JP4405617B2 - Ultrasonic imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ultrasonic imaging apparatus, and more particularly to an ultrasonic imaging apparatus that obtains a three-dimensional display image based on a plurality of tomographic images obtained by sequentially scanning a plurality of cross sections in an imaging target with ultrasonic waves.
[0002]
[Prior art]
When a cross section within an imaging target is scanned with ultrasonic waves and a cross section is imaged based on an echo reception signal, a tomographic image of a plurality of cross sections is taken while sequentially moving the cross section, and 3 based on the tomographic images. A dimensional display image is obtained. The cross section is moved by moving (scanning) the ultrasonic probe in a direction perpendicular to the cross section.
[0003]
[Problems to be solved by the invention]
Since the three-dimensional display image obtained as described above is a still image, there is a problem that it is not suitable for the purpose of observing the dynamic state of the imaging target.
[0004]
The present invention has been made to solve the above-described problems, and an object thereof is to realize an ultrasonic imaging apparatus that obtains a three-dimensional display image indicating a dynamic state of an imaging target.
[0005]
[Means for Solving the Problems]
(1) An invention according to a first aspect for solving the above-described problem is an imaging unit that sequentially scans a plurality of cross sections in an imaging target with ultrasonic waves and captures tomographic images of the plurality of cross sections based on echoes. Image forming means for forming a three-dimensional display image based on the captured tomographic image, and image display means for displaying the formed three-dimensional display image and showing one surface thereof in real time. It is the characteristic ultrasonic imaging device.
[0006]
(2) In the invention according to the second aspect for solving the above-mentioned problem, the rate of surface change by the image forming unit accompanying the change of the one surface is lower than the rate of updating the real-time image by the image display unit. The ultrasonic imaging apparatus according to (1), further comprising: a rate control unit that performs the control.
[0007]
(3) According to another aspect of the invention for solving the above-described problem, a plurality of cross-sections in an imaging target are sequentially scanned with ultrasonic waves, tomographic images of the plurality of cross-sections are taken based on echoes, and the image is taken. The ultrasonic imaging method is characterized in that a three-dimensional display image is formed based on a tomographic image, the formed three-dimensional display image is displayed, and one surface thereof is shown as a real-time image.
[0008]
(4) According to another aspect of the invention for solving the above problem, the rate of surface change in the three-dimensional display image accompanying the change of the one surface is made lower than the rate of updating the real-time image. The ultrasonic imaging method according to (3).
[0009]
(Function)
In the present invention, one surface of the three-dimensional display image is shown as a real-time image, thereby enabling real-time observation of the dynamic state of the imaging target.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment. FIG. 1 shows a block diagram of the ultrasonic imaging apparatus. This apparatus is an example of an embodiment of an ultrasonic imaging apparatus of the present invention. An example of an embodiment relating to the apparatus of the present invention is shown by the configuration of the apparatus. An example of an embodiment related to the method of the present invention is shown by the operation of the apparatus.
[0011]
The configuration of this apparatus will be described. As shown in the figure, this apparatus has an ultrasonic probe 2. The ultrasonic probe 2 is brought into contact with the subject 100 and used for transmitting and receiving ultrasonic waves. The ultrasonic probe 2 has an ultrasonic transducer array (not shown). The ultrasonic transducer array is composed of a plurality of ultrasonic transducers. Each ultrasonic transducer is made of a piezoelectric material such as PZT (titanium (Ti) zirconate (Zr) lead (Pb)) ceramics.
[0012]
The ultrasonic probe 2 is connected to the transmission / reception unit 6. The transmission / reception unit 6 drives the ultrasonic transducer array of the ultrasonic probe 2 to transmit an ultrasonic beam, and receives an echo (echo) received by the ultrasonic transducer array.
[0013]
A block diagram of the transceiver 6 is shown in FIG. As shown in the figure, the transmission / reception unit 6 includes a signal generation circuit 602. The signal generation circuit 602 repeatedly generates a pulse signal at a predetermined period and inputs the pulse signal to the transmission beam former 604. The transmission beam former 604 generates a transmission beam forming signal based on the input signal. The transmitted beam forming signal is a plurality of pulse signals given to a plurality of ultrasonic transducers constituting a transmission aperture in the ultrasonic transducer array, and each pulse signal has a delay time corresponding to the direction and focus of the ultrasonic beam. Is granted. Hereinafter, the transmission aperture is referred to as a transmission aperture.
[0014]
An output signal of the transmission beam former 604 is given as a drive signal to a plurality of ultrasonic transducers constituting a transmission aperture through a transmission / reception switching circuit 608. Each of the plurality of ultrasonic transducers to which the drive signal is given generates ultrasonic waves, and a transmission ultrasonic beam in a predetermined direction is formed by wavefront synthesis of the ultrasonic waves. The transmitted ultrasonic beam converges to a focal point set at a predetermined distance.
