JP2024034087A - Ultrasonic diagnostic device and blood flow image data generation method - Google Patents

Abstract

To improve an S/N (signal/noise) of blood flow image data in a time phase in which an influence of a heart beat is relatively small.SOLUTION: An ultrasonic diagnostic device includes a collection unit, a calculation unit, a determination unit, and a generation unit. The collection unit collects a data string of reflection wave data at the same position by collecting reflection wave data from the same position over a plurality of frames in a time direction by ultrasonic transmission and reception. The calculation unit calculates an evaluation value indicating consistency between a plurality of positions on a variation in the time direction in the data string of the reflection wave data. The determination unit determines at least one of an ultrasonic transmission condition, reception signal processing, and image processing on the basis of the evaluation value. The generation unit generates blood flow image data based on at least one of the ultrasonic transmission condition, the reception signal processing, and image processing determined by the determination unit.SELECTED DRAWING: Figure 1

Description

Embodiments of the present invention relate to an ultrasonic diagnostic apparatus and a blood flow image data generation method.

In recent years, a color flow mapping (CFM) method has been developed that can display minute blood flow at a low flow rate below the speed of the body's movement, which previously could not be displayed due to interference with body tissues. There is. For example, as such a method, there is a technology called SMI (Superb Micro-vascular Imaging) that makes it possible to generate blood flow image data depicting minute blood flows at a high frame rate and at a low flow rate. SMI is an imaging function that can efficiently suppress reflected wave (echo) signals from tissues within a limited speed range and visualize fine blood flow at low flow velocity.

Here, in SMI, there is a user's desire to further increase the sensitivity of blood flow signals. Therefore, it is conceivable to simply add and average the blood flow signals or increase the intensity of the transmitted ultrasonic waves. Here, if SMI is used to visualize a region in which tissues other than blood flow that move significantly due to heart beats (heartbeats) (e.g. left lobe of the liver, abdominal aorta, heart wall, etc.) are included in the region of interest, , periodic high-intensity artifacts occur. Therefore, when blood flow signals are simply averaged, artifacts derived from periodically occurring heartbeats are also added. Furthermore, when increasing the intensity of transmitted ultrasound, it is necessary to ensure that the amount of heat generated by the ultrasound probe does not exceed the amount of heat generated based on safety regulations. Therefore, the intensity of the transmitted ultrasound is naturally limited.

Japanese Patent Application Publication No. 2009-151140 Japanese Patent Application Publication No. 2017-192516 JP 2019-103919 Publication JP2020-36774A

The problem to be solved by the present invention is an ultrasonic diagnostic apparatus and blood flow image data generation capable of improving the S/N (Signal/Noise) of blood flow image data in a time phase in which the influence of heartbeat is relatively small. The purpose is to provide a method.

The ultrasonic diagnostic apparatus of the embodiment includes a collection section, a calculation section, a determination section, and a generation section. The collection unit collects a data string of reflected wave data at the same position by collecting reflected wave data from the same position over a plurality of frames in the time direction by ultrasonic transmission and reception. The calculation unit calculates an evaluation value indicating consistency between a plurality of positions with respect to fluctuations in the time direction of the data string of the reflected wave data. The determining unit determines at least one of ultrasound transmission conditions, received signal processing, and image processing based on the evaluation value. The generation unit generates blood flow image data based on at least one of the ultrasound transmission conditions, the received signal processing, and the image processing determined by the determination unit.

FIG. 1 is a block diagram showing a configuration example of an ultrasound diagnostic apparatus according to an embodiment. FIG. 2 is a flowchart illustrating an example of a blood flow image data generation process executed by the ultrasound diagnostic apparatus according to the embodiment. FIG. 3 shows the ultrasonic diagnostic apparatus according to the embodiment generated in step S105 when it is determined in step S104 whether to perform maximum brightness value retention calculation on the blood flow signal based on the evaluation value. FIG. 3 is a diagram showing an example of a blood flow image based on blood flow image data. FIG. 4 shows a blood flow image based on blood flow image data generated by a conventional ultrasound diagnostic device and a blood flow image based on blood flow image data generated by the ultrasound diagnostic device according to the present embodiment. It is a diagram. FIG. 5 shows a blood flow image based on blood flow image data generated by a conventional ultrasound diagnostic device and a blood flow image based on blood flow image data generated by the ultrasound diagnostic device according to the present embodiment. It is a diagram. FIG. 6 shows that a conventional ultrasound diagnostic apparatus executes a first ultrasound scan and a second ultrasound scan, and displays a B-mode image and a blood flow image superimposed on the B-mode image on a monitor in real time as a moving image. FIG. FIG. 7 shows that the ultrasonic diagnostic apparatus according to the present embodiment executes a first ultrasonic scan and a second ultrasonic scan, and converts a B-mode image and a blood flow image superimposed on the B-mode image into a moving image in real time. FIG. 3 is a diagram showing a case where the image is displayed on a monitor.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic diagnostic apparatus and a blood flow image data generation method according to an embodiment will be described below with reference to the drawings. Note that the embodiments are not limited to the following embodiments.

(Embodiment)
First, the configuration of an ultrasonic diagnostic apparatus according to an embodiment will be described. FIG. 1 is a block diagram showing a configuration example of an ultrasound diagnostic apparatus according to an embodiment. As illustrated in FIG. 1, the ultrasonic diagnostic apparatus according to the embodiment includes an ultrasonic probe 1, a monitor 2, an input device 3, and an apparatus main body 10.

The ultrasonic probe 1 is connected to the apparatus main body 10 in order to transmit and receive ultrasonic waves. The ultrasound probe 1 includes, for example, a plurality of piezoelectric vibrators. These plurality of piezoelectric vibrators generate ultrasonic waves based on a drive signal (drive pulse) supplied from a transmitting/receiving circuit 11 included in the main body 10 of the apparatus. For example, the plurality of piezoelectric vibrators transmit ultrasonic waves having an intensity corresponding to the magnitude of the voltage applied from the transmitting/receiving circuit 11 to the subject P. In addition, the plurality of piezoelectric vibrators included in the ultrasound probe 1 receive reflected waves (echoes) from the subject P, convert the received reflected waves into electrical signals (reflected wave signals), and transmit the reflected wave signals to the device. It is transmitted to the main body 10. Further, the ultrasonic probe 1 includes a matching layer provided on the piezoelectric vibrator and a backing material that prevents propagation of ultrasonic waves backward from the piezoelectric vibrator. Note that the ultrasonic probe 1 is detachably connected to the apparatus main body 10.

When ultrasonic waves are transmitted from the ultrasound probe 1 to the subject P, the transmitted ultrasound waves are successively reflected by discontinuous surfaces of acoustic impedance in the body tissue of the subject P, and are transmitted to the ultrasound probe 1 as reflected waves. is received by a plurality of piezoelectric vibrators possessed by the camera. The amplitude of the received reflected wave depends on the difference in acoustic impedance at the discontinuity surface from which the ultrasound wave is reflected. Note that when a transmitted ultrasound pulse is reflected from a moving bloodstream or a surface such as a heart wall, the reflected wave depends on the velocity component of the moving object in the ultrasound transmission direction due to the Doppler effect. , subject to frequency deviation.

Note that the embodiments are applicable even if the ultrasound probe 1 is a 1D array probe that scans the subject P in two dimensions, or a mechanical 4D probe or 2D array probe that scans the subject P in three dimensions. It is possible.

The input device 3 is implemented by a mouse, keyboard, button, panel switch, touch command screen, foot switch, trackball, joystick, or the like. The input device 3 receives various setting requests from an operator of the ultrasound diagnostic apparatus, and transfers the received various setting requests to the apparatus main body 10.

The monitor 2 displays a GUI (Graphical User Interface) for the operator of the ultrasonic diagnostic apparatus to input various setting requests using the input device 3, and displays the ultrasonic image data generated in the apparatus main body 10. Display ultrasound images, etc. The monitor 2 is realized by a liquid crystal monitor, a CRT (Cathode Ray Tube) monitor, or the like.

The device main body 10 is a device that generates ultrasound image data based on reflected wave signals transmitted from the ultrasound probe 1. The apparatus main body 10 shown in FIG. 1 can generate two-dimensional ultrasound image data based on a two-dimensional reflected wave signal, and can generate three-dimensional ultrasound image data based on a three-dimensional reflected wave signal. It is a very good device. However, the embodiment is applicable even when the device main body 10 is a device exclusively for two-dimensional data.

As illustrated in FIG. 1, the device main body 10 includes a transmitting/receiving circuit 11, a buffer 12, a B-mode processing circuit 13, a Doppler processing circuit 14, an image generation circuit 15, an image memory 16, and an internal storage circuit 17. and a processing circuit 18.

