Ultrasound diagnostic apparatus, ultrasound diagnostic system, and procedures for controlling the ultrasound diagnostic apparatus

Abstract

To more reliably calculate parameters related to tissue properties, the processor 7 in the ultrasound diagnostic apparatus 1 controls the ultrasound probe 2 to emit ultrasound pulses at a first pulse repetition frequency to the patient, emitting mechanical vibrations that have been applied by the vibrator 50 to generate shear waves. The processor 7 then creates image data representing the propagation of these shear waves based on the resulting echo signals. Furthermore, the processor 7 calculates the frequency components of the mechanical vibrations based on this image data and calculates at least one second pulse repetition frequency of the ultrasound pulses according to these frequency components. Additionally, the processor 7 controls the ultrasound probe to emit ultrasound pulses at the second pulse repetition frequency instead of the first pulse repetition frequency and calculates at least one propagation velocity of the shear waves based on the resulting echo signals.

Description

Technical Field

[0001] This invention relates to an ultrasound diagnostic apparatus and system for calculating the propagation velocity of shear waves, and a program for controlling the ultrasound diagnostic apparatus. Background Technology

[0002] Techniques for quantifying the properties of patient tissues include techniques for detecting shear waves generated within the patient's body to calculate parameters related to tissue properties. For example, Japanese Patent Application Publication No. 2019-118820 discloses an ultrasonic device for generating shear waves within the patient's body by using ultrasonic-driven pulses, and for calculating a quantitative value of viscosity based on the propagation frequency and velocity of the shear waves.

[0003] When shear waves are generated inside a patient's liver, for example, by using ultrasound-driven pulses, these shear waves are very weak and have short propagation distances and poor signal-to-noise ratios (S / N). Under such adverse conditions, it is difficult to detect shear waves and calculate parameters related to tissue properties. A more reliable method for calculating these tissue-related parameters is desired. Summary of the Invention

[0004] This invention provides a more detailed description of concepts in specific embodiments. It should not be used to determine the essential features of the claimed subject matter, nor should it be used to limit the scope of the claimed subject matter.

[0005] One mode of ultrasound diagnostic apparatus or system solves the aforementioned problem by generating shear waves by applying mechanical vibrations to a patient instead of driving pulses. The ultrasound pulses used to detect the shear waves need to be emitted at a pulse repetition frequency corresponding to the frequency components in the mechanical vibrations. Therefore, one mode of ultrasound diagnostic apparatus or system creates data representing the propagation of the shear waves based on the echo signals from ultrasound pulses emitted at a first pulse repetition frequency. The pulse repetition frequency is then determined based on the image. More specifically, one mode of ultrasound diagnostic apparatus or system includes an ultrasound probe for emitting ultrasound pulses to a patient / receiving echo signals from the patient, and a processor. The processor controls the ultrasound probe to emit the ultrasound pulses to the patient at at least one first pulse repetition frequency, emitting mechanical vibrations to the patient containing at least one frequency component, which has been applied to generate a shear wave having a frequency according to the at least one frequency component; and creates data representing the propagation of the shear waves based on the echo signals from the ultrasound pulses emitted at the first pulse repetition frequency. Furthermore, the processor calculates at least one propagation velocity of the shear waves based on the echo signals from the ultrasound pulses emitted at a pulse repetition frequency determined based on the image.

[0006] In the ultrasound diagnostic apparatus described above, the propagation velocity of the shear wave is calculated based on the echo signal obtained from an ultrasound pulse emitted at a pulse repetition frequency determined based on an image representing the propagation of the shear wave generated by mechanical vibration. By using mechanical vibration instead of a driving pulse, the propagation velocity of the shear wave can be obtained more reliably. Furthermore, a more suitable pulse repetition frequency for detecting the shear wave can be obtained based on the aforementioned image. Attached Figure Description

[0007] Figure 1 This is a block diagram illustrating an example of an ultrasound diagnostic system and ultrasound diagnostic device according to an embodiment;

[0008] Figure 2 Here is an example of a flowchart illustrating the processing in the implementation scheme;

[0009] Figure 3 This is another example of a flowchart illustrating the processing in the implementation scheme;

[0010] Figure 4 It is shown in Figure 3 The flowchart below shows an example of a flowchart for handling situations where the first pulse repetition frequency is inappropriate;

[0011] Figure 5 This is an example of a flowchart illustrating the processing in the fourth variation of the implementation scheme;

[0012] Figure 6 This is a block diagram illustrating an example of an ultrasound diagnostic system and ultrasound diagnostic apparatus according to another embodiment; and

[0013] Figure 7 It is shown in Figure 3 Another example of a flowchart for handling cases where the first pulse repetition frequency is inappropriate. Detailed Implementation

[0014] Embodiments of the invention will now be described below with reference to the accompanying drawings. Figure 1 The ultrasound diagnostic system 100 shown includes an ultrasound diagnostic device 1 and a vibrator 50. The ultrasound diagnostic device 1 includes an ultrasound probe 2, a transmitting beamformer 3, and a transmitter 4. The ultrasound probe 2 performs an ultrasound scan on the patient and receives ultrasound echoes.

[0015] More specifically, the ultrasound probe 2 has multiple vibrating elements 2a for transmitting pulsed ultrasound to a patient (not shown). These multiple vibrating elements 2a are driven by a transmitting beamformer 3 and a transmitter 4 to transmit pulsed ultrasound. The vibrating elements 2a are piezoelectric elements.

