KR102030568B1 - Ultrasound system and method of displaying doppler spectrum image - Google Patents

Abstract

The ultrasound system includes an ultrasound probe, a processor, and a display. The ultrasound probe transmits an ultrasound signal to the object and receives an ultrasound echo signal reflected from the object based on the Doppler gate set at a predetermined position of the B mode image of the object. The processor forms a Doppler signal based on the ultrasonic echo signal, forms a Doppler signal envelope representing the Doppler signal as a plurality of brightness values, determines a trace speed indicating the maximum speed of the Doppler signal based on the Doppler signal envelope, and traces Noise is filtered from the Doppler signal based on velocity, and a Doppler spectral image of the object is formed based on the filtered Doppler signal. The display unit displays a Doppler spectrum image.

Description

ULTRASOUND SYSTEM AND METHOD OF DISPLAYING DOPPLER SPECTRUM IMAGE}

FIELD The present disclosure relates to ultrasound systems, and more particularly, to ultrasound systems and methods for displaying Doppler spectral images.

Ultrasound systems have non-invasive and non-destructive properties and are widely used in the medical field for obtaining information inside an object. Without the need for a surgical operation to directly incise and observe the subject, the ultrasound system can provide a high resolution image of the inside of the subject to a physician in real time. Thus, ultrasound systems have become an important tool for diagnosing a variety of diseases.

The ultrasound system transmits an ultrasound signal to the object, and receives an ultrasound signal (that is, an ultrasound echo signal) reflected from the object to form an ultrasound image. The ultrasound echo signal shows a different pattern depending on whether the object of interest of the object is fixed or moving. For example, when the object of interest of the object is moving toward the ultrasonic probe (ie, the ultrasonic transducer) of the ultrasound system, the ultrasonic echo signal reflected from the object of interest has a relatively higher frequency than when the object of interest is stationary. Meanwhile, when the object of interest of the object is far from the ultrasonic probe of the ultrasound system, the ultrasound echo signal reflected from the object of interest has a relatively lower frequency than when the object of interest is stationary. That is, a Doppler shift occurs in the ultrasonic echo signal reflected from the moving object of interest of the object. The ultrasound system may use the Doppler deflection to obtain a Doppler signal including velocity information about the object of interest of the object, and display the obtained Doppler signal as a continuous spectrum (ie, a Doppler spectrum image) on the display unit.

The ultrasound system provides a trace process that traces the maximum velocity of the object of interest based on the obtained velocity information and displays the traced maximum velocity as a line. However, in conventional ultrasound systems, it may be difficult to accurately trace the maximum velocity of an object of interest if there is aliasing in the Doppler spectral image.

The Doppler signal, on the other hand, contains noise (eg system noise) as well as a signal representing the velocity information of the object of interest. Therefore, in the conventional ultrasound system, when the gain is adjusted, there is a problem that noise (for example, system noise) increases or decreases along with a signal indicating the velocity information of the object of interest.

Japanese Laid-Open Patent Publication No. 11-033024

The present disclosure provides embodiments of an ultrasound system and method for forming a Doppler signal envelope based on a Doppler signal of an object and determining a trace speed based on the formed Doppler signal envelope. The present disclosure also provides embodiments of an ultrasound system and method for removing noise from a Doppler signal based on the determined trace rate.

The ultrasound probe may be configured to transmit an ultrasound signal to the object and to receive an ultrasound echo signal from the object, based on a Doppler gate set at a predetermined position of a B mode image of the object. A Doppler signal is formed based on the Doppler signal, and a Doppler signal envelope is formed that represents the Doppler signal as a plurality of brightness values. And a processor configured to filter out noise on the Doppler signal based on the filtered Doppler signal, and to form a Doppler spectral image of the object based on the filtered Doppler signal, and a display configured to display the Doppler spectral image. do.

In another embodiment, a method of forming a Doppler spectral image of an object in an ultrasound system is provided. The method includes obtaining a Doppler signal based on a Doppler gate set at a predetermined position of a B mode image of an object, forming a Doppler signal envelope representing the Doppler signal as a plurality of brightness values, and Determining a trace rate representing a maximum rate of the Doppler signal, filtering noise in the Doppler signal based on the trace rate, and performing a Doppler spectral image of the object based on the filtered Doppler signal. And forming the Doppler spectrum image.