The transmitting/receiving circuit 11 controls ultrasonic scanning performed by the ultrasonic probe 1 based on instructions from a processing circuit 18, which will be described later. Note that ultrasonic scanning refers to, for example, ultrasonic transmission and reception. The transmission/reception circuit 11 includes a pulse generator, a transmission delay circuit, a pulser, etc., and supplies a drive signal to the ultrasound probe 1. The pulse generator repeatedly generates rate pulses for forming transmitted ultrasound waves at a predetermined repetition frequency (PRF: Pulse Repetition Frequency). In addition, in the transmission delay circuit, a pulse generator generates a delay time for each piezoelectric vibrator necessary for focusing the ultrasound generated from the ultrasound probe 1 into a beam shape and determining the transmission directivity. Give for each rate pulse. Further, the pulser applies a drive signal to the ultrasound probe 1 at a timing based on the rate pulse. That is, the transmission delay circuit arbitrarily adjusts the transmission direction of the ultrasonic waves transmitted from the piezoelectric vibrator surface by changing the delay time given to each rate pulse.

Note that the transmitting/receiving circuit 11 has a function that can instantaneously change the transmission frequency, transmission drive voltage, etc. in order to execute a predetermined scan sequence based on instructions from the processing circuit 18. In particular, changing the transmission drive voltage is realized by a linear amplifier-type oscillation circuit that can instantly switch its value, or by a mechanism that electrically switches multiple power supply units.

For example, under the control of the processing circuit 18, the transmitting/receiving circuit 11 causes the ultrasound probe 1 to perform an ultrasound scan that collects a data string between frames as a Doppler data string (for example, Japanese Patent No. 3724846, Japanese Patent Laid-Open No. 2014-42823 (Refer to the publication number, etc.) That is, the ultrasound probe 1 and the transmitting/receiving circuit 11 according to the present embodiment collect reflected wave data from the same position over a plurality of frames in the time direction, thereby collecting a data string of reflected wave data at the same position. The ultrasonic probe 1 and the transmitting/receiving circuit 11 are an example of a collecting section. For example, under the control of the processing circuit 18, the transmitting/receiving circuit 11 causes the ultrasound probe 1 to perform a first ultrasonic scan for acquiring information regarding the movement of a moving body within a first scanning range, and causes the ultrasound probe 1 to perform a first ultrasound scan to obtain information regarding the movement of a moving object within a second scanning range, and As a second ultrasonic scan for acquiring shape information, the ultrasonic probe 1 is caused to perform an ultrasonic scan of each of a plurality of divided ranges obtained by dividing the second scan range in a time-sharing manner during the first ultrasonic scan. Note that the first ultrasonic scan may be an ultrasonic scan in which the same scanning line is scanned once in one frame.

The transmitter/receiver circuit 11 also includes an amplifier circuit, an A/D (Analog/Digital) converter, a reception delay circuit, an adder, a quadrature detection circuit, etc., and responds to the reflected wave signal transmitted from the ultrasound probe 1. Various processes are performed to generate reflected wave data. Then, the transmitting/receiving circuit 11 stores the generated reflected wave data in the buffer 12. The amplifier circuit amplifies the reflected wave signal for each channel and performs gain correction processing. The A/D converter A/D converts the gain-corrected reflected wave signal. The reception delay circuit provides digital data with a reception delay time necessary to determine reception directivity. The adder performs addition processing of the reflected wave signals to which a reception delay time is given by the reception delay circuit. The addition process of the adder emphasizes the reflected component from the direction corresponding to the reception directivity of the reflected wave signal. Note that the process of adjusting the phase of each reflected wave signal of each element by the reception delay and adding the signals is also referred to as phasing and addition processing or beamforming processing.

The quadrature detection circuit converts the output signal of the adder into a baseband in-phase signal (I signal, I: In-phase) and a quadrature signal (Q signal, Q: Quadrature-phase). Then, the quadrature detection circuit stores the I signal and Q signal (hereinafter referred to as IQ signal) in the buffer 12 as reflected wave data.

When performing two-dimensional scanning of the subject P, the transmitting/receiving circuit 11 causes the ultrasound probe 1 to transmit a two-dimensional ultrasound beam. Then, the transmitting/receiving circuit 11 generates two-dimensional reflected wave data from the two-dimensional reflected wave signal transmitted from the ultrasound probe 1. Furthermore, when performing three-dimensional scanning of the subject P, the transmitting/receiving circuit 11 causes the ultrasound probe 1 to transmit a three-dimensional ultrasound beam. Then, the transmitting/receiving circuit 11 generates three-dimensional reflected wave data from the three-dimensional reflected wave signal transmitted from the ultrasound probe 1.

The buffer 12 is a memory that temporarily stores reflected wave data generated by the transmitting/receiving circuit 11. Specifically, the buffer 12 stores several frames of reflected wave data or several volumes of reflected wave data. For example, the buffer 12 is a FIFO (First-In/First-Out) memory, and stores reflected wave data for a predetermined frame under the control of the transmitting/receiving circuit 11. For example, when one frame of reflected wave data is newly generated by the transmitting/receiving circuit 11, the buffer 12 is controlled by the transmitting/receiving circuit 11 to store the reflected wave data of the oldest frame. is discarded and one frame of newly generated reflected wave data is stored. For example, the buffer 12 is realized by a semiconductor memory element such as a RAM (Random Access Memory) or a flash memory.

The B-mode processing circuit 13 and the Doppler processing circuit 14 are signal processing units that perform various signal processing on the reflected wave data generated from the reflected wave signal by the transmitting/receiving circuit 11. The B-mode processing circuit 13 and the Doppler processing circuit 14 are realized by, for example, a processor. The B-mode processing circuit 13 reads the reflected wave data from the buffer 12, performs logarithmic amplification, envelope detection processing, logarithmic compression, etc. on the read reflected wave data, and converts the signal strength of each of the plurality of sample points into a luminance. data (B mode data) expressed in brightness.

Note that the B-mode processing circuit 13 can change the frequency band to be visualized by changing the detection frequency through filter processing. By using the function of this B-mode processing circuit 13, the ultrasound diagnostic apparatus according to the embodiment can perform harmonic imaging such as contrast harmonic imaging (CHI). That is, the B-mode processing circuit 13 extracts harmonic component reflected wave data (harmonic data or frequency-divided wave data) using the contrast agent (microbubbles, bubbles) as a reflection source from the reflected wave data of the subject P into which the contrast agent has been injected. data) and reflected wave data (fundamental wave data) of the fundamental wave component whose reflection source is the tissue within the subject P. The B-mode processing circuit 13 can generate B-mode data for generating contrast image data from the harmonic component reflected wave data.

Furthermore, by using the filtering function of the B-mode processing circuit 13, the ultrasonic diagnostic apparatus according to the embodiment can perform tissue harmonic imaging (THI). That is, the B-mode processing circuit 13 can separate harmonic data or frequency-divided wave data, which is harmonic component reflected wave data, from the reflected wave data of the subject P. Then, the B-mode processing circuit 13 can generate B-mode data for generating tissue image data from which noise components have been removed from the harmonic component reflected wave data.

Further, when performing harmonic imaging of CHI or THI, the B-mode processing circuit 13 can extract harmonic components by a method different from the method using filter processing described above. In harmonic imaging, an imaging method called an amplitude modulation (AM) method, a phase modulation (PM) method, and an AMPM method, which is a combination of the AM method and the PM method, is performed. In the AM method, PM method, and AMPM method, ultrasonic waves with different amplitudes and phases are transmitted multiple times to the same scanning line. Thereby, the transmitting/receiving circuit 11 generates a plurality of pieces of reflected wave data for each scanning line, and outputs the generated reflected wave data. Then, the B-mode processing circuit 13 extracts harmonic components by performing addition/subtraction processing on the plurality of reflected wave data of each scanning line according to the modulation method. Then, the B-mode processing circuit 13 performs envelope detection processing and the like on the harmonic component reflected wave data to generate B-mode data.

For example, when the PM method is performed, the transmitter/receiver circuit 11 transmits ultrasound waves of the same amplitude with reversed phase polarity, such as (-1, 1), in each scan according to the scan sequence set by the processing circuit 18. Send it twice via line. Then, the transmitting/receiving circuit 11 generates reflected wave data due to the transmission of "-1" and reflected wave data due to the transmission of "1", and the B-mode processing circuit 13 adds these two reflected wave data. As a result, the fundamental wave component is removed and reflected wave data in which the second harmonic component mainly remains is generated. Then, the B-mode processing circuit 13 performs envelope detection processing and the like on this reflected wave data to generate THI B-mode data and CHI B-mode data.

Alternatively, for example, in THI, a method of imaging using second harmonic components and difference sound components included in reflected wave data has been put into practical use. In the imaging method using difference sound components, for example, a composite waveform is transmitted by combining a first fundamental wave with a center frequency of "f1" and a second fundamental wave with a center frequency of "f2" which is higher than "f1". Ultrasonic waves are transmitted from the ultrasonic probe 1. This composite waveform is a waveform that is a combination of the first fundamental wave waveform and the second fundamental wave waveform whose phases are adjusted to each other so that a difference tone component having the same polarity as the second harmonic component is generated. It is. The transmitting/receiving circuit 11 transmits the combined waveform of the transmitted ultrasonic wave twice, for example, while inverting the phase. In such a case, for example, the B-mode processing circuit 13 adds the two reflected wave data to remove the fundamental wave component and extract the harmonic component in which the difference tone component and the second harmonic component mainly remain. , envelope detection processing, etc.

