JP2017086292A - Ultrasound image diagnostic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To estimate missing signals with increased accuracy and easiness and increase the processing speed of such estimation.SOLUTION: An ultrasound image diagnostic apparatus 1 comprises: a send/receive unit 12 for generating I, Q signals as complex Doppler signals from D-mode received signals input from an ultrasound probe 11, which alternately transmits plural D-mode send ultrasound waves and plural B-mode send ultrasound waves and receives reflected ultrasound waves; a separator 18 for separating audio signals of downflow components and backflow components of blood flow from the generated I signal and Q signal; an MSE unit 19 for continuation of signals by estimating and padding missing signals for the B mode from the separated audio signals of the downflow component and backflow component; a counter separator 21 for generating continued I, Q signals from the continued audio signals of the downflow component and backflow component; and an FFT unit 22 for generating spectrum signals of the blood flow rate by analyzing the frequencies of the continued I, Q signals.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an ultrasonic diagnostic imaging apparatus.

  Ultrasound diagnosis is a simple operation of touching the ultrasound probe from the body surface, and the state of heart beat and fetal movement can be obtained as an ultrasound image, and because it is highly safe, the examination is repeated. Can do. 2. Description of the Related Art There is known an ultrasonic diagnostic imaging apparatus that is used for performing an ultrasonic diagnosis and displays an ultrasonic image.

In addition, the ultrasound diagnostic imaging apparatus outputs a blood flow velocity by outputting a B mode (B: Brightness) for displaying an ultrasonic tomographic image based on a two-dimensional luminance value of the subject and an audio signal of the blood flow of the subject. D mode to be displayed (D: Doppler, pulsed Doppler mode), color flow mode for detecting movement such as blood flow of the subject, and coloring the image according to the moving speed of the moving portion, and blood flow of the subject It can be displayed as an ultrasonic diagnostic imaging device such as a power Doppler mode that detects the power of the image and colors the image according to the magnitude of the power, and an elast mode that colors the image according to the elasticity of the tissue. Multiple display modes can be displayed.
Among these, an ultrasonic diagnostic imaging apparatus that alternately performs ultrasonic transmission for D mode and ultrasonic transmission other than D mode one by one, and simultaneously displays images of ultrasonic transmission other than D mode and D mode. Are known.
Hereinafter, the display mode other than the D mode will be described by taking the B mode as an example, but the mode displayed simultaneously with the D mode is not limited to the B mode.

  However, in this ultrasonic diagnostic imaging apparatus, since the B-mode ultrasonic transmission is transmitted during the D-mode ultrasonic transmission, the time interval of the D-mode ultrasonic transmission becomes long, so that the blood flow velocity is increased. I can not cope. In order to solve this problem, an ultrasonic transmission method shown in FIG. 5 is known. FIG. 5 is a diagram illustrating transmission of ultrasonic waves with respect to time in a segment scan.

  As shown in FIG. 5, in the segment scan, a plurality of ultrasonic transmissions for the D mode and a plurality of ultrasonic transmissions for the B mode are alternately performed in order. Horizontal arrows indicate ultrasonic transmission. For this reason, the reception signal corresponding to the ultrasonic reception in the D mode becomes discontinuous due to the ultrasonic transmission for the period TB in the B mode.

Due to the discontinuous period TB, the audio signal of the blood flow in the D mode is interrupted. Therefore, as a segment scan, a missing signal of a discontinuous portion is estimated and filled in a complex Doppler signal (IQ signal) obtained by receiving an ultrasonic wave in the D mode, and converted into an audio signal and an image signal. A Doppler signal gap processing system is known (see, for example, Patent Document 1).
For the process of estimating and filling the missing signal of the discontinuous portion, expressions such as interpolation and interpolation may be used.

  Here, with reference to FIG. 6, a conventional ultrasonic diagnostic imaging apparatus 3 as the Doppler signal gap processing system will be described. FIG. 6 is a block diagram showing a functional configuration of a conventional ultrasonic diagnostic imaging apparatus 3.

  As shown in FIG. 6, in the ultrasound diagnostic imaging apparatus 3, the transmission / reception unit 12 alternately generates a plurality of B-mode transmission signals and a plurality of D-mode transmission signals under the control of each unit by the control unit 10. Output to the ultrasound probe 11. The ultrasonic probe 11 transmits a transmission ultrasonic wave to the subject according to the transmission signal, receives the reflected ultrasonic wave, and outputs the reception signal to the transmission / reception unit 12. The transmission / reception unit 12 generates digital sound ray data and complex Doppler signals (I signal / Q signal) for the reception signals in the B mode and the D mode, respectively. The switch 13 outputs the B-mode digital sound ray data generated by the transmission / reception unit 12 to the B-mode processing unit 14, and similarly outputs the D-mode digital I signal / Q signal to the wall filter 17. The B-mode processing unit 14 generates B-mode image data from the input B-mode digital sound ray data. The DSC 15 converts the generated B-mode image data into a display image signal. The display unit 16 displays a B-mode image according to the converted image signal.

