JP4347954B2 - 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 scans a three-dimensional region in an imaging target in an acoustic ray sequence with an ultrasonic beam to capture a projected image.
[0002]
[Prior art]
An apparatus that captures a projected image by scanning a three-dimensional region within an imaging target in a ray-sequential manner with an ultrasonic beam is known from Japanese Patent Application Laid-Open No. 9-243342. This apparatus sequentially ultrasonically picks up the inside of an imaging target while moving an ultrasonic probe in a direction perpendicular to the scan plane, and projects image data of the obtained tomographic image in the sound ray direction per slice. A line image is formed, and the line images are arranged in parallel in the forming order to form a projection image.
[0003]
The line image is formed by, for example, a minimum intensity projection of a B-mode image (Minimum Intensity Projection), or a maximum value projection (Maximum Intensity Projection) of a power Doppler image or a color Doppler image (color Doppler). Thus, a projection image obtained by viewing the blood flow or blood vessel from the ultrasonic probe side is obtained.
[0004]
[Problems to be solved by the invention]
When blood vessel contrast imaging is performed, an ultrasound contrast agent mainly composed of microbubbles is injected, and imaging is performed using its unique echo characteristics. However, microbubbles are destroyed by ultrasound. Since it has the property of being easy, once it is scanned, sufficient echo is not generated even if it is scanned again. For this reason, there is a problem that an appropriate projection image is often not obtained.
[0005]
The present invention has been made to solve the above-described problems, and an object thereof is to realize an ultrasonic imaging apparatus that effectively performs projection imaging using an ultrasonic contrast agent.
[0006]
[Means for Solving the Problems]
(1) According to the first aspect of the invention for solving the above-mentioned problem, the slice region in the imaging target is scanned in the sound ray sequence with ultrasonic waves and echoes are received while the slice region is moved in the thickness direction. Ultrasonic transmitting / receiving means for moving, tomographic image forming means for forming a tomographic image of the slice region based on the received echo, and projecting image data of the tomographic image in a direction perpendicular to the thickness of the slice region An ultrasonic imaging apparatus, comprising: a line image forming unit that forms a line image for the slice region; and a projection image forming unit that forms a projection image by arranging the line images in parallel in the order of formation. An ultrasonic imaging apparatus comprising: control means for causing the means to sequentially move the slice area by a distance substantially corresponding to the thickness of the slice area; It is.
[0007]
(2) According to the second aspect of the invention for solving the above-described problem, the slice region in the imaging target is scanned in a sound ray sequence with ultrasonic waves and echoes are received while the slice region is moved in the thickness direction. Ultrasonic transmitting / receiving means for moving, tomographic image forming means for forming a tomographic image of the slice region based on the received echo, and projecting image data of the tomographic image in a direction perpendicular to the thickness of the slice region An ultrasonic imaging apparatus comprising: a line image forming unit that forms a line image for the slice region; and a projection image forming unit that forms a projection image by arranging the line images in parallel in the order of formation. A moving amount detecting means for detecting a moving amount; and each time the detected moving amount becomes a value substantially corresponding to the thickness of the slice region, the sound is transmitted to the ultrasonic transmitting / receiving means. An ultrasonic imaging apparatus characterized by comprising a control means for causing the sequential scan.
[0008]
(3) In the invention according to the third aspect for solving the above-described problem, the control means reduces the intensity until the detected movement amount becomes a value substantially corresponding to the thickness of the slice region. The ultrasonic imaging apparatus according to claim 2, wherein the ultrasonic transmission / reception unit performs acoustic ray sequential scanning using ultrasonic waves.
[0009]
(4) According to a fourth aspect of the invention for solving the above-mentioned problem, the movement amount detecting means is a time when the tomographic image forming means are different from each other on the basis of an echo reception signal corresponding to an ultrasonic wave with reduced intensity. The ultrasonic imaging apparatus according to claim 3, wherein an amount of movement of the slice region is detected based on a cross-correlation between a plurality of tomographic images formed respectively.
[0010]
(5) The fifth aspect of the invention for solving the above-described problem is that the ultrasonic wave with the reduced intensity does not substantially destroy the ultrasonic contrast agent injected into the imaging target. The ultrasonic imaging apparatus according to claim 3, wherein the ultrasonic imaging apparatus is provided.