[0015]
The echoes of the transmitted ultrasonic waves are received by a plurality of ultrasonic transducers that constitute the reception aperture of the ultrasonic probe 2. Hereinafter, the reception aperture is referred to as a reception aperture. The plurality of echo reception signals received by the plurality of ultrasonic transducers are input to the reception beam former 610 through the transmission / reception switching circuit 608. The reception beamformer 610 adds a delay corresponding to the direction of the echo reception sound ray and the focus of the echo reception to each echo reception signal and adds them to form an echo reception signal that matches the predetermined sound ray and focus. To do.
[0016]
The transmission beam former 604 performs acoustic ray sequential scanning by sequentially switching the direction of the transmission ultrasonic beam. The receiving beamformer 610 scans received rays in a sound ray sequence by sequentially switching the directions of the received sound rays. Thereby, the transmitter / receiver 6 performs scanning as shown in FIG. 3, for example. That is, the ultrasonic beam 202 extending in the z direction from the radiation point 200 scans the fan-shaped two-dimensional region 206 in the θ direction, and performs a so-called sector scan.
[0017]
When the transmission and reception apertures are formed by using a part of the ultrasonic transducer array, the apertures are sequentially moved along the array to perform scanning as shown in FIG. 4, for example. That is, when the ultrasonic beam 202 emitted from the radiation point 200 in the z direction moves on the linear locus 204, the rectangular two-dimensional region 206 is scanned in the x direction, and a so-called linear scan is performed. Is called.
[0018]
In the case where the ultrasonic transducer array is a so-called convex array formed along an arc extending in the ultrasonic transmission direction, for example, as shown in FIG. In addition, it goes without saying that the radiation point 200 of the ultrasonic beam 202 moves on the arc-shaped locus 204 and the fan-shaped two-dimensional region 206 is scanned in the θ direction, and so-called convex scan can be performed.
[0019]
The ultrasonic probe 2 is connected to an actuator 8. The actuator 8 moves the ultrasonic probe 2 in a direction perpendicular to the sound ray scanning direction in the θ direction (or the x direction, hereinafter represented by the θ direction). That is, the actuator 8 performs φ scanning. The φ scan is performed in cooperation with the θ scan. For example, the φ scan is advanced by one pitch for every scan of the θ scan. By such φ scanning, a plurality of cross sections of the imaging target 3 are sequentially scanned.
[0020]
For example, as shown in FIG. 6, the φ scan is performed by translating the ultrasonic probe 2 in a direction orthogonal to the θ scan. The z direction shown in the figure is the sound ray direction. As a result, the three-dimensional region 302 inside the imaging target 4 is scanned. In addition, the φ scan may be performed by swinging the ultrasonic probe 2 in the φ direction, for example, as shown in FIG. As shown by the central axis 300, it is preferable that the center axis of the oscillation should pass through the sound ray divergence point 208 of the θ scan in order to match the origins of the θ scan and φ scan angles. Note that the φ scan is not necessarily performed by the actuator 8 and may be performed manually by the operator.
[0021]
The transmission / reception unit 6 is connected to a B-mode processing unit 10 and a Doppler processing unit 12. The echo reception signal for each sound ray output from the transmission / reception unit 6 is input to the B-mode processing unit 10 and the Doppler processing unit 12.
[0022]
The B-mode processing unit 10 forms B-mode image data. The B-mode processing unit 10 includes a logarithmic amplifier circuit 102 and an envelope detection circuit 104 as shown in FIG. The B mode processing unit 10 logarithmically amplifies the echo reception signal by the logarithmic amplification circuit 102, envelope detection by the envelope detection circuit 104, a signal representing the intensity of the echo at each reflection point on the sound ray, that is, an A scope A (scope) signal is obtained, and B-mode image data is formed with each instantaneous amplitude of the A scope signal as a luminance value.
[0023]
The Doppler processing unit 12 forms Doppler image data. As illustrated in FIG. 9, the Doppler processing unit 12 includes an orthogonal detection circuit 120, an MTI filter (moving target indication filter) 122, an autocorrelation circuit 124, an average flow velocity calculation circuit 126, a dispersion calculation circuit 128, and a power calculation circuit 130. It has.
[0024]
The Doppler processing unit 12 performs quadrature detection of the echo reception signal by the quadrature detection circuit 120, performs MTI processing by the MTI filter 122, performs autocorrelation calculation by the autocorrelation circuit 124, and averages the autocorrelation calculation result from the autocorrelation calculation result 126. The flow velocity is obtained, the variance of the flow velocity is obtained from the autocorrelation calculation result by the dispersion calculation circuit 128, and the power of the Doppler signal is obtained from the autocorrelation calculation result by the power calculation circuit 130.