[0016] The ultrasound diagnostic apparatus 1 also includes a receiver 5 and a receiving beamformer 6. Pulsed ultrasound emitted from the vibrating element 2a is reflected within the patient's body to generate an echo returning to the vibrating element 2a. The echo is converted into an electrical signal by the vibrating element 2a; this electrical signal is the echo signal and is input to the receiver 5. The echo signal is amplified at the receiver 5 according to the desired gain and then input to the receiving beamformer 6, where receiving beamforming is performed. The receiving beamformer 6 outputs ultrasound data formed by the receiving beam.

[0017] The receiver beamformer 6 can be a hardware beamformer or a software beamformer. If the receiver beamformer 6 is a software beamformer, it may include one or more processors, including one or more of a graphics processing unit (GPU), a microprocessor, a central processing unit (CPU), a digital signal processor (DSP), or any other type of processor capable of performing logical operations. The processor constituting the receiver beamformer 6 may be constructed as a separate processor from the processor 7, which will be described later, or may be constructed as processor 7.

[0018] The ultrasound probe 2 may include all or part of the circuitry for performing transmit and / or receive beamforming. For example, all or part of the transmit beamformer 3, transmitter 4, receiver 5, and receive beamformer 6 may be located within the ultrasound probe 2.

[0019] The ultrasound diagnostic apparatus 1 also includes a processor 7 for controlling the transmitting beamformer 3, the transmitter 4, the receiver 5, and the receiving beamformer 6. Furthermore, the ultrasound diagnostic apparatus 1 includes a display 8, a memory 9, and a user interface 10.

[0020] Processor 7 includes one or more processors. Processor 7 communicates electronically with ultrasound probe 2. Processor 7 can control ultrasound probe 2 to acquire ultrasound data. Processor 7 controls which elements in vibrating element 2a are active and the shape of the ultrasonic beam emitted from ultrasound probe 2. Processor 7 also communicates electronically with display 8, and processor 7 can process ultrasound data into ultrasound images for display on display 8. The term "electronic communication" can be defined to include both wired and wireless connections. According to one embodiment, processor 7 may include a central processing unit (CPU). According to other embodiments, processor 7 may include other electronic components capable of performing processing functions, such as a digital signal processor, field-programmable gate array (FPGA), graphics processing unit (GPU), or any other type of processor. According to other embodiments, processor 7 may include multiple electronic components capable of performing processing functions. For example, processor 7 may include two or more electronic components selected from a list of electronic components, including: a central processing unit, a digital signal processor, a field-programmable gate array, and a graphics processing unit.

[0021] Processor 7 may also include a demodulator (not shown) for demodulating RF data. In another embodiment, demodulation may be performed earlier in the processing chain.

[0022] Processor 7 is adapted to perform one or more processing operations based on multiple selectable ultrasound modes on the data. Data can be processed in real time during a scanning session as echo signals are received. For the purposes of this disclosure, the term "real time" is defined as including processes performed without any intentional delay.

[0023] Data may be temporarily stored in a buffer (not shown) during ultrasound scanning, allowing the data to be processed in real-time operation or in non-real-time offline operation. In this disclosure, the term "data" may be used to refer to one or more datasets acquired using the ultrasound diagnostic apparatus 1.

[0024] Ultrasonic data can be processed by processor 7 through other or different mode-related modules (e.g., B-mode, color Doppler, M-mode, color M-mode, spectral Doppler, contrast-enhanced mode, elastography, TVI, strain, strain rate, etc.) to form ultrasound image data. For example, one or more modules can generate ultrasound images using B-mode, color Doppler, M-mode, color M-mode, spectral Doppler, contrast-enhanced mode, elastography, TVI, strain, strain rate, and combinations thereof.

[0025] The system stores image beams and / or image frames, and can record timing information indicating the time when data is acquired in the memory. These modules may include, for example, a scan conversion module for performing scan conversion operations to convert image frames from beam space coordinates to display space coordinates. A video processor module may be provided that reads image frames from the memory and displays them in real time during the procedure on the patient. The video processor module can store image frames in an image memory, read ultrasound images from the image memory, and display these ultrasound images on the display 8.

[0026] As used herein, the term "image" can be broadly interpreted to refer to both a visible image and the data representing that visible image. The term "data" can include both raw data and image data; raw data is ultrasound data prior to the scan conversion operation, while image data is data after the scan conversion operation.

[0027] In cases where processor 7 includes multiple processors, the aforementioned processing tasks to be processed by processor 7 can be handled by multiple processors. For example, a first processor can be used to demodulate and extract RF signals, while a second processor can be used to further process the data before displaying the image.

[0028] For example, if the receiving beamformer 6 is a software beamformer, the processing functions of the receiving beamformer can be executed by a single processor or by multiple processors.

[0029] Display 8 includes LED (light-emitting diode) displays, LCD (liquid crystal display), organic EL (electroluminescent) displays, etc.

[0030] The memory 9 is any known data storage medium. In the example, the ultrasound image display system 1 includes both non-transitory and transient storage media as the memory 9, and includes multiple units of the memory 9. The non-transitory storage medium is, for example, a non-volatile storage medium such as an HDD (hard disk drive) and a ROM (read-only memory). The non-transitory storage medium may include portable storage media such as a CD (optical disc) and a DVD (digital versatile optical disc). The non-transitory storage medium stores the program executed by the processor 7.

[0031] Transient storage media are volatile storage media, such as RAM (Random Access Memory).

[0032] User interface 10 can accept input from the operator. For example, user interface 10 accepts input of commands and / or information from the operator. User interface 10 is configured to include a keyboard, hard keys, trackball, rotary controls, soft keys, etc. User interface 10 may include a touchscreen for displaying soft keys, etc.

[0033] Vibrator 50 generates mechanical vibration. In this example, vibrator 50 includes a piezoelectric element to which a driving voltage is applied to generate mechanical vibration. The mechanical vibration comprises at least a first frequency component f1 and a second frequency component f2.