According to some embodiments of the present disclosure, even when there is aliasing in the Doppler spectral image of the object, the maximum velocity of the object of interest in the object may be accurately traced. Further, according to some embodiments of the present disclosure, it is possible to remove noise in the Doppler signal based on the determined trace speed. Therefore, when the gain is adjusted, only the signal representing the speed information of the object of interest may be increased or decreased.

1 is a block diagram schematically showing the configuration of an ultrasound system according to an embodiment of the present disclosure.
2 illustrates an example of a Doppler spectral image in accordance with an embodiment of the present disclosure.
3 is a block diagram schematically illustrating a configuration of a processor according to an embodiment of the present disclosure.
4 illustrates an example of a Doppler gate according to an embodiment of the present disclosure.
5 illustrates an example of a Doppler signal envelope according to an embodiment of the present disclosure.
6 illustrates an example of a first trace start line according to an embodiment of the present disclosure.
7 illustrates an example of a second trace start line and trace speed in accordance with an embodiment of the present disclosure.
8 illustrates an example of a trace line in accordance with an embodiment of the present disclosure.
9 is a flowchart illustrating a procedure of displaying a Doppler spectral image according to an embodiment of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. As used herein, the term "unit" refers to a hardware component such as software, a field-programmable gate array (FPGA), and an application specific integrated circuit (ASIC). However, "part" is not limited to software and hardware. The "unit" may be configured to be in an addressable storage medium, and may be configured to play one or more processors. Thus, as an example, "parts" means components such as software components, object-oriented software components, class components, and task components, and processors, functions, properties, procedures, subroutines, program code. Includes segments, drivers, firmware, microcode, circuits, data, databases, data structures, tables, arrays, and variables. Functions provided within a component and "part" may be combined into a smaller number of components and "parts" or further separated into additional components and "parts".

1 is a block diagram schematically illustrating a configuration of an ultrasound system according to an exemplary embodiment of the present disclosure. The ultrasound system 100 includes a control panel 110, an ultrasound probe 120, a processor 130, a storage 140, and a display 150. In the present embodiment, the processor 130 controls the control panel 110, the ultrasonic probe 120, the storage 140, and the display 150.

The control panel 110 receives input information from a user and transmits the received input information to the processor 130. The control panel 110 may include an input unit (not shown) that enables an interface between the user and the ultrasound system 100 and / or enables the user to operate the ultrasound system 100. The input unit may include an input device suitable for performing an operation such as selecting a diagnostic mode, controlling a diagnostic operation, inputting a command required for diagnosis, signal manipulation, output control, and the like, for example, a trackball, a keyboard, a button, and the like.

The ultrasonic probe 120 includes an ultrasonic transducer (not shown) configured to mutually convert an electrical signal and an ultrasonic signal. The ultrasound probe 120 converts an electrical signal provided from the processor 130 (hereinafter, referred to as a “transmission signal”) into an ultrasound signal and transmits the converted ultrasound signal to the object. The subject includes an object of interest (eg, blood flow, blood vessel wall, etc.). In addition, the ultrasound probe 120 receives an ultrasound signal (that is, an ultrasound echo signal) reflected from the object, and converts the ultrasound echo signal into an electrical signal (hereinafter, referred to as a "receive signal").

The processor 130 may control the ultrasound probe 120 to transmit the ultrasound signal to the object and to receive the ultrasound echo signal reflected from the object in response to the input information received through the control panel 110. In addition, the processor 130 forms a Doppler signal and one or more ultrasound images (eg, a B mode (Brightness mode image), a Doppler spectrum image, etc.) of the object based on the received signal provided from the ultrasound probe 120. can do.

In one embodiment, the processor 130 continuously measures the speed of the object of interest of the object in real time, as shown in FIG. 2, based on the received signal provided from the ultrasound probe 120. A Doppler spectral image 210 is shown. In FIG. 2, the newly formed spectral lines are displayed on the right side of the Doppler spectrum image 210. Spectral lines are moved / scrolled from right to left. That is, previously formed spectral lines are moved or scrolled from right to left, and newly formed spectral lines are displayed on the right. 2, the reference numeral 220 indicates a base line, the numeral 230 denotes a higher spectral line, a reference numeral 240 denotes a lower spectral line, V _{pre _max} indicates a pre-set maximum speed scale, V _{pre min} represents a preset minimum speed scale.

