JP3936450B2 - Projection image generation apparatus and medical image apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a projection image display method, a projection image generation method and apparatus, and a medical image apparatus, and in particular, a projection image display method for displaying a projection image while rotating the projection image, and a projection image for sequentially generating projection images while changing the projection direction The present invention relates to a generation method and apparatus, and a medical image apparatus provided with such a projection image generation apparatus.
[0002]
[Prior art]
For example, when a three-dimensional region in a subject is scanned with ultrasound and the internal state of the region is imaged based on an echo reception signal, the image data (data) in the three-dimensional coordinate space is, for example, A projection image is obtained by performing maximum intensity projection or minimum intensity projection.
[0003]
When the image data is based on an echo Doppler signal (Doppler image), a projection image such as a blood flow is obtained by the maximum value projection. Among Doppler images, a PDI (power Doppler indication) image showing a two-dimensional distribution of power of a Doppler signal is suitable for maximum value projection, but a CFM (color flow) showing a two-dimensional distribution of a flow velocity such as blood flow. mapping) images can also be used. When the image data is an echo intensity signal (B mode image), a projection image such as blood flow is obtained by minimum value projection.
[0004]
A plurality of such projected images are generated by changing the projection direction, and are sequentially displayed to obtain a continuously rotated projection image. In a rotating projection image, there is a difference in the movement of each part of the projection image according to the distance from the center of rotation, so by observing such movement, the front-rear relationship of each part of the projection image is grasped, and the three-dimensional display image The target shape is recognized.
[0005]
[Problems to be solved by the invention]
As described above, when recognizing the three-dimensional shape of the display image based on the rotating projection image, depending on the observer, the rotation direction of the image appears to be reversed, and the front-rear relationship of each part is confused, resulting in a three-dimensional shape. May not be recognized. That is, the above method has a problem that individual differences occur in recognition of a three-dimensional shape according to the impression forming ability of the observer.
[0006]
The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a projection image display method, a projection image generation method and apparatus, and such a projection image that facilitate the recognition of a three-dimensional shape. It is to realize a medical image device provided with a generation device.
[0007]
[Means for Solving the Problems]
(1) A first invention for solving the above-described problem is a projection image display method for displaying a projection image while rotating the projection image. The projection image is a flat projection image whose relative position is fixed with respect to the projection image. It is displayed with an image.
(2) A second invention for solving the above problem is a projection image generation method for sequentially generating projection images while changing the projection direction based on image data in a three-dimensional coordinate space, wherein the three-dimensional coordinate space A plane projection image is generated together with the projection image.
[0008]
(3) A third invention that solves the above-described problem is a projection image generation device that sequentially generates projection images based on image data in a three-dimensional coordinate space while changing the projection direction. Image generating means for generating a flat projection image together with the projection image.
[0009]
(4) According to a fourth invention for solving the above-described problem, a medical image acquisition unit that acquires an image data of a three-dimensional coordinate space by imaging a three-dimensional region in a subject, and the medical image acquisition unit Image generation means for sequentially generating a projection image based on image data and a projection image of a plane in the three-dimensional coordinate space while changing the projection direction.
[0010]
In the first to fourth aspects of the invention, it is preferable that the projection image is formed by maximum value projection from the viewpoint of obtaining a blood flow image based on an ultrasonic Doppler image.
In the first to fourth aspects of the invention, it is preferable that the projection image is formed by minimum value projection from the viewpoint of obtaining a blood flow image based on an ultrasonic B-mode image.
[0011]
In the first to fourth aspects of the invention, it is preferable that the projected image of the plane has a pattern on the surface from the viewpoint of easy identification.
In the second to fourth aspects of the invention, it is preferable that the projected image is accompanied by a hexahedron ridge line image representing the three-dimensional coordinate space from the viewpoint of facilitating the three-dimensional grasp of the projected image.
[0012]
In the fourth aspect of the invention, it is preferable that the projected image of the plane is a tomographic image of the subject in order to clarify the positional relationship of the projected image in the body.
(Function)
In the present invention, a projection image of a plane whose relative position is fixed with respect to the projection image is generated to help the recognition of the three-dimensional shape.
[0013]
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.
[0014]
FIG. 1 shows a block diagram of a medical image apparatus. This apparatus is an example of an embodiment 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.
[0015]
(Constitution)
The configuration of this apparatus will be described. As shown in FIG. 1, the apparatus includes a signal sampling unit 2. The signal collection unit 2 collects a signal for generating a medical image from the subject 4.
[0016]
The signal collection unit 2 may be in various forms depending on the type of medical image apparatus. For example, in an ultrasonic imaging apparatus, an ultrasonic probe that transmits ultrasonic waves into the subject 4 and receives echoes thereof is used. In an X-ray CT (computed tomography) apparatus, a gantry having an X-ray irradiation / detection system for scanning the subject 4 is used. In a magnetic resonance imaging (MRI) apparatus, a magnet system that collects a signal from a subject 4 using magnetic resonance is used. Any of such signal sampling units 2 can use existing ones. Other medical image apparatuses can also be used according to their types.