[0034] The vibrator 50 operates independently of the ultrasound diagnostic device 1 and has its own power supply.

[0035] The processing in this implementation scheme will be described next. Figure 2 This is a flowchart illustrating the process in this embodiment. First, at step S1, the vibrator 50 begins to apply mechanical vibration to the patient. The vibrator 50 applies mechanical vibration when it is placed on the patient's surface. In the example, the operator places the vibrator 50 on the patient's surface and activates the vibrator 50. The mechanical vibration causes shear waves in the biological tissues within the patient's body.

[0036] Next, in step S2, for a patient in which shear waves are generated by mechanical vibration, the processor 7 controls the ultrasound probe 2 to transmit / receive ultrasound pulses at a first pulse repetition frequency (PRF1) for a desired time period. Although the first pulse repetition frequency (PRF1) is a frequency capable of detecting shear waves and calculating their propagation velocity, the second pulse repetition frequency (PRF2), which will be discussed later, can calculate the propagation velocity of shear waves more reliably and accurately.

[0037] Next, in step S3, processor 7 creates data representing the propagation of an image of shear waves based on the echo signal from the ultrasonic pulse emitted in step S2. More specifically, processor 7 performs tissue Doppler processing on the echo signal from the ultrasonic pulse emitted in step S2 and creates Doppler data. Processor 7 then creates data representing the propagation of an image of shear waves based on the Doppler data. In this example, the data representing the propagation of shear waves is created using the technique described in Japanese Patent No. 6498183. The image representing the propagation of shear waves causes the shear waves to form a striped pattern. The image can be a video image.

[0038] Next, at step S4, the processor 7 calculates at least one frequency component of the mechanical vibration based on the data from the image created at step S3. Since the data from the image created at step S3 represents the periodic variation of the IQ signal obtained in tissue Doppler processing, the processor 7 calculates at least one frequency component of the mechanical vibration based on, for example, the IQ signal, the first pulse repetition frequency PRF1, and the frame rate in the ultrasonic pulse transmission / reception at step S2.

[0039] Next, in step S5, the processor 7 calculates the second pulse repetition frequency (PRF2) of the ultrasonic pulse based on the frequency components in the mechanical vibration calculated in step S4. The second pulse repetition frequency (PRF2) will now be described in detail. As previously discussed, tissue Doppler technology for detecting tissue motion is used to detect shear waves. In tissue Doppler technology, the frequency of tissue motion (i.e., the vibration frequency) has a corresponding pulse repetition frequency for the ultrasonic pulse, which allows for more reliable and accurate detection of motion. Therefore, the second pulse repetition frequency (PRF2) is a frequency set based on the frequency components in the mechanical vibration calculated in step S4 to facilitate more reliable detection of shear waves in tissue Doppler processing.

[0040] In the example, the relationship between the second pulse repetition frequency PRF2 and the frequency component in the mechanical vibration calculated at step S4 can be the relationship given by EQ.(1) described in paragraph 0016 of Japanese Patent No. 6498183. Specifically, it can be:

[0041] f = {(2m+1) / 4} * PRF2,

[0042] Where f is the frequency component of the mechanical vibration calculated in step S4, m is an integer equal to or greater than zero, and PRF2 is the second pulse repetition frequency PRF2. The above equation can be used to calculate the second pulse repetition frequency PRF2 of the ultrasonic pulse based on the frequency components of the mechanical vibration. That is,

[0043] PRF2 = 4 * f / (2m + 1).

[0044] Next, at step S6, for a patient in which shear waves are generated by mechanical vibration, processor 7 controls ultrasound probe 2 to transmit / receive ultrasound pulses at the second pulse repetition frequency PRF2 calculated at step S5 within the desired time period.

[0045] Next, in step S7, processor 7 calculates the propagation velocity of the shear wave based on the echo signal from the ultrasonic pulse emitted in step S6. Processor 7 performs tissue Doppler processing on the echo signal from the ultrasonic pulse and creates Doppler data, based on which it calculates the propagation velocity. Processor 7 can create image data representing the propagation of the shear wave based on the Doppler data. Processor 7 can also display images based on the images on display 8.

[0046] As in this embodiment, by applying continuous mechanical vibrations to the patient, a shear wave with a larger amplitude can be generated compared to the case of using ultrasound-driven pulses. Therefore, the propagation velocity of the shear wave can be calculated more reliably as a parameter related to the characteristics of the patient's tissues. Since the frequency component of the mechanical vibrations is calculated based on data representing the shear wave propagation, a more suitable second pulse repetition frequency based on the shear wave frequency can be obtained.

[0047] Next, variations of the implementation scheme will be described. First, the first variation will be described. Figure 3 and Figure 4 This is a flowchart illustrating the process of the first variant. Since the processes from step S10 to step S12 are the same as those from step S1 to step S3, their explanation will be omitted. However, in this variant, the value of the first pulse repetition frequency PRF1 at step S11 may differ from the value at step S2. At step S13, it is determined whether the first pulse repetition frequency PRF1 is appropriate. In the example, the processor 7 determines whether the first pulse repetition frequency is appropriate based on the image data obtained at step S12.

[0048] The decision made by processor 7 will be described in more detail. When the pulse repetition frequency of the ultrasound pulses used to detect the shear wave is a suitable frequency based on the frequency of the shear wave, it is assumed that the direction of travel of the shear wave displayed on the image representing the propagation of the shear wave is a specific direction of travel. Therefore, in the example, when the image obtained at step S12 is a video image indicating that the direction of travel of the shear wave is opposite to the suitable direction of travel, processor 7 determines that the first pulse repetition frequency PRF1 is inappropriate. In other examples, if the wavefront of the shear wave cannot be detected in the image obtained at step S12, or if the shear wave propagates in a direction different from the distribution of biological tissue, processor 7 may determine that the first pulse repetition frequency PRF1 is inappropriate. It should be noted that the decision-making techniques provided herein are merely exemplary.

