JP2004229958A - Ultrasonic image processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the image synthesizing performance of an ultrasonic image processing device when forming panoramic images. <P>SOLUTION: A moving amount calculating section 20 is constituted of a translational moving amount calculating section 22, a rotational moving amount calculating section 24 and an end-of-calculation discriminating section 26. The translational moving amount calculating section 22 calculates the translational moving amount between two frames. The rotational moving amount calculating section 24 calculates the rotational moving amount between the two frames. The calculation of the translational and rotational moving amounts is repeatedly executed until a prescribed ending condition is met. The end-of-calculation discriminating section 26 discriminates the end of calculation based on the prescribed ending condition and, when the ending condition is met, brings the calculation of the moving amounts to an end. An image synthesizing section 30 forms a panoramic image by synthesizing a plurality of frames based on the calculated results in the moving amounts. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ultrasonic image processing apparatus, and more particularly, to an ultrasonic image processing apparatus that forms a panoramic image.
[0002]
[Prior art]
2. Description of the Related Art There is known an apparatus that forms a panoramic image by aligning and combining a plurality of two-dimensional ultrasonic images obtained while moving an ultrasonic probe on the surface of a living body.
[0003]
In the conventional apparatus, one of two consecutive frames is divided into a plurality of sub-image regions, a comprehensive image movement is estimated and evaluated from a local movement vector of the sub-image region, and two images are estimated based on the comprehensive image movement. A panoramic image is formed by combining two frames (see Patent Document 1).
[0004]
In another conventional apparatus, a vertical projection distribution in a designated area is obtained for each of two consecutive frames, and a horizontal movement amount between the frames is evaluated by matching the projection distributions of both frames. ing. Furthermore, the designated area is divided in the vertical direction, the amount of movement in the horizontal direction is obtained for each divided area, and the amount of rotational movement between frames is evaluated based on the difference in the amount of movement between divided areas (see Patent Document 2). .
[0005]
[Patent Document 1]
JP-A-8-280688
[Patent Document 2]
JP 2000-217815 A
[0006]
[Problems to be solved by the invention]
In general, a matching operation between images by a correlation method or the like requires a huge amount of calculation, so that a processing time becomes long. As in the device described in Patent Literature 1, in order to divide an image and obtain a local motion vector, it is necessary to perform a matching operation for each local area, so that the amount of operation is further increased. Therefore, the calculation processing time for forming a panoramic image increases, and it is difficult to form a panoramic image in real time.
[0007]
Further, the device described in Patent Document 2 evaluates a horizontal movement amount between frames, but does not evaluate a vertical movement amount. Therefore, when the movement of the ultrasonic probe is accompanied by the movement in the vertical direction, there is a problem in image synthesis accuracy.
[0008]
The present invention has been made in view of such a problem in the conventional apparatus, and an object of the present invention is to improve image combining performance in forming a panoramic image.
[0009]
[Means for Solving the Problems]
(1) In order to achieve the above object, an ultrasonic image processing apparatus according to the present invention provides ultrasonic image processing for forming a panoramic image by combining a plurality of frames obtained by moving an ultrasonic probe. An apparatus for calculating a translation amount between one frame and the other frame between two frames, wherein the reference area on one frame is sequentially translated while moving each translation position on the other frame. Translational movement calculating means for calculating the translational movement amount by performing a matching calculation with the corresponding area, and means for calculating a rotational movement amount between one frame and the other frame between the two frames. While the reference area on one frame is sequentially rotated and moved at each rotational movement position and matched with a corresponding area having a combined positional relationship based on the translation amount on the other frame. A panning image by forming the panoramic image by synthesizing the two frames based on the calculated translational and rotational movement amounts. And a panoramic image forming unit.
[0010]
In the above configuration, the ultrasonic probe may be a two-dimensional array probe capable of acquiring a three-dimensional ultrasonic image, or may be a probe for acquiring a two-dimensional ultrasonic image. In the case of a three-dimensional ultrasound image, a frame means a three-dimensional volume. Further, the translation and rotation of the reference area on one frame are relative to the other frame. The corresponding area is an area having substantially the same shape as the reference area corresponding to each movement position of the reference area on the other frame. The reference area may be the same area in the translational movement calculating means and the rotational movement amount calculating means, or may be different areas. According to the above configuration, the matching calculation of the rotational movement amount is performed while sequentially rotating the reference area in a state where the already calculated translational movement amount is considered. Therefore, the matching calculation of the rotational movement amount at the unnecessary translational position is eliminated, and the calculation amount of the matching calculation of the rotational movement amount can be reduced, and the calculation amount of the moving amount calculation can be reduced. .
