JP3088586B2 - Ultrasound diagnostic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic diagnostic apparatus, and more particularly, to an ultrasonic diagnostic apparatus capable of displaying a sonogram in which noise is inconspicuous and in which a rise time of a blood flow can be easily measured.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing a window processing unit in a conventional ultrasonic diagnostic apparatus. The window processing unit 50 includes a memory 52a that stores data of the I component of the Doppler signal extracted from the ultrasonic echo signal for a predetermined period, reads data from the memory 52a in accordance with the timing of frequency analysis, and performs a predetermined window function. And a memory 52b for storing data of a Q component of a Doppler signal extracted from an ultrasonic echo signal during a predetermined period, and a memory 52b for storing data of a Q component of the Doppler signal extracted from the ultrasonic echo signal. A window function unit 53b for reading data from the memory 52b, multiplying the data by a predetermined window function, and applying the multiplied data to a frequency analysis unit (not shown).

FIGS. 7, 8, and 9 are conceptual diagrams of window processing. FIG. 7 is an example of data before window processing. The horizontal axis is the time t, and the vertical axis is the signal voltage V.
FIG. 8 is an example of a window function (Hanning window). N on the horizontal axis is the sample number, w (n) on the vertical axis
Is a weight. FIG. 9 is an example of data after window processing.

FIG. 10 is an example of a sonogram display showing a time change of a frequency spectrum. When window processing is performed using a window function having a relatively wide time width as shown in FIG. 8, a sonogram display with a lot of noise such as black sesame is obtained as shown in FIG. This is because the original ultrasonic echo signal has a property similar to noise, and the power value at each frequency varies greatly. On the other hand, when window processing is performed using a window function having a relatively narrow time width as shown in FIG. 11, a sonogram display with less noticeable black sesame noise is obtained as shown in FIG. This is because the frequency spectrum is spread by a window function having a relatively narrow time width.

[0005]

When a window function having a relatively narrow time width is used, there is an advantage that a sonogram display in which black sesame noise is inconspicuous as described above can be obtained. Another advantage is that it can easily follow changes in blood flow.
However, as shown in FIG. 13, it is difficult to determine the rise time ts of the blood flow due to the spread of the frequency spectrum, and it is difficult to measure the time T from the rise time ts of the blood flow to the completion time tp. was there. In other words, there was a tendency that it became easier to output a measured value longer than actually. Accordingly, an object of the present invention is to provide an ultrasonic diagnostic apparatus capable of displaying a sonogram in which black sesame noise is inconspicuous and in which the rise time of blood flow can be easily measured.

[0006]

An ultrasonic diagnostic apparatus according to the present invention extracts a Doppler signal from an ultrasonic echo signal,
In an ultrasonic diagnostic apparatus that analyzes the frequency of the Doppler signal and displays the time change of the frequency spectrum in a sonogram,
High-pass filter means for extracting a high-frequency portion of the Doppler signal;
Narrow window processing means for performing window processing with a relatively narrow time width on the high-frequency part of the Doppler signal, low-pass filter means for extracting the low-frequency part of the Doppler signal, and low-frequency filter means for the low-frequency part of the Doppler signal. The configuration is characterized by comprising wide window processing means for performing window processing with a relatively wide time width, and addition means for adding the signals after both window processing before or after frequency analysis. .

[0007]

According to the ultrasonic diagnostic apparatus of the present invention, the high-pass filter and the low-pass filter separate the high-frequency portion and the low-frequency portion of the Doppler signal, and the high-frequency portion is narrowed by the narrow window processing means. Window processing with a relatively narrow time width is performed, and window processing with a relatively wide time width is performed on the low-frequency portion by wide window processing means. Then, the signals subjected to both window processings are added by the adding means and then subjected to frequency analysis, or the signals subjected to both window processings are subjected to frequency analysis and then added by the adding means. Since the speed of the blood flow is low near the start time of the blood flow, the low-frequency part of the Doppler signal indicates the vicinity of the start time of the blood flow. However, since window processing with a relatively wide time width is applied to this portion, the spread of the frequency spectrum is reduced. That is, it becomes easier to determine the start time of the rise of blood flow.
On the other hand, the speed of the blood flow is high near the time when the blood flow has risen. Therefore, the high-frequency portion of the Doppler signal indicates the vicinity of the time when the blood flow has risen. However, since window processing with a relatively narrow time width is performed on this portion, the frequency spectrum is spread. That is, the black sesame noise becomes inconspicuous. Thus, a sonogram display in which black sesame noise is not conspicuous and the rise time of blood flow can be easily measured can be performed. In addition, when the energy of the steady flow is constant, there is a relationship that the energy intensity increases as the blood flow slows down. Therefore, black sesame noise is originally unlikely to occur in a place where the blood flow is slow. Therefore, even if the spread of the frequency spectrum in the low frequency band is reduced, the black sesame noise does not increase and does not hinder practical use.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail with reference to the embodiments shown in the drawings. It should be noted that the present invention is not limited by this. FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to one embodiment of the present invention. This ultrasonic diagnostic apparatus 1
, The probe 2 and the beamformer 3 transmit an ultrasonic pulse in a predetermined direction at predetermined time intervals, receive an ultrasonic echo between the transmissions, and convert the ultrasonic echo signal into a B-mode processing unit. 4 and the mixers 5a and 5b.

The B-mode processing unit 4 extracts B-mode information from the ultrasonic echo signal and outputs it to a DSC (digital scan converter) 16. The DSC 16 generates a B-mode image from the B-mode information. Then, the display 17 displays the B-mode image generated by the DSC 16.

