JPH05317313A - Ultrasonic diagnosing apparatus - Google Patents

Abstract

PURPOSE:To display an elastic image showing the hardness of a living body tissue by conducting the operation between two time series tomographic images so as to measure the travel distance and displacement on the respective points on a tomographic image, measuring or estimating the pressure in the body cavity of a diagnosed region of an examinee, and operating the modulus of elasticity of the respective points on a tomographic image from the displacement and pressure to apply hue information. CONSTITUTION:A displacement measuring means 8 performs the operation between two time series tomographic images obtained by a tomographic scanning means to measure the travel or displacement of the respective points on a tomographic image. A pressure measuring means 9 measures or estimates the pressure in a body cavity of a diagnosed region of an examinee. The elastic modulus operating means 10 operates the modulus of elasticity of the respective points on a tomographic image from the displacement and pressure obtained in the respective measuring means 8, 9 to generate elastic image data. A hue information converting means 11 applies hue information to the elastic modulus image data input from the elastic modulus operating means 10. In a switching and adding means 12, the black-and- white tomographic image data from the tomographic scanning means and the color elastic image data from the hue information converting means 11 are added or switched to be displayed on an image display means 7.

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 for obtaining a tomographic image of a diagnostic region of a subject by using ultrasonic waves, and particularly to elasticity of each point on the image from two time-series tomographic images. The present invention relates to an ultrasonic diagnostic apparatus capable of calculating a rate and displaying it as an elasticity image showing the hardness or softness of living tissue.

[0002]

2. Description of the Related Art A conventional general ultrasonic diagnostic apparatus uses ultrasonic wave transmitting / receiving means for transmitting / receiving ultrasonic waves to / from an object, and an object including a moving tissue by using a reflected echo signal from the ultrasonic wave transmitting / receiving means. The tomographic image data in the sample is repeatedly obtained at a predetermined cycle, and the image display device displays the time-series tomographic image data obtained by the tomographic scanning device. Then, the structure of the living tissue inside the subject is displayed as, for example, a B-mode image.

[0003]

However, in the conventional ultrasonic diagnostic apparatus, the structure of the living tissue inside the subject could be displayed, but whether the living tissue was hard or soft was measured. Could not be displayed. Therefore, for example, in diagnosing a blood vessel, the position of the blood vessel and the blood flow state could be displayed, but it was not clear on the image display whether the blood vessel was normal or arteriosclerosis had occurred.

In connection with this, in the ultrasonic diagnostic apparatus, as a method of measuring the displacement of each part of the target organ, a difference calculation is performed between two tomographic images continuous in time series, and the displacement is calculated from this difference image. However, it is impossible to measure the hardness and softness of each part only by the displacement thus extracted.

On the other hand, recently, an external force is applied from the body surface of the subject, and a curve in which this external force is attenuated inside the living body is assumed, and the pressure and displacement at each point are obtained from this assumed attenuation curve to determine the elasticity. The method of measuring elastic modulus and obtaining an elastic image based on this elastic modulus data is described in "Ultrasonic Imaging" Vol. 13, No. 2, April 1991 (Ultrasonic Imaging, Vo
L.13 No.2, April 1991), J. Offer by "Elastic Image"
(J.Ophier "ELASTOG-RAPHY"). Such elasticity images can measure and display the hardness and softness of living tissues, but although this method is effective mainly for relatively large organs such as the abdomen, it can be used for carotid arteries and the like. For relatively small organs or heart walls that move rapidly, it is difficult to assume a curve in which the force decays inside the living body, and the elasticity modulus cannot be easily measured, making it difficult to obtain elasticity images. Seem.

Therefore, the present invention addresses such a problem, calculates the elastic modulus of each point on the image from two time-series tomographic images, and calculates the elasticity indicating the hardness or softness of the living tissue. An object is to provide an ultrasonic diagnostic apparatus that can be displayed as an image.

