JP2004121834A - Movement tracing method for biological tissue, image diagnosing system using the tracing method, and movement tracing program for biological tissue - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quantitatively measure the movement of a tissue by using a tomographic image. <P>SOLUTION: One frame image of a motion picture formed by picking up the tomographic image of a patient is displayed (S2). A mark is displayed by being superposed with a designated region of a biological tissue which needs to be traced in one displayed frame image (S3). A sliced image of a size for including the designated region is set on the one frame image (S4). At the same time, a local image having the same size wherein the matching rate of the image with the sliced image is highest is extracted by searching other frame images of the motion picture (S5 and S6). Moving destination coordinates of the designated region are acquired based on a difference in coordinates between the local image the matching rate of which is highest and the sliced image (S7). Thus, the movement of the tissue is quantitatively measured. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention belongs to a technique for tracking movement of a living tissue applied to an ultrasonic diagnostic image, a magnetic resonance image, or an X-ray CT image, an image diagnostic apparatus using the tracking method, and a program technology thereof.

(2) Image diagnostic apparatuses such as an ultrasonic diagnostic apparatus, a magnetic resonance imaging (MRI) apparatus, and an X-ray CT apparatus all display on a monitor a tomographic image or the like of an examination part of a subject and provide the diagnosis. For example, in the case of a circulatory system and other moving organs such as the heart and blood vessels, the movements of living tissues (hereinafter, collectively referred to as “tissues”) constituting the organs are observed with a tomographic image, and the functions of the organs and the like are evaluated. Diagnosis is being performed.

Especially, if functions such as the heart can be quantitatively evaluated, the accuracy of diagnosis is expected to be further improved. For example, in the related art, a contour of a heart wall is extracted from an image obtained by an ultrasonic diagnostic apparatus, and a heart function (heart pump function) is determined based on an area, a volume, a change rate, and the like of a ventricle based on the heart wall contour. Attempts have been made to evaluate and evaluate local wall motion for diagnosis (Patent Document 1). In addition, by measuring the displacement of the tissue based on a measurement signal such as a Doppler signal, for example, imaging the distribution of local contraction or relaxation, based on this, to accurately determine the location where ventricular movement is activated or Alternatively, a method of quantitatively measuring the thickness of the heart wall during the systole has been proposed (Patent Document 2). Furthermore, a technique has been proposed in which the contours of the atria and ventricles that change every moment are extracted, the contours are superimposed on the image and displayed, and the capacity of the ventricles and the like is obtained based on the contours (Patent Document 3).

JP-A-9-13145 JP 2001-518342 A US Patent No. 5,322,067 (USP 5,322,067)

However, none of the above prior arts is a method for evaluating the overall function of the heart, and no consideration is given to measuring the tissue dynamics, which is the movement of each tissue such as the myocardium. In particular, the prior art which extracts the contour of the heart wall by image processing and measures the thickness of the heart wall based on the contour has not always achieved sufficient accuracy.

Generally, it is said that, for example, when blood does not pass through the myocardium due to a thrombus or the like, there is a causal relationship such as a decrease in myocardial movement. Therefore, if the dynamics of each tissue of the heart, such as the movement and thickness of the myocardium constituting the ventricle, can be quantitatively measured, it is possible to provide effective diagnostic information for determining a treatment method and the like. For example, if the degree of ischemia is known, it is effective as an index for selecting a treatment method for the heart such as coronary artery regeneration and specifying a treatment site. In addition, research has been conducted on the ability to quantitatively measure the dynamics of the annulus, which is useful for evaluating the overall cardiac function in heart diseases such as hypertensive cardiac hypertrophy.

対 象 The target for quantitatively measuring such tissue dynamics is not limited to the heart, but also to blood vessels. In other words, it is considered that the ability to quantitatively measure the pulse wave on the wall of a large blood vessel such as the carotid artery is effective in diagnosing arteriosclerosis.

Therefore, a first object of the present invention is to quantitatively measure the movement of a tissue using a tomographic image.

The second object of the present invention is to quantitatively measure various kinds of information on the movement of the tissue.

The third object of the present invention is to display the trajectory of the movement of the tissue on an image.

The present invention solves the above-mentioned problems by means described below.