The Doppler processing circuit 14 reads reflected wave data from the buffer 12, performs frequency analysis on the read reflected wave data, estimates motion information based on the Doppler effect of a moving object within the scanning range, and uses the estimated motion information. Generate the data shown (Doppler data). For example, the Doppler processing circuit 14 estimates the average velocity, average variance value, average power value, etc. at each of a plurality of sample points as motion information of the moving object, and generates Doppler data indicating the estimated motion information. Here, the moving body is, for example, blood flow, tissue such as the heart wall, or a contrast agent. The Doppler processing circuit 14 according to the present embodiment calculates the average blood flow velocity, the variance value of the blood flow velocity, the power value of the blood flow signal, etc. at each of a plurality of sample points as blood flow motion information (blood flow information). Doppler data indicating the estimated blood flow information is generated.

The B-mode processing circuit 13 and the Doppler processing circuit 14 are capable of processing both two-dimensional reflected wave data and three-dimensional reflected wave data. That is, the B-mode processing circuit 13 generates two-dimensional B-mode data from two-dimensional reflected wave data, and generates three-dimensional B-mode data from three-dimensional reflected wave data. Further, the Doppler processing circuit 14 generates two-dimensional Doppler data from two-dimensional reflected wave data, and generates three-dimensional Doppler data from three-dimensional reflected wave data.

Using the functions of the Doppler processing circuit 14 described above, the ultrasonic diagnostic apparatus according to the present embodiment can perform a color Doppler method, also called a color flow mapping (CFM) method. In the CFM method, ultrasonic waves are transmitted and received multiple times on multiple scanning lines. In the CFM method, by applying an MTI (Moving Target Indicator) filter to the data string at the same position, signals originating from stationary or slow-moving tissues (clutter signals) are suppressed. , extracting blood flow signals derived from blood flow. For example, when a data string of reflected wave data at the same position is input to an MTI filter, the MTI filter outputs a blood flow signal in which clutter is suppressed and blood flow components are dominant. In the CFM method, blood flow information such as blood flow velocity, blood flow dispersion, and blood flow power is estimated from this blood flow signal. An image generation circuit 15, which will be described later, generates ultrasound image data (Doppler image data) that represents the distribution of estimation results in two dimensions, for example. The monitor 2 then displays the Doppler image indicated by the Doppler image data. Note that ultrasound image data based on the distribution of estimation results of blood flow information is also referred to as blood flow image data.

As the MTI filter, a Butterworth-type IIR (Infinite Impulse Response) filter, a polynomial regression filter, or an adaptive principal component analysis filter that changes coefficients depending on the input signal is usually used. The Doppler processing circuit 14 according to this embodiment may use any of these.

The Doppler processing circuit 14 according to the embodiment using the eigenvector type MTI filter has an MTI filter generation function 14a, a calculation function 14b, a determination function 14c, a generation function 14d, and a blood flow information estimation function, as illustrated in FIG. 14e. Here, for example, each processing function executed by the MTI filter generation function 14a, calculation function 14b, determination function 14c, generation function 14d, and blood flow information estimation function 14e, which are the components of the Doppler processing circuit 14 shown in FIG. It is recorded in the internal storage circuit 17 in the form of a computer-executable program (medical image processing program). The Doppler processing circuit 14 reads each program from the internal storage circuit 17 and executes it to realize a function corresponding to each read program. In other words, the Doppler processing circuit 14 in a state where each program is read has each function shown in the Doppler processing circuit 14 of FIG. 1.

The MTI filter generation function 14a generates an MTI filter from a data string of continuous reflected wave data at the same position (same sample point) using a known technique. For example, the MTI filter generation function 14a calculates a correlation matrix of a scanning range from a data string of reflected wave data. Then, the MTI filter generation function 14a calculates the eigenvalue of the correlation matrix and the eigenvector corresponding to the eigenvalue. Then, the MTI filter generation function 14a generates an MTI filter by calculating a matrix in which the rank of the matrix in which each eigenvector is arranged is reduced based on the magnitude of each eigenvalue.

The generation function 14d uses an MTI filter to output a blood flow signal in which clutter components are suppressed and blood flow components are dominant, from a data string of continuous reflected wave data at the same position (same sample point). The generation function 14d generates a blood flow signal by inputting a data string of reflected wave data to the MTI filter and acquiring the blood flow signal output from the MTI filter. The generation function 14d is an example of a generation unit.

The blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the blood flow signal generated by the generation function 14d, and outputs Doppler data indicating the estimated blood flow information. . The blood flow information estimation function 14e is also an example of a generation unit.

Other processes executed by the generation function 14d and various processes executed by the calculation function 14b and the determination function 14c will be described later. Note that the calculation function 14b is an example of a calculation section. Further, the determination function 14c is an example of a determination unit.

The image generation circuit 15 generates ultrasound image data from the data generated by the B-mode processing circuit 13 and the Doppler processing circuit 14. The image generation circuit 15 generates two-dimensional B-mode image data representing the intensity of the reflected wave in terms of brightness from the two-dimensional B-mode data generated by the B-mode processing circuit 13. Further, the image generation circuit 15 generates two-dimensional Doppler image data in which blood flow information is visualized from the two-dimensional Doppler data generated by the Doppler processing circuit 14. The two-dimensional Doppler image data is velocity image data, dispersion image data, power image data, or image data that is a combination of these. The image generation circuit 15 generates, as blood flow image data, color Doppler image data in which blood flow information is displayed in color, or Doppler image data in which one piece of blood flow information is displayed in gray scale. .

Here, the image generation circuit 15 generally converts (scan convert) a scanning line signal sequence of ultrasonic scanning into a scanning line signal sequence of a video format typified by television etc. Generate image data. Specifically, the image generation circuit 15 generates ultrasound image data for display by performing coordinate transformation according to the scanning form of ultrasound by the ultrasound probe 1. In addition to scan conversion, the image generation circuit 15 also performs various image processing, such as image processing (smoothing processing) that regenerates an average luminance image using a plurality of image frames after scan conversion. , performs image processing (edge enhancement processing), etc. using a differential filter within the image. Further, the image generation circuit 15 synthesizes text information of various parameters, scales, body marks, etc. to the ultrasound image data.

That is, the B-mode data and Doppler data are ultrasound image data before scan conversion processing, and the data generated by the image generation circuit 15 is ultrasound image data for display after scan conversion processing. Note that B-mode data and Doppler data are also called raw data. The image generation circuit 15 generates two-dimensional ultrasound image data for display from the two-dimensional ultrasound image data before scan conversion processing.

Furthermore, the image generation circuit 15 generates three-dimensional B-mode image data by performing coordinate transformation on the three-dimensional B-mode data generated by the B-mode processing circuit 13. Further, the image generation circuit 15 generates three-dimensional Doppler image data by performing coordinate transformation on the three-dimensional Doppler data generated by the Doppler processing circuit 14. The image generation circuit 15 generates "three-dimensional B-mode image data and three-dimensional Doppler image data" as "three-dimensional ultrasound image data (volume data)."

Further, the image generation circuit 15 performs rendering processing on the volume data in order to generate various two-dimensional image data for displaying the volume data on the monitor 2. The rendering process performed by the image generation circuit 15 includes, for example, a process of performing Multi Planer Reconstruction (MPR) to generate MPR image data from volume data. Furthermore, the rendering process performed by the image generation circuit 15 includes, for example, a volume rendering (VR) process that generates two-dimensional image data that reflects three-dimensional information. Note that the image generation circuit 15 is an example of a generation section.

The image memory 16 is a memory that stores image data for display generated by the image generation circuit 15. Further, the image memory 16 can also store data generated by the B-mode processing circuit 13 and the Doppler processing circuit 14. The B-mode data and Doppler data stored in the image memory 16 can be called up by the operator after diagnosis, for example, and become ultrasound image data for display via the image generation circuit 15. Further, the image memory 16 can also store reflected wave data output by the transmitting/receiving circuit 11. For example, the image memory 16 is realized by a RAM, a semiconductor memory device such as a flash memory, a hard disk, or an optical disk.

The internal storage circuit 17 stores various data such as control programs for transmitting and receiving ultrasound waves, image processing, and display processing, diagnostic information (e.g., patient ID, doctor's findings, etc.), diagnostic protocols, and various body marks. do. Further, the internal storage circuit 17 is also used for storing image data stored in the image memory 16, etc., as necessary. Further, the data stored in the internal storage circuit 17 can be transferred to an external device via an interface (not shown). Further, the internal storage circuit 17 can also store data transferred from an external device via an interface (not shown). For example, the internal storage circuit 17 is realized by a semiconductor memory device such as a flash memory, a hard disk, or an optical disk.