[0049] The decision at step S13 can be performed by the operator. In this case, the processor 7 displays an image on the display 8 based on the image data obtained in step S12. The operator determines whether the first pulse repetition frequency PRF1 is appropriate based on the displayed image. Similar to the decision-making technique performed by the processor 7 described above, the operator can perform the decision based on the direction of travel of the shear wave or the detectability of the wavefront. The operator inputs whether the first pulse repetition frequency PRF1 is appropriate at the user interface 10.

[0050] If the processor 7 determines that the first pulse repetition frequency PRF1 is appropriate at step S13 ("Yes" at step S13), the process proceeds to the processing at step S14. Similarly, if the user interface 10 has received input from the operator indicating that the first pulse repetition frequency PRF1 is appropriate at step S13 ("Yes" at step S13), the process proceeds to the processing at step S14.

[0051] In the first variant, the appropriate first pulse repetition frequency PRF1 can be considered as the frequency of the frequency component in the mechanical vibration, that is, the frequency at which the propagation velocity of the shear wave can be reliably and accurately calculated, similar to... Figure 2 The second pulse repetition frequency PRF2 is calculated at step S5.

[0052] In step S14, processor 7 calculates the propagation velocity of the shear wave based on the Doppler data created in step S12. After the propagation velocity calculation is completed in step S14, the process is terminated.

[0053] On the other hand, if the processor 7 determines that the first pulse repetition frequency PRF1 is inappropriate ("No" at step S13), the process proceeds to the processing at step S15. Similarly, if the user interface 10 has received input from the operator indicating that the first pulse repetition frequency PRF1 is inappropriate at step S13 ("No" at step S13), the process proceeds to the processing at step S15.

[0054] From the processing in step S15 Figure 4 The flowchart is shown. Figure 5 The process from step S15 to step S18 shown is similar to the process from step S4 to step S7.

[0055] Next, a second variation will be described. The mechanical vibration applied at steps S1 and S10 described previously may include at least a first frequency component f1 and a second frequency component f2. The shear wave generated in the biological tissue within the patient's body by the mechanical vibration includes a first shear wave having a frequency according to the first frequency component f1 and a second shear wave having a frequency according to the second frequency component f2. The frequencies of the first shear wave and the second shear wave are different from each other.

[0056] The first pulse repetition frequency (PRF1) at steps S2 and S11 may comprise two first pulse repetition frequencies, PRF11 and PRF12. More specifically, the processor 7 modifies the first pulse repetition frequency (PRF1) during steps S2 and S11. The processor 7 modifies the first pulse repetition frequency (PRF1) after a desired time period has elapsed since the start of ultrasonic pulse transmission / reception at steps S2 and S11. Hereinafter, the first pulse repetition frequency (PRF1) before modification will be referred to as the first pulse repetition frequency (PRF11), and the first pulse repetition frequency (PRF12) before modification will be referred to as the first pulse repetition frequency (PRF12). Therefore, at steps S2 and S11, ultrasonic transmission / reception is performed with the first pulse repetition frequency (PRF11) for the desired time period, and then ultrasonic transmission / reception is performed with the first pulse repetition frequency (PRF12) for the desired time period.

[0057] In steps S3 and S12, processor 7 creates Doppler data based on the echo signals from the ultrasonic pulses transmitted / received at the first pulse repetition frequency PRF11, and based on the Doppler data, creates data representing a first image of the propagation of the first shear wave. Processor 7 also creates Doppler data based on the echo signals from the ultrasonic pulses transmitted / received at the first pulse repetition frequency PRF12, and based on the Doppler data, creates data representing a second image of the propagation of the second shear wave.

[0058] In step S13, it is determined whether the first pulse repetition frequency PRF11 is a suitable frequency according to the first shear wave based on the data from the first image. Furthermore, in step S13, it is determined whether the first pulse repetition frequency PRF12 is a suitable frequency according to the second shear wave based on the data from the second image.

[0059] At steps S4 and S15, processor 7 calculates the first frequency component f1 in the mechanical vibration based on the data from the first image. Except that processor 7 uses the first pulse repetition frequency PRF11 instead of the previously described first pulse repetition frequency PRF1 to calculate the first frequency component f1, this calculation technique is essentially the same as explained for step S4 previously described.

[0060] At steps S4 and S15, processor 7 further calculates the second frequency component f2 in the mechanical vibration based on the data from the second image. Except that processor 7 uses the first pulse repetition frequency PRF12 instead of the previously described first pulse repetition frequency PRF1 to calculate the second frequency component f2, this calculation technique is essentially the same as explained for step S4 previously described.

[0061] In steps S5 and S16, processor 7 calculates two second pulse repetition frequencies, PRF21 and PRF22, as the second pulse repetition frequency PRF2. The second pulse repetition frequency PRF21 is the pulse repetition frequency based on the first frequency component f1. The second pulse repetition frequency PRF22 is the pulse repetition frequency based on the second frequency component f2.

[0062] In steps S6 and S17, ultrasonic pulse transmission / reception is performed within the desired time period using the second pulse repetition frequency PRF21, and then ultrasonic pulse transmission / reception is performed within the desired time period using the second pulse repetition frequency PRF22.

[0063] In steps S7 and S18, processor 7 creates Doppler data based on the echo signal from the ultrasonic pulse emitted at the second pulse repetition frequency PRF21, and calculates the propagation velocity V1 of the first shear wave. Processor 7 also creates Doppler data based on the echo signal from the ultrasonic pulse emitted at the second pulse repetition frequency PRF22, and calculates the propagation velocity V2 of the second shear wave.