[0011]
(6) According to another aspect of the invention for solving the above-described problem, the slice region in the imaging target is scanned in a sound ray sequence with ultrasonic waves, and the slice region is moved in the thickness direction while receiving an echo. Forming a tomographic image of the slice region based on the received echo, projecting the image data of the tomographic image in a direction perpendicular to the thickness of the slice region, forming a line image for the slice region, An ultrasonic imaging method for forming a projection image by arranging the line images in parallel in the formation order, wherein the movement of the slice region is sequentially performed by a distance substantially corresponding to the thickness of the slice region. This is an ultrasonic imaging method.
[0012]
(7) According to another aspect of the invention for solving the above-described problem, the slice region in the imaging target is scanned in a sound ray sequence with ultrasonic waves and the slice region is moved in the thickness direction while receiving an echo. Forming a tomographic image of the slice region based on the received echo, projecting the image data of the tomographic image in a direction perpendicular to the thickness of the slice region, forming a line image for the slice region, An ultrasonic imaging method for forming a projection image by arranging the line images in parallel in the order of formation, wherein a movement amount of the slice region is detected, and the detected movement amount substantially corresponds to a thickness of the slice region. The ultrasonic imaging method is characterized in that the sound ray sequential scanning is performed each time the value is reached.
[0013]
(8) According to another aspect of the invention for solving the above-described problem, an acoustic ray generated by an ultrasonic wave with reduced intensity until the detected movement amount substantially corresponds to the thickness of the slice region. The ultrasonic imaging method according to (7), wherein sequential scanning is performed.
[0014]
(9) In another aspect of the invention for solving the above-described problem, the invention is based on cross-correlation between a plurality of tomographic images formed at different times based on echo reception signals corresponding to ultrasonic waves with reduced intensity. The ultrasonic imaging method according to (8), wherein a movement amount of the slice area is detected.
[0015]
(10) In another aspect of the invention for solving the above-described problem, the ultrasonic wave with the reduced intensity has an intensity that does not substantially destroy the ultrasonic contrast agent injected into the imaging target. The ultrasonic imaging method according to (8) or (9), wherein
[0016]
(Function)
In the present invention, the slice region is sequentially moved by a distance substantially corresponding to the thickness of the slice region. Alternatively, every time the amount of movement of the slice region becomes a distance substantially corresponding to the thickness of the slice region, scanning of an ultrasonic beam for imaging a projection image is performed. As a result, the unscanned area is always scanned, and a sufficient echo can be obtained from the ultrasound contrast agent.
[0017]
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.
[0018]
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 imaging target 100 and used for transmitting and receiving ultrasonic waves. In the imaging object 100, an ultrasound contrast agent 110 is injected into a blood vessel. The ultrasonic contrast agent 110 is a contrast agent mainly composed of, for example, microbubbles. Hereinafter, the ultrasound contrast agent is simply referred to as a contrast agent.
[0019]
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.
[0020]
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.
[0021]
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 unit 602. The signal generation unit 602 repeatedly generates a pulse signal at a predetermined period and inputs the pulse signal to the transmission beamformer 604. The transmission beam former 604 outputs 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 corresponds to the direction and focus of the ultrasonic beam. Delay time is given. Hereinafter, the transmission aperture is referred to as a transmission aperture.
[0022]
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 unit 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.
[0023]
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 unit 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.
[0024]
The echo reception signal is filtered by the filter 612, and a predetermined frequency component is extracted. The predetermined frequency component is, for example, a component having a frequency twice the fundamental frequency of the transmitted ultrasonic wave, that is, a second harmonic component. Thereby, an echo signal peculiar to the contrast agent 110 is extracted.
[0025]
Note that the frequency component extracted by the filter 612 is not limited to the second harmonic, but is a third or higher harmonic component, a subharmonic component having a frequency lower than the fundamental frequency, or so-called induced acoustic radiation (sAE: stimulated). An echo component unique to microbubbles such as an acoustic emission component may be extracted.
[0026]
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. The two-dimensional area 206 is an example of an embodiment of a slice area in the present invention.
[0027]
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.
[0028]
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.
[0029]
The ultrasonic beam 202 has a thickness as shown in FIG. 6, for example, when viewed in the θ direction (or the x direction, hereinafter represented by the θ direction). The thickness of the ultrasonic beam 202 is the smallest in the vicinity of the focal point 220, and the thickness t of this portion becomes the substantial thickness of the slice. The slice thickness t is determined by the convergence degree of the ultrasonic beam 202. Since the convergence degree of the ultrasonic beam 202 is determined by an acoustic lens (lens) or the like provided in front of the ultrasonic probe 2, the slice thickness t is a known value.