[0011]
Preferably, each of the translational amounts of the translational amount and the rotational amount is performed at least once, and each of the movable amount calculations is performed in a corresponding area having a combined positional relationship based on the previously calculated amount of movement. Shall be. More preferably, each movement amount calculation of the translational movement amount and the rotational movement amount is respectively performed plural times. According to the above configuration, each movement amount calculation is performed a plurality of times, so that the calculation result of the movement amount becomes more accurate.
[0012]
Preferably, the matching calculation is a calculation based on a correlation between a plurality of pixel data in the reference region and a plurality of pixel data in the corresponding region. Alternatively, the matching operation is an operation based on a minimum sum absolute difference (MSAD) method.
[0013]
Preferably, the translation amount calculating means sequentially translates the reference area within the set search area. In the above configuration, the search area is set in anticipation of the translation position of the reference area. For example, it is set so as to surround the periphery of the reference area. According to the above configuration, since the matching calculation is performed in the search region, the calculation amount can be reduced as compared with the matching calculation for the entire frame while ensuring the calculation accuracy.
[0014]
Preferably, the search area is set to a smaller area as the number of times of each movement amount calculation increases. More preferably, the apparatus further includes a repetition end determining means for determining whether to end the calculation of the translational movement amount and the rotational movement amount performed a plurality of times. According to the above configuration, the determination conditions for the repetition end can be appropriately set, so that the calculation can be performed in consideration of the balance between the calculation accuracy and the calculation speed.
[0015]
Preferably, the repetition end determination means performs the calculation end determination based on an MSAD value calculated in the calculation by the minimum sum absolute difference (MSAD) method. More preferably, the repetition end determination means performs the calculation end determination based on the rate of change of the MSAD value. More preferably, the repetition end determination means determines that the calculation has ended when the number of calculations of the translational movement amount and the rotational movement amount has reached a predetermined number.
[0016]
Preferably, at least one of the reference areas for each of the movement amount calculations is a rectangular area. More preferably, the reference area in the rotational movement amount calculating means is a circular area. In the above configuration, the circular region may be a donut-shaped region in which the center of the circle is hollowed out, a ring-shaped region having only a circumferential portion, or a partially circular arc-shaped region.
[0017]
(2) In order to achieve the above object, an ultrasonic image processing apparatus according to the present invention provides an ultrasonic image processing apparatus that forms a panoramic image by combining a plurality of frames obtained by moving an ultrasonic probe. An image processing apparatus comprising: means for calculating the amount of rotational movement between one frame and the other frame between two frames, wherein one of the reference regions on one frame is sequentially rotated while the other at each rotational movement position. A rotation movement amount calculating means for calculating the rotation movement amount by performing a matching calculation with a corresponding area on a frame; and a means for calculating a translation movement amount between one frame and the other frame between the two frames. There is a reference region on one frame which is sequentially translated while each translation position is in correspondence with a corresponding region having a combined positional relationship based on the rotational movement amount on the other frame. A translational movement calculating means for calculating the translational movement by performing a switching operation; and forming the panoramic image by synthesizing the two frames based on the calculated translational and rotational movements. And a panoramic image forming unit.
