreases, the acoustic impedance undergoes these synergistic effects and responds sensitively, significantly decreasing. Therefore, the acoustic impedance of bone is
It is a good index for judging bone density and elastic modulus. Therefore, the operator can reliably estimate the progress of osteoporosis from the value of the acoustic impedance of the bone output by the output means. For example, if the acoustic impedance is significantly smaller than the average value for that age group,
It can be seen that the osteoporosis of the bone is getting worse.

Further, instead of using the acoustic impedance of bone as an index of bone density or bone elastic modulus, the reflection coefficient at the soft tissue / bone interface, which is a monotonically increasing function of the acoustic impedance of bone, or the maximum bone echo level itself is used. The same effect as described above can be obtained as an index of density or bone elastic modulus.

[Brief description of drawings]

FIG. 1 is a block diagram showing an electrical configuration of an osteoporosis diagnostic device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an appearance of the same device.

FIG. 3 is a diagram showing a usage state of the apparatus.

FIG. 4 is a diagram showing how osteoporosis is diagnosed by the device.

FIG. 5 is a flowchart showing an operation processing procedure of the apparatus.

FIG. 6 is a diagram for explaining the operation of the same device.

[Explanation of symbols]

1 Transducer (Ultrasonic Transducer) 9 CPU (Main part of maximum echo level extraction means,
Reflection coefficient calculating means, acoustic impedance calculating means) 13 Display (output means) Ai ultrasonic impulse Ae bone echo (echo from bone) Mb bone

─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-60-60837 (JP, A) JP-A-60-83645 (JP, A) JP-A 1-503199 (JP, A) US Patent 5197475 (US , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) A61B 8/00-8/15

Claims (3)

(57) [Claims] 1. An ultrasonic wave transmitter / receiver is applied to a living body, a normal line of its transmitting / receiving surface is directed to a bone, and an ultrasonic wave impulse is intermittently oscillated while swinging within a predetermined angle range with respect to the normal line of the bone. An osteoporosis diagnostic device for diagnosing osteoporosis by emitting echoes from the bone and sequentially receiving echoes from the bone and estimating at least the state of bone density or bone elasticity based on the received echo information from the bone. And transmitting and receiving the ultrasonic wave
In the echoes from the bone received by the wave sequentially
To extract the maximum echo level by the vertical reflection echo from
Large echo level extraction means and maximum echo level extraction means
Diagnosis of osteoporosis by the maximum echo level extracted by the step
Osteoporosis diagnostic apparatus characterized by comprising an output means for outputting as an indication of. 2. An ultrasonic impulse is intermittently applied by applying an ultrasonic wave transmitter / receiver to a living body, directing a normal line of its transmitting / receiving surface toward a bone and oscillating within a predetermined angle range with respect to the normal line of the bone. In the osteoporosis diagnostic device for diagnosing osteoporosis by estimating the situation of at least bone density or bone elastic modulus based on the echo information from the received bone. Then, the echoes from the bone sequentially received by the ultrasonic transducer are dropped.
Based on the maximum echo level extraction means for extracting the maximum echo level by the direct reflection echo, and the maximum echo level extracted by the maximum echo level extraction means , the raw echo
Compute the reflection coefficient at the interface between the soft tissue of the body and the bone
Calculated by the reflection coefficient calculation means and the reflection coefficient calculation means.
An osteoporosis diagnosing device, comprising: an output unit that outputs the reflected reflection coefficient as an index for diagnosing osteoporosis. 3. An ultrasonic wave impulse is applied intermittently while applying an ultrasonic wave transmitter / receiver to a living body, directing a normal line of its transmitting / receiving surface toward a bone and oscillating within a predetermined angle range with respect to the normal line of the bone. In the osteoporosis diagnostic device for diagnosing osteoporosis by estimating the situation of at least bone density or bone elastic modulus based on the echo information from the received bone. Then, the echoes from the bone sequentially received by the ultrasonic transducer are dropped.
Maximum echo level extraction means for extracting the maximum echo level by the direct reflection echo , and a reflection coefficient at the interface between the soft tissue of the living body and the bone is calculated based on the maximum echo level extracted by the maximum echo level extraction means. Based on the reflection coefficient calculated by the reflection coefficient calculation means, and the acoustic impedance of the bone
And an acoustic impedance calculating means for calculating
The acoustic impedance of the bone calculated by the impedance calculation means.
An osteoporosis diagnosing device, comprising: an output unit that outputs a dance as an index for diagnosing osteoporosis.