[0007]

In order to achieve the above object, an ultrasonic diagnostic apparatus according to the present invention comprises an ultrasonic wave transmitting / receiving means for transmitting and receiving an ultrasonic wave to a subject, and a reflection from the ultrasonic wave transmitting / receiving means. The apparatus has a tomographic scanning unit that repeatedly obtains tomographic image data in a subject including a moving tissue using an echo signal in a predetermined cycle, and an image display unit that displays time-series tomographic image data obtained by the tomographic scanning unit. In the ultrasonic diagnostic apparatus, displacement measuring means for performing a calculation between two time-series tomographic images obtained by the tomographic scanning means to measure the amount of movement or displacement of each point on the tomographic image, and the diagnosis of the subject. Pressure measuring means for measuring or estimating the pressure inside the body cavity of the region, and elastic modulus calculating means for calculating the elastic modulus of each point on the tomographic image from the displacement and pressure obtained by the measuring means to generate elastic image data. , This Hue information converting means for inputting elastic image data from the elastic modulus calculating means to give hue information, and black and white tomographic image data from the tomographic scanning means and color elastic image data from the hue information converting means are added. Alternatively, a switching addition means for switching is provided, and the image data from the switching addition means is displayed on the image display means.

[0008]

In the ultrasonic diagnostic apparatus configured as described above, the displacement measuring means performs an operation between two time-series tomographic images obtained by the tomographic scanning means to calculate the movement amount or displacement of each point on the tomographic image. Is measured, the pressure in the body cavity of the diagnostic region of the subject is measured or estimated by the pressure measuring means, and the elastic modulus at each point on the tomographic image is calculated by the elastic modulus calculating means from the displacement and pressure obtained by the measuring means. Elastic image data is generated by the hue information converting means, the elastic image data from the elastic modulus calculating means is input to give hue information, and further, the switching addition means is used to obtain black and white tomographic image data from the tomographic scanning means. And the color elastic image data from the hue information conversion means are added or switched. Thereby, the elasticity image showing the hardness or softness of the living tissue at the diagnosis site can be displayed together with the tomographic image showing the structure of the living tissue or alone.

[0009]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an embodiment of an ultrasonic diagnostic apparatus according to the present invention. This ultrasonic diagnostic apparatus obtains a tomographic image of a diagnostic region of a subject by using ultrasonic waves and displays an elastic image showing the hardness or softness of living tissue. Tentacle 1
It has a wave transmission circuit 2, a reception circuit 3, a phasing circuit 4, a signal processing unit 5, a black and white scan converter 6, and an image display 7, and further has a displacement measuring unit 8 and a pressure measuring unit 9. An elastic modulus calculator 10, a color scan converter 11, and a switching adder 12 are provided.

The probe 1 mechanically or electronically performs beam scanning to transmit and receive ultrasonic waves to the subject. Although not shown in the drawing, it is a source of ultrasonic waves. A transducer that receives the reflected echo is built in.
The wave transmission circuit 2 generates a wave transmission pulse for driving the probe 1 to generate an ultrasonic wave, and also has a convergence point of the ultrasonic wave transmitted by a built-in wave wave phasing circuit at a certain depth. Is set to. The receiving circuit 3 amplifies the signal of the reflected echo received by the probe 1 with a predetermined gain. The phasing circuit 4 inputs the received signal amplified by the receiving circuit 3 and controls the phase thereof to form an ultrasonic beam at one point or a plurality of converging points.
Further, the signal processing unit 5 inputs the received signal from the phasing circuit 4 to perform gain correction, log compression, detection, contour enhancement,
Signal processing such as filter processing is performed. And
The probe 1, the wave transmission circuit 2, the reception circuit 3, the phasing circuit 4, and the signal processing unit 5 constitute an ultrasonic wave transmitting / receiving means, and the probe 1 receives an ultrasonic beam. One tomographic image is obtained by scanning the specimen in the body in a certain direction.

The black-and-white scan converter 6 obtains tomographic image data in the subject including the moving tissue in the ultrasonic wave transmission cycle by using the reflected echo signal output from the signal processing section 5 of the ultrasonic wave transmitting / receiving means. A tomographic scanning means for displaying data in synchronism with the television and a means for controlling the system, and an A / D converter for converting the reflection echo signal from the signal processing section 5 into a digital signal. It is composed of a plurality of frame memories for storing the tomographic image data digitized by the A / D converter in time series, a controller for controlling these operations, and the like.

The image display 7 serves as a means for displaying the time-series tomographic image data obtained by the black-and-white scan converter 6, and is output from the black-and-white scan converter 6 via a switching adder 12 to be described later. A D / A converter for converting the image data input as an analog signal into an analog signal and a color television monitor for inputting an analog video signal from the D / A converter and displaying it as an image.

