JP2003250798A - Ultrasound diagnostic equipment - Google Patents

Abstract

[PROBLEMS] To provide an ultrasonic diagnostic apparatus in which only an outline portion of a human body tissue such as a blood vessel wall, a gallbladder wall, and a stomach wall is emphasized and displayed as an image. An ultrasonic beam is transmitted into a subject, and a tomographic image of a tissue in an ultrasonic transmission / reception area in the subject is formed based on a reception signal of a reflected ultrasonic wave reflected and returned in the subject. In an ultrasonic diagnostic apparatus for displaying brightness, an edge enhancement processing unit 35 that performs edge enhancement processing on a received signal, a contour detection unit 36 that detects a contour appearing on a tomographic image of a tissue in a subject based on the received signal, Contour detection unit 3 of received signal
6. The received signal in which the first signal portion corresponding to the contour detected in step 6 is more strongly affected by the edge enhancement processing by the edge enhancement processing section than the second signal portion of the received signal excluding the first signal portion And a signal generation unit 37 that generates

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ultrasonic diagnostic apparatus for displaying a diagnostic image of internal tissue of a subject.

[0002]

2. Description of the Related Art Conventionally, an ultrasonic diagnostic apparatus for displaying internal tissues of a human body transmits an ultrasonic beam toward the inside of the human body, receives reflected ultrasonic waves reflected inside the human body, and obtains a reception signal. , A tomographic image whose brightness is modulated based on the amplitude of the received signal is two-dimensionally displayed.

However, the internal tissue of the human body has the characteristics that the attenuation characteristics of ultrasonic waves differ depending on the constituent medium and that the attenuation increases as the frequency increases. Therefore, the ultrasonic waves to be transmitted are generally 1 to 15M.
Used in the frequency range of Hz, not too high frequencies. Further, the waveform of the signal that transmits the ultrasonic pulse and is reflected by the internal tissue is strongly attenuated as the frequency is higher, so that the waveform of the received signal becomes a mountain-shaped waveform with a wide distortion skirt. Therefore, there is a limit to narrowing the pulse width of the ultrasonic pulse to improve the resolution, and even if the received signal reflected by the internal tissue is amplified and displayed as an image, the outline of the internal tissue becomes unclear. Therefore, it is general to perform edge enhancement processing on the received signal and display the image.

1 and 2 are shown in Japanese Patent Publication No. 6-93895.
FIG. 1 is a diagram showing an ultrasonic diagnostic apparatus provided with a circuit for edge enhancement, which is disclosed in Japanese Patent Laid-Open Publication No. H11-242, FIG. 1 is a schematic configuration of the ultrasonic diagnostic apparatus, and FIG. 2 is an output waveform until edge enhancement. Shows the process of.

In FIG. 1, a probe 3, a pulser circuit 2 for generating a pulse, a rate pulse generation circuit 1 for triggering the pulser circuit 2, and a logarithm for logarithmically amplifying a reflected wave received by the probe 3. An amplifier 4, a detection circuit 5 for obtaining a video signal from the amplified reflected wave, a delay circuit 6 for delaying the video signal, an inverting amplifier 7 for inverting and amplifying the phase of the delayed video signal, and a delay An amplifier 8 that amplifies a video signal that is not applied, an adder 9 that adds a video signal that is delayed and a video signal that is not delayed, a limiting circuit 10 that discards a non-display signal, and an A / D converter 11. , A frame memory 12, a D / A converter 13, and a monitor 14 for displaying a video signal.

In FIG. 2, (a) shows the output waveform of the detection circuit 5. (B) shows the output waveform of the amplifier 8 without delay. The amplitude of the output waveform of the detection circuit 5 is (1+
α) doubled. (C) shows the output waveform of the inverting amplifier 7 which delays and inverts the phase. The amplitude is (-α) times the output waveform of the detection circuit 5, and the phase is delayed by τ. (D) shows the output waveform of the adder 9. (E) is
The output waveform of the limiting circuit 10 is shown. As is clear from (d) and (e), the rising portion and the falling portion of the waveform are emphasized as compared with the output waveform of the detection circuit 5 shown in (a).

Various other methods are known as the methods for edge enhancement. However, in the received signal received from the internal tissue of the human body, in addition to the signal forming the contour of the internal tissue, weak signals reflected by the soft tissue inside the human body include signals that strengthen or weaken due to interference. There is. This signal is called a speckle component, and is displayed as a spot-like bright spot in the tomographic image when the tomographic image of the internal tissue of the human body is displayed based on the received signal. .