[0017]
The signal collection unit 2 is connected to the image generation unit 6 and inputs a signal collected from the subject 4 to the image generation unit 6. The image generation unit 6 generates an image based on the signal input from the signal collection unit 2. The signal collection unit 2 and the image generation unit 6 are an example of an embodiment of a medical image acquisition unit in the present invention.
[0018]
The image generation unit 6 may be in various forms depending on the type of medical image apparatus. For example, in an ultrasonic imaging apparatus, an apparatus that obtains a B-mode image based on the intensity of an ultrasonic echo or an apparatus that obtains a Doppler image based on an echo Doppler signal is used. Doppler images include PDI images and CFM images.
[0019]
In the X-ray CT apparatus, an apparatus (computer or the like) that reprojects projection data of a plurality of views of the subject 4 and reconstructs a tomographic image is used. In the MRI apparatus, an apparatus (such as a computer) that reconstructs an image by inverse Fourier (Fourie) transformation of a magnetic resonance signal is used. Any of these image generators 6 can be used. Other medical image apparatuses can also be used according to their types.
[0020]
An image processing unit 8 is connected to the image generation unit 6. The image processing unit 8 captures the image generated by the image generation unit 6 and performs image processing for generating a projection image. The image processing unit 8 is an example of an embodiment of image generation means in the present invention. The image processing unit 8 is configured using, for example, a computer. The image processing unit 8 will be described later.
[0021]
A display unit 10 is connected to the image processing unit 8 to display an image output from the image processing unit 8 and other information. The display unit 10 is composed of, for example, a color graphic display device.
[0022]
The signal collecting unit 2, the image generating unit 6, the image processing unit 8, and the display unit 10 are connected to the control unit 14. The control unit 14 is configured using, for example, a computer. The control unit 14 gives control signals to these units to control their operation. In addition, a status notification signal or the like is input from each unit to the control unit 14.
[0023]
An operation unit 16 is connected to the control unit 14 so that various commands and information can be input by the operator. The operation unit 16 includes, for example, an operation console provided with a keyboard and other operation tools. The image processing unit 8, the display unit 10, the control unit 14, and the operation unit 16 are an example of the embodiment of the projection image generation apparatus of the present invention.
[0024]
FIG. 2 shows a block diagram of the image processing unit 8. As shown in the figure, the image processing unit 8 has an image memory 80. The image memory 80 stores image data 30 input from the image generation unit 6 as shown in FIG. 3, for example. The image data 30 is image data relating to a three-dimensional region in the subject 4. x, y, z are coordinate axes perpendicular to each other.
[0025]
The image data 30 is configured by image data representing a plurality of tomographic images 302 of the subject 4. The tomographic image 302 is an image of a cross section parallel to the xz plane. The plurality of tomographic images 302 have different positions on the y-axis. The tomographic image 302 includes a blood flow image 304. The tomographic image and the blood flow image are represented by a single location.
[0026]
The image memory 80 is connected to the arithmetic unit 82. The arithmetic device 82 generates a projection image based on the image data 30 in the image memory 80. The projection image is generated by maximum value projection when the blood flow image 304 is obtained as a high-luminance image such as a Doppler image or a contrast image. On the other hand, when a low-luminance image is obtained like a blood flow image in an ultrasonic B-mode image, a projection image is generated by minimum value projection.
[0027]
Specifically, the projection direction 32 is set in the three-dimensional coordinate space shown in FIG. 3, and a projection image on the projection plane 34 set perpendicular to the projection direction 32 is obtained. For this purpose, a plurality of grid points 36 corresponding to the pixels of the projection image are set on the projection plane 34, and a line of sight 38 parallel to the projection direction 32 is set for each grid point 36. Note that the grid points and the line of sight are represented by a single location.
[0028]
Then, as the image data of the lattice point 36, for example, as shown in FIG. 4A, the maximum value projection image is obtained by adopting the maximum value of the image data (pixel value) on the line of sight 38. Further, for example, as shown in FIG. 5B, the minimum value projection image is obtained by adopting the minimum value of the image data on the line of sight 38.
[0029]
In obtaining the projection image, the arithmetic unit 82 adds the image data of the planar image 306 to the back of the image data 30 in the y direction, for example, in the three-dimensional coordinate space as shown in FIG. Perform projection or minimum projection. The planar image 306 is, for example, an image of a plane (xz plane) parallel to the tomographic image 302, and the pixel values thereof are uniform over the entire surface, for example.
[0030]
The pixel value of the planar image 306 is set to a value smaller than the pixel value of the blood flow image 304 but larger than the pixel value of an image other than the blood flow image 304 in the case of maximum value projection, and in the case of minimum value projection, for example, The value is larger than the pixel value of the blood flow image 304 but smaller than the pixel value of an image other than the blood flow image 304. A specific method for setting such values will be described later.