The storage 140 sequentially stores the received signal formed by the ultrasonic probe 120 for each frame. In addition, the storage 140 sequentially stores the Doppler signals formed by the processor 130. In addition, the storage 140 stores one or more ultrasound images formed by the processor 130. In addition, the storage 140 may store instructions for operating the ultrasound system 100.

The display unit 150 displays one or more ultrasound images (eg, a B mode image, a Doppler spectrum image, etc.) formed by the processor 130. In addition, the display unit 150 may display suitable information about the ultrasound image or the ultrasound system 100.

3 is a block diagram schematically illustrating a configuration of a processor 130 according to an embodiment of the present disclosure. The processor 130 includes a transmitter 310. The transmitter 310 forms a transmission signal for obtaining an ultrasound image of the object. In an exemplary embodiment, as illustrated in FIG. 4, the transmitter 310 forms a transmission signal for obtaining a Doppler signal corresponding to the Doppler gate 420 set at a predetermined position of the B mode image 410 of the object. . In Fig. 4, reference numeral 430 denotes a blood vessel wall. The transmission signal is provided to the ultrasonic probe 120. The ultrasound probe 120 converts the transmission signal into an ultrasound signal and transmits the converted ultrasound signal to the object. In addition, the ultrasound probe 120 receives the ultrasound echo signal reflected from the object to form a received signal.

Referring back to FIG. 2, the processor 130 further includes a transmit / receive switch 320 and a receiver 330. The transmission and reception switch 320 serves as a duplexer for switching the transmitter 310 and the receiver 330. For example, when the ultrasound probe 120 alternately transmits and receives the transmit / receive switch 320, the transmitter / receiver 320 may properly transmit the transmitter 310 or the receiver 330 to the ultrasound probe 120 (that is, the ultrasound transducer). It acts as a switching or electrical connection.

In the processor 130, the receiver 330 amplifies a received signal received from the ultrasound probe 120 through the transceiving switch 320, and converts the amplified received signal into a digital signal. The receiver 330 may include a time gain compensation (TGC) unit (not shown) for compensating for attenuation normally generated while the ultrasonic signal passes through the object, and an analog-to-digital conversion for converting an analog signal into a digital signal. (analog to digital conversion) unit (not shown) and the like.

The processor 130 further includes a signal forming unit 340. The signal forming unit 340 performs beamforming on the digital signal provided from the receiving unit 330 to form a reception focus signal. In addition, the signal forming unit 340 forms a Doppler signal corresponding to the Doppler gate 420 based on the reception focus signal.

The processor 130 further includes a signal processor 350. The signal processor 350 determines a trace speed for tracing the maximum velocity of blood flow at the Doppler gate 420 based on the Doppler signal provided from the signal generator 340. In addition, the signal processor 350 filters the noise in the Doppler signal based on the determined trace speed.

In one embodiment, the signal processor 350 forms a Doppler signal envelope representing a Doppler signal provided from the signal forming unit 340 as a plurality of brightness values. For example, as illustrated in FIG. 5, the signal processing unit 350 forms a Doppler signal envelope 530 corresponding to the spectral line 510 based on the Doppler signal provided from the signal forming unit 340. . In FIG. 5A, the horizontal axis represents time and the vertical axis represents speed. In Fig. 5B, the horizontal axis represents speed and the vertical axis represents brightness (intensity). That is, the Doppler signal envelope 520 may be an envelope representing a Doppler signal existing between the baseline 220 and the preset maximum speed scale V _{pre _} max as a plurality of brightness values.

The signal processor 350 determines the peak of the generated Doppler signal envelope 520. For example, as illustrated in FIG. 5, the signal processor 350 determines the maximum brightness value in the Doppler signal envelope 520 and determines the determined maximum brightness value as the peak 530 of the Doppler signal envelope 520. do.

The signal processor 350 determines a threshold for estimating noise in the Doppler signal envelope 520 based on the determined peak 530. As an example, as illustrated in FIG. 5, the signal processor 350 determines any one of brightness values in the range of 30 to 60% of the determined peak 530 (that is, the maximum brightness value) as a threshold value. As another example, the signal processor 350 determines the brightness value of the range of 50% of the determined peak 530 as the threshold value 540.