Therefore, when the edge enhancement processing is applied to the received signal, not only the signal forming the contour of the internal tissue but also the speckle component is enhanced at the same time.

FIG. 3 is a diagram showing an example of an image in which the detected signal is edge-emphasized as it is and displayed in brightness, and the brightness-displayed portion is shown in a darkened state for convenience of illustration.

As can be seen from FIG. 3, the speckle component forms fine spots on the soft tissue of the human body and is displayed with the same brightness as the contour of the tissue, so that the contour of the tissue is difficult to see.

[0011]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention is an ultrasonic diagnostic apparatus in which only a contour portion of a human body tissue such as a blood vessel wall, a gallbladder wall, a stomach wall is emphasized and displayed, and a diagnostic image which is easy to see is displayed. The purpose is to provide.

[0012]

An ultrasonic diagnostic apparatus of the present invention that achieves the above object transmits an ultrasonic beam into a subject and reflects ultrasonic waves reflected and returned in the subject. In an ultrasonic diagnostic apparatus for displaying a tomographic image of a tissue in an ultrasonic transmission / reception area in a subject on the basis of a received signal, an edge enhancement processing unit that performs edge enhancement processing on the received signal, and the above based on the received signal. A contour detection unit that detects a contour that appears on the tomographic image of the tissue in the subject, and a first signal portion of the received signal that corresponds to the contour detected by the contour detection unit is the received signal. And a signal generation unit that generates a reception signal that is more strongly affected by the edge enhancement processing by the edge enhancement processing unit than the second signal portion excluding the first signal portion.

Here, it is preferable that the contour detecting section detects a region where the change of the low frequency component of the received signal is large as the contour, and the maximum point and the minimum of the low frequency component of the received signal. The area may be determined such that the area having a large absolute value of the potential difference between the maximum point and the minimum point that are adjacent to each other is large.

As described above, the contour portion of the tomographic image is detected from the region where the change of the low frequency component of the reception signal is large, and the detected contour portion generates a reception signal which is strongly affected by the edge enhancement processing. Since the tomographic image is displayed with brightness,
An image with clear contours and less noise can be obtained.

Further, the signal generation unit adopts the received signal subjected to the edge enhancement processing by the edge enhancement processing unit for the first signal portion, and the edge enhancement processing unit for the second signal portion. The received signal before being subjected to the edge enhancement processing by the above may be adopted, and the first received signal after being subjected to the edge enhancement processing by the edge enhancement processing unit and the edge enhancement processing by the edge enhancement processing may be performed. The second received signal before being received is weighted and added, and the first signal processing portion includes:
The first received signal may be given a greater weight and the second received signal may be given a smaller weight as compared with the second signal processing section.

In this way, the signal subjected to the emphasis processing and the signal not subjected to the emphasis processing are switched to display the luminance, or the signal subjected to the weighting addition of the signal subjected to the emphasis processing and the signal not subjected to the emphasis processing. Since it is possible to display the brightness using, it is possible to adjust the contrast of the contour portion according to the user's preference.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the ultrasonic diagnostic apparatus of the present invention will be described below.

FIG. 4 is a diagram showing an ultrasonic diagnostic apparatus according to the first embodiment of the present invention.

In FIG. 4, the ultrasonic diagnostic apparatus includes a probe 30 in which a plurality of transducers for transmitting an ultrasonic beam into a subject and receiving reflected ultrasonic waves reflected in the subject are arranged. A pulse generation circuit 31a for applying a pulse voltage to each transducer (not shown) of the probe 30 and a reception circuit 3 for obtaining a reception signal from a signal received by each transducer.
1b and a transmission / reception circuit 31 having a beam receiving signal.
A beam forming circuit 40 for forming, a bandpass filter 32 for removing an unnecessary signal from a reception signal for each ultrasonic beam, a detection circuit 33 for removing a high frequency component from an output signal of the bandpass filter 32, and a detection circuit 33. An amplifier 34 that logarithmically amplifies the tomographic image signal from which the high-frequency component has been removed, and an edge enhancement process that emphasizes the logarithmically amplified received signal for each ultrasonic beam so that the rising portion and the falling portion of the amplitude become large. And a contour detection unit 36 that detects, as a contour portion, a region in which a change in the low-frequency component is large, from the low-frequency component formed by the reception signal for each ultrasonic beam, and a contour detection unit 36 that detects the contour portion as a contour portion. The received region whose amplitude is emphasized by the edge emphasizing processing unit 35 is adopted as the contoured area, and is defined as a contour portion. For the regions other than the detected region, the signal generation unit 37 that generates the reception signal in which only the contour portion is emphasized by adopting the reception signal before being emphasized by the edge emphasis processing unit 35, and the signal generation unit 37. And a display section 38 for displaying the luminance of the tomographic image based on the received signal in which only the contour portion is emphasized.