[0031]
When a projection image is generated as described above from the image data 30 to which the planar image 306 is added, the image data of the blood flow image 304 is projected on the line of sight 38 that has passed through the portion where the blood flow image 304 exists. The image data of the planar image 306 is obtained as a projection value on the line of sight 38 that has passed through the portion where the blood flow image 304 does not exist. Thus, for example, as shown in FIG. 5, a projection image composed of a combination of the blood flow image 304 and the planar image 306 is generated.
[0032]
The planar image 306 may have an appropriate graphic pattern such as a lattice pattern or a checkered pattern instead of a plane with uniform pixel values. This is preferable in terms of improving the distinguishability of the planar image 306.
[0033]
In the case of maximum value projection, the planar image 306 may be formed of image data having a larger value (higher brightness) than the image data of the blood flow image 304. However, in order to preferentially project the blood flow image 304 in front of the planar image 306, the following method is generally used.
[0034]
That is, for example, as shown in FIG. 6, in the process of determining an appropriate threshold value d for the pixel value and sequentially obtaining the maximum value in the depth direction along the line of sight 38, the pixel value once exceeds the threshold value d. Next, when it falls below the threshold value d, the search for the maximum value is terminated. Thus, the maximum value obtained so far becomes the projection value. Therefore, at this time, the pixel value of the innermost plane image 306 in the direction of the line of sight 38 is not projected regardless of the value, and a projection image of the blood flow image 304 can be obtained. Needless to say, the pixel value of the planar image 306 is projected where the line of sight 38 does not pass through the blood flow image 304. A specific example of such maximum value search will be described later.
[0035]
If this method is used, the image data that gives the brightness and pattern of the planar image 306 may have a larger value than the image data of the blood flow image 304, and the restriction on the image data forming the planar image 306 can be eliminated. it can. Therefore, when the tomographic image 302 is a Doppler image, the planar image 306 can be a B-mode image of the innermost cross section in the y direction, and the high-intensity portion of the B-mode image is in front of the blood flow image 304. Never go out. The use of the B-mode image in this way is preferable in that the positional relationship between the blood flow image 304 and the body tissue is clarified.
[0036]
A frame memory 84 is connected to the arithmetic unit 82. The frame memory 84 stores the image data of the projection image generated by the arithmetic unit 82 as described above.
[0037]
The image data in the frame memory 84 is given to the display unit 10 and displayed as a visible image as shown in FIG. 7, for example. In FIG. 7, the blood flow image 304 and the planar image 306 are displayed with different brightness or color based on the difference in pixel values so that the observer can distinguish them. When the planar image 306 is a pattern image or a B-mode image, it is not always necessary to change the color. For the convenience of the observer, it is preferable to display the ridge lines of the hexahedron 308 representing the three-dimensional coordinate space in which the image data 30 is present at the time of display.
[0038]
The arithmetic unit 82 generates the projected images one by one while changing the projection direction 32 little by little. By sequentially displaying projected images with slightly different projection directions 32 on the display unit 10, a visual effect as if the image is rotating is obtained.
[0039]
FIG. 8 shows a display example of such an image. FIG. 8B is a projection image that is projected directly on the xz plane in FIG. 3. From this state, by projecting the projection direction to the left and right with respect to the xz plane, it is shown in FIG. 8A or FIG. As described above, the shapes of the blood flow image 304 and the planar image 306 change, and the position of the ridge line indicating the hexahedron 308 changes.
[0040]
The display image that changes in this way visually gives the impression that the blood flow image 304 protrudes from the planar image 306, so that the sense of depth becomes clear and the three-dimensional shape of the blood flow image 304 is recognized. It becomes easy. Also, the direction of rotation can be clearly recognized.
[0041]
The arrangement of the planar image 306 is not limited to the innermost part in the y direction, and may be placed in the middle of the series of tomographic images 302. In such a case, for example, as shown in FIG. 9, the blood flow image 304 is displayed so as to penetrate the planar image 306. Even in such a display image, the three-dimensional shape of the blood flow image 304 can be easily grasped by relying on the planar image 306.
[0042]
The planar image 306 does not need to be parallel to the xz plane and may be any image whose position is fixed in the three-dimensional coordinate space.
(Operation)
The operation of this apparatus will be described. Based on a command given from the operator through the operation unit 16, the operation of the apparatus proceeds under the control of the control unit 14.
[0043]
FIG. 10 shows a flow chart of the operation of this apparatus.
First, in step 502, a medical image of the subject 4 is acquired. That is, a signal is collected from the subject 4 by the signal collection unit 2 and an image is generated by the image generation unit 6 based on the signal. Signal collection is performed on a three-dimensional region in the body of the subject 4, and an image of the three-dimensional region is generated based on the three-dimensional region. As shown in FIG. 3, the images are generated as a plurality of tomographic images 302 in a three-dimensional region in the subject 4.
[0044]
Signal acquisition and image generation of a three-dimensional region are performed by, for example, performing three-dimensional scanning in which an ultrasonic probe is gradually moved perpendicularly to an ultrasonic scanning surface and capturing a tomographic image of each cross section in an ultrasonic imaging apparatus. Do. In the case of an X-ray CT apparatus or an MRI apparatus, imaging is performed by multi-slice scan. In that case, a contrast agent or the like is injected into the subject 4 in advance as necessary.