[0018]
(3) In order to achieve the above object, a computer program according to the present invention provides a computer program for forming a panoramic image by synthesizing a plurality of frames obtained by moving an ultrasonic probe. A program for calculating a translation amount between one frame and the other frame between two frames, and sequentially translating a reference region on one frame while moving the reference region on the other frame at each translation position. A translational movement amount calculating means for calculating the translational movement amount by performing a matching calculation with the corresponding region, a means for calculating a rotational movement amount between one frame and the other frame between the two frames, On the other hand, the reference area on the frame is sequentially rotated, and at each rotational movement position, the combined positional relationship based on the translation amount on the other frame is determined. Rotation movement amount calculating means for calculating the rotation movement amount by performing a matching calculation with the corresponding region, and synthesizing the two frames based on the calculated translation movement amount and rotation movement amount, thereby obtaining the panorama. It is assumed that the computer functions as a panoramic image forming unit for forming an image.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 shows a preferred embodiment of an ultrasonic image processing apparatus according to the present invention, and FIG. 1 is a block diagram showing the overall configuration. The probe 10 transmits and receives ultrasonic waves to and from a space in a living body including a target tissue, for example, a blood vessel, while being in contact with the surface of the living body. The transmission / reception unit 12 transmits and receives ultrasonic waves via the probe 10 to acquire echo data from within a living body. The acquisition of the echo data is performed while moving the probe 10 on the surface of the living body, for example, along a blood vessel. Therefore, the transmission / reception unit 12 acquires the echo data in a frame unit corresponding to the position of the probe 10 on the surface of the living body. The movement of the probe 10 may be performed manually or mechanically by a user.
[0021]
The signal processing unit 14 performs a B-mode signal process on the echo data acquired by the transmission / reception unit 12 to form a two-dimensional B-mode image in frame units. In addition, the signal processing unit 14 may execute a predetermined process according to various operation modes. Specifically, Doppler signal processing, color Doppler signal processing, and the like may be executed. The movement amount calculation unit 20 calculates the movement amount between frames for the ultrasound image for each frame formed by the signal processing unit 14, for example, a two-dimensional B-mode image for each frame. The movement amount calculation unit 20 includes a translation movement amount calculation unit 22, a rotation movement amount calculation unit 24, and a calculation end determination unit 26.
[0022]
The translation amount calculation unit 22 calculates the translation amount between one frame and the other frame between the two frames. Further, the rotational movement amount calculation unit 24 calculates the rotational movement amount between one frame and the other frame between the two frames. The calculation of the translational movement amount and the calculation of the rotational movement amount are repeatedly executed until a predetermined termination condition is satisfied. The calculation end determination unit 26 determines the calculation end based on a predetermined end condition, and ends the movement amount calculation when the end condition is satisfied. The operations of the translational movement calculator 22, the rotational movement calculator 24, and the calculation end determiner 26 will be described later in detail.
[0023]
The image synthesizing unit 30 performs translation and rotation for each frame based on the movement amount calculated by the movement amount calculation unit 20, and forms a panoramic image by combining a plurality of frames. The formed panoramic image is displayed on the display unit 34.
[0024]
FIG. 2 is a diagram showing a panoramic image formed by the ultrasonic image processing device of FIG. The panoramic image shown in FIG. 2 is a panoramic image of the blood vessel 40 in the living body. That is, the ultrasonic images 42a, 42b, 42c, and 42d for each frame obtained by moving the probe along the blood vessel 40 on the surface of the living body are determined based on the amount of movement calculated for each frame. This is an image in which a plurality of corrected images are superimposed. As shown in FIG. 2, the image of the blood vessel 40 in each frame is acquired with a gradual shift depending on the position of the probe, and a plurality of frames are superimposed to form a continuous image of the long blood vessel 40. It is formed as one image.
[0025]
FIG. 3 is a diagram for explaining a calculation method of a movement amount calculation performed in the movement amount calculation unit 20 of the ultrasonic image processing apparatus of FIG. In FIG. 3, an ultrasonic image for each frame formed by the signal processing unit (reference numeral 14 in FIG. 1) is represented by an image n with a number n corresponding to the acquisition time. That is, the image n-1 corresponds to the frame at the time immediately before the image n.
[0026]
The translation amount calculation unit (reference numeral 22 in FIG. 1) sets a rectangular reference area 50 in the image n-1, as shown in FIG. The reference area 50 is set, for example, at the center of the image n-1 based on a user operation. The reference area 50 may be automatically set by the device. Next, the translation amount calculation unit 22 sets a search area 52 in the image n as shown in FIG. The search area 52 is set, for example, based on a user operation, and is set so as to surround a rectangular area 56 corresponding to a reference area position located at the center of the image n. The search area 52 may be automatically set by the device.
