JP3317988B2 - Ultrasound bone diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for diagnosing a bone by ultrasonic waves.

[0002]

2. Description of the Related Art Conventionally, X-rays have been used for diagnosing osteoporosis. However, in recent years, it has been experimentally verified that the relationship between bone attenuation and sound speed due to ultrasonic waves and bone density is related. Devices that do this are also emerging. The conventional technology transmits an ultrasonic wave having two frequency components as described in U.S. Pat.No. 4,913,157, extracts two frequency components from a received signal transmitted through a subject, and outputs a low-frequency signal and a high-frequency signal. The sound velocity and attenuation are obtained as bone diagnostic indices by comparing. There, the arrival time of the ultrasonic wave and the spectrum are mainly used.
An ultrasonic probe is provided at both ends of the caliper to measure and correct the distance to the object to be measured. In U.S. Pat. No. 4,930,511 (JP-A-2-104337), two vibration elements are arranged at a known distance, and a reference material and a bone part are inserted. The sound velocity and the attenuation are determined from the spectrum. US Patent
In Japanese Patent No. 4926870, similarly to the above, ultrasonic probes are provided at both ends of a caliper, and positions are set so that a typical waveform transmitted through a bone part is obtained, and measurement of sound speed and attenuation is performed. I do.

[0003]

In the prior art, in order to obtain a bone diagnostic index by obtaining a sound speed from an arrival time of an ultrasonic wave, an accurate measurement of the distance between ultrasonic probes and a sound speed of a soft tissue are known. In addition, it is important to set accurately between the two ultrasonic probes of the subject. Regarding attenuation, even though the signal is transmitted at two frequencies, all the information is not used. There was also an effect of the shape of the bone. Further, it is necessary to perform an operation such as accurately fixing a portion to be measured between two ultrasonic probes in the measuring device, and there is a problem in reproducibility. An object of the present invention is not affected by the shape of the bone, further reduces the influence of soft tissue other than the bone, and obtains a bone diagnostic index without measuring the distance between two ultrasonic probes. It is to provide a diagnostic method. Another object is to provide a simple bone diagnostic apparatus.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method in which a first ultrasonic probe for transmitting a wave and a second ultrasonic probe for receiving a wave are opposed to each other via a subject. In an apparatus for determining physical properties such as attenuation and sound speed of a living body, ultrasonic waves are transmitted at a first frequency f1 by a first ultrasonic probe, and an object is detected by a second ultrasonic probe. Receiving the ultrasonic signal transmitted through
Next, an ultrasonic wave is transmitted from the first ultrasonic probe at a second frequency f2 different from the first frequency f1, and an ultrasonic signal transmitted through the subject by the second ultrasonic probe. Receive waves. First
Frequency shift f with respect to f1 of the frequency of the received signal of the second ultrasonic probe with respect to the transmission of the ultrasonic wave of frequency f1
1 ′ and the second with respect to the transmission of the ultrasonic wave having the second frequency f2.
The frequency shift f2 'of the frequency of the received signal of the ultrasonic probe with respect to f2 is obtained, and the frequency shifts f1' and f2 '
The physical index of the subject placed between the two ultrasonic probes is obtained by calculating the ratio of

[0005] The first ultrasonic probe and the second ultrasonic probe are each composed of an ultrasonic probe in which a single or a plurality of vibrating elements are arranged. The ultrasonic probe and the second ultrasonic probe are arranged so as to have the same focal position. Further, the above-described measurement is repeatedly performed while sequentially moving the opposing first ultrasonic probe and second ultrasonic probe, and only signals transmitted through the region of interest of the subject are integrated and averaged.

[0006] Further, the vibration elements are arranged in a ring shape, arranged in a belt shape on the body surface of a site of interest, and connected to an arithmetic processing unit having a control function such as a personal computer or an existing ultrasonic diagnostic apparatus. A bone diagnostic device is configured.