The signal processor 350 determines the trace speed of the Doppler signal based on the Doppler signal envelope 520 and the threshold 540. For example, as illustrated in FIG. 6, the signal processor 350 may be below the threshold 540 at the Doppler signal envelope 520 between the preset maximum speed scale V _{pre _} max and the baseline 220. Select the corresponding Doppler signal envelope (see dashed line in FIG. 6). The signal processor 350 determines the midpoint X _c1 (ie, the midpoint between the preset maximum speed scale V _{pre_max} and X ₁ ) of the selected Doppler signal envelope (see the dashed-dotted line in FIG. 6), and determines the determined midpoint. The first trace start line 610 is determined based on (X _c ). Subsequently, as illustrated in FIG. 7, the signal processor 350 may have a threshold 540 or less at the Doppler signal envelope 520 between the preset maximum speed scale V _{pre _} max and the first trace start line 610. Select the Doppler signal envelope corresponding to the dashed-dotted line in FIG. The signal processor 350 determines the midpoint X _c2 (that is, the midpoint between the preset maximum speed scale V _{pre_max} and X ₂ ) of the selected Doppler signal envelope (see the dashed-dotted line in FIG. 7), and determines the determined midpoint. The second trace start line 710 is determined based on (X _c2 ). Subsequently, the signal processing unit 350 performs a trace process on the Doppler signal envelope 520 to determine the trace speed from the second trace start line 710 to the baseline 220, so as to first exceed the threshold 540. The brightness value 720 is determined. The signal processor 350 determines the speed corresponding to the determined brightness value 720 as the trace speed of the Doppler signal. The determined trace velocity may be displayed as trace line 810 in the Doppler spectral image 210, as shown in FIG. 8.

In another embodiment, the signal processor 350 may filter out noise (eg, impact noise) that is equal to or greater than a predetermined speed (eg, 200%) of the determined trace speed. As an example, the signal processor 350 may include an intermediate value filter (not shown) having a predetermined size. That is, the signal processor 350 selects a trace speed (hereinafter, referred to as "current trace speed") corresponding to the current Doppler signal. The signal processor 350 selects a trace speed (hereinafter, referred to as "previous trace speed") corresponding to the Doppler signal before the current Doppler signal based on the current trace speed. The previous trace speed is determined by the predetermined size of the median filter. The signal processor 350 sorts the current trace speed and the previous trace speed in ascending order, determines the trace speed of the intermediate value from the aligned trace speed, and determines the trace speed of the intermediate value as the trace speed of the current Doppler signal. As another example, the signal processor 350 may include a moving average filter having a predetermined size. That is, the signal processor 350 selects a current trace speed corresponding to the current Doppler signal. The signal processor 350 selects a previous trace speed corresponding to the Doppler signal before the current Doppler signal based on the current trace speed. The previous trace speed may be determined according to the predetermined size of the moving average filter. The signal processor 350 determines an average trace speed of the current trace speed and the previous trace speed, and determines the average trace speed as the trace speed corresponding to the current Doppler signal.

In another embodiment, the signal processor 350 filters noise (eg, system noise) in the Doppler signal based on the determined trace rate. For example, the signal processor 350 determines a threshold (hereinafter, referred to as a "filtering threshold") for filtering noise by applying a preset value to the determined trace speed. As an example, the signal processor 350 determines a speed in the range of 80 to 120% of the determined trace speed as the filtering threshold. The signal processor 350 filters the Doppler signal corresponding to the speed exceeding the filtering threshold as noise.

Although the upper spectral line 230 has been described as determining the trace rate and filtering the noise, the lower spectral line 240 may be filtered in a similar manner.

Referring back to FIG. 3, the processor 130 further includes an image forming unit 360. The image forming unit 360 forms a spectral line, that is, a Doppler spectrum image, based on the Doppler signal filtered by the signal processor 350. In addition, as illustrated in FIG. 8, the shape forming unit 360 forms the trace line 810 based on the trace speed determined by the signal processing unit 350.