[0030]
The ultrasonic probe 2 is connected to an actuator 8. The actuator 8 moves the ultrasonic probe 2 in a direction orthogonal to the θ scanning direction. This direction is called the φ direction. That is, the actuator 8 performs φ scanning.
[0031]
The φ scan is performed, for example, by translating the ultrasonic probe 2 in a direction orthogonal to the θ scan, as shown in FIG. As a result, the three-dimensional region 302 inside the imaging target 100 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. The portion including the ultrasonic probe 2, the transmission / reception unit 6, and the actuator 8 is an example of an embodiment of the ultrasonic transmission / reception means in the present invention.
[0032]
The transmission / reception unit 6 is connected to the B-mode processing unit 10. An echo reception signal for each sound ray output from the transmission / reception unit 6 is input to the B-mode processing unit 10. 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 amplifier circuit 102, envelope-detects it by the envelope detection circuit 104, and indicates a signal representing the intensity of echo generated by the contrast medium 110 on the sound ray, that is, an A scope ( (scope) signal is obtained, and B-mode image data relating to the contrast medium 110 is formed using the instantaneous amplitude of the A scope signal as a luminance value.
[0033]
The B mode processing unit 10 is connected to the image processing unit 14. The image processing unit 14 forms a B-mode image based on data input from the B-mode processing unit 10. Further, as will be described later, a line image is formed based on the B-mode image, and a projection image is formed based on the line image.
[0034]
As shown in FIG. 9, the image processing unit 14 includes a sound ray data memory 142, a digital scan converter (DSC) 144, an image memory 146, and an image connected by a bus 140. A processing processor 148 is provided.
[0035]
The B-mode image data input for each sound ray from the B-mode processing unit 10 is stored in the sound ray data memory 142. By sequentially scanning the imaging target 100 for a plurality of slices, the sound ray data memory 142 stores a plurality of slices of image data. As a result, a sound ray data space is formed in the sound ray data memory 142. Hereinafter, the image data for each slice stored in the sound ray data memory 142 will be referred to as a sound ray data frame (data frame).
[0036]
The DSC 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 DSC 144 is stored in the image memory 146. That is, the image memory 146 stores physical space image data.
[0037]
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 forming a projection image. This data processing will be described later.
[0038]
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 display unit 16 is configured using, for example, a graphic display.
[0039]
The transmission / reception unit 6, actuator 8, B-mode processing unit 10, 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 operation. The control unit 18 also receives various signals such as a notification signal from each unit to be controlled. Ultrasonic imaging is executed under the control of the control unit 18. The control unit 18 is an example of an embodiment of control means in the present invention.
[0040]
The control unit 18 controls the transmission / reception unit 6 and the actuator 8 to coordinately perform the θ scan and the φ scan, and advances the φ scan by one pitch for every scan of the θ scan. . One pitch of φ scan is equal to the slice thickness t. By such φ scan, a plurality of adjacent slices in the imaging target 100 are scanned in order without overlapping.
[0041]
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.
[0042]
FIG. 11 shows a block diagram of an image processor 148 related to projection image formation. As shown in the figure, the image processor 148 includes a tomographic image forming unit (unit) 482, a line image forming unit 484, and a projected image forming unit 486. Each of these units is realized by, for example, a computer program.
[0043]
The tomographic image forming unit 482 is an example of an embodiment of tomographic image forming means in the present invention. The line image forming unit 484 is an example of an embodiment of a line image forming unit in the present invention. The projection image forming unit 486 is an example of the embodiment of the projection image forming means in the present invention.
[0044]
The tomographic image forming unit 482 includes the function of the DSC 144 and forms a tomographic image of the contrast agent 110, that is, a B-mode image, based on the sound ray data read from the sound ray data memory 142. From this B-mode image, the line image forming unit 484 forms a line image. Line image formation will be described with reference to FIG.
[0045]
For example, it is assumed that a tomographic image 90i as shown in FIG. 12 is obtained by θ scanning, and the tomographic image 90i includes a blood vessel cross-sectional image 92i. The blood vessel cross-sectional image 92i is based on an echo of the contrast medium 110 and is a portion having a high signal intensity.
[0046]
The line image forming unit 484 projects the maximum value in the z direction on the image data of the tomographic image 90i to obtain the line image 93i. The line image 93i is a one-dimensional image on the projection plane 940.
[0047]
When the tomographic image 90j of the next slice is obtained, the line image 93j is obtained in the same manner. Similarly, each time a tomographic image 90k,... Is obtained, line images 93k,.
