JP2719707B2 - Image display method of color Doppler MTI device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an image display method of a color Doppler MTI apparatus for extracting a motion target by MTI processing and displaying a Doppler shift thereof in color.

(Prior Art) An ultrasonic diagnostic apparatus transmits an ultrasonic signal into a subject,
This is a device that receives a signal reflected from a reflector and returns, and displays an image. When the reflector is moving, the frequency of the received echo is different from the transmission frequency, and when the reflector is moving towards the probe, the reception frequency is higher than the transmission frequency, and vice versa. It gets low when you go away. The frequency shift is proportional to the movement speed of the reflector. By utilizing the Doppler effect, for example, the direction and speed of blood flowing in the heart or blood vessels can be known. There is a color Doppler system in which only a moving target is extracted from a reflected echo signal by a fixed target erasing device (hereinafter referred to as MTI), and the frequency shift, that is, the Doppler shift, is displayed in color.

(Problems to be Solved by the Invention) By the way, in order to obtain a color image of this Doppler at a minimum required speed of 30 frames per second (30 FPS) as a circulatory system doctor, the scanning field angle is reduced to about 30 °. I have no choice. This is because it is necessary to perform scanning while transmitting and receiving each sound ray 4 to 8 times. However, this limit angle of view 30
The problem is that the ° scan is too narrow. However, this has the aspect that it cannot be stopped in principle.

The present invention has been made in view of the above points, and an object of the present invention is to realize a color Doppler MTI apparatus capable of increasing an effective frame rate without reducing an angle of view.

(Means for Solving the Problems) According to the present invention for solving the above problems, an image display method of a color Doppler MTI apparatus for extracting a motion target by MTI processing and displaying its Doppler shift in color is provided within a scanning range of a fixed distance. The present invention is characterized in that a sound ray having a motion target to be subjected to the MTI process is determined, and only the sound ray is subjected to the MTI process and the number of scans is increased.

(Operation) A B-mode scan is sometimes performed to find a sound ray having a lumen to be subjected to MTI processing, and MTI processing is performed only on the sound ray or a pixel having a lumen to reduce the amount of processing, thereby obtaining a wide angle of view. To increase the frame rate within the range.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram of a scanning method according to an embodiment of the present invention. In FIG, 1 is a region of interest specified as portion to be particularly observed in the subject, the region of interest 1 is within the distance range of Z _i. Reference numeral 2 denotes a motion target in the region of interest 1 to be subjected to the MTI processing, in particular, an MTI including a lumen such as a heart or a blood vessel having blood flow.
In the processing area, lumen a, the scanning field angle theta ₁ of the region containing the b, the second region of the scanning field angle theta ₂ of the region including the lumen c are shown in FIG. Since the lumens e and d are outside the region of interest 1, they are not targeted. B to find this MTI processing area 2
Scan the mode from time to time to find lumens a, b, c, etc.
The processing area 2 is determined, the MTI processing area 2 is scanned for transmission and reception, and signal processing is performed for the purpose of MTI processing. Lumen a, b, c
And the like, an echo portion below a certain signal level may be used as a lumen.

Further, as shown in FIG. 2, Z _p Z _q of the corresponding section of the lumen a or the lumen b in the MTI processing area 2 in FIG.
Only the MTI processing can be performed, and the other pixel parts can be skipped without processing. Regardless of the type of device used for this purpose, whether it is an analog type or a digital type, a hard-wired type MTI device requires a significant change in its configuration and data flow, but a digital signal processor chip ( If the data processing is described by a program as software using a DSP chip), MTI processing of pixels only in the lumen as shown in FIG. 2 can be performed without difficulty. That is, if the value of each pixel (expressed by the absolute value of a complex number) stored in the bipolar video temporary file of the echo of the MTI processing area 2 read out for processing is equal to or greater than a certain value, the MTI processing is performed. It is sufficient to move to the next pixel, and if it is less than a certain value, program the MTI processing.

FIG. 3 is a block diagram of a configuration of a typical embodiment for carrying out the above method. In the figure, reference numeral 11 denotes an ultrasonic probe which converts an electric signal of a transmission waveform into an ultrasonic signal, transmits the ultrasonic signal, and converts the received ultrasonic signal into an electric signal.
Reference numeral 12 denotes a transmission beamformer for receiving a signal from the carrier oscillator 13 to form a transmission beam, a transmission circuit including a transmission driving circuit for generating power required for transmission, and an ultrasonic probe 11. And a receiving unit including a receiving beamformer for converting the received signal into an original series signal and other accessory circuits. 14 detects the received signal from the transmission / reception unit 12 using the signal from the carrier oscillator 13 as a reference signal,
This is a quadrature detector that separates the signals, and the output signal is an AD converter
At 15 it is converted to a digital signal. 16 is an AD converter
Reference numeral 15 denotes a bipolar video file composed of n line buffers, frame buffers or field buffers corresponding to n sound rays for temporarily filing the digitized i and q signals. A signal processing unit 17 performs an absolute value calculation of a signal for each sound ray read from the bipolar video file 16, selects a signal of a certain level or less and applies an MTI filter, or performs a Doppler shift detail value for color determination. The MTI processing area 2 or the lumens a, b, c, etc. are determined. Reference numeral 18 denotes a display buffer and a scan conversion unit for temporarily storing the signals processed by the signal processing unit 17, sequentially reading out the signals, and converting the signals into television-type signals for CRT display, and the output signals thereof are displayed on a display device (not shown). Is output and displayed. Reference numeral 19 denotes a controller that receives a clock from the carrier oscillator 13 and controls the timing of each circuit.