9 is a flowchart illustrating a procedure of displaying a Doppler spectral image according to an embodiment of the present disclosure. The processor 130 obtains a Doppler signal corresponding to the Doppler gate 420 set at a predetermined position of the B mode image 410 of the object (S902).

The processor 130 forms the Doppler signal envelope 520 as shown in FIG. 5 based on the obtained Doppler signal (S904). The processor 130 determines a peak of the Doppler signal envelope 520 (S906). For example, the processor 130 determines the maximum brightness value in the Doppler signal envelope 520 and determines the determined maximum brightness value as the peak of the Doppler signal envelope 520.

The processor 130 determines a threshold for estimating noise in the Doppler signal based on the peak of the Doppler signal envelope 520 (S908). As an example, the processor 130 determines any one of brightness values in the range of 30 to 60% of the peak of the Doppler signal envelope 520 as a threshold. As another example, the processor 130 determines a brightness value in the range of 50% of the peak of the Doppler signal envelope 520 as a threshold.

The processor 130 determines a first trace start line based on the Doppler signal envelope and a threshold value (S910). For example, the processor 130 corresponds to the threshold 540 or less in the Doppler signal envelope 520 between the preset maximum speed scale V _{pre _} max and the baseline 220, as shown in FIG. 6. A Doppler signal envelope (see dashed line in Fig. 6) is selected. The processor 130 determines the midpoint of the selected Doppler signal envelope (see dashed line in FIG. 6) and determines the first trace start line 610 based on the determined midpoint.

The processor 130 determines a second trace start line based on the Doppler signal envelope, the threshold value, and the first trace start line (S910). For example, the processor 130 may have a threshold 540 at the Doppler signal envelope 520 between the preset maximum speed scale V _{pre _} max and the first trace start line 610, as shown in FIG. 7. The Doppler signal envelope (see the dashed-dotted line in FIG. 7) corresponding to the following is selected. The processor 130 determines the midpoint of the selected Doppler signal envelope (see the dashed-dotted line in FIG. 7) and determines the second trace start line 710 based on the determined midpoint.

The processor 130 determines a trace speed of the Doppler signal based on the second trace start line (S914). For example, the processor 130 traces the Doppler signal envelope 520 from the second trace start line 710 to the baseline 220, as shown in FIG. 7, first exceeding the threshold 540. The brightness value 720 is determined. The processor 130 determines the speed corresponding to the determined brightness value 720 as the trace speed of the Doppler signal.

The processor 130 filters the noise in the Doppler signal based on the determined trace speed (S916). For example, processor 130 filters the impact noise at trace line 810 based on the determined trace rate and filters system noise in the Doppler signal based on the filtered trace rate.

The processor 130 forms a Doppler spectral image based on the filtered Doppler signal (S918). The Doppler spectrum image may be displayed on the display unit 150. In addition, the trace speed may be displayed on the display unit 150 as the trace line 810 as shown in FIG. 8.

While specific embodiments have been described, these embodiments have been presented by way of example and should not be construed as limiting the scope of the disclosure. The novel methods and apparatus of the present disclosure may be embodied in a variety of other forms and furthermore, various omissions, substitutions and changes in the embodiments disclosed herein can be made without departing from the spirit of the present disclosure. The claims appended hereto and their equivalents should be construed to include all such forms and modifications as fall within the scope and spirit of the disclosure.

100: ultrasonic system 110: control panel
120: ultrasonic probe 130: processor
140: storage unit 150: display unit
210: Doppler spectrum image 220: baseline
310: transmitting unit 320: transmission and reception switch
330: receiving unit 340: signal forming unit
350: signal processor 360: image forming unit
410: B mode image 420: Doppler gate
430: blood vessel wall 510: spectral line
520: Doppler signal envelope 530: peak
540: threshold
V _{pre _max} : Preset maximum speed scale
V _{pre _min} : preset minimum speed scale
610: first trace start line 710: second trace start line
720: trace speed 810: trace line

Claims (18)