The processing circuit 18 controls the entire processing of the ultrasonic diagnostic apparatus. Specifically, the processing circuit 18 controls the transmitting/receiving circuit 11 and the B mode based on various setting requests input by the operator via the input device 3 and various control programs and various data read from the internal storage circuit 17. It controls the processing of the processing circuit 13, Doppler processing circuit 14, and image generation circuit 15. For example, the processing circuit 18 controls ultrasound scanning by controlling the ultrasound probe 1 via the transmission/reception circuit 11. Normally, in the CFM method, a B-mode image based on B-mode image data, which is tissue image data, is displayed on the monitor 2 along with a blood flow image based on blood flow image data indicating blood flow information. In order to perform such display, the processing circuit 18 causes the ultrasound probe 1 to perform a first ultrasound scan to acquire blood flow information within the first scan range. The first ultrasound scan is, for example, an ultrasound scan for collecting blood flow image data in Doppler mode. Further, the first ultrasonic scan is, for example, an ultrasonic scan in which the same scanning line is scanned once in one frame. Note that the first scanning range is set as a region of interest (ROI) by the user operating the input device 3.

In addition to the first ultrasound scan, the processing circuit 18 causes the ultrasound probe 1 to perform a second ultrasound scan for acquiring information on the shape of the tissue within the second scan range. The second ultrasound scan is, for example, an ultrasound scan for collecting B-mode image data in B-mode.

The processing circuit 18 controls the ultrasound probe 1 via the transmission/reception circuit 11 to execute the first ultrasound scan and the second ultrasound scan. Note that the first scanning range and the second scanning range may be the same range, the first scanning range may be smaller than the second scanning range, or the second scanning range may be smaller than the first scanning range. It's okay.

Further, the processing circuit 18 controls the monitor 2 to display an ultrasound image indicated by the display ultrasound image data stored in the image memory 16 and the internal storage circuit 17. Note that the transmitting/receiving circuit 11 and the like built into the device main body 10 may be configured with hardware such as an integrated circuit, but may also be a program modularized in terms of software. The processing circuit 18 is realized by, for example, a processor. The processing circuit 18 is an example of a generation section and also an example of a control section.

The overall configuration of the ultrasonic diagnostic apparatus according to the embodiment has been described above. As described below, the ultrasonic diagnostic apparatus according to the embodiment is configured to be able to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

FIG. 2 is a flowchart illustrating an example of a blood flow image data generation process executed by the ultrasound diagnostic apparatus according to the embodiment. Further, the blood flow image data generation process shown in FIG. 2 is an example of a process when the ultrasound diagnostic apparatus executes the above-described first ultrasound scan. Further, the blood flow image data generation process shown in FIG. 2 corresponds to a blood flow image data generation method.

As shown in FIG. 2, the ultrasonic probe 1 and the transmitting/receiving circuit 11 transmit and receive reflected waves from the same position by collecting reflected wave data from the same position over a plurality of frames (packet length L) in the time direction. After collecting a data string of wave data (step S101), the ultrasound diagnostic apparatus executes each process in steps S102 to S106. That is, in this embodiment, the ultrasound diagnostic apparatus collects one frame of reflected wave data every time it collects a data string including reflected wave data at the same position for the packet length L used when generating the MTI filter. Each time a data string of wave data is collected, each process in steps S102 to S106 is executed.

Next, the MTI filter generation function 14a generates an MTI filter using a known technique using the data string of reflected wave data at the same position collected in step S101 (step S102).

Next, the calculation function 14b calculates an evaluation value indicating the consistency between a plurality of positions (sample points) regarding the temporal variation of the data string of the reflected wave data collected in step S102 (step S103). For example, the calculation function 14b calculates, for each frame, the spatial average value of the phase dispersion of a plurality of reflected wave data at the same position included in a data string, and calculates the spatial average value of the phase dispersion of a plurality of reflected wave data included in a data string between a plurality of positions with respect to temporal fluctuations of the data string of reflected wave data. Calculated as an evaluation value indicating consistency. Note that the calculation function 14b may normalize the evaluation value so that it falls within a predetermined range (for example, a range of 0 to 1).

As described above, the Doppler processing circuit 14 according to the present embodiment is a Butterworth-type IIR (Infinite Impulse Response) filter, a polynomial regression filter, or an adaptive type that changes coefficients depending on the input signal. Although any of the principal component analysis filters may be used, here, as an example, the calculation function 14b calculates the reflected wave based on the eigenvalues calculated when the MTI filter generation function 14a generates the MTI filter. An evaluation value indicating the consistency between a plurality of positions (sample points) may be calculated with respect to the temporal variation of the data string. Hereinafter, a case will be described in which the calculation function 14b calculates, based on the eigenvalues, an evaluation value that becomes higher as the variation in the time direction of reflected wave data is smaller. Eigenvalue expansion of a data string yields eigenvectors corresponding to multiple principal components and their eigenvalues. When the variation in the reflected wave data in the time direction is relatively large, that is, when various signal patterns are detected as main components, the eigenvalues of more eigenvectors become larger. Such a case is considered to be a time phase in which the influence of heartbeat is large. On the other hand, when the variation in the reflected wave data in the time direction is relatively small, a large eigenvalue converges to a small eigenvector. Therefore, by evaluating the degree of convergence of the eigenvalues, it is possible to estimate the influence of the heartbeat in that time phase. An example of the evaluation value is normalizing the sum of eigenvalues up to a certain degree by the sum of eigenvalues of all degrees.

Next, the determination function 14c determines at least one of ultrasound transmission conditions, received signal processing, and image processing based on the evaluation value calculated in step S103 (step S104).

The process in step S104 will be explained using a specific example. For example, in step S104, the determination function 14c first determines whether the evaluation value is equal to or greater than a threshold value. When the value of the evaluation value is equal to or greater than the threshold value, it is considered that the time phase in which the reflected wave data used when calculating the evaluation value was collected is a time phase in which the influence of heartbeat is relatively small. On the other hand, if the value of the evaluation value is less than the threshold value, it is considered that the time phase in which the reflected wave data used when calculating the evaluation value was collected is a time phase in which the influence of heartbeat is relatively large.

Then, in step S104, the determination function 14c executes at least one process among a plurality of processes (first process to sixth process) described below.

(First process)
For example, as the first process performed in step S104, the determination function 14c inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102 based on the evaluation value. It is determined whether or not to perform an averaging process that adds and averages the blood flow signals output from the MTI filter in the time direction.

For example, when the evaluation value is greater than or equal to the threshold, the determination function 14c determines to perform an averaging process that adds and averages the blood flow signals output from the MTI filter in the time direction. On the other hand, when the evaluation value is less than the threshold value, the determination function 14c determines not to perform averaging processing that adds and averages the blood flow signals output from the MTI filter in the time direction.

(Second processing)
Further, as a second process performed in step S104, the determination function 14c adds and averages the blood flow image data obtained from the data string of the reflected wave data collected in step S101 in the time direction based on the evaluation value. Determine whether or not to perform averaging processing.

For example, when the evaluation value is equal to or greater than the threshold value, the determination function 14c determines to perform an averaging process that adds and averages the blood flow image data in the time direction. On the other hand, when the evaluation value is less than the threshold value, the determination function 14c determines not to perform the averaging process of adding and averaging the blood flow image data in the time direction.

(Third process)
Furthermore, as a third process performed in step S104, the determination function 14c inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102 based on the evaluation value. It is determined whether or not to perform maximum brightness value holding calculation (peak hold) on the blood flow signal output from the MTI filter.

For example, when the evaluation value is equal to or greater than the threshold value, the determination function 14c determines to perform maximum brightness value retention calculation on the blood flow signal. On the other hand, when the evaluation value is less than the threshold value, the determination function 14c determines not to perform the maximum brightness value retention calculation on the blood flow signal.

(Fourth process)
Further, as a fourth process performed in step S104, the determination function 14c holds the maximum brightness value for the blood flow image data obtained from the data string of the reflected wave data collected in step S101, based on the evaluation value. Decide whether to perform the calculation.

For example, when the evaluation value is equal to or greater than the threshold, the determination function 14c determines to perform the maximum brightness value retention calculation on the blood flow image data. On the other hand, when the evaluation value is less than the threshold value, the determination function 14c determines not to perform the maximum brightness value retention calculation on the blood flow image data.

(Fifth process)
Furthermore, as a fifth process performed in step S104, the determination function 14c determines the magnitude of the voltage to be applied to the ultrasound probe 1 as an ultrasound transmission condition based on the evaluation value.

For example, the determination function 14c determines the first voltage as the voltage to be applied to the ultrasound probe 1 when the value of the evaluation value is equal to or greater than the threshold value. On the other hand, the determination function 14c determines the second voltage as the voltage to be applied to the ultrasound probe 1. The magnitude of the first voltage is greater than the magnitude of the second voltage. The magnitude of the first voltage is, for example, greater than the magnitude of the voltage applied to a conventional ultrasound probe when collecting conventional blood flow image data. Further, the magnitude of the first voltage and the magnitude of the second voltage are determined so that the amount of heat generated by the ultrasound probe 1 within a predetermined time does not exceed the amount of heat generated based on safety regulations.

(Sixth process)
Furthermore, as a sixth process performed in step S104, the determination function 14c determines the thinning rate in the time direction of the data string of the reflected wave data collected in step S101, based on the evaluation value.