[0027]
The translation amount calculator 22 translates the rectangular area 56 corresponding to the reference area 50 within the set search area 52, and moves the image in the reference area 50 and the rectangular area 56 at each moving position of the rectangular area 56. A matching operation with the image is performed, and the match area 54 is specified. As the matching operation, an MSAD (Minimum-Sum-Absolute-Difference: minimum sum absolute difference) method is used. That is, in the search area 52 shown in FIG. 3B, the rectangular area 56 is moved up, down, left, and right, and a SAD (Sum-Absolute-Difference: sum absolute difference) value is calculated at each movement position. The area having the minimum value is specified as the match area 54.
[0028]
Here, the SAD value is the sum of absolute differences between pixel values of corresponding pixels between the reference area 50 of the image n-1 and the rectangular area 56 of the image n. The pixel value is a value corresponding to each pixel. For example, the luminance value of each pixel is a pixel value. When the pixel value is the luminance value of each pixel, the SAD value is obtained by calculating the absolute value of the difference between the luminance value of each pixel in the reference area 50 and the luminance value of the corresponding pixel in the rectangular area 56, for all the pixels in the area. The result is summation over the pixels. That is, if the image in the reference area 50 and the image in the rectangular area 56 completely match, the SAD value is 0. Generally, the smaller the SAD value, the higher the degree of approximation between the two images. Note that the matching operation performed in the translation amount operation unit 22 is not limited to the MSAD method, and a rectangular area 56 having the highest correlation is generally matched using a correlation method generally used for image matching. The area 54 may be determined.
[0029]
Next, as shown in FIG. 3B, the translation amount calculator 22 calculates the translation difference vector V between the rectangular area 56 before the translation corresponding to the reference area position and the match area 54. Calculate. That is, ΔX, which is the difference between the X coordinate of the center of gravity of the match area 54 and the X coordinate of the center of gravity of the rectangular area 56, and the difference between the Y coordinate of the center of gravity of the match area 54 and the Y coordinate of the center of gravity of the rectangular area 56. A certain ΔY is calculated. By specifying the translation difference vector V in this way, it is possible to specify to which position the image in the reference area 50 in the image n-1 has been translated in the image n, and accordingly, the image The translational relationship between n-1 and the image n is specified.
[0030]
When the translation difference vector V is calculated by the translation amount calculation unit 22, the rotation amount calculation unit (reference numeral 24 in FIG. 1), as shown in (c) of FIG. The rectangular area 58 in which the area is translated by the translation difference vector V is rotated, and a matching operation is performed between the image in the reference area 50 and the image in the rectangular area 58 at each rotational movement position of the rectangular area 58, and the match area Specify 60. The rotational movement amount calculation unit 24 sets the rectangular area 58 to a predetermined unit angle in the + θ direction and the −θ direction with the center of gravity P as the rotation center point, for example, 0.1 ° within a search range of + 3 ° to -3 °. The rotation is performed in units, and a matching operation is performed between the image in the reference area 50 and the image in the rectangular area 58 at each rotation position.
[0031]
As the matching operation, the above-described MSAD method is used. That is, the rectangular area 58 shown in FIG. 3C is rotated and moved by a predetermined angle unit, the SAD value is calculated at each rotational movement position, and the area where the SAD value is minimum is specified as the match area 60. Note that the matching calculation performed in the rotational movement amount calculation unit 24 is not limited to the MSAD method, and a rectangular area having the highest correlation is generally determined using a correlation method used for image matching. 60 may be determined. When the match area 60 is specified, the rotational movement difference Δθ between the rectangular area 58 before the rotational movement and the match area 60 is determined, as shown in FIG. Is specified. (As will be described later with reference to FIGS. 7 and 8, after the rotational movement relationship is specified, it is possible to further calculate the translational movement relationship.)
[0032]
In the above description, after the translational movement calculator 22 calculates the translational difference vector V, the rotational movement calculator 24 determines the rotational movement difference Δθ based on the calculation result. After calculating the rotational movement difference Δθ, the translational movement calculation unit 22 may determine the translational movement difference vector V based on the calculation result.
[0033]
Further, in the above description, the rotation / movement amount calculation unit 24 determines the rotation / movement difference Δθ by rotating / moving the rectangular area 58, but it is also possible to set an area specific to the rotation / movement instead of the rectangular area 58. is there.