  The wall filter 17 removes a slow wall component from the input D-mode digital I signal / Q signal as compared with the blood flow based on the movement of the visceral wall and body movement of the subject. An MSE (Missing Signal Estimation) unit 19B estimates and fills the missing signal of the discontinuous portion of the B mode from the digital I signal / Q signal from which the wall component has been removed, and makes it continuous. The separator 18B separates the continuous I signal / Q signal into digital audio signals (forward flow component: Fwd, backward flow component: Bwd) of the forward flow component and the backward flow component of the blood flow. The speaker 20 outputs the audio signal Fwd of the forward flow component from the L side and outputs the audio signal Bwd of the reverse flow component from the R side.

  An FFT (Fast Fourier Transform) unit 22 performs fast Fourier transform on the continuous I signal / Q signal, generates blood flow velocity spectrum data for the FFT waveform, and outputs the spectrum data to the DSC 15. The DSC 15 converts the spectrum data into an image signal having an FFT waveform for display, and displays the FFT waveform image on the display unit 16 together with the B-mode image.

US Patent Application Publication No. 2010/0106021

  However, in the conventional ultrasonic diagnostic imaging apparatus 3, since both the I signal and the Q signal include the audio component of the forward flow component and the backward flow component, one of the audio signal of the forward flow component and the backward flow component is not present. In the case of a stationary component, the MSE unit 19B estimates the missing signal of the I signal and the Q signal, and the other non-stationary audio signal component is also affected, resulting in a continuous complex Doppler signal (I signal / Q signal). The accuracy of was reduced. Further, since the MSE unit 19B performs processing on the complex Doppler signal, the method of estimating the missing signal is limited and the processing speed is slow.

  An object of the present invention is to increase the accuracy of missing signal estimation, easily perform missing signal estimation, and increase the processing speed.

In order to solve the above-mentioned problem, the invention described in claim 1
An ultrasound diagnostic imaging apparatus that generates images in a plurality of display modes,
A transmission unit that alternately transmits a plurality of transmission ultrasonic waves in a D mode that is one of the plurality of display modes and a plurality of transmission ultrasonic waves in a display mode other than the D mode of the plurality of display modes; 2 types of complex signals of a first complex signal and a second complex signal as a D-mode complex Doppler signal are generated from the received signal input from the ultrasonic probe that generates the received signal. A receiver,
A separation unit that separates the first direction component and the second direction component of the blood flow from the generated first complex signal and second complex signal;
A missing signal estimator that estimates and fills in a missing signal in a display mode other than the D mode from the separated audio signals of the first direction component and the second direction component,
An inverse separation unit that generates a continuous first complex signal and a continuous second complex signal from the continuous first direction component and second direction component audio signals;
A frequency analysis unit that frequency-analyzes the continuous first complex signal and the continuous second complex signal to generate a spectrum signal of a blood flow velocity.

A second aspect of the present invention is the ultrasonic diagnostic imaging apparatus according to the first aspect,
An audio output unit for outputting audio signals of the continuous first direction component and second direction component;
A display unit for displaying the generated spectrum signal of the blood flow velocity.

Claim 3 is the ultrasonic diagnostic imaging apparatus according to claim 1 or 2,
The missing signal estimation unit estimates a missing signal for a display mode other than the D mode by using a different algorithm for the separated audio signal of the first direction component and the audio signal of the second direction component. Fill and continue.

A fourth aspect of the present invention is the ultrasonic diagnostic imaging apparatus according to any one of the first to third aspects,
The separation unit is
A first filter for filtering the first complex signal generated by the receiver;
A second filter for filtering the second complex signal generated by the receiver;
A first inversion unit for inverting the sign of the filtered second complex signal;
A first adder for adding the filtered first complex signal and the filtered second complex signal to generate an audio signal of the first direction component;
A second addition unit that adds the filtered first complex signal and the inverted second complex signal to generate an audio signal of the second direction component;
The difference between the phase shift amounts of the first and second filters is 90 degrees.

A fifth aspect of the present invention is the ultrasonic diagnostic imaging apparatus according to the fourth aspect,
A wall component removal unit that removes a wall component from the first complex signal and the second complex signal generated by the reception unit and outputs the wall component to the separation unit;
The first filter is a first delay filter that delays the first complex signal from which the wall component has been removed,
The second filter is a first phase shift filter that shifts the phase of the second complex signal from which the wall component has been removed.

A sixth aspect of the present invention is the ultrasonic diagnostic imaging apparatus according to the fourth aspect,
The first filter is a second phase shift filter that shifts the phase of the first complex signal generated by the receiving unit, reduces low frequency components including wall components, and passes high frequency components,
The second filter is a third phase shift filter that shifts the phase of the second complex signal generated by the receiving unit, reduces low frequency components including wall components, and passes high frequency components.