Here, in the present invention, a displacement measuring unit 8 is provided branching from the output side of the black-and-white scan converter 6 and a pressure measuring unit 9 is provided in parallel with the displacement measuring unit 8 and elastic members are provided at the subsequent stage thereof. A modulus calculator 10 is provided, a color scan converter 11 is provided on the output side of the elastic modulus calculator 10, and a switching adder 12 is provided on the output sides of the color scan converter 11 and the black-and-white scan converter 6. It is provided.

The displacement measuring unit 8 serves as a means for performing a calculation between two time-series tomographic images obtained by the black and white scan converter 6 to measure the amount of movement or displacement of each point on the tomographic image. Then, the movement vector (displacement direction and magnitude) of each point on the tomographic image is measured by two-dimensional correlation processing from the two tomographic images continuous in time series output from the black-and-white scan converter 6. Is becoming As a method of detecting this movement vector, there are a block matching method and a gradient method. The block matching method divides an image into blocks each including N × N pixels,
The block closest to the block of interest in the current frame is searched for in the previous frame, and predictive coding is performed by referring to this block.

The pressure measuring unit 9 serves as a means for measuring or estimating the pressure inside the body cavity of the diagnostic region of the subject 13, and FIG.
As shown in, for example, a catheter or the like as the pressure sensor 15 is inserted into the blood vessel 14 at the diagnosis site, and the detection signal measured by the pressure sensor 15 is taken in to directly measure the blood pressure in the blood vessel 14. There is. However, inserting a catheter into the body cavity of the diagnostic site causes pain to the subject, so the second method is to indirectly estimate the blood pressure in the body cavity by measuring from the body surface of the subject. There is a method of measuring the maximum and minimum blood pressures from the collected Korotkoff sounds, determining the rising and falling points of the blood pressure waveform from the pulse waveform, and estimating the blood pressure waveform from these four parameters. Furthermore, as a third method, a method of measuring blood pressure by utilizing an ultrasonic resonance phenomenon for blood bubbles can be considered. According to the second or third method,
It is possible to reduce the pain caused to the subject.

Then, the elastic modulus computing unit 10 computes the elastic modulus of each point on the tomographic image from the moving amount and the pressure obtained by the displacement measuring unit 8 and the pressure measuring unit 9, respectively, and generates elastic image data. It is a means for calculating the Young's modulus by dividing the change in pressure by the change in the amount of movement.

Further, the color scan converter 11 is
The elastic image data output from the elastic modulus calculation unit 10 serves as a hue information conversion unit that inputs hue information such as red, green, and blue. For example, image data having a large elastic modulus is converted into a red code. However, image data having a small elastic modulus is converted into a blue code.

Further, the switching adder 12 receives the black-and-white tomographic image data from the black-and-white scan converter 6 and the color elastic image data from the color scan converter 11, and adds or switches the two image data. However, the switching is made so that only the tomographic image data in black and white or the elastic image data in color is output, or both image data are added and combined and output. The image data output from the switching adder 12 is sent to the image display 7.

Next, the operation of the ultrasonic diagnostic apparatus configured as described above will be described. First, the transmitting circuit 2 applies a high-voltage electric pulse to the probe 1 in contact with the body surface of the subject 13 to emit an ultrasonic wave, and the probe 1 receives a reflected echo signal from the diagnostic site. .. Next, the received signal is input to the receiving circuit 3 and pre-amplified, and then input to the phasing circuit 4. The received signal whose phase is adjusted by the phasing circuit 4 is subjected to signal processing such as compression and detection in the next signal processing unit 5, and then the black-and-white scan converter 6
To enter. In the black-and-white scan converter 6, the received signal is A / D converted and stored in a plurality of internal frame memories as a plurality of tomographic image data that are continuous in time series.

Next, of the tomographic image data stored in the black-and-white scan converter 6, two pieces of image data which are continuous in time series are sequentially read out and input to the displacement measuring section 8 to be inputted into the two-dimensional displacement distribution. Ask for. The calculation of the two-dimensional displacement distribution is performed by, for example, the block matching method as the above-described movement vector detection method, which will be described in detail below with reference to FIG.