An image diagnostic apparatus of the present invention is an image diagnostic apparatus that includes an imaging unit that captures a tomographic image of a subject and a display unit that displays a moving image obtained by the imaging unit. An operation unit designated by a mark and a tracking unit for extracting the tomographic image corresponding to the part designated by the mark and tracking the movement of the tomographic image by the mark are provided. In this case, a configuration in which an imaging unit is separately provided may be adopted. The tracking unit may include a display control unit that tracks the movement of the image part specified by the mark and moves the display position of the mark.

Further, the motion tracking method of the living tissue of the present invention includes a first step of displaying one frame image of a moving image obtained by capturing a tomographic image of the subject, and a motion in the displayed one frame image. A second step of inputting a command to superimpose and display a mark on a specified part of the living tissue to be tracked to set the specified part, and a third step of setting a cut-out image including the specified part in the one frame image A fourth step of retrieving another frame image of the moving image to extract a local image of the same size having the highest matching degree between the cut-out image and the image; and a local image having the highest matching degree and the cut-out state. Obtaining a destination coordinate of the designated part based on a coordinate difference between the images.

Specifically, the designated portion of the living tissue whose movement is to be tracked is designated by superimposing a mark such as a designated point on one frame image (still image) of the moving image. Then, an area including the designated portion corresponding to the mark is automatically set as a clipped image of a predetermined size, or an area frame of the clipped image is input and set on the still image. Next, the position where the set cutout image has moved in the subsequent frame image is tracked by image correlation processing such as a so-called block matching method that searches for a local image of the same size having the highest matching degree between the cutout image and the image. . Thus, the position of the local image having the highest image matching degree can be tracked as the destination of the cut-out image. Then, the coordinate difference between the cut-out images before and after the movement corresponds to the coordinate difference before and after the movement of the designated part.

Therefore, the moving direction and the moving amount of the designated part can be measured based on the coordinate difference between the cut-out images before and after the movement, so that the movement of the designated part can be quantitatively measured. For example, it is possible to quantitatively obtain measurement information, which is a physical quantity relating to a movement such as a moving amount, a moving speed, and a moving direction of a designated portion. Further, by displaying the change of the measurement information on the display unit in a diagram, the viewer can easily observe the movement of the designated part.

Such a tracking process is performed by applying the image correlation method to still another frame image of the moving image, using the local image having the highest matching degree of the image extracted by the search as a new cutout image, The destination coordinates of the designated part can be sequentially obtained. Then, the movement coordinates of the designated part can be displayed by storing the destination coordinates of the designated part and superimposing the mark on the moving image at the coordinate position of the movement destination. This makes it easy to observe the movement of the designated part.

For example, if two designated sites are set in the living tissue, for example, if at least two designated sites are set across the myocardium, a distance between the two designated sites, a change in the distance, a change speed of the distance, The rate of change of the distance, that is, the thickness of the myocardium, the thickness change, the thickness change speed, and the like can be quantitatively measured. In this case, the accuracy of the diagnosis can be further improved by displaying the diagram of the measured values related to the heart and the electrocardiographic waveform in association with the time axis. That is, since tracking of myocardial dynamics and changes in myocardial thickness can be quantitatively tracked, it becomes possible to specify an ischemic site in ischemic heart disease. In addition, since the myocardial dynamics can be quantified, the degree of ischemia can be known, and it can be used as an index for selecting a treatment method such as coronary artery regeneration and specifying a treatment site. Furthermore, tracking the movement of the annulus may help to assess overall cardiac function in heart diseases such as hypertensive cardiac hypertrophy.

In addition, a plurality of designated portions are set along the myocardium, the moving direction of each designated portion is determined, the reference point of the moving direction of the myocardium is set as the center of gravity, and the direction toward the center of gravity and the color in the opposite direction are changed, and the time is changed. The change can be displayed as an image. According to this, the pump function of the heart can be easily grasped by image display. In this case, luminance modulation can be performed according to the moving speed. Further, a plurality of designated sites can be designated along the inner wall of the ventricle, and the volume of the ventricle and a change in the volume can be obtained based on a straight line connecting the plurality of designated sites or an approximate curve of the straight line. According to this, dynamic information (information of movement) such as a change in volume of the ventricle can be quantitatively and accurately measured.