[0048]
The projection image forming unit 486 forms a projection image by arranging these line images 93i, j, k,... In parallel in the scan order. The formed projection image is an image obtained by projecting the image of the blood vessel 920 onto the projection surface 940. For example, as shown in FIG. 13, the travel state of the blood vessel 920 is viewed from the ultrasonic probe 2 side.
[0049]
Note that the image data may be projected only on image data belonging to an appropriate region of interest set on the slice plane. This is preferable in that, for example, only blood vessels located in a desired depth range in the body are projected.
[0050]
The operation of this apparatus will be described. The operator positions the ultrasonic probe 2 connected to the actuator 8 at a desired position of the imaging target 100 and operates the operation unit 20 to perform imaging. Hereinafter, imaging is performed under the control of the control unit 18.
[0051]
The transmission / reception unit 6 scans the inside of the imaging target 100 through the ultrasonic probe 2 in the order of sound rays, and receives the echoes one by one. The B-mode processing unit 10 obtains B-mode image data for each sound ray based on the echo reception signal.
[0052]
The image processing unit 14 stores the B-mode image data for each sound ray input from the B-mode processing unit 10 in the sound ray data memory 142. As the φ scan progresses, for example, as conceptually shown in FIG. 14, a plurality of slices 900 to 910 of the three-dimensional region 302 are sequentially scanned, and a plurality of sound ray data frames storing these image data are sequentially reproduced. It is formed in the line data memory 142. The three-dimensional region 302 includes a blood vessel 920. Contrast agent 110 is present in blood vessel 920.
[0053]
Based on such sound ray data, the tomographic image forming unit 482 forms tomographic images of a plurality of slices 900 to 910. The line image forming unit 484 forms a line image based on the plurality of tomographic images, and the projection image forming unit 486 forms a projection image based on the line image.
[0054]
By displaying such a projection image on the display unit 16, the display screen travels the blood vessel 920 from the top to the bottom of the screen as the φ scan of the ultrasonic probe 2 progresses, for example, as shown in FIG. 15. The state is gradually projected.
[0055]
After the φ scan exceeds the range corresponding to the display range of the screen, the display image is scrolled upward as shown in FIG. 16, and a new image appears from the lower end of the screen, and the old image appears from the upper end of the screen. Exit.
[0056]
Here, the θ scan and the φ scan are performed in a coordinated manner, and a plurality of adjacent slices are sequentially scanned in the imaging target 100, so that each slice is scanned for the first time. It becomes. Therefore, sufficient echoes can be obtained from the contrast medium 110 in any slice. This makes it possible to appropriately perform projection imaging using a contrast agent.
[0057]
FIG. 17 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.
[0058]
In FIG. 17, the same parts as those shown in FIG. In this apparatus, the actuator 8 continuously performs the φ scan of the ultrasonic probe 2. The speed of φ scan need not be constant. The actuator 8 includes a movement distance detector 82. The movement distance detector 82 is an example of an embodiment of the movement amount detection means in the present invention. The moving distance detector 82 detects the moving distance of φ scanning of the ultrasonic probe 2 by the actuator 8 and notifies the control unit 18 of the detected distance.
[0059]
The control unit 18 causes the transmission / reception unit 6 to perform the θ scan every time the moving distance of the φ scanning of the ultrasonic probe 2 detected by the moving distance detector 82 becomes a distance corresponding to the slice thickness t. Thereby, it is possible to sequentially scan a plurality of adjacent slices in the imaging target 100 without overlapping, and similarly to the apparatus shown in FIG. 1, it is possible to effectively perform projection imaging using a contrast agent. it can.
[0060]
FIG. 18 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.
[0061]
In FIG. 18, the same parts as those shown in FIG. Also in this apparatus, the actuator 8 continuously performs φ scan of the ultrasonic probe 2. The speed of φ scan need not be constant.
[0062]
In this apparatus, the control unit 18 further switches the intensity of the transmitted ultrasonic wave of the transmission / reception unit 6 between two levels of strength and weakness. The weak transmitted ultrasound is of a level that does not substantially destroy the contrast agent 110. The controller 18 scans with a strong ultrasonic wave once and then performs a scan with a weak ultrasonic wave for a while and causes a strong ultrasonic wave scan again when a condition described later is satisfied. Repeat the operation.
[0063]
In this apparatus, the image processor 148 of the image processor 14 has a configuration as shown in FIG. The configuration shown in the figure is the same as that shown in FIG. 11 except for the cross-correlation calculation unit 488. The cross correlation operation unit 488 is realized by, for example, a computer program.