In FIG. 2, the current frame is the m-th frame and the previous frame is the (m-1) th frame. Then, the image on each frame is divided into a plurality of blocks composed of N × N pixels. Here, the moving object on the image is the (m
-1) It is assumed that the position has moved from the position A ₁ of the frame to the position A ₂ of the m-th frame. In such a state, the value at the pixel position (Nk, Nl) at the upper left end in each block of N × N pixels is set as Xm (Nk, Nl) with the m-th frame as the encoding target frame. Then, the value at the pixel position (Nk + i, Nl + j) at the upper left end in the block whose position is shifted by (i, j) on the (m-1) th frame of the previous frame is set to Xm-1 (Nk + i, Nl + j). .. Therefore, the absolute value sum Sij of the difference between the block in the (m-1) th frame and the block in the mth frame is calculated by the following formula. Then, various Sij are calculated by variously changing (i, j) indicating the movement of the position, the minimum value thereof is obtained, and (i, j) at this time is set as the movement vector. This movement vector,
That is, if the displacement is ΔL, Becomes However, p is a pixel pitch.

The change over time of the displacement ΔL thus obtained is shown, for example, in FIG. 3 (a).
The sampling interval S is the same as the imaging time T shown in FIG. 3C, and is, for example, about 1 to 100 ms. The waveform of this change in displacement ΔL with time repeats substantially the same waveform corresponding to one heartbeat. As a result, the two-dimensional displacement distribution is obtained as ΔL / L using the equation (2).

On the other hand, in the pressure measuring unit 9, the blood vessel 14
The blood pressure is measured by the pressure sensor 15 inserted inside, and the measurement signal is held in the pressure measuring unit 9. The time change of the pressure ΔP measured in this way is shown in, for example, FIG. Here again, the sampling interval S is the same as the imaging time T shown in FIG.

Next, the displacement measuring unit 8 and the pressure measuring unit 9
The respective measurement signals output from the elastic modulus calculator 1
0 is input, and the elastic modulus (Young's modulus) Ym is calculated by the following equation. The change over time of the elastic modulus Ym thus obtained is shown in, for example, FIG. in this case,
At each sampling point for each imaging time T, the calculation is performed using the above equation (3). Although FIG. 3C shows the time change of one pixel on the image, this calculation is performed two-dimensionally. That is, since the displacement measuring unit 8 can perform a two-dimensional displacement measurement, it is possible to obtain a two-dimensional distribution of the elastic modulus Ym by the above equation (3). As a result, the elastic modulus at each point for each image that is continuous in time series is obtained, and two-dimensional elastic image data is continuously obtained.

FIG. 4 is an explanatory view schematically showing the blood vessel 14 at the diagnosis site of the subject 13. It is assumed that the blood vessel 14 'shown by the broken line is in the contracted state and the blood vessel 14 shown by the solid line is in the expanded state. Corresponding to the blood pressure change ΔP inside the blood vessel, the blood vessel wall is ΔL
It shows how it changes. From this fact, it can be said that a large displacement ΔL is a soft blood vessel and a small displacement ΔL is a hard blood vessel with respect to the same pressure change ΔP. Therefore, as can be seen from the above equation (3),
In the case of a soft blood vessel, the value of the calculated elastic modulus Ym becomes small, and in the case of a hard blood vessel, the value of the elastic modulus Ym becomes large. That is, conversely, when the elastic modulus Ym is obtained by the equation (3),
The hardness or softness of the living tissue can be measured according to the magnitude of the value.

The elasticity image data obtained as described above is then input to the color scan converter 11,
Converted to hue information. Here, image data of a hard tissue having a large elastic modulus Ym is converted into a red code, for example, and image data of a soft tissue having a small elastic modulus Ym is converted into a blue code. After that, the switching adder 1
The image is added and combined with the black-and-white tomographic image via 2 or is separately sent to the image display device 7 and displayed as an image on the screen. FIG. 5 is an explanatory view showing an example of the image display, and shows an example in which a part of the black and white B-mode image 16 is replaced with a colorized elastic image 17. In addition to this, a colorized elastic image 17 may be superimposed and displayed on the entire image of the B-mode image 16. In addition, it may be displayed in various modified combinations.

Regarding the formation of the elastic image described above,
In the above formula (3), an example has been described in which Young's modulus Ym of the biological tissue is obtained and elasticity image data is generated, but the present invention is not limited to this, and other parameters may be used to calculate the elasticity modulus. .. For example, parameters that describe the hardness and physical properties of the arterial wall, such as the stiffness parameter β, the pressure elastic coefficient Ep, and the incremental elastic coefficient Einc, may be used.

Here, the stiffness parameter β
Is However, P is the intravascular pressure, Ps is the reference internal pressure (minimum blood pressure or 1
00 mmHg), R is the extravascular radius at the intravascular pressure P, and Rs is the extravascular radius with respect to the reference internal pressure Ps. Is. This β is
It is a parameter that includes not only the material of the blood vessel wall but also the thickness and diameter of the blood vessel wall.