[0007]

The first ultrasonic probe transmits an ultrasonic wave at the first frequency f1, receives the ultrasonic signal transmitted through the subject by the second ultrasonic probe, and then transmits the ultrasonic signal. Transmitting an ultrasonic wave from the first ultrasonic probe at a second frequency f2 different from the first frequency, and receiving an ultrasonic signal transmitted through the subject by the second ultrasonic probe; I do. The frequency shift f1 'of the frequency of the received signal of the second ultrasonic probe with respect to the transmission of the ultrasonic wave of the first frequency f1 with respect to f1, and the second with respect to the transmission of the ultrasonic wave of the second frequency f2. The frequency shift f2 'with respect to the frequency f2 of the received signal of the ultrasonic probe is determined, and the ratio between the frequency shifts f1' and f2 'is determined, whereby the object placed between the two ultrasonic probes is obtained. , The diagnostic index can be obtained.

[0008] The first ultrasonic probe and the second ultrasonic probe are each composed of an ultrasonic probe in which a single or a plurality of vibrating elements are arranged. The ultrasonic probe and the second ultrasonic probe are arranged so as to have the same focal position, and the first ultrasonic probe and the second ultrasonic probe facing each other are repeatedly moved while being sequentially moved. Since the above measurement is performed, it is possible to integrate and average only signals transmitted through the site of interest of the subject, and to reduce the influence from a medium other than the bone.

Further, a vibration element is arranged in a ring shape and arranged in a belt shape on the body surface of a site of interest, and this is connected to an arithmetic processing unit having a control function such as a personal computer, for example, to provide a small and general-purpose bone diagnosis. The apparatus can be a simple bone diagnostic apparatus that can be connected to an existing ultrasonic diagnostic apparatus or installed as an option.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIGS. FIG. 1 shows a basic configuration of a bone diagnostic apparatus according to a first embodiment of the present invention and a method for obtaining a bone diagnostic index. This bone diagnostic apparatus is a transmission circuit 1 for transmitting ultrasonic waves.
A first ultrasonic probe 2 for transmission connected to the transmission circuit 1, a second ultrasonic probe 3 for reception provided opposite thereto, and an ultrasonic probe It comprises a signal processing unit 4 for obtaining the physical information of the bone by processing the ultrasonic signal received by the tentacle 3 and obtaining a diagnostic index, and a display unit 5. The subject is placed between the first and second ultrasonic probes 2 and 3 as shown in FIG. Here, the physical information of bone refers to density, sound speed, attenuation, and the like. When irradiating ultrasound to bone containing a lot of spongy material,
The ultrasonic wave transmitted through the bone received by the second ultrasonic probe 3 is received with a certain time difference between the low frequency component 100 and the high frequency component 101 as shown in FIG. The low-frequency component 100 that appears first is a spongy material 6 having a large attenuation inside the bone.
The high-frequency component 101 that is transmitted through the surface and is close to the transmitted frequency that appears later is an ultrasonic signal that has propagated on the bone surface, that is, the so-called cortical bone 7. Therefore, the high-frequency component 101 has little attenuation and has a frequency substantially close to the transmitted frequency. Here, assuming that the transmission frequency is f, the propagation distance of the ultrasonic wave in the subject is d, the half width of the transmission pulse is a, and the attenuation constant is B, the center frequency f ′ of the reception wave is expressed by the following equation (1).
Given by

F ′ = fa− ² · d · B (1) A method of obtaining a bone diagnostic index will be described below. As shown in the timing chart of FIG. 3, two or more types of ultrasonic pulses having different frequencies are transmitted from the first ultrasonic probe 2 for transmission. In this embodiment, two types of frequencies are used. First, the transmitting pulse 102 is radiated at the first frequency f1, and after the ultrasonic signal is received by the second ultrasonic probe 3 for receiving, the second pulse is different from the first frequency. A transmission pulse 103 is emitted at a frequency f2 of 2. The ultrasonic signal received by the second ultrasonic probe 3 for reception includes a low-frequency component 104 transmitted through the spongy material 6 and having a frequency shifted to f3 by attenuation, and mainly propagates on the bone surface. Frequency f4
High frequency component 105 appears. A similar received signal appears as a low-frequency component 106 of frequency f5 and a high-frequency component 107 of frequency f6 by the transmission pulse 103 of the second frequency f2. Here, a ratio between a received signal transmitted by the first frequency f1 and a received signal transmitted by the next frequency f2 is calculated. For example, taking the ratio of the frequencies of the low-frequency components gives Equation (2).