For example, when the evaluation value is equal to or greater than the threshold, the determination function 14c determines the first thinning rate as the thinning rate of the reflected wave data included in the data string. On the other hand, when the evaluation value is less than the threshold, the determination function 14c determines a second thinning rate as the thinning rate of the reflected wave data included in the data string. The first thinning rate is greater than the second thinning rate.

Next, the ultrasound diagnostic apparatus generates blood flow image data based on at least one of the ultrasound transmission conditions, received signal processing, and image processing determined in step S104 (step S105).

The process in step S105 will be explained using a specific example. In step S105, the ultrasound diagnostic apparatus executes various processes described below in accordance with at least one of the ultrasound transmission conditions, received signal processing, and image processing determined in step S104.

(When performing averaging processing that adds and averages blood flow signals in the time direction)
For example, if it is determined in step S104 to perform averaging processing in which the blood flow signals output from the MTI filter are added and averaged in the time direction, in step S105, the ultrasound diagnostic apparatus determines to perform averaging processing. Aggregation and averaging processing is performed on a plurality of blood flow signals of different time phases. Thereby, the ultrasonic diagnostic apparatus obtains the averaged blood flow signal (the blood flow signal after the averaging). In this way, the ultrasonic diagnostic apparatus generates the averaged blood flow signal.

A specific example of performing averaging processing on a plurality of blood flow signals of different time phases will be described. For example, as described above, in the ultrasound diagnostic apparatus, each process in steps S102 to S106 is executed each time a data string of reflected wave data for one frame is collected. That is, each process in steps S102 to S106 is repeatedly executed. Here, for example, the blood flow image data generation process shown in FIG. 2 is repeated N times (N is a natural number), and the current blood flow image data generation process corresponds to the Nth frame, and ) A case will be described in which it is determined in step S104 to perform averaging processing in which the blood flow signals output from the MTI filter are added and averaged in the time direction for consecutive frames. In this case, blood flow signals for (K-1) frames from the (N-K+1)th frame to the (N-1)th frame have already been generated.

Then, in order to obtain a blood flow signal corresponding to the Nth frame, the ultrasonic diagnostic apparatus performs the following processing. For example, the generation function 14d applies the MTI filter generated in step S102 of the blood flow image data generation process corresponding to the Nth frame to the MTI filter generated in step S101 of the blood flow image data generation process corresponding to the Nth frame. A blood flow signal corresponding to the Nth frame is generated by inputting a data string of reflected wave data and acquiring a blood flow signal output from the MTI filter.

Then, the generation function 14d adds and averages M blood flow signals for M frames from the (NM+1)th frame to the Nth frame. Thereby, the generation function 14d obtains the blood flow signal after the addition and averaging (the blood flow signal after the addition and averaging). In this way, in step S105, the generation function 14d generates the averaged blood flow signal. Then, in step S105, the blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the averaged blood flow signals generated by the generation function 14d. Outputs Doppler data indicating blood flow information. Then, in step S105, the image generation circuit 15 generates blood flow image data from Doppler data indicating the estimated blood flow information.

The blood flow image data generated in this way is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Furthermore, since the blood flow signals are averaged, the S/N of the blood flow image data is improved. Therefore, according to the ultrasonic diagnostic apparatus according to the present embodiment, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

(When not performing averaging processing that adds and averages blood flow signals in the time direction)
A case where it is determined in step S104 not to perform the averaging process of adding and averaging the blood flow signals output from the MTI filter in the time direction will be described. In this case, the ultrasonic diagnostic apparatus executes various processes described below in step S105.

For example, in step S105, the generation function 14d inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102, and obtains the blood flow signal output from the MTI filter. to generate a blood flow signal. Then, in step S105, the blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the blood flow signal generated by the generation function 14d. Output Doppler data shown. Then, in step S105, the image generation circuit 15 generates blood flow image data from Doppler data indicating the estimated blood flow information.

(When it is decided to perform averaging processing that adds and averages blood flow image data in the time direction)
Next, if it is determined in step S104 to perform an averaging process of adding and averaging the blood flow image data in the time direction, in step S105, the ultrasound diagnostic apparatus performs an averaging process at different times determined to perform the averaging process. Addition and averaging processing is performed on a plurality of phase blood flow image data. Thereby, the ultrasonic diagnostic apparatus obtains averaged blood flow image data (blood flow image data after averaging). In this way, the ultrasound diagnostic apparatus generates blood flow image data after averaging.

A specific example of performing averaging processing on a plurality of blood flow image data of different time phases will be described. Here, for example, the blood flow image data generation process shown in FIG. 2 is repeated N times, the current blood flow image data generation process corresponds to the Nth frame, and the blood flow image data is A case will be described in which it is decided to perform an averaging process of adding and averaging in the time direction. In this case, blood flow image data for (K-1) frames from the (N-K+1)th frame to the (N-1)th frame have already been generated.

Then, in order to obtain blood flow image data corresponding to the Nth frame, the ultrasound diagnostic apparatus performs the following processing. For example, the generation function 14d applies the MTI filter generated in step S102 of the blood flow image data generation process corresponding to the Nth frame to the MTI filter generated in step S101 of the blood flow image data generation process corresponding to the Nth frame. A blood flow signal corresponding to the Nth frame is generated by inputting a data string of reflected wave data and acquiring a blood flow signal output from the MTI filter. Then, in step S105, the blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the blood flow signal generated by the generation function 14d. Output Doppler data shown. Then, in step S105, the image generation circuit 15 generates blood flow image data from the Doppler data indicating the estimated blood flow information. In this way, the image generation circuit 15 generates blood flow image data corresponding to the Nth frame.

Then, the image generation circuit 15 adds and averages M frames of blood flow image data from the (NM+1)th frame to the Nth frame. Thereby, the image generation circuit 15 obtains blood flow image data after being averaged (blood flow image data after being averaged). In this way, in step S105, the image generation circuit 15 generates blood flow image data after addition and averaging.

The blood flow image data generated in this way is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Furthermore, since the blood flow image data is averaged, the S/N of the blood flow image data is improved. Therefore, according to the ultrasonic diagnostic apparatus according to the present embodiment, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

(When not performing averaging processing that adds and averages blood flow image data in the time direction)
A case where it is determined in step S104 not to perform the averaging process of adding and averaging blood flow image data in the time direction will be described. In this case, in step S105, the ultrasonic diagnostic apparatus performs processing that is executed when it is determined in step S104 not to perform the averaging process of adding and averaging the blood flow signals output from the MTI filter in the time direction. Similar processing is executed to generate blood flow image data.

(When performing maximum brightness value retention calculation on blood flow signal)
For example, if it is determined in step S104 to perform maximum brightness value retention calculation on the blood flow signal output from the MTI filter, in step S105, the ultrasound diagnostic apparatus determines to perform maximum brightness value retention calculation. Maximum brightness value retention calculation is performed on a plurality of blood flow signals of different time phases. Thereby, the ultrasonic diagnostic apparatus obtains a blood flow signal subjected to maximum brightness value retention calculation (a blood flow signal after maximum brightness value retention calculation). In this way, the ultrasonic diagnostic apparatus generates the blood flow signal after the maximum brightness value retention calculation.

A specific example will be described in which maximum brightness value retention calculation is performed on a plurality of blood flow signals of different time phases. For example, the blood flow image data generation process shown in FIG. A case will be described in which it is decided to perform the maximum brightness value retention calculation on the current signal. In this case, blood flow signals for (K-1) frames from the (N-K+1)th frame to the (N-1)th frame have already been generated.

Then, in order to obtain the blood flow signal corresponding to the Nth frame, the ultrasonic diagnostic apparatus performs processing similar to the processing when it is decided to perform averaging processing of adding and averaging the blood flow signals in the time direction. is performed to generate a blood flow signal corresponding to the Nth frame.

Then, the generation function 14d performs maximum brightness value retention calculation on M blood flow signals for M frames from the (NM+1)th frame to the Nth frame. Thereby, the generation function 14d obtains the blood flow signal after the maximum brightness value retention calculation (the blood flow signal after the maximum brightness value retention calculation). In this manner, in step S105, the generation function 14d generates the blood flow signal after the maximum brightness value retention calculation. Then, in step S105, the blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the blood flow signal generated by the generation function 14d after the maximum brightness value retention calculation. , outputs Doppler data indicating estimated blood flow information. Then, in step S105, the image generation circuit 15 generates blood flow image data from Doppler data indicating the estimated blood flow information.

The blood flow image data generated in this way is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Furthermore, since the maximum brightness value retention calculation is performed on the blood flow information, the S/N of the blood flow image data is improved. Therefore, according to the ultrasonic diagnostic apparatus according to the present embodiment, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

FIG. 3 shows an image generated in step S105 when the ultrasonic diagnostic apparatus according to the embodiment determines whether to perform maximum brightness value retention calculation on the blood flow signal based on the evaluation value 20 in step S104. FIG. 2 is a diagram showing an example of blood flow images 21 and 22 based on blood flow image data. For example, assume that the threshold used in step S104 is "0.9". In this case, the blood flow image 21 is a blood flow image obtained by performing a maximum brightness value retention calculation on M blood flow signals for M frames from the (NM+1)th frame to the Nth frame. This is a blood flow image based on flow image data. The blood flow image 21 shown in FIG. 3 clearly depicts the blood flow in the heart wall and lumen, but has relatively few artifacts.