In the above circuit, the transmitted ultrasonic wave is transmitted and received by the transmitting and receiving unit 12.
A sound ray is formed at, and the ultrasound probe 11 irradiates the inside of the subject. The reflected wave from the subject is an ultrasonic probe
The signal is received by 11, amplified by the transmission / reception unit 12, converted into a series signal, and input to the quadrature detector 14. The quadrature detector 14 performs quadrature detection on the signal received from the transmission / reception unit 12 using the signal from the carrier oscillator 13 as a reference signal, and outputs an i signal and a q signal. This output signal is converted into a digital signal by the AD converter 15 and is temporarily stored in the bipolar video file 16 sequentially for each sound ray, for each frame, or for each field. When data is combined for each sound ray, for each frame, or for each field, the data is read out and read by the signal processing unit 17.
Is input to The signal processing unit 17 is composed of a large number of DSPs, calculates the absolute value of the bipolar video signal, determines the lumen, selects the sound ray including the lumen, or the pixel only in the lumen, and sets the MTI. Processing is performed, and processing such as color determination based on the Doppler shift frequency is performed. The display buffer and the scan converter 18 temporarily store the above signals in a buffer memory, and when the required amount of signals is obtained, convert the signals into signals for CRT display by the scan converter and send them to the display device. The controller 19 controls the repetition frequency of the transmission pulse signal, and can control the frequency to be changed to a frequency at which the farthest end reflected wave of the region where the moving target to be subjected to the MTI process is present can be received.

As described above, by using the method of the present embodiment and the apparatus for implementing the method, only the signal to be subjected to the MTI processing is extracted and the image is displayed after the MTI processing. Signal processing can be performed quickly, and the same performance can be achieved with less resources.

The present invention is not limited to the above embodiment.
In the above embodiment, the middle luminance or high luminance portion in the B mode image is completely excluded from the MTI processing. Since it is sometimes desired to display the middle and high luminance portions in the B-mode image, the procedure of discriminating the signal level and extracting only the signal of a certain level or less described in the above-described embodiment is sometimes stopped to view the whole. You can also. In this case, it may be considered that the processing time of several tens to several hundreds of sound rays or several tens to several hundreds of frames of sound rays, that is, several hundreds μS to several S in time.

(Effect of the Invention) As described in detail above, according to the present invention, only the lumen where necessary blood or the like is present is extracted and MTI processing is performed, so that the processing time is shortened and the angle of view is narrowed. It is possible to increase the frame rate without any problem, and the effect in practical use is great.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a scanning method according to one embodiment of the present invention, FIG. 2 is an explanatory diagram of a method of performing signal processing of another embodiment of the present invention, and FIG. 3 is a method of an embodiment of the present invention. FIG. 2 is a block diagram of an apparatus for performing the above. DESCRIPTION OF SYMBOLS 1 ... Region of interest, 2 ... MTI processing area 11 ... Ultrasonic probe, 12 ... Transceiving unit 14 ... Quadrature detector 16 ... Bipolar video file 17 ... Signal processing unit 18 ... Display buffer and scan conversion unit

Claims (4)

(57) [Claims] 1. An image display method of a color Doppler MTI apparatus for extracting a motion target by MTI processing and displaying a Doppler shift thereof in color, the MT present within a scanning range of a fixed distance.
An image display method for a color Doppler MTI apparatus, wherein a sound ray having a movement target to be subjected to I processing is determined, and only the sound ray is subjected to MTI processing and the number of scans is increased to perform the processing. 2. The method according to claim 1, wherein only a region where the moving target exists on the sound ray having the moving target to be subjected to the MTI processing within the scanning range is MTI.
2. The image display method for a color Doppler MTI device according to claim 1, wherein signal processing is performed as a pixel range to be processed. 3. The image display method for a color Doppler MTI apparatus according to claim 1, wherein a test scan for determining an area in the scan range where a motion target to be subjected to MTI processing is to be performed is performed as needed. 4. A pulse repetition frequency of a transmission / reception sequence for MTI processing is set to a frequency necessary and sufficient to be able to receive also a farthest end reflected wave in a region where a moving target to be subjected to MTI processing exists. The image display method for a color Doppler MTI device according to claim 1, wherein the image display method is controllable.