[0025]
As a result, data representing the average flow velocity such as blood flow in the imaging target 4 and its dispersion and the power of the Doppler signal, that is, Doppler image data, is obtained for each sound ray. The flow velocity is obtained as a component in the sound ray direction. The direction of the flow is distinguished from a direction of approaching and a direction of moving away.
[0026]
The B mode processing unit 10 and the Doppler processing unit 12 are connected to the image processing unit 14. The image processing unit 14 configures a B-mode image and a Doppler image, respectively, based on data input from the B-mode processing unit 10 and the Doppler processing unit 12, respectively.
[0027]
The ultrasonic probe 2, the transmission / reception unit 6, the actuator 8, the B-mode processing unit 10, the Doppler processing unit 12, and the image processing unit 14 described above are an example of an embodiment of an imaging unit in the present invention.
[0028]
As shown in FIG. 10, the image processing unit 14 includes a sound ray data memory 142, a digital scan converter 144, an image memory 146, and an image processing processor connected by a bus 140. (Processor) 148 is provided.
[0029]
B-mode image data and Doppler image data input for each sound ray from the B-mode processing unit 10 and the Doppler processing unit 12 are stored in the sound ray data memory 142, respectively. By sequentially scanning the imaging target 4 for a plurality of cross sections, the sound ray data memory 142 stores the image data of the plurality of cross sections. Hereinafter, the image data for each cross-section stored in the sound ray data memory 142 is referred to as a sound ray data frame (data frame).
[0030]
The digital scan converter 144 converts sound ray data space data into physical space data by scan conversion. Thereby, the image data in the sound ray data space is converted into image data in the physical space. The image data converted by the digital scan converter 144 is stored in the image memory 146. That is, the image memory 146 stores physical space image data.
[0031]
The image processor 148 performs predetermined data processing on the data in the sound ray data memory 142 and the image memory 146. The image processor 148 is configured using, for example, a computer. Data processing of the image processor 148 includes data processing for obtaining a three-dimensional display image. Further, as will be described later, data processing for combining a three-dimensional display image with a real time image is included. The image processor 148 is an example of an embodiment of the image forming means in the present invention.
[0032]
A display unit 16 is connected to the image processing unit 14. The display unit 16 receives an image signal from the image processing unit 14 and displays an image based on the image signal. The portion composed of the image processing unit 14 and the display unit 16 is an example of an embodiment of the image display means in the present invention. The display unit 16 is configured using, for example, a graphic display.
[0033]
The transmission / reception unit 6, actuator 8, B-mode processing unit 10, Doppler processing unit 12, image processing unit 14, and display unit 16 are connected to the control unit 18. The control unit 18 gives control signals to these units to control their operations. The control unit 18 is an example of an embodiment of rate control means in the present invention. Under the control of the control unit 18, the B mode operation and the Doppler mode operation are executed. An operation unit 20 is connected to the control unit 18. The operation unit 20 is operated by an operator, and inputs desired commands and information to the control unit 18. The operation unit 20 includes, for example, an operation panel including a keyboard and other operation tools.
[0034]
The operation of this apparatus will be described. The operator positions the ultrasonic probe 2 connected to the actuator 8 at a desired location of the imaging target 4 and operates the operation unit 20 to perform an imaging operation in, for example, a power Doppler mode. Thereafter, the imaging operation is performed under the control of the control unit 18.
[0035]
In the power Doppler mode, the transmission / reception unit 6 scans the inside of the imaging target 4 through the ultrasonic probe 2 in the order of sound rays and receives the echoes one by one. At that time, ultrasonic waves are transmitted and echoes are received a plurality of times per sound ray. The Doppler processing unit 12 performs quadrature detection on the echo reception signal by the quadrature detection circuit 120, performs MTI processing by the MTI filter 122, obtains autocorrelation by the autocorrelation circuit 124, and obtains power by the power calculation circuit 130 from the autocorrelation result. . This calculated value becomes Doppler image data representing the power of the Doppler signal for each sound ray. The MTI processing in the MTI filter 122 is performed using a plurality of echo reception signals per sound ray.
[0036]
The image processing unit 14 stores the power Doppler image data for each sound ray input from the Doppler processing unit 12 in the sound ray data memory 142. The power Doppler image data represents an image of a blood vessel or the like. The image data in the sound ray data memory 142 is converted into physical space image data by the digital scan converter 144, given to the display unit 16 through the image memory 146, and displayed as a visible image. The operator observes the display image and grasps the internal state of the imaging target 4.