(When maximum brightness value retention calculation is not performed on blood flow signal)
A case will be described in which it is determined in step S104 not to perform maximum brightness value retention calculation on the blood flow signal output from the MTI filter. In this case, in step S105, the ultrasonic diagnostic apparatus performs processing that is executed when it is determined in step S104 not to perform the averaging process of adding and averaging the blood flow signals output from the MTI filter in the time direction. Similar processing is executed to generate blood flow image data. A blood flow image based on the blood flow image data generated in this manner is, for example, the blood flow image 22 shown in FIG. 3 above. There are relatively many artifacts in the blood flow image 22, and the blood flow depicted in the blood flow image 22 is unclear.

(When it is decided to perform maximum brightness value retention calculation on blood flow image data)
Next, when it is determined in step S104 to perform the maximum brightness value retention calculation on the blood flow image data, in step S105, the ultrasound diagnostic apparatus performs the maximum brightness value retention calculation at a different time when it is determined to perform the maximum brightness value retention calculation. Maximum brightness value retention calculation is performed on a plurality of phase blood flow image data. Thereby, the ultrasonic diagnostic apparatus obtains blood flow image data subjected to maximum brightness value retention calculation (blood flow image data after maximum brightness value retention calculation). In this way, the ultrasonic diagnostic apparatus generates blood flow image data after the maximum brightness value retention calculation.

A specific example of performing maximum brightness value retention calculation on a plurality of blood flow image data of different time phases will be described. Here, for example, the blood flow image data generation process shown in FIG. 2 is repeated N times, the current blood flow image data generation process corresponds to the Nth frame, and the blood flow image data is A case will be described in which it is decided to perform the maximum brightness value holding calculation for the image. In this case, blood flow image data for (K-1) frames from the (N-K+1)th frame to the (N-1)th frame have already been generated.

Then, in order to obtain blood flow image data corresponding to the N-th frame, the ultrasound diagnostic apparatus performs the same process as when it is decided to perform averaging processing that adds and averages the blood flow image data in the time direction. The following processing is performed to generate blood flow image data corresponding to the Nth frame.

Then, the image generation circuit 15 performs a maximum brightness value holding operation on M blood flow image data for M frames from the (NM+1)th frame to the Nth frame. Thereby, the image generation circuit 15 obtains blood flow image data after the maximum brightness value retention calculation (blood flow image data after the maximum brightness value retention calculation). In this way, in step S105, the image generation circuit 15 generates blood flow image data after the maximum brightness value retention calculation.

The blood flow image data generated in this way is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Further, since the maximum brightness value retention calculation is performed on the blood flow image data, the S/N of the blood flow image data is improved. Therefore, according to the ultrasonic diagnostic apparatus according to the present embodiment, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

(When maximum brightness value retention calculation is not performed on blood flow image data)
A case where it is determined in step S104 not to perform maximum brightness value retention calculation on blood flow image data will be described. In this case, in step S105, the ultrasonic diagnostic apparatus performs processing that is executed when it is determined in step S104 not to perform the averaging process of adding and averaging the blood flow signals output from the MTI filter in the time direction. Similar processing is executed to generate blood flow image data.

(When the first voltage is determined as the voltage applied to the ultrasound probe 1)
Next, a case where the first voltage is determined as the voltage applied to the ultrasound probe 1 in step S104 will be described. Here, for example, a case will be described in which the blood flow image data generation process shown in FIG. 2 is repeated N times and the current blood flow image data generation process corresponds to the Nth frame.

In order to obtain blood flow image data corresponding to the Nth frame, the ultrasound diagnostic apparatus performs various processes described below to generate blood flow image data corresponding to the Nth frame.

For example, in the blood flow image data generation process repeated N times, the generation function 14d identifies the time interval at which the first voltage is determined based on the timing at which the first voltage was determined at step S104. For example, the generation function 14d identifies a plurality of intervals between two temporally adjacent timings from a plurality of timings at which the first voltage is determined. Then, the generation function 14d calculates the average value of the plurality of specified intervals.

The processing circuit 18 then determines the first voltage based on the average value of the plurality of intervals calculated by the generation function 14d and the timing at which the first voltage was determined by the generation function 14d in step S104. Predict the timing of decisions. To explain with a specific example, the processing circuit 18 sets the timing when the average value of the plurality of intervals is added to the timing when the first voltage is determined in step S104, and the timing when the first voltage is determined next. Predict as.

Then, the processing circuit 18 controls the transmitting/receiving circuit 11 so as to cause the ultrasound probe 1 to transmit ultrasound at the predicted timing by applying the first voltage to the ultrasound probe 1 at the predicted timing. . Thereby, the transmitting/receiving circuit 11 controls the ultrasound probe 1 to transmit ultrasound at the predicted timing by applying the first voltage to the ultrasound probe 1 at the predicted timing. As a result, the ultrasound probe 1 transmits ultrasound at the predicted timing. Then, the image generation circuit 15 of the ultrasound diagnostic apparatus generates blood flow image data from the Doppler data indicating blood flow information obtained by transmitting the ultrasound waves. The blood flow image data generated in this manner is blood flow image data corresponding to the Nth frame.

The blood flow image data corresponding to the Nth frame generated in this manner is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Further, for example, a first voltage is applied to the ultrasound probe 1 that is larger than the voltage applied to a conventional ultrasound probe when collecting conventional blood flow image data. Therefore, the S/N of blood flow image data is improved. Furthermore, as described above, the magnitude of the first voltage and the magnitude of the second voltage are determined so that the amount of heat generated by the ultrasound probe 1 within a predetermined time does not exceed the amount of heat generated based on safety regulations. It is being Therefore, according to the ultrasound diagnostic apparatus according to the present embodiment, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small without exceeding the amount of heat generated based on safety regulations. can.

(When the second voltage is determined as the voltage applied to the ultrasound probe 1)
Next, a case where the second voltage is determined as the voltage applied to the ultrasound probe 1 in step S104 will be described. In this case, the ultrasound diagnostic apparatus generates blood flow image data corresponding to the Nth frame in the same manner as when the first voltage is determined. For example, the ultrasound diagnostic apparatus generates blood flow image data corresponding to the Nth frame by applying a second voltage to the ultrasound probe 1 instead of the first voltage.

As described above, in both the cases where the first voltage is determined and the second voltage is determined, the ultrasound probe 1 and the transmitting/receiving circuit 11 select the voltage determined by the determination function 14c (the second voltage). By transmitting ultrasonic waves according to the first voltage or the second voltage, a data string of reflected wave data at the same position is collected. The determined voltage is an example of ultrasound transmission conditions. Specifically, by applying a voltage of the magnitude determined by the determination function 14c to the ultrasound probe 1, the ultrasound probe 1 and the transmitting/receiving circuit 11 generate ultrasonic waves according to the magnitude of the applied voltage. By transmitting , a data string of reflected wave data at the same position is collected. Then, the Doppler processing circuit 14 and the image generation circuit 15 generate blood flow image data corresponding to the Nth frame based on the data string of the collected reflected wave data.

(When the first thinning rate is determined as the thinning rate of reflected wave data included in the data string)
Next, a case where the first thinning rate is determined as the thinning rate of the reflected wave data included in the data string in step S104 will be described. In step S105, the ultrasound diagnostic apparatus generates blood flow image data obtained from a data string of reflected wave data in which reflected wave data has been thinned out based on the determined first thinning rate.

For example, in step S105, the generation function 14d inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102, and obtains the blood flow signal output from the MTI filter. to generate a blood flow signal.

Then, in step S105, the blood flow information estimation function 14e estimates blood flow information by performing calculations such as autocorrelation calculation using the blood flow signal generated by the generation function 14d. Output Doppler data shown. Then, in step S105, the image generation circuit 15 generates blood flow image data from Doppler data indicating the estimated blood flow information.

The blood flow image data generated in this way is image data that is relatively less affected by heartbeat and effectively depicts blood flow components. Further, according to the ultrasound diagnostic apparatus according to the present embodiment, since the reflected wave data is thinned out by the first thinning rate which is a relatively high thinning rate, relatively slow blood flow is clearly visualized. Blood flow image data can be generated.

(When the second thinning rate is determined as the thinning rate of reflected wave data included in the data string)
Next, a case where the second thinning rate is determined as the thinning rate of the reflected wave data included in the data string in step S104 will be described. In step S105, the ultrasound diagnostic apparatus generates blood flow image data obtained from a data string of reflected wave data in which reflected wave data has been thinned out based on the determined second thinning rate. In this case, the ultrasound diagnostic apparatus generates blood flow image data using the same method as when the first thinning rate is determined. For example, an ultrasound diagnostic apparatus generates blood flow image data using a data string of reflected wave data in which reflected wave data is thinned out based on a second thinning rate instead of the first thinning rate.