The present invention is not limited to measuring the motion of each part of the heart, but can be applied to pulse wave measurement of a large blood vessel wall such as a carotid artery. For example, the degree of arteriosclerosis can be determined by setting a plurality of designated portions in the longitudinal direction of the blood vessel wall, quantitatively measuring the movement amounts of these designated portions, and comparing the measured amounts.

Here, in order to further improve the accuracy of the image tracking process, when the moving image is captured by an ultrasonic imaging method, an RF signal corresponding to the moving image is stored, and correction using the RF signal is performed. Can be added. In this case, the destination coordinates of the designated part are obtained based on the coordinate difference between the local image having the highest matching degree and the cut-out image, and a plurality of the RF signals corresponding to the periphery of the destination coordinates are extracted. The cross-correlation of the plurality of RF signals thus obtained is obtained, and the destination coordinates are corrected according to the position of the maximum value of the cross-correlation.

Furthermore, in order to reduce the processing time for extracting a local image of the same size having the highest degree of coincidence between the cut image and the image, the search range is set to a set number of pixels (for example, 3 to 10 pixels vertically, horizontally, and so on) more than the cut image. It is preferable to set a large area. That is, the range of movement of the living tissue is generally limited to a narrow area.

On the other hand, in the above-described case, it is preferable that the size of the cut-out image is set to an area having a size including a living tissue different from the living tissue of the designated portion. If the size of the cut-out image is too small, many matching local images appear, and a true destination may not be specified. Conversely, if the size of the cut-out image is too large, it may run out of the image area of the moving image and cannot be measured. .

The image diagnostic apparatus of the present invention includes a storage unit that stores a moving image obtained by capturing a tomographic image of a subject, a display unit that can display the moving image, an operation unit that inputs a command, and the display unit. An automatic tracking unit that tracks the movement of the living tissue of the moving image displayed on the moving image, and a signal transmission path that connects the storage unit, the display unit, the operation unit, and the automatic tracking unit. The operation unit wants to track a motion in the command to display one frame image of the moving image stored in the storage unit on the display unit and the one frame image displayed in response to the command. Means for inputting a command to superimpose and display a mark on a designated portion of the living tissue, wherein the automatic tracking section sets the designated portion corresponding to the position of the mark in the one frame image displayed on the display section. Set the cropped image of the included size A cut-out image setting unit, a cut-out image tracking unit that reads another frame image of the moving image from the storage unit, and extracts a local image of the same size having the highest degree of matching between the cut-out image and the image, The movement amount calculating means for calculating the coordinate difference between the local image having the highest value and the cut-out image, and the movement tracking means for calculating the destination coordinates of the specified part based on the coordinate difference can be configured.

Further, the movement tracking program of the living tissue of the present invention reads out one frame image of a moving image obtained by capturing a tomographic image of the subject from the storage unit in response to a command from the console, and displays the frame image on the display unit. One step, a second step of requesting a command input for superimposing and displaying a mark on a designated portion of a living tissue whose motion is to be tracked in the displayed one frame image, and input setting from an operation console according to the request. A third step of obtaining coordinates of a designated portion of the living tissue corresponding to the mark, a fourth step of setting a cutout image having a size including the designated portion as the one frame image, and another frame of the moving image. A fifth step of retrieving an image and extracting a local image of the same size having the highest degree of coincidence between the cut image and the image; Characterized in that it comprises a sixth step of determining the destination coordinates of the designated region based on the difference.

According to the present invention, the movement of the tissue can be quantitatively measured using the tomographic image. Further, according to another invention, it is possible to quantitatively measure various kinds of information relating to the movement of the tissue. According to still another aspect, the trajectory of the movement of the tissue can be displayed on the image.