[0064]
Here, the line image forming unit 484 forms a line image based on a tomographic image obtained by scanning with a strong transmitted ultrasonic wave. Note that the strength of transmitted ultrasonic waves is notified from the control unit 18.
[0065]
The cross-correlation calculation unit 488 receives a tomographic image from the tomographic image forming unit 482. The cross-correlation calculation unit 488 performs a cross-correlation calculation on a plurality of tomographic images captured with weak ultrasonic waves and notifies the control unit 18 of the result. Note that the strength of transmitted ultrasonic waves is notified from the control unit 18.
[0066]
FIG. 20 shows a conceptual diagram of the cross-correlation calculation of the cross-correlation calculation unit 488 as the φ scan progresses. As shown in the figure, if the slice Sa is scanned with strong transmitted ultrasonic waves, the next scan is performed with weak transmitted ultrasonic waves. Thereby, the slice Sb slightly shifted in the φ direction from the slice Sa is scanned with weak transmitted ultrasonic waves. The slice Sb has many overlapping portions with the slice Sa, where the contrast agent 110 in the blood vessel 920 is destroyed by the previous strong transmitted ultrasonic wave and disappears. Such a tomographic image of the slice Sb is first input to the cross-correlation calculation unit 488.
[0067]
The next scan is also performed with weak transmitted ultrasound. At this time, the slice Sc slightly shifted in the φ direction from the slice Sb is scanned. The tomographic image of this slice Sc is input to the cross-correlation calculation unit 488.
[0068]
The cross correlation calculation unit 488 obtains the cross correlation of the tomographic image of the slice Sc with respect to the tomographic image of the slice Sb. Since the slice Sc has many overlapping portions with the slice Sb, a high correlation is obtained for the two tomographic images.
[0069]
The next scan is also performed with weak transmitted ultrasound. Thereby, a slice Sd (not shown) that is slightly shifted in the φ direction from the slice Sc is scanned. The tomographic image of this slice Sd is input to the cross-correlation calculation unit 488.
[0070]
The cross correlation calculation unit 488 obtains the cross correlation of the tomographic image of the slice Sd with respect to the tomographic image of the slice Sb. Since slice Sd still has many overlapping portions with slice Sb, a relatively high correlation can be obtained. By repeating this process, the cross-correlation between the tomographic image of the slice Sb and each tomographic image obtained sequentially is obtained.
[0071]
Eventually, the moving distance in the φ direction becomes a distance corresponding to the slice thickness t, and a cross-correlation with the tomographic image of the slice Sj is obtained. In the slice Sj, most of the contrast medium 110 is substantially undestructed. For this reason, the tomogram of the slice Sj has a very low correlation with the tomogram of the slice Sb.
[0072]
The control unit 18 monitors the correlation calculation result of each time, and it is assumed that the moving distance of the φ scan reaches a distance corresponding to the slice thickness t when the correlation value has interrupted a predetermined threshold value. The portion composed of the cross-correlation calculation unit 488 and the control unit 18 is an example of the embodiment of the movement amount detection means in the present invention.
[0073]
When this state is reached, the control unit 18 causes the next scan to be performed with a strong transmitted ultrasonic wave. As a result, the slice Sk slightly shifted in the φ direction from the slice Sj is scanned with strong transmitted ultrasonic waves. In the slice Sk, the contrast agent 110 exists in an undestructed state, so that appropriate contrast imaging can be performed with strong transmitted ultrasonic waves.
[0074]
The line image forming unit 484 forms a line image based on the tomographic image of the slice Sk, and the projection image forming unit 486 forms a projection image by arranging this line image with the line image for the slice Sa. Imaging is performed by repeating the above operation. Since the projection image is formed based on the tomographic image of the slice in which the contrast medium 110 is surely present, a high-quality projection image can be obtained.
[0075]
The example in which the ultrasonic probe is mechanically displaced to scan the three-dimensional region has been described above. However, the scanning of the three-dimensional region is not limited thereto. For example, the ultrasonic probe including a two-dimensional array of ultrasonic transducers Of course, it may be performed electronically.
[0076]
Further, although an example of forming a projection image obtained by projecting a tomographic image in the z direction has been described, the projection direction may be the θ or x direction, and in short, may be a direction perpendicular to the slice thickness.