Next, the processing circuit 18 causes the monitor 2 to display blood flow image data based on the blood flow image data generated in step S105 (step S106), and ends the blood flow image data generation process shown in FIG. 2.

4 and 5 show a blood flow image based on blood flow image data generated by a conventional ultrasound diagnostic device and a blood flow image based on blood flow image data generated by the ultrasound diagnostic device according to the present embodiment. FIG. For example, the blood flow image 23 shown in FIG. 4 is a blood flow image based on end-diastolic blood flow image data generated by a conventional ultrasound diagnostic apparatus. Further, the blood flow image 24 shown in FIG. 4 is a blood flow image based on blood flow image data in the end-diastole phase generated by the ultrasound diagnostic apparatus according to the present embodiment. Note that at the end of diastole, the evaluation value is equal to or greater than the threshold value. The blood flow image 24 is a blood flow image based on blood flow image data generated in step S105 when it is determined in step S104 to perform maximum brightness value retention calculation on the blood flow signal. Comparing the blood flow image 23 and the blood flow image 24, the blood flow image 24 has a higher blood flow signal intensity and a larger blood flow area than the blood flow image 23. Therefore, it is easier for the user to visually recognize the blood flow in the blood flow image 24 than in the blood flow image 23.

The blood flow image 25 shown in FIG. 5 is a blood flow image based on blood flow image data at the end of systole generated by a conventional ultrasound diagnostic apparatus. Further, the blood flow image 26 shown in FIG. 5 is a blood flow image based on blood flow image data at the end of systole generated by the ultrasound diagnostic apparatus according to the present embodiment. Note that in the end systole, the evaluation value is equal to or greater than the threshold, similar to the end diastole. The blood flow image 26 is a blood flow image based on the blood flow image data generated in step S105 when it is determined in step S104 to perform maximum brightness value retention calculation on the blood flow signal. Comparing the blood flow image 25 and the blood flow image 26, the blood flow image 26 has a higher blood flow signal intensity and a larger blood flow area than the blood flow image 25. Therefore, the user can more easily visually recognize the blood flow in the blood flow image 26 than in the blood flow image 25.

FIG. 6 shows that a conventional ultrasound diagnostic apparatus executes the above-described first ultrasound scan and second ultrasound scan, and generates a B-mode image 90 and a blood flow image 91 superimposed on the B-mode image 90 in real time. It is a figure which shows the case where it is displayed on a monitor as a moving image. FIG. 7 shows a B-mode image 30 and a blood flow superimposed on the B-mode image 30 in real time when the ultrasonic diagnostic apparatus according to the present embodiment executes the above-described first ultrasonic scan and second ultrasonic scan. 3 is a diagram showing a case where an image 31 is displayed on the monitor 2 as a moving image. FIG. In FIG. 6, blood flow information within a region of interest 92 set as the first scanning range is depicted in a blood flow image 91. Further, in FIG. 7 , blood flow information within the region of interest 32 set as the first scanning range is depicted in the blood flow image 31 .

Further, in FIG. 6, among the blood flow images 91 displayed as moving images on the monitor, a blood flow image 91a in a time phase in which the influence of heartbeat is relatively small is shown. Similarly, in FIG. 7, among the blood flow images 31 displayed as moving images on the monitor 2, a blood flow image 31a in a time phase in which the influence of heartbeat is relatively small is shown.

Comparing the blood flow image 91a and the blood flow image 31a, the signal level of artifacts around the blood flow is lower in the blood flow image 31a than in the blood flow image 91a. Note that in a time phase where the influence of heartbeat is relatively large, there is no difference between the blood flow image 91 and the blood flow image 31.

The ultrasonic diagnostic apparatus according to the embodiment has been described above. According to the ultrasonic diagnostic apparatus according to the embodiment, as described above, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

(Modified example of embodiment)
Note that in the ultrasound diagnostic apparatus according to the embodiment described above, there are relatively many artifacts in the blood flow image during a time phase in which the influence of heartbeat is relatively large. Therefore, by obscuring the blood flow information depicted in the blood flow image displayed on the monitor 2 during the time phase where the influence of heartbeat is relatively large, the blood flow information depicted in the blood flow image displayed on the monitor 2 can be The blood flow information depicted in the blood flow image displayed in 2 may be clearly recognized by the user. Therefore, an ultrasonic diagnostic apparatus that performs such processing will be described as an ultrasonic diagnostic apparatus according to a modification of the embodiment.

For example, in a modification of the embodiment, if it is determined in step S104 not to perform the averaging process of adding and averaging the blood flow signals in the time direction, the averaging process of adding and averaging the blood flow image data in the time direction. If it is decided not to perform the maximum brightness value retention calculation on the blood flow signal, if it is decided not to perform the maximum brightness value retention calculation on the blood flow image data, , the second voltage is determined as the voltage applied to the ultrasound probe 1, and the second thinning rate is determined as the thinning rate of the reflected wave data included in the data string. In one case, the determination function 14c executes any one of the three processes (first process, second process, and third process) described below. That is, in step S104, if the evaluation value is less than the threshold, the ultrasound diagnostic apparatus further executes any one of the three processes described below.

First, the first process will be explained. In step S104, if the evaluation value is less than the threshold, the determination function 14c executes, as a first process, a process of determining an amplitude attenuation amount for attenuating the amplitude of the blood flow signal. That is, the determination function 14c determines the amplitude attenuation amount based on the evaluation value. Here, in the first process, the amplitude attenuation amount is a fixed value.

Then, in step S105, the generation function 14d inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102, according to the amplitude attenuation amount determined in step S104. Attenuates the amplitude of the blood flow signal output from the filter. Then, in step S105, the blood flow information estimating function 14e estimates blood flow information by performing calculations such as an autocorrelation calculation using the blood flow signal whose amplitude has been attenuated, and performs a Doppler indicating the estimated blood flow information. Output data. Then, in step S105, the image generation circuit 15 generates blood flow image data from the Doppler data indicating the estimated blood flow information. That is, in step S105, the blood flow information estimation function 14e and the image generation circuit 15 generate blood flow image data based on the blood flow signal whose amplitude has been attenuated.

Next, the second process will be explained. In step S104, if the evaluation value is less than the threshold, the determination function 14c first inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102 as a second process. As a result, the phase shift amount (Doppler shift amount) within a unit time of the blood flow signal output from the MTI filter is calculated. Then, the determination function 14c uses the calculated phase shift amount and an amplitude attenuation function that outputs an amplitude attenuation amount for attenuating the amplitude of the blood flow signal with respect to the input phase shift amount. A process for determining an amplitude attenuation amount for attenuating the amplitude of a flow signal is executed. That is, the determination function 14c determines the amplitude attenuation amount from the phase shift amount within a unit time of the blood flow signal using the amplitude attenuation function. Here, an amplitude attenuation function is stored in the internal storage circuit 17 such that the larger the input phase shift amount is, the smaller the output amplitude attenuation amount is, and the determination function 14c determines the amplitude attenuation amount. The amplitude attenuation function stored in the internal storage circuit 17 at this time is acquired from the internal storage circuit 17. Then, in step S104, the determining function 14c inputs the phase shift amount into the obtained amplitude attenuation function, and uses the amplitude attenuation amount output from the amplitude attenuation function as the amplitude attenuation amount for attenuating the blood flow signal. decide.

In the second process, in step S105, the ultrasound diagnostic apparatus generates blood flow image data by performing the same process as the first process using the amplitude attenuation determined in step S104. do.

Next, the third process will be explained. In step S104, if the evaluation value is less than the threshold, the determination function 14c first inputs the data string of the reflected wave data collected in step S101 to the MTI filter generated in step S102 as a third process. By this, the amplitude of the blood flow signal output from the MTI filter is calculated. Then, the determination function 14c attenuates the amplitude of the blood flow signal using the calculated amplitude and an amplitude attenuation function that outputs an amplitude attenuation amount for attenuating the amplitude of the blood flow signal with respect to the input amplitude. The process of determining the amount of amplitude attenuation for the purpose of That is, the determination function 14c determines the amount of amplitude attenuation from the amplitude of the blood flow signal using the amplitude attenuation function. Here, an amplitude attenuation function is stored in the internal storage circuit 17 such that the larger the input amplitude is, the smaller the output amplitude attenuation amount is. The amplitude attenuation function stored in the storage circuit 17 is acquired from the internal storage circuit 17. Then, in step S104, the determining function 14c inputs the amplitude into the obtained amplitude attenuation function, and determines the amount of amplitude attenuation output from the amplitude attenuation function as the amount of amplitude attenuation for attenuating the blood flow signal.

Then, in the third process, in step S105, the ultrasonic diagnostic apparatus performs a process similar to the first process or the second process using the amplitude attenuation amount determined in step S104. Generate flow image data.