[0045]
Next, in step 504, the captured image is taken into the image memory 80. As a result, the image data 30 is stored in the image memory 80.
Next, in step 506, the operator designates the type of the planar image 306 and the arrangement in the three-dimensional coordinate space and designates the projection direction through the operation unit 16. The projection direction is specified, for example, in increments of 1 ° within a range of 45 ° to the left and right around the direction facing the xz plane. However, the present invention is not limited to this, and a plurality of desired directions in the three-dimensional coordinate space may be arbitrarily designated.
[0046]
Next, in step 508, the calculation device 82 generates a projection image. Projection images are generated sequentially in a plurality of designated projection directions. The projection image generation method is as described above.
[0047]
Next, in step 510, image display is performed. Thereby, the projection image is displayed on the display unit 10. As the projection direction changes, the shape of the display image changes, for example, as shown in FIG. 8, giving the viewer the impression that the image is rotating. At this time, since the planar image 306 is included in the rotated image, the three-dimensional shape of the blood flow image 304 can be easily grasped by using it. Also, the rotation direction of the image can be clearly identified.
[0048]
The above is an example in which a medical image apparatus is provided with a projection image generation function. ), Work station, personal computer, etc., separate from the medical imaging device, connect to the medical imaging device to obtain the captured image, and based on that, project as described above Of course, an image may be generated. In this case, a doctor console, a workstation, a personal computer, or the like is an example of an embodiment of the projection image generation apparatus according to the present invention.
[0049]
(Examples of specific embodiments of the invention)
Next, a case where the medical image apparatus is an ultrasonic imaging apparatus will be described as a specific example. FIG. 11 is a block diagram of the ultrasonic imaging apparatus. An ultrasonic imaging apparatus is an example of an embodiment of the medical imaging apparatus of the present invention.
[0050]
The configuration of this apparatus will be described. As shown in FIG. 11, the present apparatus has an ultrasonic probe 72. The ultrasonic probe 72 has an ultrasonic transducer array (not shown). The ultrasonic transducer array is formed along, for example, an arc projecting forward. That is, the ultrasonic probe 72 is a convex probe. The ultrasonic probe 72 is used in contact with the subject 74 by an operator (not shown).
[0051]
The ultrasonic probe 72 is connected to the transmission / reception unit 76. The transmission / reception unit 76 transmits a ultrasonic wave into the subject 74 by giving a drive signal to the ultrasonic probe 72. The transmission / reception unit 76 also receives an echo signal from the subject 74 received by the ultrasonic probe 72.
[0052]
A block diagram of the transmission / reception unit 76 is shown in FIG. In the drawing, a transmission timing (timing) generation circuit 602 periodically generates a transmission timing signal and inputs it to a transmission beamformer 604.
[0053]
The transmission beamformer 604 is based on the transmission timing signal, and transmits a beam forming signal, that is, a plurality of drives that drive a plurality of ultrasonic transducers (transducers) in the ultrasonic transducer array with a time difference. A signal is generated and input to the transmission / reception switching circuit 606.
[0054]
The transmission / reception switching circuit 606 inputs a plurality of drive signals to a selector 608. The selector 608 selects a plurality of ultrasonic transducers constituting a transmission aperture from the array of ultrasonic transducers, and supplies a plurality of drive signals to them.
[0055]
The plurality of ultrasonic transducers respectively generate a plurality of ultrasonic waves having a phase difference corresponding to the time difference between the plurality of drive signals. An ultrasonic beam is formed by wavefront synthesis of these ultrasonic waves. The transmission direction of the ultrasonic beam is determined by the transmission aperture selected by the selector 608.
[0056]
Transmission of the ultrasonic beam is repeatedly performed at regular time intervals by a transmission timing signal generated by the transmission timing generation circuit 602. The transmission direction of the ultrasonic beam is sequentially changed by switching the transmission aperture with the selector 608. As a result, the inside of the subject 74 is scanned by sound rays formed by the ultrasonic beam. That is, the inside of the subject 74 is scanned in a sound ray sequence.
[0057]
The selector 608 also selects a plurality of ultrasonic transducers constituting the reception aperture from the array of ultrasonic transducers, and inputs the plurality of echo signals received by the ultrasonic transducers to the transmission / reception switching circuit 606. It has become.
[0058]
The transmission / reception switching circuit 606 is configured to input a plurality of echo signals to the reception beam former 610. The receiving beam former 610 adjusts the phase by giving a time difference to a plurality of echo reception signals, and then adds them to form a beam forming of the reception wave, that is, an echo reception signal on the reception sound ray. Yes. The selector 608 scans the received sound ray in accordance with the transmission.