[0064] In step S14, the processor 7 calculates the propagation velocity V1 of the first shear wave based on Doppler data, which is created from the echo signal of the ultrasonic pulse emitted at the first pulse repetition frequency PRF11. The processor 7 also calculates the propagation velocity V2 of the second shear wave based on Doppler data, which is created from the echo signal of the ultrasonic pulse emitted at the first pulse repetition frequency PRF12.

[0065] In the second variant, processor 7 can use a first propagation velocity V1 and a second propagation velocity V2 to calculate parameters related to the characteristics of the patient tissue. An example of parameter calculation will now be described below.

[0066] The propagation speed of a shear wave varies with its frequency. Specifically, the higher the frequency of the shear wave, the higher its propagation speed. Furthermore, the degree of change in propagation speed relative to frequency, i.e., the change in frequency distribution and the slope of the propagation speed, depends on the viscosity of the medium through which the shear wave propagates. Therefore, processor 7 uses a first propagation speed V1 and a second propagation speed V2, along with a first frequency component f1 and a second frequency component f2, as parameters to calculate a viscosity-related value. Since the frequency of the shear wave depends on the frequency of the mechanical vibration, the first frequency component f1 and the second frequency component f2 are used here to calculate the viscosity-related value. In this example, the viscosity-related value is the distribution of frequency components f1 and f2 and the slope of propagation speeds V1 and V2, i.e., (V2-V1) / (f2-f1). Processor 7 can also calculate the viscosity coefficient based on the slope.

[0067] Next, a third variation will be described. In the third variation, similar to the second variation, the mechanical vibration applied at steps S1 and S10 described above includes at least a first frequency component f1 and a second frequency component f2, and generates a first shear wave and a second shear wave.

[0068] However, unlike the second variant, the value of the first pulse repetition frequency PRF1 at steps S2 and S11 is one. Therefore, data representing the propagation of the shear wave are created at steps S3 and S12.

[0069] At step S13, the first pulse repetition frequency PRF1 is determined to be a suitable frequency according to the first shear wave and the second shear wave based on the data of the image created at step S12.

[0070] In steps S4 and S15, based on the image data, processor 7 calculates the first frequency component f1 in the mechanical vibration. Furthermore, in steps S4 and S15, based on the image data, processor 7 calculates the second frequency component f2 in the mechanical vibration.

[0071] In steps S5 and S16, processor 7 calculates the second pulse repetition frequency PRF2. However, processor 7 calculates the second pulse repetition frequency PRF2 based on the first frequency component f1 and the second frequency component f2. In this example, the second pulse repetition frequency PRF2 is a common multiple of the first frequency component f1 and the second frequency component f2. The common multiple can be the least common multiple.

[0072] Alternatively, the pulse repetition frequency PRF2 can be the pulse repetition frequency that satisfies the two equations derived from EQ.(1) described in paragraph 0016 of Japanese Patent No. 6498183 mentioned above, as given below:

[0073] PRF2 = 4 * f1(2m + 1), and

[0074] PRF2 = 4 * f2(2n + 1)

[0075] Where m and n are integers equal to or greater than zero, and PRF2 is the pulse repetition frequency PRF2.

[0076] In steps S7 and S18, processor 7 creates Doppler data based on the echo signals from the ultrasonic pulses emitted at the second pulse repetition frequency PRF2 in steps S6 and S17, and calculates the propagation velocity V1 of the first shear wave and the propagation velocity V2 of the second shear wave.

[0077] In step S14, the propagation velocity V1 of the first shear wave and the propagation velocity V2 of the second shear wave are calculated based on the Doppler data created in step S12.

[0078] In the third variant, similar to the second variant, the viscosity-related value can be calculated using the first propagation velocity V1 and the second propagation velocity V2.

[0079] Next, the fourth variant will be described. Figure 5 This is a flowchart illustrating the process in the fourth variation. The process at step S30 is the same as the processes at steps S1 and S10. Next, at step S31, the processor 7 controls the ultrasound probe 2 to transmit / receive ultrasound pulses at the desired pulse repetition frequency within the desired time period. As in step S11, the processor 7 initially sets the first pulse repetition frequency PRF1 to the desired pulse repetition frequency.

[0080] In step S32, processor 7 creates data representing the propagation of the shear wave in a manner similar to steps S3 and S12.

[0081] In step S33, similar to step S13, it is determined whether the desired pulse repetition frequency set in step S31 is appropriate based on the data of the image created in step S32 or based on that image. If the first pulse repetition frequency PRF1 is set in step S31, it is determined in step S33 whether the first pulse repetition frequency PRF1 is appropriate.

[0082] If it is determined at step S33 that the first pulse repetition frequency PRF1 is unsuitable ("No" at step S33), the process proceeds to step S34. On the other hand, if it is determined at step S33 that the first pulse repetition frequency PRF1 is suitable ("Yes" at step S13), the process proceeds to step S35. In step S35, the processor 7 calculates the propagation speed of the shear wave based on the Doppler data created in step S32.

[0083] In step S34, the processor 7 modifies the first pulse repetition frequency PRF1 to a third pulse repetition frequency PRF3. In this example, the third pulse repetition frequency PRF3 has a value obtained by incrementing or decrementing the value of the first pulse repetition frequency PRF1 by a pre-specified frequency Δα. The pulse repetition frequency modified from the initially set first pulse repetition frequency PRF1 will be referred to herein as the third pulse repetition frequency PRF3.