(Other variations)
In the above-described embodiments or modified examples, the ultrasound diagnostic apparatus is an electrocardiograph that acquires an electrocardiogram (ECG) as a biological signal of the subject P, or an electrocardiogram that acquires a heart sound as a biological signal of the subject P. The device may include a phonocardiograph that obtains the heart sounds to be obtained. The calculation function 14b may then correct the evaluation value based on the biological signal acquired by the electrocardiograph or the phonocardiograph. For example, end-systole and end-diastole are time phases in which the influence of heartbeat is relatively small. Therefore, if the biosignal is a highly accurate signal, the time phase indicated by the biosignal is end-systole or end-diastole, and the evaluation value is smaller than the threshold, the evaluation value is considered to be incorrect. Therefore, in such a case, the calculation function 14b corrects the evaluation value so that it becomes larger than the threshold value. This allows processing to be performed using correct evaluation values. An electrocardiograph and a phonocardiograph are examples of acquisition units.

The term "processor" used in the above explanation refers to, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), an Application Specific Integrated Circuit (ASIC), a programmable logic device (for example, Refers to circuits such as a simple programmable logic device (SPLD), a complex programmable logic device (CPLD), and a field programmable gate array (FPGA). A processor realizes its functions by reading and executing a program stored in a memory circuit. Note that instead of storing the program in the memory circuit, the program may be directly incorporated into the circuit of the processor. In this case, the processor realizes its functions by reading and executing a program built into the circuit. Note that each processor in this embodiment is not limited to being configured as a single circuit for each processor, but may also be configured as a single processor by combining multiple independent circuits to realize its functions. good. Furthermore, a plurality of components in FIG. 1 may be integrated into one processor to realize its functions.

In the above description of the embodiments, each component of each illustrated device is functionally conceptual, and does not necessarily need to be physically configured as illustrated. In other words, the specific form of distributing and integrating each device is not limited to what is shown in the diagram, and all or part of the devices can be functionally or physically distributed or integrated in arbitrary units depending on various loads, usage conditions, etc. Can be integrated and configured. Furthermore, all or any part of each processing function performed by each device can be realized by a CPU and a program that is analyzed and executed by the CPU, or can be realized as hardware using wired logic.

Further, the blood flow image data generation method described in the above embodiment can be realized by executing a program prepared in advance for executing blood flow image data generation processing on a computer such as a personal computer or a workstation. Can be done. A computer such as a personal computer or a workstation is an example of a medical image processing device. The program can be distributed via a network such as the Internet. Further, this program can also be executed by being recorded on a computer-readable recording medium such as a hard disk, flexible disk (FD), CD-ROM, MO, DVD, etc., and being read from the recording medium by the computer.

According to at least one embodiment or modification described above, it is possible to improve the S/N of blood flow image data in a time phase in which the influence of heartbeat is relatively small.

Although several embodiments of the invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included within the scope and gist of the invention as well as within the scope of the invention described in the claims and its equivalents.

1 Ultrasonic probe 10 Apparatus body 14 Doppler processing circuit 14b Calculation function 14c Determination function 14d Generation function 14e Blood flow information estimation function 15 Image generation circuit 18 Processing circuit

Claims (13)

a collection unit that collects a data string of reflected wave data at the same position by collecting reflected wave data from the same position over multiple frames in the time direction by ultrasonic transmission and reception;
a calculation unit that calculates an evaluation value indicating consistency between a plurality of positions with respect to fluctuations in the time direction of the data string of the reflected wave data;
a determining unit that determines at least one of ultrasound transmission conditions, received signal processing, and image processing based on the evaluation value;
a generation unit that generates blood flow image data based on the at least one of the ultrasound transmission conditions, the received signal processing, and the image processing determined by the determination unit;
An ultrasonic diagnostic device equipped with: The determining unit inputs the data string of the reflected wave data to a filter obtained from the data string of the reflected wave data based on the evaluation value, thereby suppressing clutter and improving blood flow output from the filter. Determine whether or not to perform averaging processing that adds and averages blood flow signals including derived blood flow components in the time direction;
The generation unit generates an averaged blood flow signal by performing the averaging process on a plurality of blood flow signals of different time phases determined by the determining unit to perform the averaging process, generating the blood flow image data based on the generated averaged blood flow signal;
The ultrasonic diagnostic apparatus according to claim 1. The determining unit determines, based on the evaluation value, whether to perform an averaging process of averaging blood flow image data obtained from the data string of the reflected wave data in a time direction;
The generation unit performs the addition on the plurality of blood flow image data in different time phases obtained from the data strings of the plurality of reflected wave data in different time phases determined by the determination unit to perform the averaging process. Generate blood flow image data after averaging by performing averaging processing,
The ultrasonic diagnostic apparatus according to claim 1. The determining unit inputs the data string of the reflected wave data to a filter obtained from the data string of the reflected wave data based on the evaluation value, thereby suppressing clutter and improving blood flow output from the filter. determining whether to perform maximum brightness value retention calculation on the blood flow signal including the derived blood flow component;
The generation unit performs the maximum brightness value retention calculation on a plurality of blood flow signals of different time phases that are determined by the determination unit to perform the maximum brightness value retention calculation, thereby obtaining the maximum brightness value retention calculation after the maximum brightness value retention calculation. generating a blood flow signal, and generating the blood flow image data based on the generated blood flow signal after the maximum brightness value holding calculation;
The ultrasonic diagnostic apparatus according to claim 1. The determining unit determines, based on the evaluation value, whether to perform a maximum brightness value retention calculation on the blood flow image data obtained from the data string of the reflected wave data,
The generation unit generates a plurality of blood flow image data in different time phases obtained from a data string of the plurality of reflected wave data in different time phases determined by the determination unit to perform the maximum brightness value retention calculation. generating blood flow image data after the maximum brightness value holding calculation by performing the maximum brightness value holding calculation;
The ultrasonic diagnostic apparatus according to claim 1. The collection unit collects a data string of reflected wave data at the same position by transmitting ultrasound according to the ultrasound transmission conditions determined by the determination unit,
The generation unit generates blood flow image data based on the data string of the reflected wave data collected by the collection unit transmitting ultrasound according to the ultrasound transmission conditions.
The ultrasonic diagnostic apparatus according to claim 1. The collection unit includes an ultrasonic probe that transmits ultrasonic waves according to the applied voltage,
The determining unit determines the magnitude of the voltage applied to the ultrasound probe as the ultrasound transmission condition,
By applying a voltage having a magnitude determined by the determining unit to the ultrasound probe, the collecting unit transmits ultrasound waves corresponding to the magnitude of the applied voltage to detect reflections at the same position. Collect data strings of wave data,
The ultrasonic diagnostic apparatus according to claim 6. The determining unit determines a thinning rate in the time direction of the data string of the reflected wave data based on the evaluation value,
The generation unit generates the blood flow image data obtained from the data string of the reflected wave data in which the reflected wave data has been thinned out based on the thinning rate determined by the determination unit.
The ultrasonic diagnostic apparatus according to claim 1. The determining unit determines an amplitude attenuation amount based on the evaluation value,
The generation unit is
According to the amplitude attenuation amount determined by the determining section, the data string of the reflected wave data is input to a filter obtained from the data string of the reflected wave data, thereby suppressing clutter and reducing blood flow output from the filter. Attenuates the amplitude of the blood flow signal containing the blood flow component derived from the flow,
generating the blood flow image data based on the blood flow signal with the amplitude attenuated;
The ultrasonic diagnostic apparatus according to claim 1. The determining unit inputs the data string of the reflected wave data to a filter obtained from the data string of the reflected wave data using an amplitude attenuation function that outputs an amplitude attenuation amount in response to an input of a phase shift amount. Determining an amplitude attenuation amount from the phase shift amount within a unit time of a blood flow signal that is output from the filter and includes a blood flow component originating from the blood flow with suppressed clutter,
The generation unit is
attenuating the amplitude of the blood flow signal according to the amplitude attenuation amount determined by the determining unit, and generating the blood flow image data based on the blood flow signal with the amplitude attenuated;
The ultrasonic diagnostic apparatus according to claim 1. The determining unit inputs the data string of the reflected wave data to a filter obtained from the data string of the reflected wave data, using an amplitude attenuation function that outputs an amplitude attenuation amount in response to an input amplitude. Determine the amplitude attenuation amount from the amplitude of the blood flow signal that is output from the device and includes a blood flow component derived from the blood flow with suppressed clutter,
The generation unit is
attenuating the amplitude of the blood flow signal according to the amplitude attenuation amount determined by the determining unit, and generating the blood flow image data based on the blood flow signal with the amplitude attenuated;
The ultrasonic diagnostic apparatus according to claim 1. further comprising an acquisition unit that acquires biological signals of the subject;
The collection unit collects a data string of the reflected wave data by transmitting and receiving the ultrasonic waves to and from the subject,
The calculation unit corrects the evaluation value based on the biological signal acquired by the acquisition unit.
The ultrasonic diagnostic apparatus according to claim 1. By collecting reflected wave data from the same position over multiple frames in the time direction by ultrasonic transmission and reception, a data string of reflected wave data at the same position is collected,
Calculating an evaluation value indicating consistency between a plurality of positions with respect to fluctuations in the time direction of the data string of the reflected wave data,
determining at least one of ultrasound transmission conditions, received signal processing, and image processing based on the evaluation value;
generating blood flow image data based on the at least one of the determined ultrasound transmission conditions, the received signal processing, and the image processing;
Blood flow image data generation method.

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