The invention according to claim 7 is the ultrasonic diagnostic imaging apparatus according to any one of claims 1 to 6,
The inverse separation unit includes: a fourth phase shift filter that shifts the phase of the continuous first direction component audio signal generated by the missing signal estimation unit;
A second delay filter that delays the continuous second direction component audio signal generated by the missing signal estimation unit;
A second inversion unit for inverting the sign of the delayed audio signal of the second direction component;
A third adder that adds the phase-shifted first direction component audio signal and the inverted second direction component audio signal to generate a continuous first complex signal;
A fourth adder for adding the phase-shifted first direction component audio signal and the delayed second direction component audio signal to generate a continuous second complex signal; With
The difference in phase shift amount between the fourth phase shift filter and the second delay filter is 90 degrees.

The invention according to claim 8 is the ultrasonic diagnostic imaging apparatus according to any one of claims 1 to 7,
The first complex signal is an I signal of a D-mode complex Doppler signal,
The second complex signal is a Q signal of a D-mode complex Doppler signal,
The first direction component is a forward component of blood flow;
The second direction component is a backflow component of blood flow.

The invention according to claim 9 is the ultrasonic diagnostic imaging apparatus according to any one of claims 1 to 7,
The first complex signal is a Q signal of a D-mode complex Doppler signal,
The second complex signal is an I signal of a D-mode complex Doppler signal,
The first direction component is a backflow component of blood flow,
The second direction component is a forward flow component of blood flow.

  According to the present invention, the accuracy of missing signal estimation can be increased, missing signal estimation can be easily performed, and the processing speed can be increased.

It is a block diagram which shows the function structure of the ultrasonic image diagnostic apparatus of embodiment of this invention. (A) is a block diagram which shows the structure of a 1st separator. (B) is a block diagram showing a configuration of a first counter separator. It is a block diagram which shows the function structure of the ultrasonic image diagnostic apparatus of a modification. (A) is a block diagram which shows the structure of a 2nd separator. (B) is a block diagram showing a configuration of a second counter separator. It is a figure which shows transmission of the ultrasonic wave with respect to time in a segment scan. It is a block diagram which shows the function structure of the conventional ultrasonic image diagnostic apparatus.

  Embodiments and modifications according to the present invention will be described in detail in order with reference to the accompanying drawings. The present invention is not limited to the illustrated example.

(Embodiment)
Embodiments according to the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a functional configuration of the ultrasonic diagnostic imaging apparatus 1 according to the present embodiment. FIG. 2A is a block diagram showing the configuration of the separator 18. FIG. 2B is a block diagram showing the configuration of the counter separator 21.

The ultrasonic diagnostic imaging apparatus 1 according to the present embodiment transmits a B-mode transmission ultrasonic wave to the subject and simultaneously receives the received D-mode image and the B-mode image in the subject. The internal state in the subject is imaged as an ultrasonic tomographic image (B mode image) based on the received signal corresponding to the reflected ultrasonic wave from the transmitter, and the transmission ultrasonic wave for D mode is transmitted to the subject. At the same time, based on the received signal corresponding to the received reflected ultrasonic wave, an audio signal of the blood flow of the subject is output as audio to generate an FFT waveform indicating the blood flow velocity, and displayed simultaneously with the B-mode image. The ultrasonic diagnostic imaging apparatus 1 repeatedly transmits a plurality of ultrasonic waves for D mode and a plurality of ultrasonic waves for B mode alternately by the segment scan shown in FIG.
As already described, the B mode here is an example, and the other modes displayed at the same time as the D mode may be any modes other than the D mode display that can be displayed as the ultrasonic diagnostic apparatus.

  As shown in FIG. 1, the ultrasonic diagnostic imaging apparatus 1 includes a control unit 10, an ultrasonic probe 11, a transmission / reception unit 12, a switch 13, a B-mode processing unit 14, a DSC 15, and a display unit 16. A wall filter 17 as a wall component removal unit, a separator 18 as a separation unit, an MSE unit 19 as a missing signal estimation unit, a speaker 20 as an audio output unit, and a counter separator 21 as a reverse separation unit And an FFT unit 22 as a frequency analysis unit.

  The control unit 10 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory), and reads various processing programs such as a system program stored in the ROM to read the RAM. The operation of each part of the ultrasonic diagnostic imaging apparatus 1 is centrally controlled according to the developed program. The ROM is configured by a nonvolatile memory such as a semiconductor, and stores a system program corresponding to the ultrasonic diagnostic imaging apparatus 1, various processing programs that can be executed on the system program, various data, and the like. These programs are stored in the form of computer-readable program code, and the CPU sequentially executes operations according to the program code. The RAM forms a work area for temporarily storing various programs executed by the CPU and data related to these programs. The control unit 10 is connected to an operation unit (not shown) that receives an input of a Doppler gate (sample volume) that designates a portion for measuring a blood flow velocity in the D mode on the B mode image.

  The ultrasonic probe 11 transmits a transmission ultrasonic wave according to the transmission signal input from the transmission / reception unit 12, receives a reflected ultrasonic wave from the subject, and transmits / receives a reception signal corresponding to the reflected ultrasonic wave. To the unit 12. The ultrasonic probe 11 includes transducers made of piezoelectric elements, and a plurality of the transducers are arranged in a one-dimensional array in the azimuth direction, for example. Note that the vibrators may be arranged in a two-dimensional array. Further, the number of vibrators can be arbitrarily set. In the present embodiment, a linear scanning electronic scanning probe is used for the ultrasonic probe 11, but either an electronic scanning method or a mechanical scanning method may be used, and a linear scanning method, Either the sector scanning method or the convex scanning method can be adopted.