[0084] Once the third pulse repetition frequency (PRF3) is set in step S34, the processor 7 controls the ultrasound probe 2 in step S31 to transmit / receive ultrasound pulses at the third pulse repetition frequency (PRF3) for the desired time period. Then, in step S32, image data is created based on the echo signals from the ultrasound pulses transmitted / received at the third pulse repetition frequency (PRF3), and subsequently, in step S33, it is determined whether the third pulse repetition frequency (PRF3) is suitable. If it is determined that the third pulse repetition frequency (PRF3) is unsuitable, in step S34, a pre-specified frequency Δα is added or subtracted again to set a new third pulse repetition frequency (PRF3), and the processing in step S31 is then performed again.

[0085] On the other hand, if it is determined at step S33 that the third pulse repetition frequency PRF3 is appropriate ("Yes" at step S33), the process proceeds to processing step S35, where the propagation speed of the shear wave is calculated based on the Doppler data created in the preceding step S32. The third pulse repetition frequency PRF3 determined to be appropriate at step S33 can be considered as the second pulse repetition frequency PRF2.

[0086] Although the invention has been described with reference to specific embodiments, various changes and / or equivalent substitutions may be made without departing from the scope and spirit of the invention. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of the invention without departing from the scope and spirit of the invention. Therefore, the invention is not limited to the specific embodiments disclosed herein, and the invention is intended to cover all embodiments falling within the appended claims.

[0087] For example, the vibrator 50 can be connected to the ultrasound diagnostic device 1. In this case, power can be supplied from the ultrasound diagnostic device 1 to the vibrator 50.

[0088] In addition, the ultrasound diagnostic system 100 may include a first vibrator 51 and a second vibrator 52, replacing the vibrator 50, such as Figure 6 As shown. Although the basic configuration of the first vibrator 51 and the second vibrator 52 is the same as that of the vibrator 50, the first vibrator 51 generates mechanical vibration with a first frequency component f1, while the second vibrator 52 generates mechanical vibration with a second frequency component f2.

[0089] Furthermore, in the first variation, the first pulse repetition frequency PRF1 can be set based on the frequency components of the mechanical vibration. In this case, the first pulse repetition frequency PRF1 is a frequency at which the propagation velocity of the shear wave can be reliably and accurately calculated. However, the frequency components of the mechanical vibration can change due to factors such as the deterioration of the vibrator over time. In this case, it is necessary to reset the first pulse repetition frequency based on the frequency components of the mechanical vibration before the change. Therefore, a decision can be made based on whether the first pulse repetition frequency PRF1 needs to be reset. Figure 3 The decision is made at step S13. More specifically, at step S13, the processor 7 calculates the frequency components in the mechanical vibration based on the data from the image created in step S12, in a manner similar to step S4. Next, the processor 7 compares the calculated frequency components in the mechanical vibration with the frequency components in the mechanical vibration before the change corresponding to the first pulse repetition frequency PRF1. The frequency components in the mechanical vibration before the change are known. Next, if the difference between the compared frequency components exceeds the desired range, the processor 7 determines that the first pulse repetition frequency PRF1 is unsuitable. On the other hand, if the difference between the compared frequency components falls within the desired range, the processor 7 determines that the first pulse repetition frequency PRF1 is suitable.

[0090] If the first pulse repetition frequency PRF1 is inappropriate, the processor 7 may output a warning. The warning may be displayed on the display 8 or output from the speaker of the ultrasound diagnostic device 1 (omitted in the accompanying drawings).

[0091] If the first pulse repetition frequency PRF1 is deemed inappropriate, the process proceeds to step S18, and no further execution is required thereafter. Figure 5 The processing at step S17 in the process. Therefore, ultrasonic transmission / reception is performed using the second pulse repetition frequency PRF2 instead of the first pulse repetition frequency PRF1. The second pulse repetition frequency PRF2 is based on the frequency component in the altered mechanical vibration.

[0092] Similarly, the decision at step S13 in the second variation can be made based on whether the first pulse repetition frequencies PRF11 and PRF12 need to be reset.

[0093] Furthermore, in the first variant, it can be determined whether the second pulse repetition frequency PRF2 calculated in step S16 is appropriate. Reference will now be made to... Figure 7The flowchart in the diagram describes the processing in this case. Once the second pulse repetition frequency PRF2 is calculated in step S16, the process proceeds to step S40. In step S40, the processor 7 controls the ultrasound probe 2 to transmit / receive ultrasound pulses at the second pulse repetition frequency PRF2 within the desired time period, as in steps S6 and S17.

[0094] Next, in step S41, the processor 7 creates image data representing the propagation of the shear wave based on the echo signal from the ultrasonic pulse emitted in step S40, in a manner similar to steps S3, S12, and S32. Next, in step S42, in a manner similar to step S13, it determines whether the second pulse repetition frequency PRF2 is appropriate based on the data from the image created in step S41 or based on that image.

[0095] If it is determined at step S42 that the second pulse repetition frequency PRF2 is unsuitable ("No" at step S42), the process proceeds to step S43. On the other hand, if it is determined at step S42 that the second pulse repetition frequency PRF2 is suitable ("Yes" at step S42), the process proceeds to step S44. In step S44, the processor 7 calculates the propagation speed of the shear wave based on the Doppler data created in step S41.

[0096] At step S43, the processor 7 modifies the second pulse repetition frequency PRF2. In the example, the modified second pulse repetition frequency PRF2 has a value obtained by incrementing or decrementing the value of the original second pulse repetition frequency PRF2 by a pre-specified frequency Δα.

[0097] Once the second pulse repetition frequency PRF2 is modified in step S43, the process returns to the processing in step S40. In step S40, ultrasound pulses are transmitted / received at the modified second pulse repetition frequency PRF2, and subsequent processing is performed.