A method of displaying a Doppler spectral image of an object in an ultrasound system,
Obtaining a Doppler signal based on a Doppler gate set at a predetermined position of a B mode image of the object;
Forming a Doppler signal envelope representing the Doppler signal as a plurality of brightness values;
Determining a trace rate representing a maximum velocity of the Doppler signal based on the Doppler signal envelope;
Filtering noise in the Doppler signal based on the trace rate;
Forming a Doppler spectral image of the object based on the filtered Doppler signal;
Displaying the Doppler spectral image
Including,
Determining the trace speed,
Determining a peak of the Doppler signal envelope;
Determining a threshold for estimating the noise in the Doppler signal envelope based on the determined peaks;
Determining a trace start position on the Doppler signal envelope based on the threshold value;
Determining the trace speed at the Doppler signal envelope based on the trace start position
How to include. delete The method of claim 1, wherein the determining of the threshold value comprises:
Determining any of the brightness values in the range of 30% to 60% of the peak as the threshold value
How to include. The method of claim 3, wherein determining the threshold value comprises:
Determining a brightness value corresponding to a range of 50% of the peak as the threshold value
How to include. The method of claim 1, wherein determining the trace start position comprises:
Selecting a first Doppler signal envelope below the threshold from the Doppler signal envelope;
Determining a first midpoint of the first Doppler signal envelope;
Determining a first trace start position of the Doppler signal envelope based on the first midpoint;
Selecting a second Doppler signal envelope below the threshold from the Doppler signal envelope based on the first trace start position;
Determining a second midpoint of the second Doppler signal envelope;
Determining a second trace start position of the Doppler signal envelope based on the second midpoint
How to include. The method of claim 5, wherein determining the trace speed comprises:
Determining the trace speed based on the second trace start position of the Doppler signal envelope
How to include. The method of claim 1, wherein filtering the noise comprises:
Determining a filtering threshold for filtering the noise by applying a preset value to the determined trace rate;
Filtering the noise in the Doppler signal based on the filtering threshold
How to include. 8. The method of claim 7, wherein the filtering threshold comprises a speed ranging from 80 to 120% of the determined trace speed. The method according to any one of claims 1 and 3 to 8,
Filtering impact noise above a predetermined rate of the determined trace rate
How to include more. As an ultrasonic system,
An ultrasound probe configured to transmit an ultrasound signal to the object and receive an ultrasound echo signal from the object based on a Doppler gate set at a predetermined position of a B mode image of the object;
Forming a Doppler signal based on the ultrasonic echo signal, forming a Doppler signal envelope representing the Doppler signal as a plurality of brightness values, and determining a trace velocity representing the maximum speed of the Doppler signal based on the Doppler signal envelope A processor configured to filter noise in the Doppler signal based on the trace rate, and form a Doppler spectral image of the object based on the filtered Doppler signal;
A display unit configured to display the Doppler spectrum image
Including,
The processor determines a peak of the Doppler signal envelope, determines a threshold for estimating the noise in the Doppler signal envelope based on the determined peak, and starts a trace on the Doppler signal envelope based on the threshold value. And a signal processor configured to determine a position and determine the trace velocity in the Doppler signal envelope based on the trace start position. delete The ultrasound system of claim 10, wherein the processor is configured to determine any one of brightness values in the range of 30% to 60% of the peak as the threshold. The ultrasound system of claim 12, wherein the processor is configured to determine a brightness value in the range of 50% of the peak as the threshold value. The processor of claim 10, wherein the processor selects a first Doppler signal envelope corresponding to the threshold value or less from the Doppler signal envelope, determines a first midpoint of the first Doppler signal envelope, and applies the first midpoint to the first midpoint. Determine a first trace start position of the Doppler signal envelope, select a second Doppler signal envelope below the threshold value from the Doppler signal envelope based on the first trace start position, and perform the second Doppler And a signal processor configured to determine a second midpoint of the signal envelope and to determine a second trace start position of the Doppler signal envelope based on the second midpoint. 15. The ultrasound system of claim 14 wherein the processor is configured to determine the trace velocity based on the second trace start position of the Doppler signal envelope. The method of claim 10, wherein the processor is configured to apply a preset value to the determined trace rate to determine a filtering threshold for filtering the noise and to filter the noise in the Doppler signal based on the filtering threshold. Ultrasonic system comprising a signal processing unit configured. 17. The ultrasound system of claim 16 wherein the filtering threshold comprises a speed ranging from 80 to 120% of the determined trace speed. 18. The ultrasound system of any of claims 10 and 12 to 17, wherein the processor is further configured to filter out impact noise above a predetermined speed of the determined trace speed.

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