[0034]
FIG. 4 is a diagram for explaining another calculation method of the rotation movement amount calculation performed in the rotation movement amount calculation unit 24 of the ultrasonic image processing apparatus of FIG. As shown in FIG. 4A, the rotational movement amount calculation unit 24 sets a ring-shaped area 70 as a reference area in the image n-1. The ring-shaped region 70 is a set of pixels on the circumference with a radius r that can be arbitrarily set. Further, based on the translation difference vector V calculated by the translation amount calculation unit 22, the rotation amount calculation unit 24 sets the ring-shaped region 70 in the image n to a position where the ring-shaped region 70 is translated by the translation difference vector V. (See FIG. 4 (b)). Then, the rotational movement amount calculation unit 24 extracts a luminance value, which is a pixel value of a pixel on the circumference, along each circumference of the ring-shaped area 70 and the corresponding area 72.
[0035]
FIG. 5 is a diagram showing luminance values of pixels on the circumference of each of the ring-shaped region 70 and the corresponding region 72 in FIG. 5, the horizontal axis represents the angle θ in FIG. 4, and the vertical axis represents the luminance value. The luminance value in the upper part (a) corresponds to the ring-shaped area 70, and the luminance value in the lower part (b) corresponds to the corresponding area 72. As shown in FIG. 5, there is a deviation of the angle Δθ between the luminance value of the ring-shaped area 70 in the upper part (a) and the luminance value of the corresponding area 72 in the lower part (b). Therefore, by calculating Δθ in FIG. 5 by the matching calculation, Δθ, which is the shift between the ring-shaped region 70 and the corresponding region 72, is determined. In this way, by using the ring-shaped region 70, it is possible to simplify the matching calculation in the rotational movement to the matching calculation for the one-dimensional data shown in FIG.
[0036]
FIG. 6 is a diagram illustrating another shape of the reference region used in the rotational movement amount calculation unit 24 of the ultrasonic image processing device in FIG. FIG. 6A illustrates a donut-shaped reference area, and the rotational movement amount calculation unit 24 obtains radial projection data from a center point in the donut-shaped area. The projection data is, for example, a value obtained by adding all luminance values of pixels in the same radial direction. The rotational movement amount calculation unit 24 performs the matching calculation by replacing the luminance values of the ring-shaped region 70 and the corresponding region 72 in FIG. 4 with the projection data of the donut-shaped region. That is, the vertical axis in FIG. 5 corresponds to the projection data. FIG. 6B shows a circular reference area. Radial projection data is obtained from the center point, and a matching calculation is performed in the same manner as in the case of the donut shape area.
[0037]
The reference area may have various setting positions and shapes. For example, by including a characteristic portion such as an edge or a contour of a living tissue in the reference region, the reference region can be made smaller and the processing time can be reduced. That is, in the ultrasound image, the statistic value such as the variance or difference of the local image is evaluated, and for example, by setting the reference region in a local region having a large variance, the Settings can be made.
[0038]
FIG. 7 is a flowchart showing a processing operation of forming a panoramic image by the ultrasonic image processing apparatus of FIG. The processing operation of forming a panoramic image will be described with reference to FIG. The configuration described in FIG. 1 will be described with the reference numerals in FIG.
[0039]
In step 1, the control unit 32 controls the transmission / reception unit 12 and the signal processing unit 14 to acquire an ultrasonic image for each frame. At this time, the probe 10 acquires a frame corresponding to each movement position while moving. In step 2, the movement amount calculation unit 20 sets a search area for the ultrasonic image (see FIG. 3). At this time, the search area is set so as to surround the periphery of the reference area. In step 3, the movement amount calculator 20 calculates the movement amounts ΔX, ΔY, Δθ (see FIG. 3).
[0040]
Next, in step 4, the calculation end determination unit 26 determines whether or not the movement amount calculation needs to be repeated. When the MSAD method is used as a matching calculation in the movement amount calculation in step 3 as a criterion for repetition determination, a normalized MSAD value is used. That is, if the normalized MSAD value is larger than the predetermined threshold value, it is determined that the repetition operation is necessary, and if the normalized MSAD value is equal to or less than the predetermined threshold value, it is determined that the repetition operation is unnecessary. Here, the normalized MSAD value is calculated as (MSAD / average value of pixel values in the reference area). When the correlation method is used for the matching operation, it may be determined that the repetition operation is necessary if the correlation coefficient is smaller than the predetermined threshold, and it may be determined that the repetition operation is unnecessary if the correlation coefficient is equal to or more than the predetermined threshold. .