[0077]
【The invention's effect】
As described above in detail, according to the present invention, it is possible to realize an ultrasonic imaging apparatus that effectively performs projection imaging using an ultrasonic contrast agent.
[Brief description of the drawings]
FIG. 1 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
2 is a block diagram of a transmission / reception unit of the apparatus shown in FIG. 1. FIG.
FIG. 3 is a conceptual diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2;
4 is a conceptual diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2;
FIG. 5 is a conceptual diagram of sound ray scanning by the transmission / reception unit shown in FIG. 2;
FIG. 6 is a conceptual diagram of an ultrasonic beam.
7 is a conceptual diagram of φ scanning by the apparatus shown in FIG. 1;
8 is a conceptual diagram of φ scanning by the apparatus shown in FIG. 1;
9 is a block diagram of a B-mode processing unit of the apparatus shown in FIG.
10 is a block diagram of an image processing unit of the apparatus shown in FIG. 1. FIG.
FIG. 11 is a block diagram of the image processor shown in FIG.
12 is a conceptual diagram of line image formation by the line image forming unit shown in FIG.
13 is a conceptual diagram of projection image formation by the projection image formation unit shown in FIG.
14 is a conceptual diagram of multi-slice scanning by the apparatus shown in FIG. 1. FIG.
15 is a conceptual diagram of a projected image display by the apparatus shown in FIG.
16 is a conceptual diagram of a projected image display by the apparatus shown in FIG.
FIG. 17 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 18 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 19 is a block diagram of an image processor in the apparatus shown in FIG.
20 is a conceptual diagram of φ scanning by the apparatus shown in FIG.
[Explanation of symbols]
2 Ultrasonic probe 6 Transmission / reception unit 8 Actuator 10 B mode 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 DSC
146 Image memory 148 Image processor 482 Tomographic image forming unit 484 Line image forming unit 486 Projected image forming unit 488 Cross correlation operation unit

Claims (4)

A tomographic image is formed by scanning an ultrasonic beam transmitted from an ultrasonic probe over an imaging target into which a contrast agent has been injected over a two-dimensional region, and the ultrasonic probe is gradually moved to form an image of the tomographic image. An ultrasonic imaging apparatus that performs scanning of a three-dimensional region of the ultrasonic beam by forming a plurality of tomographic images having different positions in the thickness direction,
The ultrasonic probe transmits a high-intensity ultrasonic beam that destroys the contrast agent bubble and a low-intensity ultrasonic beam that does not destroy the contrast agent bubble,
A tomographic image forming means for forming a tomographic image of the two-dimensional region based on an echo received from the imaging target;
A calculation means for performing a cross-correlation calculation for two tomographic images formed by transmitting an ultrasonic beam having a low intensity;
Line image forming means for projecting image data of a tomographic image formed by transmitting the ultrasonic beam having a high intensity in a certain direction to form a line image for the tomographic image;
A projection image forming means for arranging the line images in parallel in the formation order to form a projection image;
The ultrasonic beam having the high intensity is transmitted to form a tomographic image. Next, the ultrasonic beam having the low intensity is transmitted to form a first tomographic image, the ultrasonic probe is moved, and the ultrasonic probe is moved. When an ultrasonic beam having a low intensity is transmitted to form a second tomographic image and the cross-correlation calculation is performed on the first and second tomographic images, When the ultrasonic probe is moved, a high-intensity ultrasonic beam is transmitted to form a tomographic image, and when the correlation exceeds a predetermined value, the ultrasonic probe is further moved to increase the intensity. Ultrasonic imaging comprising: a control unit that repeats the process of transmitting a small ultrasonic beam to form a third tomographic image, and performing a cross-correlation calculation on the first and third tomographic images. apparatus. The ultrasonic imaging apparatus according to claim 1,
The two-dimensional region scanned by the ultrasonic beam is a sector scan of a sector ultrasonic probe, a linear scan of a linear array ultrasonic probe, or a linear scan of a convex array ultrasonic probe. A characteristic ultrasonic imaging apparatus. The ultrasonic imaging apparatus according to claim 1 or 2,
The three-dimensional region in which the ultrasonic beam is scanned is obtained by moving the ultrasonic probe in parallel with the thickness direction of the tomographic image, or the ultrasonic probe is used with the scanning direction of the two-dimensional region as the rotation axis. An ultrasonic imaging apparatus characterized by being caused to swing. The ultrasonic imaging apparatus according to any one of claims 1 to 3,
An ultrasonic imaging apparatus comprising an actuator for moving the ultrasonic probe.

Images