Further, the piezoelectric modulus Ep is However, δ indicates an increment. Is. Therefore, this expression (5) is equivalent to the expression of the above expression (3), but physiologically defined by the above term.

Further, the incremental elastic modulus Einc is However, R ₀ is the outer radius of the blood vessel, Ri is the inner radius of the blood vessel, and ν is the Poisson's ratio (it is 0.5 because the blood vessel wall can be regarded as incompressible). Is. This incremental elastic modulus Einc is considered to represent the physical properties of the arterial wall and is a medically extremely important parameter.

In the example shown in FIG. 1, the case where the probe 1 is brought into contact with the body surface of the subject 13 has been described.
The present invention is not limited to this, and can be similarly applied when a transesophageal probe or an intravascular probe is used.

[0032]

Since the present invention is constructed as described above,
The displacement measuring means calculates between two time-series tomographic images obtained by the tomographic scanning means to measure the amount of movement or displacement of each point on the tomographic image, and the pressure measuring means measures the body cavity of the diagnostic region of the subject. The inner pressure is measured or estimated, the elastic modulus at each point on the tomographic image is calculated from the displacement and pressure obtained by each of the measuring means by the elastic modulus calculating means to generate elastic image data, and the hue information converting means calculates the elastic pressure. The elasticity image data from the elastic modulus calculation means is input to give hue information, and the switching addition means adds the black and white tomographic image data from the tomographic scanning means and the color elasticity image data from the hue information conversion means. Or it can be switched. Thereby, the elasticity image showing the hardness or softness of the living tissue at the diagnosis site can be displayed together with the tomographic image showing the structure of the living tissue or alone. Therefore, for example, in diagnosing a blood vessel, it can be diagnosed on an image display whether the blood vessel is normal or arteriosclerosis is occurring.

[Brief description of drawings]

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

FIG. 2 is a diagram for explaining a block matching method for obtaining a two-dimensional displacement distribution,

FIG. 3 is a graph showing how the obtained displacement, pressure, and elastic modulus change with time;

FIG. 4 is an explanatory diagram schematically showing blood vessels at a diagnosis site,

FIG. 5 is an explanatory diagram showing a display example of the obtained B-mode tomographic image and elasticity image.

[Explanation of symbols]

1 ... Probe, 2 ... Transmitting circuit, 3 ... Receiving circuit, 4 ...
Phase adjusting circuit, 5 ... Signal processing section, 6 ... Monochrome scan converter, 7 ... Image display, 8 ... Displacement measuring section, 9 ...
Pressure measuring unit, 10 ... Elastic modulus computing unit, 11 ... Color scan converter, 12 ... Switching adder, 13 ... Subject, 14 ... Blood vessel, 15 ... Pressure sensor, 16 ... B-mode image, 17 ... Elasticity image.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinji Kishimoto No. 2-11, Shinjuyoji, Kashiwa-shi, Chiba Prefecture Inside the Institute for Research and Development, Hitachi Medical Co., Ltd. (72) Toshiro Kondo, Kyoji-shi, Chiba 2 2 No. 1 inside the Ritsudoko Medical Research Institute Co., Ltd.

Claims (1)

[Claims] 1. An ultrasonic wave transmitting / receiving means for transmitting and receiving ultrasonic waves to and from a subject, and tomographic image data in the subject including a moving tissue are repeated at a predetermined cycle using reflected echo signals from the ultrasonic wave transmitting / receiving means. In an ultrasonic diagnostic apparatus having a tomographic scanning unit obtained by the above method and an image display unit for displaying time-series tomographic image data obtained by the tomographic scanning unit Displacement measuring means for calculating the amount of movement or displacement of each point on the tomographic image by performing calculation with, pressure measuring means for measuring or estimating the pressure inside the body cavity of the diagnosis site of the subject, and the measuring means Elastic modulus calculation means for calculating elastic modulus at each point on the tomographic image from the displacement and pressure to generate elastic image data, and a hue for giving hue information by inputting the elastic image data from the elastic modulus calculation means. information The conversion means and the switching addition means for adding or switching the black and white tomographic image data from the tomographic scanning means and the color elastic image data from the hue information converting means are provided, and the image data from the switching and adding means is converted into the image data. An ultrasonic diagnostic apparatus characterized in that it is displayed on a display means.