[0059]
For example, scanning shown in FIG. 13 is performed by the ultrasonic probe 72 and the transmission / reception unit 76. That is, as shown in the figure, when the sound ray 202 emitted from the radiation point 200 moves on the arc 204, the fan-shaped two-dimensional region 206 is scanned in the θ direction, and so-called convex scan is performed. When the sound ray 202 is extended in a direction opposite to the ultrasonic wave transmission direction (z direction), all the sound rays intersect at one point 208. A point 208 is a divergence point of all sound rays. The operator performs three-dimensional scanning by gradually moving the ultrasonic probe 72 in a direction perpendicular to the two-dimensional region 206.
[0060]
The transmission / reception unit 76 is connected to the B-mode processing unit 10 and the Doppler processing unit 12. The echo reception signal for each sound ray output from the transmission / reception unit 76 is input to the B-mode processing unit 710 and the Doppler processing unit 712. A portion including the ultrasonic probe 72, the transmission / reception unit 76, the B-mode processing unit 710, and the Doppler processing unit 712 is an example of an embodiment of the medical image acquisition unit in the present invention.
[0061]
The B mode processing unit 710 forms B mode image data. The B-mode processing unit 710 includes a logarithmic amplification circuit 102 and an envelope detection circuit 104 as shown in FIG. The B-mode processing unit 710 logarithmically amplifies the echo reception signal by the logarithmic amplification circuit 102, detects the envelope by the envelope detection circuit 104, and indicates a signal indicating 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 by using each instantaneous amplitude of the A scope signal as a luminance value.
[0062]
The Doppler processing unit 712 forms Doppler image data. As shown in FIG. 15, the Doppler processing unit 712 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. Yes.
[0063]
The Doppler processing unit 712 performs quadrature detection on 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 by the average flow velocity calculation circuit 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.
[0064]
As a result, the blood flow in the subject 74 and other data representing the average flow velocity and dispersion of the Doppler signal source (hereinafter referred to as blood flow or the like) and the power of the Doppler signal, that is, Doppler image data is stored for each sound ray. Is obtained. 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.
[0065]
The B mode processing unit 710 and the Doppler processing unit 712 are connected to the image processing unit 714. The image processing unit 714 is an example of an embodiment of image generation means in the present invention. The image processing unit 714 generates a projection image based on data input from the B-mode processing unit 710 and the Doppler processing unit 712, respectively.
[0066]
As shown in FIG. 16, the image processing unit 714 includes a sound ray data memory 142, a digital scan converter 144, an image memory 146, and an image processor connected by a bus 140. (prosessor) 148 is provided.
[0067]
The B-mode image data and Doppler image data input for each sound ray from the B-mode processing unit 710 and the Doppler processing unit 712 are stored in the sound ray data memory 142, respectively. As a result, a sound ray data space is formed in the sound ray data memory 142.
[0068]
The digital scan converter 144 converts sound ray data space data into physical space data by scan conversion. 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. The image processor 148 performs predetermined data processing on the data in the sound ray data memory 142 and the image memory 146, respectively. The details of the data processing will be described later.
[0069]
A display unit 716 is connected to the image processing unit 714. The display unit 716 receives an image signal from the image processing unit 714 and displays an image based on the image signal. Note that the display unit 716 can display a color image.
[0070]
The transmission / reception unit 76, B-mode processing unit 710, Doppler processing unit 712, image processing unit 714, and display unit 716 are connected to the control unit 718. The control unit 718 gives a control signal to each of these units to control its operation. Various notification signals are input from each part to be controlled. Under the control of the control unit 718, the B mode operation and the Doppler mode operation are executed.
[0071]
An operation unit 720 is connected to the control unit 718. The operation unit 720 is operated by an operator, and inputs desired commands and information to the control unit 718. The operation unit 720 is configured by an operation panel including a keyboard and other operation tools, for example.
[0072]
The operation of this apparatus will be described. The operator abuts the ultrasonic probe 72 on a desired portion of the subject 74 and operates the operation unit 720 to perform imaging using, for example, both the B mode and the Doppler mode. Imaging is performed by time-division operation in the B mode and the Doppler mode under the control of the control unit 718. That is, for example, every time the Doppler mode scan is performed several times, the mixed scan of the B mode and the Doppler mode is performed at a rate of performing the B mode scan once. The operator takes an image of the three-dimensional region while moving the ultrasonic probe 72 perpendicularly to the scan plane.
[0073]
In the B mode, the transmission / reception unit 76 scans the inside of the subject 74 in the order of sound rays through the ultrasonic probe 72 and receives the echoes one by one. The B-mode processing unit 710 logarithmically amplifies the echo reception signal input from the transmission / reception unit 76 by the logarithmic amplifier circuit 102, detects the envelope by the envelope detection circuit 104, obtains an A scope signal, and based on that, obtains an A scope signal. B-mode image data is formed.
[0074]
The image processing unit 714 stores the B-mode image data for each sound ray input from the B-mode processing unit 710 in the sound ray data memory 142. As a result, a sound ray data space for B-mode image data is formed in the sound ray data memory 142. By performing imaging on a three-dimensional area, a three-dimensional sound ray data space is formed.