[0012] f3 / f5 = (f1-a 2 · d · B 1) / (f2-a 2 · d · B 2) (2) a second ultrasonic for ultrasonic wave transmission of the first frequency f1 A frequency shift f1 ′ of the frequency of the received signal of the probe with respect to f1, and a frequency shift f2 of the frequency of the received signal of the second ultrasonic probe with respect to f2 with respect to the transmission of the ultrasonic wave of the second frequency f2. And frequency shifts f1 ′ and f1
'When determining the ratio of, f1' 2 / f2 '= (f1-f3) / (f2-f5) = B 1 / B 2 (3) , and the unknown constants, between the two ultrasonic probes The propagation distance d of the ultrasonic wave in the placed subject is canceled. It is possible to determine the change in the attenuation constant (the attenuation constants at frequencies f1 and f2 are B ₁ and B ₂ ) depending on the frequency regardless of the propagation distance d of the ultrasonic wave (the half width a of the transmitted pulse is the frequency. Assuming constant). Although the trabecular bone is entangled vertically and horizontally in the spongy bone, it gradually shifts to a coarse state as the disease progresses, and the difference in attenuation constant depending on the frequency becomes more pronounced depending on the progress of the disease. Therefore, by this method, a bone diagnostic index can be obtained by determining the attenuation constant or the frequency shift ratio at different frequencies. For example, the progress of the disease, the normal abnormality of the bone, and the like can be grasped from the diagnostic index.

In this embodiment, the case where two types of frequencies are used has been described. However, the frequency is not limited to two types.
Waves are transmitted from the first ultrasonic probe 2 for transmission, a plurality of frequency shifts are measured, two frequency shifts are selected from these, a ratio of the frequency shifts is obtained, and a more effective bone diagnostic index is obtained. You can also ask.

The calculation of the attenuation constant or the frequency shift and the calculation of the attenuation constant or the ratio of the frequency shift are performed by the signal processing unit 4 and transmitted by the first ultrasonic probe 2 for transmission. The processing is executed based on the ultrasonic signal and the ultrasonic signal received by the second ultrasonic probe 3 for reception, and the result is displayed on the display unit 5.

Next, a method of obtaining a bone diagnostic index according to a second embodiment of the present invention will be described. In the typical received signal waveform of FIG. 2, low frequency component 100 and high frequency component 1
It takes the intensity ratio of 01 or the ratio of the power spectrum. In general, aging decreases in spongy bone mass
Faster than that of the cortex. The low-frequency component 100 has information on the spongy material 6, and the high-frequency component 101 has information on the cortex 7, so that information on bone loss can be obtained by taking the ratio between the two. Of course, as in the first embodiment, the attenuation constant ratio A obtained from the low frequency components 104 and 106 and the high frequency components 105 and 107 (FIG. 3) obtained by the method of transmitting ultrasonic waves having a plurality of different frequencies. ), The ratio A / B of the damping constant ratio B can be used as a diagnostic index.

Based on an ultrasonic signal transmitted by the first ultrasonic probe 2 for transmission and an ultrasonic signal received by the second ultrasonic probe 3 for reception. In addition, the intensity ratio of the low frequency component 100 and the high frequency component 101 or the power spectrum ratio, the attenuation constant ratio A obtained from the low frequency components 104 and 106, and the attenuation constant ratio obtained from the high frequency components 105 and 107 (FIG. 3) The ratio A / B of B is obtained by the signal processing unit 4 and the result is displayed on the display unit 5.