(Embodiment 1)
An image diagnostic apparatus according to an embodiment to which the movement tracking method of a biological tissue according to the present invention is applied will be described with reference to FIGS. FIG. 1 shows a procedure of a living tissue movement tracking method of the present embodiment, and FIG. 2 is a block diagram of an image diagnostic apparatus to which the living tissue movement tracking method of FIG. 1 is applied. As shown in FIG. 2, the image diagnostic apparatus includes an image storage unit 1 that stores a moving image obtained by capturing a tomographic image of a subject, a display unit 2 that can display the moving image, and an operation of inputting a command. A console 3, an automatic tracking unit 4 for tracking the movement of the living tissue in the moving image displayed on the display unit 2, a dynamic information calculation unit 5 for calculating various measurement information based on the tracking result of the automatic tracking unit 4, , And a signal transmission line 6 formed by connecting them. The image storage unit 1 stores, on-line or off-line, a moving image obtained by capturing a tomographic image of a subject from the diagnostic imaging device 7 indicated by a broken line. As the diagnostic image capturing device 7, a diagnostic device such as an ultrasonic diagnostic device, a magnetic resonance imaging (MRI) device, and an X-ray CT device can be applied.

The operation console 3 is formed so that an instruction to display one frame image of a moving image stored in the image storage unit 1 on the display unit 2 can be input. In addition, a command for superimposing and displaying a mark on a designated portion of a living tissue whose movement is to be tracked in one frame image displayed in response to the command is formed so as to be inputtable.

The automatic tracking unit 4 includes a control unit 8 that controls the entire diagnostic imaging apparatus, and a cutout image that sets a cutout image having a size including a designated portion corresponding to the position of the mark in one frame image displayed on the display unit 2. A setting unit 9, a cutout image tracking unit 10 that reads another frame image of the moving image from the image storage unit 1 and extracts a local image of the same size having the highest matching degree between the cutout image and the image, The system includes a moving amount calculating means 11 for calculating a coordinate difference between a high local image and a cut-out image, and a moving tracking means 12 for calculating a destination coordinate of a designated part based on the coordinate difference. In addition, the dynamic information calculation unit 5 quantitatively calculates measurement information, which is a physical quantity related to a movement such as a movement amount, a movement speed, and a movement direction of the designated part, based on the destination coordinates of the designated part obtained by the automatic tracking unit 4. And a function of displaying the change of the measurement information on the display unit 2 in a diagram.

Next, a detailed functional configuration of the diagnostic imaging apparatus according to the present embodiment will be described along with an operation according to the processing procedure illustrated in FIG. First, the movement tracking operation of the living tissue starts when a command to select the movement tracking mode of the tissue is input from the console 3 (S1). The control means 8 of the automatic tracking unit 4 reads out the first frame image ft (t = 0) of the moving image from the image storage unit 1 and displays it on the display unit 2 (S2). For example, it is assumed that a tomographic image of the ventricle 21 of the heart shown in FIG. 3 is displayed as the first frame image f0. In FIG. 3, when the operator wants to select a specific part of the myocardium 22 as the designated part of the living tissue whose movement is to be tracked, the operator operates the mouse of the operation unit 3 or the like to overlap the frame image f0 with the mark. A certain designated point 23 is displayed. Then, the designated point 23 is moved and operated so as to be superimposed and displayed on a desired designated part, and the designated part is input and set. In FIG. 3, reference numeral 24 denotes a mitral valve.

When the designated point 23 is input and set, the control means 8 takes in the coordinates of the designated point 23 on the frame image f0 and sends it to the cut-out image setting means 9 (S3). As shown in FIG. 4A, the cut-out image setting means 9 sets a rectangular area having a size of 2 (A + 1) pixels vertically (horizontally and horizontally) (where A is a natural number) around the image of the designated point 23 as the cut-out image 25. It is set (S4). Here, it is preferable that the size of the cut-out image 25 be set to an area having a size including a living tissue different from the living tissue at the designated point 23. For example, as shown in FIG. 3, the area is set to a size exceeding the boundary of the myocardium 22. This is because, when the size of the cut-out image 25 is too small, many matching local images appear, and the true destination cannot be specified. On the other hand, when the size is too large, the cut-out image 25 protrudes from the image area of the frame image f0 and cannot be measured. Is caused.