The probe and the transmission / reception circuit are connected to each other, and the output of the transmission / reception circuit is supplied to the bandpass filter 32.
The output of the bandpass filter 32 is input to the detection circuit 33, the output of the detection circuit 33 is input to the amplifier 34 and the contour detection unit 36, and the output of the amplifier 34 is the edge enhancement processing unit 35 and the signal generation unit 37. The output of the contour detection unit 36 is input to the signal generation unit 37, and the output of the signal generation unit 37 is input to the display unit 38.

Here, the amplifier 34 may be provided between the bandpass filter 32 and the detection circuit 33, and the output of the detection circuit 33 may be input to the contour detection section 36, the edge enhancement processing section 35, and the signal generation section 37. .

The edge enhancement processing unit 35 of the present embodiment, as shown in the block diagram of FIG. 5, has multiplication circuits 35a and 35b.
, A delay circuit 35c and an adder circuit 35d are included in the known edge enhancement circuit, but the invention is not limited to this. The signal F input to the edge enhancement processing unit 35
One of (x) is multiplied by a coefficient (1 + α) in the multiplication circuit 35a to be a signal (1 + α) F (x), and the other is delayed by a delay circuit by a time τ and a coefficient (−α) is obtained in the multiplication circuit 35b. Signal (-α) F (x + τ) multiplied by
Becomes These two signals are further added by the adder circuit 35c, the rising part and the falling part of the signal F (x) are emphasized, and the signal (1+) having a large amplitude is added.
It is output as α) F (x) + (− α) F (x + τ).

Further, the contour detection section 36 strengthens the low-level and high-frequency speckle components (for example, reflected by the soft wall of human body tissue) contained in the received signal for each ultrasonic beam and mutually interfere with each other. , The signals that weakened each other) are removed, only the high-frequency and low-frequency components are extracted, and the region where the extracted low-frequency components have a large change is detected as the contour portion of the human body tissue. The maximum point and the minimum point of the component are obtained, for example, from the points where the polarities of the adjacent amplitude differences are inverted, and the contour part is the area where the absolute value of the signal level (voltage etc.) of the difference between the maximum point and the minimum point is large. Has the function of detecting as. Then, the received signal is binarized into a region detected as a contour part and a region not detected, and an identification signal (1) is output for a region detected as a contour part and an identification signal (0) is output for a region not detected.

Specifically, the contour detecting section 36 can be constructed by, for example, a low-pass filter and a comparison operation circuit. The low-pass filter detects the low-frequency component of the detection output of the received signal for each ultrasonic beam, and the comparison calculation circuit finds the difference between adjacent numerical values, and the point at which the polarity changes from positive to negative is A point that shifts from minus to plus is set as a minimum point, and an absolute value of a difference between an adjacent maximum point and a minimum point is obtained and compared with a predetermined threshold value to output a binarized identification signal.

In the present embodiment, the low-pass filter is an FIR filter having a cutoff frequency that can be arbitrarily set and a linear phase characteristic, but the present invention is not limited to this. In addition to the binarized identification symbol, the comparison operation circuit can also output a multi-valued identification symbol according to the signal level of the difference between the maximum point and the minimum point. An ultrasonic diagnostic apparatus using multi-valued identification symbols will be described in the second embodiment.

The signal generator 37 has a logic gate, and opens and closes the gate based on the identification symbol (0 or 1) output by the contour detector 36. When the identification symbol is 1, the gate (G1) 37a is closed to allow the received signal subjected to the edge enhancement processing to pass through, and the gate (G2)
37b blocks the received signal before being opened to receive edge enhancement. On the other hand, when the identification code is 0, the gate (G1) 3
7a is opened to block the received signal subjected to the edge enhancement, and gate (G2) 37b is closed to allow the received signal before the edge enhancement processing to pass. Therefore, the signal generator 37
From the above, the received signal subjected to the emphasis processing by the edge emphasis processing unit 35 is output only to the area detected by the contour detection unit 36 as the contour, and the other areas are subjected to the edge emphasis processing before being subjected to the edge emphasis processing. The received signal is output.

Since the received signal output from the signal generating section 37 is input to the display section 38, the display section 38 displays the tomographic image with a high contrast in which the contour portion is emphasized and which has a strong contrast.

FIG. 6 is a diagram exemplifying the waveform of a received signal in the periphery of the edge emphasis processing section or the contour detection section of the first embodiment.