[0098] Furthermore, the above-described embodiment can be a method for controlling an ultrasound diagnostic device, the device comprising: an ultrasound probe for transmitting ultrasound pulses to a patient / receiving echo signals from the patient; and a processor, the method comprising the following steps:

[0099] The processor controls the ultrasound probe to emit ultrasound pulses toward the patient at at least one first pulse repetition frequency, and to emit mechanical vibrations toward the patient containing at least one frequency component, the mechanical vibrations being applied to generate shear waves having frequencies according to the at least one frequency component;

[0100] The processor creates data representing the propagation of the shear wave based on the echo signal from the ultrasonic pulse emitted at the first pulse repetition frequency; and

[0101] The processor calculates at least one propagation velocity of the shear wave based on the echo signal from an ultrasonic pulse emitted at a pulse repetition frequency determined based on the image.

[0102] The embodiments shown in the accompanying drawings and described above are merely exemplary embodiments and are not intended to limit the scope of the appended claims, including any equivalents included within the scope of the claims. Various modifications are possible and will be apparent to those skilled in the art. Any combination of non-mutually exclusive features described herein is intended to be within the scope of the invention. That is, features of the embodiments may be combined with any suitable aspect described above, and optional features of any aspect may be combined with any other suitable aspect. Similarly, features listed in dependent claims may be combined with non-mutually exclusive features of other dependent claims, particularly where the dependent claims are subordinate to the same independent claim. In some jurisdictions that claim a single dependent claim, such dependent claims may have been used in practice, but this should not be construed as meaning that features in dependent claims are mutually exclusive.

Claims

1. An ultrasound diagnostic device, comprising: An ultrasound probe, used to transmit ultrasound pulses to a patient / receive echo signals from a patient; as well as Processor, the processor being adapted to: The ultrasound probe is controlled to emit ultrasound pulses toward the patient at at least one first pulse repetition frequency, and to emit mechanical vibrations toward the patient containing at least one frequency component, the mechanical vibrations being applied to generate shear waves in the patient having frequencies according to the at least one frequency component; Data representing the propagation of the shear wave is created based on the echo signal from the ultrasonic pulse emitted at the first pulse repetition frequency; and At least one propagation velocity of the shear wave is calculated based on the echo signal from an ultrasonic pulse emitted at a pulse repetition frequency determined based on the image. Wherein, the pulse repetition frequency determined based on the image is a second pulse repetition frequency set instead of the first pulse repetition frequency, and the processor controls the ultrasound probe to emit the ultrasound pulse at the second pulse repetition frequency instead of the first pulse repetition frequency; The processor further calculates the at least one frequency component in the mechanical vibration based on the image, and calculates the second pulse repetition frequency based on the frequency component.

2. The ultrasound diagnostic device according to claim 1, wherein: The pulse repetition frequency determined based on the image is the first pulse repetition frequency.

3. The ultrasound diagnostic device according to claim 1, wherein: The second pulse repetition frequency is a pulse repetition frequency set in place of the first pulse repetition frequency when it is determined that the first pulse repetition frequency is inappropriate based on the image.

4. The ultrasound diagnostic device according to claim 3, wherein: The processor makes a decision based on the image, and when it determines that the first pulse repetition frequency is inappropriate, the processor controls the ultrasound probe to emit the ultrasound pulse at the second pulse repetition frequency.

5. The ultrasound diagnostic device according to claim 3, comprising: monitor; as well as The user interface for accepting operator input, wherein The processor displays the image on the display based on the image data, and once the user interface has accepted input from the operator who has determined that the first pulse repetition frequency is inappropriate based on the image, the processor controls the ultrasound probe to emit the ultrasound pulse at the second pulse repetition frequency instead of the first pulse repetition frequency.

6. The ultrasound diagnostic device according to claim 1, wherein: The processor is adapted to: If determining the first pulse repetition frequency based on the image is inappropriate, the first pulse repetition frequency shall be modified to the third pulse repetition frequency; The ultrasonic probe is controlled to emit the ultrasonic pulse at the third pulse repetition frequency; and The image is refreshed based on the echo signal from the ultrasound pulse emitted at the third pulse repetition frequency, and The second pulse repetition frequency is the third pulse repetition frequency that is determined to be appropriate based on the image after the refresh.

7. The ultrasound diagnostic device according to claim 6, wherein: The processor determines whether the first pulse repetition frequency and the third pulse repetition frequency are appropriate.

8. The ultrasound diagnostic device according to claim 6, comprising: monitor; as well as The user interface for accepting operator input, wherein: The processor The image is displayed on the display, and once the user interface has accepted input from the operator who has determined that the first pulse repetition frequency is inappropriate based on the image, the processor modifies the first pulse repetition frequency to the third pulse repetition frequency; and After the refresh, the image displayed on the display is refreshed based on the image, and The user interface accepts input from the operator, which is the result of determining the appropriate repetition frequency of the third pulse based on the image after the refresh.

9. The ultrasound diagnostic device according to claim 3, wherein: The first pulse repetition frequency is based on the frequency of a frequency component before the change of at least one frequency component contained in the mechanical vibration applied to the patient, and The processor Calculate the at least one frequency component in the mechanical vibration based on the image, and The processor compares at least one frequency component of the calculated mechanical vibration with the frequency component before the change, and when it is determined that the first pulse repetition frequency is inappropriate, the processor controls the ultrasonic probe to emit the ultrasonic pulse at the second pulse repetition frequency instead of the first pulse repetition frequency.

10. The ultrasound diagnostic apparatus according to any one of claims 1 to 9, wherein: The processor performs tissue Doppler processing on the echo signal from the ultrasound pulse emitted at the first pulse repetition frequency to create Doppler data, and creates data representing an image of the propagation of the shear wave based on the Doppler data.