  The transmission / reception unit 12 transmits a plurality of D-mode transmission signals (drive signals), which are electrical signals corresponding to the input Doppler gate, and a plurality of B-mode transmission signals, which are electrical signals, under the control of the control unit 10. The ultrasonic probe 11 generates electricity alternately and supplies it to the ultrasonic probe 11, and generates a plurality of D-mode and B-mode transmission ultrasonic waves alternately. And a reception unit that alternately receives a plurality of D-mode reception signals and a plurality of B-mode reception signals as signals. The receiving unit includes, for example, an amplifier, an A / D conversion circuit, a phasing addition circuit, and a phase detector.

  The receiving unit amplifies the input B-mode reception signal by an amplifier with a predetermined amplification factor set in advance for each individual path corresponding to each transducer, and amplifies it by an A / D conversion circuit. The received analog signal is converted into a digital received signal, and a phase delay is given to each individual path corresponding to each transducer with respect to the A / D converted received signal by the phasing and adding circuit. And adding them (phasing addition) to generate sound ray data. The receiving unit amplifies the input D-mode received signal by an amplifier at a predetermined amplification factor set for each individual path corresponding to each transducer, and by an A / D conversion circuit. A method known as quadrature detection by converting an amplified analog received signal into a digital received signal, phasing and adding the A / D converted received signal by a phasing and adding circuit, and a phase detector. Thus, blood flow signals whose phases are different from each other by 90 degrees are phase-detected and extracted from the phased and added reception signals to generate digital complex Doppler signals (I signal / Q signal).

  The switch 13 is a 1-input 2-output switch. Under the control of the control unit 10, the output of the B-mode sound ray data input from the transmission / reception unit 12 is switched to the B-mode processing unit 14 side. The output of the mode I signal / Q signal is switched to the wall filter 17 side.

  Under the control of the control unit 10, the B-mode processing unit 14 performs envelope detection processing, logarithmic amplification, and the like on the sound ray data input from the switch 13, and performs gain adjustment and the like to perform luminance conversion. B-mode image data is generated. In other words, the B-mode image data represents the intensity of the received signal by luminance.

  The DSC 15 coordinates the B-mode image data input from the B-mode processing unit 14 under the control of the control unit 10, converts it into a display image signal, and the spectrum for the FFT waveform input from the FFT unit 22. The signal is converted into an image signal for display, and the B-mode image and the FFT waveform image are synthesized.

  The display unit 16 is a display device such as an LCD (Liquid Crystal Display), a CRT (Cathode-Ray Tube) display, an organic EL (Electronic Luminescence) display, an inorganic EL display, or a plasma display. The display unit 16 displays the composite image of the B-mode image and the FFT waveform on the display screen according to the image signal input from the DSC 15 under the control of the control unit 10.

  The wall filter 17 is a filter that removes a wall component based on the movement and body movement of the internal organ wall of the subject from the D-mode digital I signal / Q signal input from the switch 13.

The separator 18, based on the digital I signal / Q signal input from the wall filter 17, is a digital audio signal (a forward flow component in which the blood flow approaches the ultrasonic probe 11 and a reverse flow component in the reverse direction in which the blood flow moves away. Separated into a forward flow component: Fwd and a reverse flow component: Bwd).
Here, the separator 18 will be described with reference to FIG. The separator 18 includes a delay filter 181, a phase shift filter 182, an inversion unit 183, and addition units 184 and 185.

The delay filter 181 is a filter that outputs the digital I signal input from the wall filter 17 with a predetermined time delay. The phase shift filter 182 performs a phase shift that shifts the phase by 90 degrees with respect to the digital Q signal input from the wall filter 17, and has a function of reducing the low frequency component and passing the high frequency component with respect to the Q signal. It is a filter that has both. That is, the difference in phase shift amount between the delay filter 181 and the phase shift filter 182 is 90 degrees.
The purpose of the delay by the delay filter 181 is to compensate for the time delay with respect to the I signal generated by phase shifting the Q signal by the phase shift filter 182. Therefore, the delay filter 181 delays the I signal by a delay time equivalent to the delay time by the phase shift filter 182.

The inverting unit 183 inverts the sign of the digital Q signal input from the phase shift filter 182. The adder 184 adds the I signal input from the delay filter 181 and the Q signal input from the phase shift filter 182 to generate a digital forward flow component audio signal Fwd and outputs it to the MSE unit 19. The adding unit 185 adds the I signal input from the delay filter 181 and the inverted Q signal input from the inverting unit 183, generates a digital backflow component audio signal Bwd, and outputs the audio signal Bwd to the MSE unit 19.
The configuration in which the I signal is input to the delay filter 181 and the Q signal is input to the phase shift filter 182 has been described. However, the I signal and the Q signal are relative signals. It is also possible to input an I signal to the shift filter 182.