[0041]
In addition, by making use of the fact that the MSAD value and the correlation coefficient settle down to a constant value by repeating the repeated calculation, it is determined whether or not the repeated calculation is necessary based on the change rate of the MSAD value and the correlation coefficient. Is also good. Furthermore, by providing an upper limit value for the number of repetitions, it may be determined that the calculation is completed when the number of repetitions is three, for example, based on the number of repetitions. If the calculation end determination unit 26 determines that repetition calculation is necessary, the process proceeds to step 5, and if it is determined that repetition calculation is unnecessary, the process proceeds to step 6.
[0042]
In step 5, the movement amount calculation unit 20 sets a search area for the next movement amount calculation. Since the match area is determined in step 3, the search area is set so as to surround the periphery of the match area. Further, the search area to be reset can be set smaller than the search area set last time. Then, returning to step 3, a new match area is determined in the reset search area, and the movement amounts ΔX, ΔY, Δθ are calculated. By repeating steps 3 to 5 in this way, the movement amount calculations are repeated, and a more accurate movement amount calculation result is obtained.
[0043]
If it is determined in step 4 that the repetitive operation is unnecessary, the process proceeds to step 6, in which the image synthesizing unit 30 synthesizes the images based on the calculation results of the movement amounts ΔX, ΔY, and Δθ, and obtains the images by the synthesis. The panoramic image is displayed on the display unit 34 (see FIG. 2). Then, it is determined whether or not the synthesis has been completed for all the frames necessary for forming the panoramic image. If it is determined that the synthesis has not been completed, the process returns to step 1 and the moving amount calculation for the next frame is performed. Is performed again. If it is determined that the synthesis for all the frames has been completed, the flow ends. When the end of the formation of the panoramic image is determined in step 6, the end may be determined by an instruction of the end button by the user, or the end may be determined when the probe 10 is separated from the body surface. Good. That is, when the probe 10 is separated from the surface of the living body and the ultrasonic wave is emitted in the air, the ultrasonic image becomes completely dark. Therefore, when the average luminance value of the reference region is determined to be a value close to 0, the probe It is automatically determined that 10 has left the body surface.
[0044]
FIG. 8 is a flowchart showing another processing operation of forming a panoramic image by the ultrasonic image processing apparatus of FIG. The processing operation of forming a panoramic image will be described with reference to FIG. The configuration described in FIG. 1 will be described with the reference numerals in FIG.
[0045]
In step 1, the control unit 32 controls the transmission / reception unit 12 and the signal processing unit 14 to acquire an ultrasonic image for each frame. At this time, the probe 10 acquires a frame corresponding to each movement position while moving. In step 2, the movement amount calculation unit 20 sets a search area for the ultrasonic image (see FIG. 3). At this time, the search area is set so as to surround the periphery of the reference area. In step 3, the movement amount calculator 20 calculates the movement amounts ΔX, ΔY, Δθ (see FIG. 3).
[0046]
Next, in step 4, the calculation end determination unit 26 determines whether or not the movement amount calculation needs to be repeated. The repetition determination is performed based on the normalized MSAD value, the correlation coefficient, and the number of repetitions, as in step 4 in FIG. If the calculation end determination unit 26 determines that repetitive calculation is necessary, the process proceeds to step 5, and if it is determined that repetitive calculation is unnecessary, the process proceeds to step 10.
[0047]
In step 5, the movement amount calculation unit 20 sets a search area for the next movement amount calculation. Since the match area is determined in step 3, the search area is set so as to surround the periphery of the match area. Then, the process proceeds to step 6, in which a new match area is determined in the reset search area, and the movement amounts ΔX and ΔY are calculated. Further, in step 7, similarly to step 4, the calculation end determination unit 26 determines whether or not the movement amount calculation needs to be repeated. Here, if it is determined that the repetitive operation is necessary, the process proceeds to step 8, and if it is determined that the repetitive operation is unnecessary, the process proceeds to step 10.