FIG. 4 shows an example of a circuit configuration according to a third embodiment of the present invention which makes it possible to easily perform spectrum analysis of a received signal by using a transmitted pulse as a chirp signal. FIG. 4B shows an example of the transmission waveform of the chirp signal.
By using the transmission pulse as a chirp signal, a wideband signal having a good S / N can be obtained. FIG. 4A shows the configuration of the apparatus. As in FIG. 1, a transmitting circuit 1 for transmitting ultrasonic waves, a first ultrasonic probe 2 for transmitting chirp signals connected to the transmitting circuit 1, A second ultrasonic probe 3 for receiving waves provided, and a signal processing for processing ultrasonic signals received by the ultrasonic probe 3 to obtain physical information on bones and obtain a diagnostic index And a display unit 5. The subject is placed between the first and second ultrasonic probes 2 and 3 as in FIG. The received signals captured by the second ultrasonic probe 3 for receiving waves are input to a plurality of filters 14 connected in parallel. This output becomes the spectral intensity. This is used by the processing unit 15 for various calculations such as the intensity ratio of the spectrum. Although not shown here, by performing pulse compression processing on the chirp signal, it is possible to use the chirp signal for calculating the arrival time of ultrasonic waves or to realize a short pulse when displaying an image.

FIG. 5 shows a fourth embodiment of the ultrasonic probe which can be used in the first to third embodiments of the present invention. The first ultrasonic probe 2 for transmitting waves and the second ultrasonic probe 3 for receiving waves have the same focal position. By setting the focal point to be in the region of interest of the subject, it is possible to reduce the influence other than the region of interest. The ultrasonic waves 9 transmitted from the first ultrasonic probe 2 for transmitting waves pass through the bone and generate a focus on the spongy material 6 in the region of interest. This focal point was configured to match the focal point of the second ultrasonic probe 3 for receiving waves.

A description will be given of a fifth embodiment relating to an ultrasonic probe which can be used in the first to third embodiments according to the present invention. The ultrasonic probe for transmitting and / or receiving waves may be a variable focus by using an ultrasonic probe having an array of a plurality of vibrating elements. In particular, by using the ultrasonic probe connected to the conventional ultrasonic diagnostic apparatus for the ultrasonic probe 2 for transmitting, it is possible to easily change the beam of the transmitted ultrasonic wave and change the focal point. The ultrasonic probe 3 for receiving waves can also easily obtain bone diagnostic information by connecting to a conventional ultrasonic diagnostic apparatus and changing the signal processing and display method of the conventional apparatus.

A description will be given of a sixth embodiment relating to an ultrasonic probe which can be used in the first to third embodiments according to the present invention. An ultrasonic probe for transmitting and receiving waves has a plurality of vibrating elements arranged one-dimensionally or two-dimensionally. Each vibrating element has a changeover switch. A configuration for transmitting and receiving sound waves may be employed. In such a configuration, as shown in FIG. 2, data may be acquired only in the case of a combination of transmitted and received waves that can obtain a typical received waveform including a low-frequency component and a high-frequency component.

FIG. 6 shows an embodiment of the ultrasonic probe having such a configuration. A large number of vibrating elements 11 are arranged in an annular shape, and one or a plurality of vibrating elements are transmitted with a diameter as a wave,
A beam is formed and received using one or a plurality of opposing vibrating elements as an aperture.

As shown in FIG. 7, data is obtained by transmitting and receiving while shifting the diameter of the opposing aperture, for example, in the direction of the arrow in FIG. Then, as in the fourth embodiment, only the typical received waveform as shown in FIG. 2 is processed as data while passing through the region of interest.