  Returning to FIG. 1, the MSE unit 19 estimates and fills the missing signal of the discontinuous portion of the B mode from the digital audio signal Fwd / Bwd input from the separator 18 according to the control of the control unit 10 and makes it continuous. The digital audio signals Fwd / Bwd are real numbers and independent from each other. For this reason, the MSE unit 19 uses the AR (Auto Regressive) model prediction, the MA (Moving Average) model prediction, the ARMA ( The missing signal of the discontinuous portion of the B mode is estimated and filled using a prediction by AutoRegressive and Moving Average).

但し、ε_n：ホワイトノイズを満たす撹乱項（誤差項）、ε_n〜Norm(0,σ)、σ^２：分散であり、ｙ_n：ｎ番目の予測値（推定値）である。
つまり、ＡＲモデルでは、予測値ｙ_nは、ｍ個過去の値の加重値に誤差が加わった値である。式（１）における係数ａ_nはYule-Walker方程式として知られる以下の関係式（２），（３）から導出することができる。

The AR model is a model that expresses a current value using a past observation value and normal noise in a time series signal. The AR model of order m is formulated as the following formula (1).

Where ε _n is a disturbance term (error term) that satisfies white noise, ε _{n to} Norm (0, σ), σ ^{2 is} variance, and y _n is an _nth predicted value (estimated value).
That is, in the AR model, the predicted value y _n is a value error is applied to a weight value of m or past values. The following equation is the coefficient a _n in the formula (1), known as Yule-Walker equation (2) can be derived from (3).

  The MA model is a model in which a predicted value is a weighted sum of disturbance terms (white noise that cannot be observed) dating back to the past from this term. The ARMA model is a model obtained by combining the AR model and the MA model.

  The MSE unit 19 also includes, as a missing signal estimation method (algorithm), a method of estimating and filling the missing signal by temporally inverting the input forward flow component and backward flow component audio signals Fwd and Bwd, There is a method in which the missing signal values of the audio signals Fwd and Bwd are replaced with 0 when the audio signals Fwd and Bwd of the input forward and backward flow components are low in level. Further, the MSE unit 19 may be configured to estimate and fill in the missing signals for the B mode with different algorithms for the input audio signals Fwd and Bwd of the forward flow component and the reverse flow component, respectively, and to make them continuous. For example, when the signal level of one of the forward flow component and the backward flow component audio signals Fwd and Bwd is small, the missing signal of the audio signal having a low signal level is replaced with 0 to fill the audio signal having a high signal level. On the other hand, it is good also as filling a missing signal with the missing signal estimation method with high precision, such as prediction by AR model.

  The speaker 20 is a stereo speaker of L (left) and R (right), outputs a digital forward flow component audio signal Fwd input from the MSE unit 19 from the L side, and receives the same digital backflow. The component audio signal Bwd is output as audio from the R side.

The counter separator 21 converts the audio signal of the digital forward flow component and the reverse flow component input from the MSE unit 19 into a digital complex Doppler signal (I signal / Q signal).
Here, the counter separator 21 will be described with reference to FIG.
As shown in FIG. 2B, the counter separator 21 includes a phase shift filter 211, a delay filter 212, an inversion unit 213, and addition units 214 and 215.

The phase shift filter 211 is a filter that shifts the phase by 90 degrees with respect to the digital forward flow component audio signal Fwd input from the MSE unit 19 and outputs it, and reduces the low frequency component of the audio signal Fwd. is there. The delay filter 212 is a filter that outputs the digital backflow component audio signal Bwd input from the MSE unit 19 with a predetermined delay. That is, the phase shift amount difference between the phase shift filter 211 and the delay filter 212 is 90 degrees.
The purpose of the delay by the delay filter 212 is to compensate for the delay time for the audio signal Bwd generated by phase-shifting the audio signal Fwd by the phase shift filter 211. Therefore, the delay filter 212 delays the audio signal Bwd by a delay time equivalent to the delay time by the phase shift filter 211.

The inversion unit 213 inverts the sign of the digital backflow component audio signal Bwd input from the delay filter 212. The adding unit 214 adds the digital forward flow component audio signal Fwd input from the phase shift filter 211 and the digital inverted reverse flow component audio signal Bwd input from the inversion unit 213 to obtain a digital I signal. Generate and output to the FFT unit 22. The adder 215 adds the digital forward flow component audio signal Fwd input from the phase shift filter 211 and the digital reverse flow component audio signal Bwd input from the delay filter 212 to generate a digital Q signal and performs FFT. To the unit 22.
If the Q signal is input to the delay filter 181 and the I signal is input to the phase shift filter 182, the audio signal Fwd having the forward flow component and the audio signal Bwd having the reverse flow component are respectively switched and output.

  Returning to FIG. 1, the FFT unit 22 generates the spectrum data of the blood flow velocity for the FFT waveform by performing the fast Fourier transform as the frequency analysis of the I signal / Q signal input from the counter separator 21 according to the control of the control unit 10. And output to the DSC 15.