In FIG. 6, the first stage shows the waveform of the received signal output from the amplifier before being enhanced by the edge enhancement processing section, and the second stage is the received signal enhanced by the edge enhancement processing section. In the third stage, the maximum points and the minimum points of the low-frequency components obtained by the contour detecting section are indicated by black circles, and in the fourth step, the contour portion detected by the contour detecting section is subjected to emphasis processing. The waveforms of the received signals that have not been subjected to the emphasis processing are shown. The fifth stage shows that the edge emphasis process is performed by subtracting the signal level shown in the second stage from the signal level shown in the fourth stage. The waveform (reference) of the signal which extracted only the applied area is shown. In each stage, the vertical axis represents the signal level,
The horizontal axis represents the time (depth) until the ultrasonic wave is transmitted from the probe and the reflected wave is received.

The waveform of the second stage is emphasized as compared with the waveform of the first stage, the change in the amplitude is large, and the waveform is sharp. In the third stage, the low-frequency component is extracted by passing the signal of the first stage through a low-pass filter, and the region in which the absolute value of the difference between the maximum point and the minimum point adjacent to each other is large is the change in the low-frequency component. Is a large area and is detected as a contour portion. Further, the region where the change is large coincides with the section on which the edge enhancement processing is performed, which is shown in the fifth stage.
Therefore, the waveform of the received signal output from the signal generation unit shown in the fourth stage is a waveform in which emphasis processing is applied only to the region detected by the contour detection unit in which the change in the low frequency component is large. I can confirm.

FIG. 7 is a diagram showing an image in which the contour portion is emphasized and luminance-displayed in the ultrasonic diagnostic apparatus of the present embodiment. For convenience of illustration, the luminance-displayed portion is shown in a darkened state. Is. For comparison, the same diagnostic site shown in FIG. 3 is displayed.

The tomographic image shown in FIG. 7 is different from that shown in FIG. 3 in that the contrast of the contour portion is strongly displayed and the speckle portion having the strong contrast in the soft tissue portion disappears. Therefore, the tomographic image is displayed in a state where the contour portion of the tissue can be easily distinguished.

Next, a second embodiment of the present invention will be described.

FIG. 8 is a diagram showing an ultrasonic diagnostic apparatus according to the second embodiment of the present invention. The ultrasonic diagnostic apparatus according to the second embodiment is different from the ultrasonic diagnostic apparatus according to the first embodiment shown in FIG. 4 in the identification signal and the signal generating section output from the contour detecting section, Since the other components are common, the same components are designated by the same reference numerals, and only different points will be described.

The contour detecting section 36 detects a low frequency component of the received signal by passing it through a low pass filter, obtains a local maximum point and a local minimum point by a comparison calculator, and detects the magnitude of change in the low frequency component. , And outputs a multi-valued identification signal according to the magnitude of the change.

The signal generator 39 determines a look-up table (hereinafter referred to as "LUT") 39d for determining the coefficients (k1, k2) based on the identification signal output from the contour detector 36, and its determination. Multiplier circuits 39a and 39b for respectively multiplying the received coefficient, which is input from the edge enhancement processing unit 35 and which has been subjected to the edge enhancement processing, and the received signal, which is input from the amplifier 34 and has not been subjected to the edge enhancement processing, And an adder circuit 39c for adding the received signals multiplied by the respective coefficients.

Here, the coefficients k1 and k2 set in the LUT 39d are used for weighted addition of the reception signal input from the edge enhancement processing section 35 and the reception signal input from the amplifier 34 in the addition circuit 39c. For example, a plurality of coefficients having different weights are prepared so that the coefficient becomes 1 when k1 and k2 are added.
The operator can adjust the contrast by selecting any one of a plurality of coefficients set in the LUT based on the contrast of the displayed diagnostic image.

In the present embodiment, different identification symbols are output according to the absolute value of the difference between the adjacent maximum point and minimum point of the low frequency component detected by the contour detecting section 36. The signal generator 39 conforms to the identification symbol,
The coefficients k1 and k2 are set with reference to the LUT 39d. When the coefficients k1 and k2 are set, the multiplication circuit 39a multiplies the reception signal input from the edge enhancement processing unit 35 by k1, and the multiplication circuit 39b multiplies the reception signal input from the logarithmic amplifier by k2. . Then, the adder circuit 39c adds the received signals multiplied by the coefficients k1 and k2, respectively,
The weighted addition received signal is output.