On the other hand, the mixers 5a and 5b extract the I and Q components of the Doppler signal from the ultrasonic echo signal.
These I component and Q component are used as baseband filters 6a,
6b, wall filters 7a and 7b, programmable gain amplifiers 8a and 8b, anti-aliasing filter 9
a, 9b, and input to the window processing unit 10 via the AD converters 19a, 19b. Window processing unit 10
Performs window processing on the I and Q components and outputs the result to the FFT unit 15. The FFT unit 15 calculates a frequency spectrum by frequency analysis and outputs this to the DSC 16. The DSC 16 generates a sonogram display image from the frequency spectrum. Then, the display 17 performs a sonogram display.

FIG. 2 is a block diagram showing the configuration of the window processing unit 10. The window processing unit 10 includes a high-pass filter 1 for extracting a high-frequency portion of the I component of the Doppler signal.
1ah, a memory 12ah for storing data for a predetermined period of the high frequency part, a narrow window function unit 13ah for reading data from the memory 12ah in accordance with the timing of frequency analysis and multiplying by a window function having a relatively narrow time width. , A low-pass filter 11al for extracting the low-frequency portion of the I component of the Doppler signal, a memory 12al for storing data of the low-frequency portion for a predetermined period, and a time width for reading data from the memory 12al in accordance with the timing of frequency analysis. A wide window function unit 13al that multiplies a relatively wide window function, and the narrow window function unit 1
An adder 14 a that adds the output of 3ah and the output of the wide window function unit 13 al and supplies the result to the FFT unit 15 is provided. Further, the window processing unit 10 calculates the Q of the Doppler signal.
A high-pass filter 11bh for extracting a high-frequency part of the component, and a memory 12bh for storing data of the high-frequency part for a predetermined period
And the memory 1 according to the timing of frequency analysis.
A narrow window function unit 13bh for reading data from 2bh and multiplying by a window function having a relatively narrow time width;
A low-pass filter 11bl for extracting the low-frequency portion of the Q component of the Doppler signal; a memory 12bl for storing data of the low-frequency portion for a predetermined period; A wide window function unit 13bl that multiplies a relatively wide window function, an output of the narrow window function unit 13bh and an output of the wide window function unit 13bl are added, and FFT is performed.
An adder 14b provided to the unit 15 is provided. FIG.
AD converters 19a and 19b of the window processing unit 10
High-pass filters 11ah and 11bh, low-pass filter 11
It may be provided after al and 11bl.

FIG. 3 shows high-pass filters 11ah and 11bh.
(HPF) and low-pass filters 11al and 11bl
FIG. 4 is a view showing an example of the characteristic (LPF) of FIG. These have transfer characteristics such that the sum becomes "1". Note that fx in the drawing is a substantial maximum value of the frequency component, and is empirically determined depending on the part.

FIG. 4 is an illustration of a window function (NWF) having a relatively narrow time width and a window function (WWF) having a relatively wide time width. These have the same central part in order to match the phase.

FIG. 5 shows an example of a sonogram display obtained by the ultrasonic diagnostic apparatus 1. Blood flow rise start time t
In the vicinity of s, the spread of the frequency spectrum is small, and it is easy to determine the start time ts. On the other hand, in the vicinity of the blood flow rising completion time tp, the frequency spectrum is broadened, and black sesame noise is not noticeable. That is, a sonogram display is obtained in which black sesame noise is not conspicuous and the rise time T of the blood flow is easy to measure.

As another embodiment, adders 14a, 14
b is provided after the FFT unit 15, and the signals after both high-band and low-band window processing are subjected to frequency analysis and then added. In this case, the same effect as above can be obtained.

[0016]

According to the ultrasonic diagnostic apparatus of the present invention, it is possible to display a sonogram in which black sesame noise is not conspicuous and the rise time of blood flow can be easily measured.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic diagnostic apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a window processing unit in the ultrasonic diagnostic apparatus of FIG.

FIG. 3 is an exemplary diagram of characteristics of a high-pass filter and a low-pass filter in the ultrasonic diagnostic apparatus of FIG.

4 is an exemplary diagram of a window function having a relatively narrow time width and a window function having a relatively wide time width in the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 5 is an exemplary view showing a sonogram display obtained by the ultrasonic diagnostic apparatus of FIG. 1;

FIG. 6 is an exemplary view of a window processing unit in a conventional ultrasonic diagnostic apparatus.

FIG. 7 is a view showing an example of data before window processing.

FIG. 8 is an exemplary diagram of a window function having a relatively wide time width.

FIG. 9 is a view showing an example of data after window processing.

FIG. 10 is an exemplary diagram of a sonogram display when a window function having a relatively wide time width is used.

FIG. 11 is an exemplary diagram of a window function having a relatively narrow time width.

FIG. 12 is an illustration of a sonogram display when a window function having a relatively narrow time width is used.

FIG. 13 is an explanatory diagram of a rising characteristic of a blood flow.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic diagnostic apparatus 10 Window processing part 11ah, 11bh High-pass filter 11al, 11bl Low-pass filter 13ah, 13bh Narrow window function part 13al, 13bl Wide window function part 14a, 14b Addition part

Claims (1)

(57) [Claims] 1. An ultrasonic diagnostic apparatus for extracting a Doppler signal from an ultrasonic echo signal, analyzing the frequency of the Doppler signal, and displaying a time change of a frequency spectrum in a sonogram, a high-pass filter for extracting a high-frequency portion of the Doppler signal. A narrow window processing means for performing a relatively narrow window processing on a high frequency part of the Doppler signal, a low frequency filter means for extracting a low frequency part of the Doppler signal, and a low frequency part of the Doppler signal. An ultrasonic diagnostic apparatus comprising: wide window processing means for performing window processing with a relatively wide time width; and addition means for adding the signals after both window processing before or after frequency analysis. .