  With respect to each unit included in the ultrasonic diagnostic imaging apparatus 1, some or all of the functions of each functional block can be realized as a hardware circuit such as an integrated circuit. The integrated circuit is, for example, an LSI (Large Scale Integration), and the LSI may be referred to as an IC, a system LSI, a super LSI, or an ultra LSI depending on the degree of integration. Further, the method of circuit integration is not limited to LSI, but may be realized by a dedicated circuit or a general-purpose processor, and connection and setting of circuit cells in FPGA (Field Programmable Gate Array) and LSI can be reconfigured. A reconfigurable processor may be used. Further, some or all of the functions of each function block may be executed by software. In this case, the software is stored in one or more storage media such as a ROM, an optical disk, or a hard disk, and the software is executed by the arithmetic processor.

  As described above, according to the present embodiment, the ultrasound diagnostic imaging apparatus 1 generates D-mode and B-mode images. The ultrasonic diagnostic imaging apparatus 1 alternately transmits a plurality of transmission ultrasonic waves in the D mode and a plurality of transmission ultrasonic waves in the B mode to the ultrasonic probe 11 and receives the reflected ultrasonic waves to generate reception signals. The transmitter / receiver 12 generates an I signal and a Q signal as a D-mode complex Doppler signal from the D-mode reception signal input from the ultrasonic probe 11, and the blood flow is generated from the generated I signal and Q signal. Separator 18 that separates speech signals Fwd and Bwd of the forward flow component and the backward flow component, and an MSE unit that estimates and fills the missing signals for the B mode from the separated speech signals Fwd and Bwd of the forward flow component and the backward flow component and makes them continuous. 19, a counter separator 21 for generating a continuous I signal and a Q signal from the continuous forward flow component and the back flow component audio signals Fwd and Bwd, and the continuous I signal and the Q signal Comprises an FFT unit 22 for generating a spectrum signal of the blood flow velocity by frequency analysis, the.

  For this reason, since the missing signal is estimated and filled from the audio signals Fwd and Bwd of the forward flow component and the backward flow component that are real numbers and independent from each other, the accuracy of the missing signal estimation for the B mode can be improved. Signal estimation can be performed easily and the processing speed can be increased.

  Further, the ultrasonic diagnostic imaging apparatus 1 includes a speaker 20 that outputs audio signals Fwd and Bwd of continuous forward flow components and reverse flow components, a display unit 16 that displays a spectrum signal of the generated blood flow velocity, Is provided. For this reason, the audio signals Fwd and Bwd of the forward flow component and the backward flow component can be output as audio based on the D-mode reception signal, and the spectrum signal of the blood flow velocity can be displayed as the FFT waveform.

  Further, the MSE unit 19 estimates and fills the separated audio signals Fwd and Bwd of the forward flow component and the audio signals Fwd and Bwd of the backward flow components by using different algorithms and burying them. For this reason, the missing signals for the B mode can be estimated and filled with different algorithms according to the audio signal of the forward flow component and the audio signal of the reverse flow component, and can be made continuous. For example, when the signal level of one of the audio signals Fwd and Bwd of the input forward flow component and the reverse flow component is low, the missing signal of the audio signal having a low signal level is replaced with 0 to reduce the calculation amount, With respect to a speech signal having a high signal level, it is possible to fill the missing signal by a missing signal estimation method with high accuracy such as prediction using the AR model, thereby improving the accuracy of the missing signal estimation.

  The ultrasonic diagnostic imaging apparatus 1 further includes a wall filter 17 that removes a wall component from the I signal and the Q signal generated by the transmission / reception unit 12 and outputs the result to the separator 18. The separator 18 includes a delay filter 181 that delays the I signal from which the wall component has been removed, a phase shift filter 182 that shifts the phase of the Q signal from which the wall component has been removed, reduces the low frequency component, and passes the high frequency component, An inversion unit 183 that inverts the sign of the phase-shifted Q signal, an addition unit 184 that adds the delayed I signal and the phase-shifted Q signal to generate the audio signal Fwd of the forward component, and the delay An adder 185 that adds the I signal and the inverted Q signal to generate an audio signal Bwd having a backflow component. The difference in the phase shift amount between the delay filter 181 and the phase shift filter 182 is 90 degrees. For this reason, the configuration of the separator 18 can be simplified by using the delay filter 181 having no filtering function.

  In addition, the counter separator 21 includes a phase shift filter 211 that shifts the phase of the continuous forward component audio signal Fwd generated by the MSE unit 19, and the continuous backflow component audio generated by the MSE unit 19. A delay filter 212 that delays the signal Bwd, an inversion unit 213 that inverts the polarity of the delayed backflow component audio signal Bwd, a phase-shifted forward component audio signal Fwd, and an inverted backflow component audio signal Bwd Are added together to generate a continuous I signal, and a phase-shifted forward flow component audio signal Fwd and a delayed backflow component audio signal Bwd are added together to produce a continuous Q signal. And an adding unit 215 to generate. The difference in phase shift amount between the phase shift filter 211 and the delay filter 212 is 90 degrees. For this reason, it is possible to easily generate a continuous I signal and a Q signal from the continuous forward flow component and back flow component audio signals Fwd and Bwd.