[0048]
In step 8, a new match area is determined in the search area reset in step 5, and the movement amount Δθ is calculated. Then, in step 9, similarly to step 4, the calculation end determination unit 26 determines whether or not the movement amount calculation needs to be repeated. Here, if it is determined that the repetitive operation is necessary, the process returns to step 5, and if it is determined that the repetitive operation is unnecessary, the process proceeds to step 10. By repeating steps 5 to 9 in this manner, the movement amount calculations are repeated, and a more accurate movement amount calculation result is obtained.
[0049]
If it is determined in step 4, step 7, or step 9 that the repetitive calculation is unnecessary, the process proceeds to step 10, and in step 10, the image combining unit 30 combines the images based on the calculation results of the movement amounts ΔX, ΔY, Δθ. Is performed, and the panoramic image obtained by the synthesis is displayed on the display unit 34 (see FIG. 2). Then, it is determined whether or not the synthesis has been completed for all the frames necessary for forming the panoramic image. If it is determined that the synthesis has not been completed, the process returns to step 1 and the moving amount calculation for the next frame is performed. Is performed again. If it is determined that the synthesis for all the frames has been completed, the flow ends.
[0050]
In step 3, the translation amounts ΔX and ΔY and the rotation amount Δθ are calculated at one time, but only the translation amounts ΔX and ΔY or only the rotation amount Δθ may be calculated.
[0051]
As described above, a panoramic image is formed by the ultrasonic image processing apparatus of FIG. Note that the ultrasonic image processing apparatus in FIG. 1 may be formed in an ultrasonic diagnostic apparatus, or a part of the configuration in FIG. 1 may be formed in a computer. For example, the moving amount calculating unit 20 and the image synthesizing unit 30 are made to function in a computer, and a panoramic image is formed by performing a synthesizing process on a B-mode image for each frame obtained from the ultrasonic diagnostic apparatus. It may be displayed on the display unit of the device.
[0052]
The ultrasonic image for each frame used for forming a panoramic image is not limited to a normal B-mode image, and may be a harmonic image, a color Doppler image, or an ultrasonic contrast image using a contrast agent. .
[0053]
【The invention's effect】
As described above, the ultrasonic image processing apparatus according to the present invention makes it possible to improve the image combining performance in forming a panoramic image.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an ultrasonic image processing apparatus according to the present invention.
FIG. 2 is a diagram showing a panoramic image formed by the ultrasonic image processing apparatus of FIG.
FIG. 3 is a diagram for explaining a calculation method of a movement amount calculation performed in a movement amount calculation unit.
FIG. 4 is a diagram for explaining another calculation method of the rotational movement amount calculation performed in the rotational movement amount calculation unit.
FIG. 5 is a diagram showing luminance values of pixels on the circumference of each of the ring-shaped region and the corresponding region in FIG. 4;
FIG. 6 is a diagram showing another shape of a reference area used in the rotational movement amount calculation unit.
FIG. 7 is a flowchart illustrating a processing operation of the ultrasonic image processing apparatus of FIG. 1;
FIG. 8 is a flowchart illustrating another processing operation of the ultrasonic image processing apparatus of FIG. 1;
[Explanation of symbols]
22 translational movement calculator, 24 rotational movement calculator, 26 calculation end determiner, 30 image synthesizer, 50 reference area, 52 search area.

Claims (15)

An ultrasonic image processing apparatus that forms a panoramic image by combining a plurality of frames obtained by moving the ultrasonic probe,
Means for calculating the translation amount between one frame and the other frame between two frames, wherein the reference region on one frame is sequentially translated while each translation position corresponds to the corresponding region on the other frame. Translational movement amount calculating means for calculating the translational amount by performing a matching calculation;
Means for calculating the amount of rotational movement between one frame and the other frame between the two frames, wherein the translational movement on the other frame at each rotational movement position while sequentially rotating the reference area on one frame A rotational movement amount calculating means for calculating the rotational movement amount by performing a matching operation with a corresponding region having a combined positional relationship based on the amount;
A panoramic image forming unit configured to form the panoramic image by combining the two frames based on the calculated translation amount and rotation amount;
An ultrasonic image processing apparatus comprising: The ultrasonic image processing apparatus according to claim 1,
Each of the translational amounts of the translational amount and the rotational amount is calculated at least once, and each of the calculated amounts is performed in a corresponding area having a combined positional relationship based on the previously calculated amounts.