11. The ultrasound diagnostic apparatus according to any one of claims 1 to 9, wherein tissue Doppler processing is performed on the echo signal from the ultrasound pulse emitted at the second pulse repetition frequency to create Doppler data, and the propagation velocity of the shear wave is calculated based on the Doppler data.

12. The ultrasound diagnostic device according to claim 1, wherein: The mechanical vibration includes at least a first frequency component and a second frequency component. The shear wave comprises a first shear wave having a frequency according to the first frequency component and a second shear wave having a frequency according to the second frequency component. The first pulse repetition frequency is modified after a required period of time has elapsed since the ultrasonic pulses were first transmitted / received at the first pulse repetition frequency. The data representing the propagation of the shear wave includes data from a first image before the modification of the first pulse repetition frequency and data from a second image after the modification. The at least one propagation velocity includes a first propagation velocity of the first shear wave and a second propagation velocity of the second shear wave, the first propagation velocity being calculated based on the echo signal from the ultrasound pulse emitted at a pulse repetition frequency determined based on the first image, and the second propagation velocity being calculated based on the echo signal from the ultrasound pulse emitted at a pulse repetition frequency determined based on the second image. The processor further uses the first propagation velocity and the second propagation velocity to calculate parameters related to the patient's tissue characteristics.

13. The ultrasound diagnostic apparatus according to claim 12, wherein: If the first pulse repetition frequency before modification is determined to be appropriate based on the first image, and if the first pulse repetition frequency after modification is determined to be appropriate based on the second image, the pulse repetition frequency determined based on the first image is the first pulse repetition frequency before modification, and the pulse repetition frequency determined based on the second image is the first pulse repetition frequency after modification.

14. The ultrasound diagnostic apparatus according to claim 12, wherein: The first frequency component in the mechanical vibration is calculated based on the data from the first image. The second frequency component in the mechanical vibration is calculated based on the data from the second image. If the first pulse repetition frequency before modification based on the first image is inappropriate, and if the first pulse repetition frequency after modification based on the second image is inappropriate, the pulse repetition frequency determined based on the image is a second pulse repetition frequency set instead of the first pulse repetition frequency. The processor controls the ultrasound probe to transmit the ultrasound pulses at the second pulse repetition frequency instead of the first pulse repetition frequency, and furthermore, after a certain period of time has elapsed since the transmission / reception of the ultrasound pulses began at the second pulse repetition frequency, the processor modifies the pulse repetition frequency according to the first frequency component to the pulse repetition frequency according to the second frequency component. The first propagation velocity is calculated based on the echo signal from the ultrasonic pulse emitted at the second pulse repetition frequency according to the first frequency component, and The second propagation velocity is calculated based on the echo signal from the ultrasonic pulse emitted at the second pulse repetition frequency according to the second frequency component.

15. The ultrasound diagnostic device according to claim 1, wherein: The mechanical vibration includes at least a first frequency component and a second frequency component. The shear wave comprises a first shear wave having a frequency according to the first frequency component and a second shear wave having a frequency according to the second frequency component. The at least one propagation velocity includes a first propagation velocity of the first shear wave and a second propagation velocity of the second shear wave, the velocities being calculated based on the echo signal from the ultrasound pulse emitted at the pulse repetition frequency determined based on the image, and The processor further uses the first propagation velocity and the second propagation velocity to calculate parameters related to the patient's tissue characteristics.

16. The ultrasound diagnostic apparatus according to claim 15, wherein: If it is appropriate to determine the first pulse repetition frequency based on the image, then the pulse repetition frequency determined based on the image is the first pulse repetition frequency.

17. The ultrasound diagnostic apparatus according to claim 15, wherein: The first frequency component of the mechanical vibration is calculated based on the data from the image, and furthermore, the second frequency component of the mechanical vibration is calculated based on the data from the image. If determining the first pulse repetition frequency based on the image is inappropriate, the pulse repetition frequency determined based on the image is a second pulse repetition frequency set instead of the first pulse repetition frequency, and The second pulse repetition frequency is based on the frequencies of the first frequency component and the second frequency component.

18. An ultrasound diagnostic system, comprising: An ultrasound probe, used to transmit ultrasound pulses to a patient / receive echo signals from a patient; processor; as well as A vibrator for applying mechanical vibration, comprising at least one frequency component, to the patient, wherein The processor is adapted to: The ultrasound probe is controlled to emit ultrasound pulses to the patient at at least one first pulse repetition frequency, and to emit shear waves to the patient that have been generated by the mechanical vibration and have frequencies according to the at least one frequency component. Data representing the propagation of the shear wave is created based on the echo signal from the ultrasonic pulse emitted at the first pulse repetition frequency; and At least one propagation velocity of the shear wave is calculated based on the echo signal from an ultrasonic pulse emitted at a pulse repetition frequency determined based on the image. Wherein, the pulse repetition frequency determined based on the image is a second pulse repetition frequency set instead of the first pulse repetition frequency, and the processor controls the ultrasound probe to emit the ultrasound pulse at the second pulse repetition frequency instead of the first pulse repetition frequency; The processor further calculates the at least one frequency component in the mechanical vibration based on the image, and calculates the second pulse repetition frequency based on the frequency component.

19. The ultrasound diagnostic system according to claim 18, wherein: The number of vibrators is one.

20. The ultrasound diagnostic system according to claim 18, wherein: The vibrator is configured to include at least a first vibrator and a second vibrator. The first vibrator applies mechanical vibration with a first frequency component, and The second vibrator applies mechanical vibration with a second frequency component.

21. A program product for controlling an ultrasound diagnostic apparatus according to any one of claims 1 to 17.

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