(Modification)
A modification of the above embodiment will be described with reference to FIGS. FIG. 3 is a block diagram showing a functional configuration of the ultrasonic diagnostic imaging apparatus 1 of the present modification. FIG. 4A is a block diagram showing a configuration of the separator 18A. FIG. 4B is a block diagram showing a configuration of the counter separator 21A.

  In this modification, the same members as those in the above embodiment are denoted by the same reference numerals, and the description thereof is omitted. As shown in FIG. 3, the ultrasonic diagnostic imaging apparatus 2 of the present modification example is similar to the ultrasonic diagnostic imaging apparatus 1 of the above-described embodiment, in which an ultrasonic probe 11, a transmission / reception unit 12, a switch 13, , A B-mode processing unit 14, a DSC 15, a display unit 16, an MSE unit 19, a speaker 20, a counter separator 21, and an FFT unit 22, and further includes a separator 18A.

  The separator 18A converts the digital I signal / Q signal input from the switch 13 into audio signals Fwd and Bwd of digital forward and backward components. As shown in FIG. 4A, the separator 18A includes phase shift filters 181A and 182A, an inversion unit 183, and addition units 184 and 185.

  The separator 18A removes the wall component of the digital I signal / Q signal input from the switch 13 and converts it into audio signals Fwd and Bwd of digital forward flow components and reverse flow components. The phase shift filter 181A is a filter that performs phase shift by shifting the phase of the digital I signal input from the switch 13 by −45 degrees, and outputs a low frequency component including a wall component and passes a high frequency component. It is. The phase shift filter 182A reduces the low frequency component including the wall component of the digital Q signal input from the switch 13 and passes the high frequency component, and performs a phase shift for shifting the phase by +45 degrees with respect to the Q signal. This is the output filter. That is, the phase shift filters 181A and 182A have a wall component removal function as a wall filter.

  The difference in phase shift amount between the phase shift filter 181A and the phase shift filter 182A is 90 degrees. Note that the phase shift amounts of the phase shift filters 181A and 182A are not limited to the above example. The phase shift amounts of the phase shift filters 181A and 182A may be other values such that the difference between them is 90 degrees.

  Further, in the ultrasonic diagnostic imaging apparatus 2, a counter separator 21 </ b> A shown in FIG. 4B may be provided instead of the counter separator 21. As shown in FIG. 4B, the counter separator 21A includes phase shift filters 211A and 212A, an inversion unit 213, and addition units 214 and 215.

  The phase shift filter 211A performs a phase shift that shifts the phase of the digital forward flow component audio signal Fwd input from the MSE unit 19 by −45 degrees and outputs it, and reduces the low frequency component of the audio signal Fwd and passes the high frequency component. It is a filter to do. The phase shift filter 212A reduces the low frequency component of the digital backflow component audio signal Bwd input from the MSE unit 19 and passes the high frequency component, and shifts the phase by +45 degrees with respect to the audio signal Bwd. This is a filter that performs output. That is, the difference in phase shift amount between the phase shift filter 211A and the phase shift filter 212A is 90 degrees. Note that the phase shift amounts of the phase shift filters 211A and 212A are not limited to the above example. The phase shift amounts of the phase shift filters 211A and 212A may be other values such that the difference between them is 90 degrees.

  Similarly to the ultrasound diagnostic imaging apparatus 1, for each unit included in the ultrasound diagnostic imaging apparatus 2, some or all of the functional blocks are executed by a hardware circuit such as an integrated circuit or software. May be.

  As described above, according to the present modification, the separator 18A includes the phase shift filter 181A that shifts the phase of the I signal generated by the transmission / reception unit 12, removes the low-frequency component including the wall component, and passes the high-frequency component, and the transmission / reception unit. 12, a phase shift filter 182A that shifts the phase of the Q signal generated by 12 and removes a low-frequency component including a wall component and passes the high-frequency component, an inversion unit 183 that inverts the sign of the phase-shifted Q signal, An adder 184 that generates the forward-flow component audio signal Fwd by adding the shifted I signal and Q signal, and adds the phase-shifted I signal and the inverted Q signal to generate a reverse-flow component audio signal. And a difference between the phase shift amounts of the phase shift filters 181A and 182A is 90 degrees. For this reason, since the wall filter 17 is not provided, the configuration of the ultrasonic diagnostic imaging apparatus 2 can be simplified.

  Note that the descriptions in the above-described embodiments and modifications are examples of a suitable ultrasonic diagnostic imaging apparatus according to the present invention, and the present invention is not limited to this.

  For example, in the ultrasonic diagnostic imaging apparatus 1 of the above embodiment, the counter separator 21 may be replaced with the counter separator 21A.

  Further, in the ultrasonic diagnostic imaging apparatus 1, the separator 18 may be replaced with a separator 18A having no wall component removal function. In this configuration, the phase shift filters 181A and 182A do not have a wall component removal function as a wall filter.