An ultrasonic image processing apparatus characterized by the above-mentioned. An ultrasonic image processing apparatus according to claim 2,
The ultrasonic image processing apparatus, wherein each of the translation amount calculation and the rotation amount calculation is executed a plurality of times. The ultrasonic image processing apparatus according to claim 1,
The ultrasonic image processing apparatus according to claim 1, wherein the matching calculation is a calculation based on a correlation between a plurality of pixel data in the reference region and a plurality of pixel data in the corresponding region. The ultrasonic image processing apparatus according to claim 1,
The ultrasonic image processing apparatus according to claim 1, wherein the matching operation is an operation based on a minimum sum absolute difference (MSAD) method. The ultrasonic image processing apparatus according to claim 1,
The ultrasonic image processing apparatus according to claim 1, wherein said translation amount calculating means sequentially translates said reference area within a set search area. An ultrasonic image processing apparatus according to claim 6,
The ultrasonic image processing apparatus according to claim 1, wherein the search area is set to a smaller area as the number of movement amount calculations is repeated. An ultrasonic image processing apparatus according to claim 3,
An ultrasonic image processing apparatus, further comprising: a repetition end determination unit that performs a calculation end determination of the translational movement amount and the rotational movement amount performed a plurality of times. An ultrasonic image processing apparatus according to claim 8,
The matching operation is an operation based on a minimum sum absolute difference (MSAD) method,
The ultrasonic image processing apparatus according to claim 1, wherein the repetition end determination unit performs the operation end determination based on an MSAD value calculated in the operation based on the minimum sum absolute difference (MSAD) method. The ultrasonic image processing apparatus according to claim 9,
The ultrasonic image processing apparatus, wherein the repetition end determination unit performs the calculation end determination based on a change rate of the MSAD value. An ultrasonic image processing apparatus according to claim 8,
The ultrasonic image processing apparatus, wherein the repetition end determination unit determines that the calculation is completed when the number of calculations of the translational movement amount and the rotational movement amount reaches a predetermined number. The ultrasonic image processing apparatus according to claim 1,
At least one of the reference regions for each of the movement amount calculations is a rectangular region. The ultrasonic image processing apparatus according to claim 1,
The ultrasonic image processing apparatus according to claim 1, wherein the reference area in the rotational movement amount calculating means is a circular area. An ultrasonic image processing apparatus that forms a panoramic image by combining a plurality of frames obtained by moving the ultrasonic probe,
Means for calculating the amount of rotational movement between one frame and the other frame between two frames, wherein the reference area on one frame is sequentially rotated and moved at each rotational movement position with the corresponding area on the other frame. Rotation movement amount calculation means for calculating the rotation movement amount by performing a matching calculation;
Means for calculating the amount of translation between one frame and the other frame between the two frames, wherein the reference region on one frame is sequentially translated while the rotational movement on the other frame at each translation position. A translational movement amount calculation means for calculating the translational movement amount by performing a matching calculation with a corresponding region having a combined positional relationship based on the amount;
A panoramic image forming unit configured to form the panoramic image by combining the two frames based on the calculated translation amount and rotation amount;
An ultrasonic image processing apparatus comprising: A computer program for forming a panoramic image by combining a plurality of frames obtained by moving the ultrasound probe,
Means for calculating the translation amount between one frame and the other frame between two frames, wherein the reference region on one frame is sequentially translated while each translation position corresponds to the corresponding region on the other frame. A translational movement calculating means for calculating the translational movement by performing a matching calculation;
Means for calculating the amount of rotational movement between one frame and the other frame between the two frames, wherein the translational movement on the other frame at each rotational movement position while sequentially rotating the reference area on one frame A rotational movement amount calculating means for calculating the rotational movement amount by performing a matching calculation with a corresponding region having a combined positional relationship based on the amount;
A panoramic image forming unit that forms the panoramic image by synthesizing the two frames based on the calculated amount of translation and rotation;
Program to make a computer function as a computer.

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