Here, the coefficient k1 is set to a value larger than the coefficient k2. Therefore, the signal generator 39
When a contour portion is detected by the contour detecting unit, the received signal input from the edge enhancement processing unit 35 is added to the amplifier 34.
Since the coefficient k1 larger than that of the received signal input from is multiplied and weighted and added, the received signal with the degree of emphasis changed according to the magnitudes of k1 and k2 is output.

The received signals weighted and added by the adder circuit 39c are input to the display section 38, and a tomographic image with adjusted contrast is displayed.

[0041]

As described above, according to the ultrasonic diagnostic apparatus of the present invention, the contour portion of the tomographic image inside the human body is detected based on the received signal, and the detected contour portion is emphasized. Since the tomographic image is displayed in brightness by using the received signal that has been subjected to, there is little noise and it is easy to see, and the contrast between the contour part of human body tissue and other parts is strong
It is possible to display a diagnostic image in which the contour portion can be easily identified.

[Brief description of drawings]

FIG. 1 is a diagram showing an ultrasonic diagnostic apparatus using an edge enhancement circuit disclosed in Japanese Patent Publication No. 6-93895.

FIG. 2 is a diagram showing a process of an output waveform until edge enhancement.

FIG. 3 is a diagram showing an example of an image in which a signal after detection is edge-enhanced as it is and brightness-displayed.

FIG. 4 is a diagram showing an ultrasonic diagnostic apparatus according to the first embodiment of the present invention.

FIG. 5 shows a block diagram of an edge enhancement processing unit.

FIG. 6 is a diagram exemplifying a waveform of a received signal around the edge enhancement processing unit or the contour detection unit according to the first embodiment.

FIG. 7 is a diagram showing an image in which a contour portion is emphasized and brightness-displayed in the ultrasonic diagnostic apparatus of this embodiment.

FIG. 8 is a diagram showing an ultrasonic diagnostic apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

30 probes 31 Transmitter / receiver circuit 32 bandpass filter 33 Detection circuit 34 Amplifier 35 Edge Enhancement Processing Unit 35a, 35b, 39a, 39b Multiplier circuit 35c delay circuit 35d, 39c adder circuit 36 contour detector 37, 39 Signal generator 37a Gate (G1) 37b Gate (G2) 38 Display 39d LUT 40 beam forming circuit

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Izumi Tsubone             3-39-4 Hongo, Bunkyo-ku, Tokyo Fukuda             Electronic Co., Ltd. F-term (reference) 4C301 CC01 EE04 EE11 HH52 JB07                       JB23 JB27 JB29 JB32 JB38                       JC08 JC13                 4C601 EE02 EE09 JB16 JB21 JB22                       JB28 JB31 JB34 JB35 JB36                       JB40 JB45 JB47 JC09 JC15                       JC20

Claims (5)

[Claims] 1. A tomographic image of a tissue in an ultrasonic wave transmission / reception region in a subject based on a received signal of a reflected ultrasonic wave which is transmitted by transmitting an ultrasonic beam into the subject and returned in the subject. In an ultrasonic diagnostic apparatus for displaying luminance, an edge enhancement processing unit that performs edge enhancement processing on the received signal, and contour detection that detects a contour appearing on the tomographic image of the tissue in the subject based on the received signal. And a first signal portion of the received signal, which corresponds to the contour detected by the contour detection unit, is more edge-shaped than a second signal portion of the received signal excluding the first signal portion. An ultrasonic diagnostic apparatus comprising: a signal generation unit that generates a reception signal that is strongly affected by the edge enhancement processing by the enhancement processing unit. 2. The ultrasonic diagnostic apparatus according to claim 1, wherein the contour detecting section detects, as the contour, an area in which a change in a low frequency component of the received signal is large. 3. The contour detecting section obtains a maximum point and a minimum point of a low frequency component of the received signal, and changes the area in which the absolute value of the potential difference between the maximum point and the minimum point adjacent to each other is large. The ultrasonic diagnostic apparatus according to claim 2, wherein the ultrasonic diagnostic apparatus is a large area. 4. The signal generation unit adopts a received signal subjected to edge enhancement processing by the edge enhancement processing unit for the first signal portion, and the edge enhancement processing unit for the second signal portion. The ultrasonic diagnostic apparatus according to claim 1, wherein a received signal before being subjected to the edge enhancement processing by the method is adopted. 5. The signal generation unit outputs a first reception signal after being subjected to edge enhancement processing by the edge enhancement processing unit and a second reception signal before being subjected to edge enhancement processing by the edge enhancement processing. Weighted addition, wherein the signal generation unit has a greater weight for the first received signal than the second signal processed portion for the first signal processing portion; The ultrasonic diagnostic apparatus according to claim 1, wherein a smaller weight is given to the signal.