[0075]
In the Doppler mode, the transmission / reception unit 76 scans the inside of the subject 74 in the order of sound rays through the ultrasonic probe 72 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.
[0076]
The Doppler processing unit 712 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 calculates the average flow velocity by the average flow velocity calculation circuit 126 from the autocorrelation result. , The variance is obtained by the dispersion operation circuit 128, and the power is obtained by the power operation circuit 130.
[0077]
Each of these calculated values becomes Doppler image data representing, for each sound ray, an average flow velocity such as a blood flow, its dispersion, and the power of the Doppler signal. The MTI processing in the MTI filter 122 is performed using a plurality of echo reception signals per sound ray.
[0078]
The image processing unit 714 stores the Doppler image data for each sound ray input from the Doppler processing unit 712 in the sound ray data memory 142. At this time, the Doppler image data is written as CFM image image data obtained by adding dispersion to the flow velocity and image data for power Doppler images. The B-mode image, CFM image, and power Doppler image are written in separate areas.
[0079]
As a result, sound ray data spaces for CFM image data and power Doppler image data are formed. By performing imaging on a three-dimensional area, a three-dimensional sound ray data space is formed. That is, sound ray image data similar to the three-dimensional image data 30 shown in FIG. 3 is formed in the sound ray data memory 142 for the B-mode image, the CFM image, and the power Doppler image, respectively.
[0080]
The image processor 148 scans and converts the B-mode image data, the CFM image data, and the power Doppler image data in the sound ray data memory 142 by the digital scan converter 144 and writes them in the image memory 146. The image processor 148 writes the B-mode image, CFM image, and power Doppler image in separate areas. As a result, the three-dimensional image data 30 shown in FIG. 3 is obtained for each of the B-mode image, the CFM image, and the power Doppler image.
[0081]
The B-mode image shows a tomographic image of the body tissue on the scan plane. The CFM image is an image showing a two-dimensional distribution of velocity such as blood flow on the scan plane. The power Doppler image is an image indicating the location of blood flow or the like on the scan plane.
[0082]
The operator operates the operation unit 720 to display a B-mode image, a CFM image, or a power Doppler image on the display unit 716 and observe a desired cross section, and diagnoses a lesion. In displaying the CFM image or the power Doppler image, the B-mode image and the CFM image (or the power Doppler image) are synthesized, and for example, as shown in FIG. 17, the CFM image (or the power Doppler image) is formed on the tomographic image 160 of the tissue. Image) 162 is displayed in a superimposed manner, and a state of blood flow or the like is diagnosed in association with a tomographic image of a body tissue.
[0083]
The tomographic image 160 of the tissue is displayed as a monochrome image. The CFM image (or power Doppler image) 162 is displayed as a color image. The CFM image represents the blood flow directions opposite to each other by, for example, red and blue, shows the flow velocity by their luminance, and shows the dispersion of the flow velocity by the degree of green contamination. The power Doppler image is displayed in, for example, a pink color and indicates the signal intensity with the luminance. At this time, a color bar 164 is simultaneously displayed on the screen, and a reference for reading the flow velocity (or signal intensity) from the CFM image (or power Doppler image) 162 is used. Note that when only the B-mode image is displayed, the color bar 164 is changed to a gray scale.
[0084]
Next, generation of a projection image by this apparatus will be described. Below, the example which produces | generates a projection image by maximum value projection about a power Doppler image is demonstrated.
First, the operator sets the pixel value of the planar image 306 shown in FIG. In setting the pixel value, for example, the operator causes the display unit 716 to display a histogram of the pixel value of the power Doppler image, as shown in FIG. On the histogram, the pixel value p1 of the planar image 306, for example, a pixel value p1 smaller than the pixel value of the blood flow image or larger than the pixel value of the non-blood flow image, or A pixel value p2 larger than the pixel value is designated. The pixel value p <b> 1 or the pixel value p <b> 2 gives luminance when displaying the planar image 306.
[0085]
The operator also designates the display color of the designated pixel value p1 or p2. For the pixel value p1 smaller than the pixel value of the blood flow image, for example, a blue color is designated. For the pixel value p2 larger than the pixel value of the blood flow image, for example, an orange color is designated. Hereinafter, an example in which the pixel value is p2 and the display color is an orange system will be described.
[0086]
Next, the operator designates the arrangement of the planar image 306. Thereby, for example, the innermost position in the y direction in FIG. 3 is designated as the position of the planar image 306.
Next, the operator designates the projection direction of the image data 30. Thereby, for example, a range of 45 ° left and right around the direction (y direction) facing the cross section 302 in the plane parallel to the xy plane in FIG. 3 is specified in increments of 1 °.
After the above setting or designation, the operator commands generation of a power Doppler image projection image by maximum value projection. Thereafter, a projection image is generated under the control of the control unit 718.