[0037]
As the φ scan progresses, for example, as schematically shown in FIG. 11, a plurality of cross-sections 900 to 910 of the three-dimensional region 302 are sequentially scanned, and a plurality of sound ray data frames storing those image data are sequentially obtained as sound rays. It is formed in the data memory 142. The three-dimensional region 302 includes a blood vessel 920.
[0038]
After completing the φ scan, the operator commands creation and display of a three-dimensional display image. Based on such a command, the image processor 148 forms and displays a three-dimensional display image from a plurality of sound ray data frames. Thereby, for example, as shown in FIG. 12, a three-dimensional display image 302 ′ corresponding to the three-dimensional region 302 is displayed. Cross-sectional images 922 and 924 of the blood vessel 920 can be seen on the surface facing the right diagonal and the surface facing the left diagonal of the three-dimensional display image 302 ′.
[0039]
A surface (hereinafter referred to as a front surface) facing the right oblique side of the three-dimensional display image 302 ′ corresponds to a cross section 910, and is a θ scanning surface at the end point of φ scanning. This section continues the θ scan even after the φ scan is completed. Therefore, the image processor 148 generates a tomographic image based on the echo data obtained sequentially and displays it on the position of the cross section 910 in the three-dimensional display image 302 ′. As a result, a real-time image of the cross section 910 is displayed in front of the three-dimensional display image 302 ′.
[0040]
Since the front image becomes a real-time image in this way, the three-dimensional display image 302 displays the activity state of the imaging target every moment in real time unlike a conventional still image. Therefore, in addition to the three-dimensional structure of the imaging region based on this image, the activity status can be observed in real time, and image diagnosis can be performed more effectively.
[0041]
When the position of the ultrasound probe 2 is changed from this state and the θ scanning plane is changed to the cross section 906, the image processor 148 corresponds to the real time image corresponding to the cross section 906 in the three-dimensional display image 302 ′ as shown in FIG. It is displayed at the position to be. Further, when the ultrasonic probe 2 is tilted and the θ scanning plane is inclined, for example, as shown in FIG. 14, a real-time image is displayed on a corresponding oblique section.
[0042]
In this case, the real-time image update process and the display position update process compete with each other in the image processor 148, but the control unit 18 determines that the number of real-time image update processes per unit time, that is, the image update rate is the display position update. It is designed to be higher than the rate. Thereby, the real-time property of image display can be improved.
[0043]
The example of image display based on power Doppler image data has been described above, but it goes without saying that the image data is not limited to power Doppler image data, and flow velocity distribution image data or B-mode image data may be used. Absent.
[0044]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to realize an ultrasonic imaging apparatus that obtains a three-dimensional display image indicating a dynamic state of an imaging target.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 2 is a block diagram of a part of the apparatus shown in FIG.
3 is a schematic diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2; FIG.
4 is a schematic diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2; FIG.
5 is a schematic diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2; FIG.
6 is a schematic diagram of φ scan by the apparatus shown in FIG. 1;
FIG. 7 is a schematic diagram of φ scan by the apparatus shown in FIG.
8 is a block diagram of a part of the apparatus shown in FIG.
9 is a block diagram of a part of the apparatus shown in FIG.
FIG. 10 is a block diagram of a part of the apparatus shown in FIG.
11 is a schematic diagram of multi-section scanning by the apparatus shown in FIG. 1. FIG.
12 is a schematic diagram of a three-dimensional display image obtained by the apparatus shown in FIG.
13 is a schematic diagram of a three-dimensional display image obtained by the apparatus shown in FIG.
14 is a schematic diagram of a three-dimensional display image obtained by the apparatus shown in FIG.
[Explanation of symbols]
2 Ultrasonic probe 6 Transmission / reception unit 8 Actuator 10 B mode processing unit 12 Doppler processing unit 14 Image processing unit 16 Display unit 18 Control unit 20 Operation unit 100 Imaging target 140 Bus 142 Sound ray data memory 144 Digital scan converter 146 Image memory 148 Image processor 302 ′ Three-dimensional display image 902 to 910, 930

Claims (1)

Imaging that sequentially changes the position of the scanning plane by ultrasonic waves within the imaging target, fixes the scanning plane at the end, and captures tomographic images of a plurality of cross sections corresponding to the scanning plane whose position has been changed based on echoes Means,
Image forming means for forming a three-dimensional display image based on the captured tomographic image;
An ultrasonic imaging apparatus comprising: an image display unit that displays the formed three-dimensional display image and simultaneously shows a cross-section corresponding to the fixed scanning plane in the three-dimensional display image as a real-time image.

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