An acoustic coupling element such as a water bag which has a flexible shape inside the annular vibration element array 27 may be provided, or the arranged vibration elements themselves may be a polymer piezoelectric substance or a composite. It may be made of a flexible material such as a piezoelectric body, and may be directly in close contact with the subject like a band, and may be surrounded. In such a configuration, accuracy can be improved by integrating and averaging only signals transmitted through the region of interest. Such integration and averaging of the received signal transmitted through the region of interest is performed by the signal processing unit 4.
Executed in

In this embodiment, if the array is a fixed toroidal vibrating element array and the distance between the vibrating elements is known, each of the vibrating elements is first used for both transmission and reception, and the reflected echo on the bone surface is measured to determine , The influence of propagation paths other than bone can be removed from the time when the transmitted wave arrives at the time of the next transmitted wave measurement, and the sound velocity of the bone itself can be calculated. Alternatively, as is clear from FIG. 2, the high-frequency component 101 is modulated by multiple reflections generated between the bone surface of the low-frequency component and the ultrasonic probe, and the low-frequency component 100 is modulated by passing through a low-pass filter. Since the distance between the bone and the ultrasonic probe can be measured by observing multiple reflections, the distance between the bone itself and the sound velocity can be obtained in the same manner as described above.

In the embodiment according to the present invention, in the configuration using the array-shaped ultrasonic probe, the signal
The display unit 5 can also display a B-mode tomographic image. For example, it is possible to transmit a wave by one vibrating element and receive by one or a plurality of other vibrating elements, shift the combination of transmission and reception, and reproduce an image using an aperture synthesis method or the like. Of course, an A-mode waveform can also be displayed.

In the embodiment of the present invention, by using an arithmetic processing unit having a control function such as a personal computer for the signal processing unit 4, the display unit 5 and the like, it is possible to record for a long time with a small size and a general purpose. It is possible to realize a bone diagnostic apparatus capable of immediately grasping a change in a medical condition by using a chronological record.

FIG. 8 is a schematic view showing one embodiment of such an apparatus. The adapter 21 is connected to the laptop personal computer 20, and the annular vibration element array 27 is connected. The display of the laptop personal computer 20 can display an A-mode waveform, a bone diagnostic index, a bone state evaluation result, a tomographic image, and the like. Of course, various data can be stored, a long-term recording can be performed, and a temporal change can be displayed.

FIG. 9 shows the configuration of the adapter 21. GP
Interface section 22 for IB, I / O, etc., wave transmitting circuit 2
3, a changeover switch 24, a wave receiving circuit 25, an A / D converter 26, and a memory and the like are incorporated if necessary. It operates according to instructions from software, a driving pulse is output by a transmitting circuit 23, a vibrating element is selected by a changeover switch 24, a received signal is subjected to analog processing such as amplification by a receiving circuit 25, and A / D The signal is converted into a digital signal by the converter 26, and is taken into the personal computer 20 to perform various signal processing and calculations described above.

FIG. 10 shows an example of the changeover switch 24 for transmitting or receiving waves with one vibrating element. FIG.
Reference numeral 1 denotes an example of a case where the aperture is constituted by a plurality of vibration elements. By providing the switch 12 connected to the transmitting circuit and the switch 13 connected to the receiving circuit on the vibrating element 11,
Switching can be performed by turning on the switch on the transmitting side when transmitting waves and turning on the switch on the receiving side when receiving waves.

There are no particular restrictions on the site to be measured by the present apparatus, but it is preferable to be around the calcaneus, knee scapula or wrist joint of the radius.

[0031]

According to the present invention, the frequency shift f1 'of the frequency of the received signal of the second ultrasonic probe with respect to the transmission of the ultrasonic wave of the first frequency f1 with respect to f1, and the second frequency The frequency shift f2 'of the frequency of the received signal of the second ultrasonic probe with respect to the transmission of the ultrasonic wave of f2 with respect to f2 is obtained, and the ratio of the frequency shifts f1' and f2 'is obtained. The diagnostic index can be obtained by canceling the distance of the subject placed between the acoustic probes.

The first ultrasonic probe and the second ultrasonic probe are each composed of an ultrasonic probe in which a single or a plurality of vibrating elements are arranged. The ultrasonic probe and the second ultrasonic probe are disposed so as to have the same focal position, and furthermore, an arbitrary vibration element of an arbitrary vibrating element can be detected from the first ultrasonic probe and the second ultrasonic probe that are opposed to each other. Since transmission and reception can be performed in combination, only signals transmitted through the region of interest of the subject can be integrated and averaged, and the influence from a medium other than bone can be reduced.