[0087]
The projection image is generated by the image processor 148, for example, on the image data 30 relating to the power Doppler image stored in the image memory 146. The image data 30 is added with the image data of the planar image 306 set as described above. Note that the projection image may be generated using the sound ray image data in the sound ray data memory 142 as designated by the operator. However, in that case, it is necessary to convert the projection image into a physical space image later by the digital scan converter 144. Below, the example which produces | generates a projection image about the image data of the image memory 146 is demonstrated.
[0088]
FIG. 19 shows a flowchart for generating a projection image by maximum value projection (MIP) processing. As shown in the figure, a pixel to be processed, that is, a lattice point 36 on the projection plane 34 is selected (S1), and the image data (Doppler power value P) on the line of sight 38 corresponding to the selected pixel is MIP. Processing is performed (S2).
[0089]
Next, it is checked whether the threshold flag (flag) has already been set (S3). The threshold flag indicates whether or not the MIP-processed Doppler power value P has exceeded a threshold value (threshold value d in FIG. 6) designated in advance by the operator even once. The bit set to (register) is indicated by “1”.
[0090]
If the threshold flag is not set, if the MIP-processed Doppler power value P is equal to or greater than the threshold, the threshold flag is set. If the threshold flag is less than the threshold, the threshold flag is not set. (S4, S5).
[0091]
Next, it is determined whether or not MIP processing has been performed for all image data in the depth direction of the line of sight 38 (S8), and if there is unprocessed image data, the process returns to the beginning. By repeating the above operation, MIP processing is sequentially performed on the image data in the depth direction of the line of sight 38. In this case, even if the threshold flag is already set, if the Doppler power value P is not less than the threshold, the MIP process is continued (S6, S8).
[0092]
On the other hand, when the threshold flag is already set and the Doppler power value P is less than the threshold, the MIP process for the selected pixel is terminated (S7). Thus, the MIP process for one grid point 36 is completed. In this way, the MIP process as shown in FIG. 6 is performed.
[0093]
When the MIP process for one pixel is completed, another pixel (grid point) on the projection plane 34 is selected and the same MIP process is repeated (S9). In this way, the MIP process for all the pixels on the projection plane 34 is executed.
[0094]
By the way, when the Doppler power value P includes noise having a substantially constant amplitude or a fibrillation component of the subject 74, a waveform such as noise once has a threshold value with a single threshold value as described above. If the value falls below the threshold value after exceeding the threshold value, the MIP processing may be aborted and correct MIP processing may not be performed. In such a case, two threshold values TH1 and TH2 are used instead of a single threshold value. Note that TH1> TH2.
[0095]
FIG. 20 shows a flowchart of the operation when two threshold values are used. In the figure, the condition for setting the threshold flag is that the Doppler power value is greater than or equal to the first threshold value TH1 (S4), and the condition for ending the MIP process is the second condition. Is less than the threshold value TH2 (S6). Other processes are the same as those shown in FIG.
[0096]
By operating according to this flowchart, for example, as shown in FIG. 21, when the Doppler power value P first exceeds the first threshold value TH1 and then falls below the second threshold value TH2, the MIP The process ends and the maximum value during that time can be obtained.
[0097]
On the other hand, when only the single threshold value TH1 is used, when the Doppler power value P once exceeds the threshold value due to the influence of noise or the like and then falls below it, as shown in FIG. It ends in error and the original maximum value cannot be obtained.
[0098]
By the MIP processing as described above, a projection image in one projection direction as shown in FIG. 8A is generated, for example. The projected images are sequentially changed, and corresponding projected images are generated one by one. By sequentially displaying such projection images on the display unit 716, it is possible to obtain a display image that rotates, for example, as in (a) → (b) → (c) of FIG.
[0099]
In such a display image, the blood flow image 304 is displayed in, for example, a pink color, the planar image 306 is displayed in, for example, an orange-based high luminance color, and the ridge line of the hexahedron 308 is displayed in, for example, white. By rotating the projection image with the plane image 306, the rotation direction becomes clear and the three-dimensional recognition of the blood flow image 304 becomes easy.
[0100]
【The invention's effect】
As described above in detail, according to the present invention, a projection image display method, a projection image generation method and apparatus, and a medical image including such a projection image generation apparatus, which facilitate the recognition of a three-dimensional shape. An apparatus can be realized.
[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 an example apparatus according to an embodiment of the present invention.
FIG. 3 is a conceptual diagram of projection image generation in an apparatus according to an example of an embodiment of the present invention.
FIG. 4 is a conceptual diagram of pixel value generation in an apparatus according to an example of an embodiment of the present invention.
FIG. 5 is a diagram showing an example of a projected image in an apparatus according to an example of an embodiment of the present invention.
FIG. 6 is a conceptual diagram of pixel value generation in an apparatus according to an example of an embodiment of the present invention.
FIG. 7 is a conceptual diagram of projected image display in an apparatus according to an example of an embodiment of the present invention.
FIG. 8 is a conceptual diagram of projected image display in an apparatus according to an example of an embodiment of the present invention.
FIG. 9 is a conceptual diagram of projected image display in an apparatus according to an example of an embodiment of the present invention.