  Further, the detailed configuration and detailed operation of each part constituting the ultrasonic diagnostic imaging apparatuses 1 and 2 in the above-described embodiments and modifications can be appropriately changed without departing from the spirit of the present invention.

1, 2, 3 Ultrasonic diagnostic imaging apparatus 10 Control unit 11 Ultrasonic probe 12 Transmission / reception unit 13 Switch 14 B mode processing unit 15 DSC
16 Display unit 17 Wall filter 18, 18A, 18B Separator 181 Delay filter 182, 181A, 182A Phase shift filter 183 Inversion unit 184, 185 Adder unit 19, 19B MSE unit 20 Speaker 21, 21A Counter separator 211, 211A, 212A Phase shift Filter 212 Delay filter 213 Inversion unit 214, 215 Addition unit 22 FFT unit

Claims (9)

An ultrasound diagnostic imaging apparatus that generates images in a plurality of display modes,
Transmission in which a plurality of transmission ultrasonic waves in the D mode which is one of the plurality of display modes and a plurality of transmission ultrasonic waves in display modes other than the D mode in the plurality of display modes are alternately transmitted to the ultrasonic probe. 2 of the first complex signal and the second complex signal as D-mode complex Doppler signals from the received signal input from the ultrasonic probe that has received the reflected ultrasound and generated the received signal. A receiver for generating a complex signal of a kind;
A separation unit that separates the first direction component and the second direction component of the blood flow from the generated first complex signal and second complex signal;
A missing signal estimator that estimates and fills in a missing signal in a display mode other than the D mode from the separated audio signals of the first direction component and the second direction component,
An inverse separation unit that generates a continuous first complex signal and a continuous second complex signal from the continuous first direction component and second direction component audio signals;
An ultrasonic diagnostic imaging apparatus comprising: a frequency analysis unit configured to perform frequency analysis on the continuous first complex signal and the continuous second complex signal to generate a spectrum signal of blood flow velocity. An audio output unit for outputting audio signals of the continuous first direction component and second direction component;
The ultrasound diagnostic imaging apparatus according to claim 1, further comprising: a display unit configured to display the generated blood flow velocity spectrum signal.   The missing signal estimation unit estimates a missing signal for a display mode other than the D mode by using a different algorithm for the separated audio signal of the first direction component and the audio signal of the second direction component. The ultrasonic diagnostic imaging apparatus according to claim 1, wherein the ultrasonic diagnostic imaging apparatus is embedded and continuous. The separation unit is
A first filter for filtering the first complex signal generated by the receiver;
A second filter for filtering the second complex signal generated by the receiver;
A first inversion unit for inverting the sign of the filtered second complex signal;
A first adder for adding the filtered first complex signal and the filtered second complex signal to generate an audio signal of the first direction component;
A second addition unit that adds the filtered first complex signal and the inverted second complex signal to generate an audio signal of the second direction component;
The ultrasonic diagnostic imaging apparatus according to any one of claims 1 to 3, wherein a difference in phase shift amount between the first and second filters is 90 degrees. A wall component removal unit that removes a wall component from the first complex signal and the second complex signal generated by the reception unit and outputs the wall component to the separation unit;
The first filter is a first delay filter that delays the first complex signal from which the wall component has been removed,
The ultrasound diagnostic imaging apparatus according to claim 4, wherein the second filter is a first phase shift filter that shifts a phase of the second complex signal from which the wall component is removed. The first filter is a second phase shift filter that shifts the phase of the first complex signal generated by the receiving unit, reduces low frequency components including wall components, and passes high frequency components,
5. The third filter is a third phase shift filter that shifts the phase of the second complex signal generated by the receiving unit to reduce a low-frequency component including a wall component and pass a high-frequency component. The ultrasonic diagnostic imaging apparatus described in 1. The inverse separation unit includes: a fourth phase shift filter that shifts the phase of the continuous first direction component audio signal generated by the missing signal estimation unit;
A second delay filter that delays the continuous second direction component audio signal generated by the missing signal estimation unit;
A second inversion unit for inverting the sign of the delayed audio signal of the second direction component;
A third adder that adds the phase-shifted first direction component audio signal and the inverted second direction component audio signal to generate a continuous first complex signal;
A fourth adder for adding the phase-shifted first direction component audio signal and the delayed second direction component audio signal to generate a continuous second complex signal; With
The ultrasound diagnostic imaging apparatus according to any one of claims 1 to 6, wherein a difference in phase shift amount between the fourth phase shift filter and the second delay filter is 90 degrees. The first complex signal is an I signal of a D-mode complex Doppler signal,
The second complex signal is a Q signal of a D-mode complex Doppler signal,
The first direction component is a forward component of blood flow;
The ultrasound diagnostic imaging apparatus according to claim 1, wherein the second direction component is a backflow component of blood flow. The first complex signal is a Q signal of a D-mode complex Doppler signal,
The second complex signal is an I signal of a D-mode complex Doppler signal,
The first direction component is a backflow component of blood flow,
The ultrasonic diagnostic imaging apparatus according to claim 1, wherein the second direction component is a forward flow component of blood flow.

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