Further, a vibration element is arranged in a ring shape, and is arranged in a belt shape on the body surface of a site of interest, and this is connected to an arithmetic processing unit having a control function such as a personal computer. Alternatively, it can be a simple bone diagnostic apparatus which can be connected to an existing ultrasonic diagnostic apparatus and installed as an option.

[Brief description of the drawings]

FIG. 1 is a block diagram of a bone diagnostic apparatus according to the present invention.

FIG. 2 is an explanatory diagram of an ultrasonic signal transmitted through a bone.

FIG. 3 is a timing chart for repeating transmission and reception of ultrasonic waves a plurality of times according to the present invention.

FIGS. 4A and 4B are a block diagram of an apparatus when a transmission pulse according to the present invention is used as a chirp signal, and FIGS.

FIG. 5 is a cross-sectional view of an embodiment in which the focal points of the ultrasonic probe for transmitting and the ultrasonic probe for receiving are the same according to the present invention.

FIG. 6 is a perspective view of an ultrasonic probe in which vibration elements are arranged in an annular shape for use in bone diagnosis according to the present invention.

FIG. 7 is an explanatory diagram showing an example of ultrasonic beam formation by an ultrasonic probe in which vibrating elements are arranged in an annular shape for use in bone diagnosis according to the present invention.

FIG. 8 is a block diagram of a bone diagnostic apparatus using a personal computer according to the present invention.

FIG. 9 is a block diagram showing a configuration example of an adapter for connecting a personal computer and an ultrasonic probe according to the present invention.

FIG. 10 is a circuit diagram of a changeover switch for a vibrating element when transmitting and receiving ultrasonic waves with one vibrating element according to the present invention.

FIG. 11 is a circuit diagram of a vibration element changeover switch when transmitting and receiving ultrasonic waves by a plurality of vibration elements according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transmission circuit, 2 ... Ultrasonic probe for transmission, 3 ... Ultrasonic probe for reception, 4 ... Signal processing part, 5 ... Display part, 6 ... Sponge, 7 ... Cortex, 8 ... Body surface.

Continuation of the front page (72) Inventor Norio Yokozawa 2-1 Shinjyuyo, Kashiwa-shi, Chiba Hitachi Medical Research Laboratory Co., Ltd. (56) References JP-A-49-38490 (JP, A) JP-A-60-83645 ( JP, A) JP-A-57-55136 (JP, A) JP-A-58-183154 (JP, A) JP-A-62-167542 (JP, A) JP-A-1-503199 (JP, A) JP-A Hei 4-501519 (JP, A) US Patent 4,083,232 (US, A) US Patent 4,421,119 (US, A) US Patent 4,774,959 (US, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) A61B 8/00

Claims (1)

(57) [Claims] A first ultrasonic probe for transmitting an ultrasonic pulse to a subject; a first ultrasonic probe interposed between the first ultrasound probe and the first ultrasonic probe; A second ultrasonic probe for receiving an ultrasonic pulse transmitted through the subject; a transmitting unit configured to transmit a plurality of ultrasonic pulses having different frequencies from the first ultrasonic probe; Frequency shift of the center frequency of the low frequency component of the first received signal with respect to the transmission of the ultrasonic pulse of the first frequency with respect to the first frequency
And a second to the transmission of the ultrasonic pulse at the second frequency.
The second frequency of the center frequency of the low frequency component of the received signal
A first ratio of a frequency shift to a number is obtained,
The first frequency of the center frequency of the high frequency component of the received signal
Frequency shift with respect to the number, and the frequency of the center frequency of the high frequency component of the second received signal with respect to the second frequency
A second ratio with respect to the shift is obtained, and the first ratio and the second ratio are calculated.
Signal processing means asking you to the ratio of the specific bone diagnosing device by ultrasound, characterized in that it comprises a display means for displaying the processed result of the signal processing means.