FIG. 10 is a flowchart of the operation of the apparatus according to the example of the embodiment of the present invention.
FIG. 11 is a block diagram of an exemplary apparatus according to an embodiment of the present invention.
FIG. 12 is a block diagram of a transmission / reception unit in an apparatus according to an example of an embodiment of the present invention.
FIG. 13 is a conceptual diagram of sound ray scanning by an apparatus according to an example of an embodiment of the present invention.
FIG. 14 is a block diagram of a B-mode processing unit in an apparatus according to an example of an embodiment of the present invention.
FIG. 15 is a block diagram of a Doppler processing unit in an example apparatus according to an embodiment of the present invention;
FIG. 16 is a block diagram of an image processing unit in an apparatus according to an example of an embodiment of the present invention.
FIG. 17 is a conceptual diagram of image display in an apparatus according to an example of an embodiment of the present invention.
FIG. 18 is a conceptual diagram of histogram display in an apparatus according to an example of an embodiment of the present invention.
FIG. 19 is a flowchart of MIP processing of an apparatus according to an example of an embodiment of the present invention;
FIG. 20 is a flowchart of MIP processing of the apparatus according to the example of the embodiment of the present invention;
FIG. 21 is a conceptual diagram of pixel value generation in an apparatus according to an example of an embodiment of the present invention.
[Explanation of symbols]
2 Signal sampling unit
4 subjects
6 Image generator
8 Image processing unit
10 Display section
14 Control unit
16 Operation unit
80 image memory
82 Arithmetic unit
84 frame memory
30 Image data
32 Projection direction
34 Projection plane
36 grid points
38 eyes
302 Tomographic image
304 Blood flow image
306 Plane image
308 hexahedron
72 Ultrasonic probe
74 subjects
76 Transceiver
710 B-mode processing unit
712 Doppler processor
714 Image processing unit
716 display
718 control unit
720 operation unit
602 Transmission timing generation circuit
604 Transmitting beamformer
606 Transmission / reception switching circuit
608 selector
610 Receiving beamformer
102 Logarithmic amplifier circuit
104 Envelope detection circuit
120 Quadrature detection circuit
122 MTI filter
124 Autocorrelation circuit
126 Average flow velocity calculation circuit
128 Distributed arithmetic circuit
130 Power calculation circuit
140 Bus
142 Sound ray data memory
144 Digital scan converter
146 Image memory
148 image processor
200 Radiation point
202 Sound ray
204 arc
206 2D region
208 Divergence point

Claims (4)

A projection image generation device that sequentially generates projection images based on image data in a three-dimensional coordinate space while changing the projection direction,
Image generating means for generating a projection image of a plane in the three-dimensional coordinate space together with the projection image;
When the maximum value projection processing proceeds in the depth direction on each line of sight corresponding to each pixel on the projection plane, the projection image exceeds the predetermined threshold value and further proceeds in the depth direction. In addition, the projection image generation apparatus obtained by the maximum value projection process for ending the maximum value projection process on the line of sight when the value of the image data on the line of sight becomes less than the predetermined threshold. A projection image generation device that sequentially generates projection images based on image data in a three-dimensional coordinate space while changing the projection direction,
Image generating means for generating a projection image of a plane in the three-dimensional coordinate space together with the projection image;
When the maximum value projection processing is advanced in the depth direction on each line of sight corresponding to each pixel on the projection plane, the projection image has been processed further in the depth direction when the maximum value projected value exceeds the first threshold value. Sometimes, when the value of the image data on the line of sight is less than the second threshold value that is smaller than the first threshold value, the maximum value projection process that ends the maximum value projection process on the line of sight is obtained. A projection image generating apparatus characterized by the above. Medical image acquisition means for acquiring an image data of a three-dimensional coordinate space by imaging a three-dimensional region in a subject;
Image generation means for sequentially generating a projection image based on the image data acquired by the medical image acquisition means and a projection image of a plane in the three-dimensional coordinate space while changing the projection direction;
When the maximum value projection processing proceeds in the depth direction on each line of sight corresponding to each pixel on the projection plane, the projection image exceeds the predetermined threshold value and further proceeds in the depth direction. In addition, the medical image apparatus is obtained by a maximum value projection process for ending the maximum value projection process on the line of sight when the value of the image data on the line of sight becomes less than the predetermined threshold. Medical image acquisition means for acquiring an image data of a three-dimensional coordinate space by imaging a three-dimensional region in a subject;
Image generation means for sequentially generating a projection image based on the image data acquired by the medical image acquisition means and a projection image of a plane in the three-dimensional coordinate space while changing the projection direction;
When the maximum value projection processing is advanced in the depth direction on each line of sight corresponding to each pixel on the projection plane, the projection image has been processed further in the depth direction when the maximum value projected value exceeds the first threshold value. Sometimes, when the value of the image data on the line of sight is less than the second threshold value that is smaller than the first threshold value, the maximum value projection process that ends the maximum value projection process on the line of sight is obtained. A medical image apparatus characterized by the above.

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