The cut-out image tracking means 10 reads the next frame image f1 of the moving image from the image storage unit 1, and extracts a local image of the same size having the highest degree of matching between the cut-out image 25 and the image (S5). This extraction process applies an image correlation method called a so-called block matching method. If this extraction processing is performed for the entire area of the frame image f1, the processing time will be too long. Therefore, in order to shorten the extraction processing time, in the present embodiment, the search is performed on the search area 26 shown in FIG. 4B, which is sufficiently smaller than the frame image f1. That is, the search area 26 is a rectangular area in which the number B of pixels having a fixed swing width is added to the cut-out image 25 vertically and horizontally. The number of pixels B is larger than the movement amount of the tissue related to the designated part, and is set to, for example, 3 to 10 pixels. This is because the range of movement of the circulatory system such as the heart is limited to a small area in a normal visual field. In this way, the local images 27 of the same size in the search area 26 are sequentially shifted to determine the degree of coincidence of the image with the cut-out image 25.

Next, a local image 27max having the highest degree of image matching is extracted from the plurality of searched local images 27, and the local image 27max is set as a destination of the cut-out image 25, and the coordinates of the local image 27max are obtained (S6). The coordinates of these images are represented by the coordinates of the center pixel or the coordinates of any corner of the rectangular area. Then, a coordinate difference between the local image 27max and the cut-out image 25 is obtained, and based on the coordinate difference, the destination coordinates of the designated point 23 are obtained and stored, and displayed over the frame image f1 of the display unit 2 (S7). The relative position between the local image 27max and the designated point 23 in the cut-out image 25 is treated as not changing.

The dynamic information calculation unit 5 calculates various types of measurement information relating to the movement of the designated point 23, that is, the movement of the tissue at the designated part, based on the destination coordinates of the designated point 23 obtained in S7 (S8). That is, the moving direction and the moving amount can be quantitatively measured based on the coordinates of the designated part before and after the movement. Further, it is possible to quantitatively obtain measurement information which is a physical quantity relating to the movement of the designated portion, such as the movement amount, the movement speed, and the movement direction.

Based on the measurement information thus obtained, the dynamic information calculation unit 5 further displays various measurement information relating to the movement of the designated point 23 and changes thereof on the display unit in a graph (S9). Thus, the viewer can easily observe the movement of the designated part.

Next, the process proceeds to step S10, where it is determined whether or not the tracking of the designated point 23 has been completed for all the frame images of the moving image. If there is an unprocessed frame image, the process returns to step S5 to perform the processes of S5 to S10. repeat. When the tracking of the designated point 23 is completed for all the frame images, the tracking processing operation ends.

As described above, according to the present embodiment, the coordinates of the movement destination of the designated point 23 can be sequentially obtained by applying the image correlation method, so that the movement of the designated part can be quantitatively and accurately easily performed. Therefore, it is possible to provide diagnosis information accurately.

Here, a specific example of measuring the movement of the designated portion of the living tissue using the above embodiment will be described with reference to FIGS. FIG. 5 is an example of an image in which measurement information relating to the movement of the designated point 23 shown in FIG. 3 is displayed on the display unit 2. FIG. 5A shows the movement locus of the designated point 23 superimposed on the moving image by a broken line. This is an example. FIGS. 7B and 7C show the time change and the moving speed of the moving amount of the designated point 23, respectively. FIGS. 9D and 9E show another example in which the moving trajectory of the designated point 23 is superimposed and displayed on the moving image. FIG. FIG. 5E shows the movement locus by a solid line.

On the other hand, FIG. 6 sets two designated points 23 with the heart wall of the myocardium 22 interposed therebetween, measures the distance between the two designated points 23, and changes in the distance, and graphs them to the display unit 2. This is an example of the display. As a result, the thickness of the myocardium and the change in thickness can be quantitatively grasped. Also, the change rate of the thickness of the myocardium can be calculated and displayed. This change rate can be expressed as a percentage of the change in the thickness of the myocardium before and after the change with respect to the thickness of the myocardium before the change. In these cases, the accuracy of diagnosis can be further improved by displaying the graph of the measurement value relating to the heart and the information such as the ECG waveform and the heart sound waveform on the display unit 2 in association with the time axis. That is, since tracking of myocardial dynamics and changes in myocardial thickness can be quantitatively tracked, it becomes possible to specify an ischemic site in ischemic heart disease. In addition, since the myocardial dynamics can be quantified, the degree of ischemia can be known, and it can be used as an index for selecting a treatment method such as coronary artery regeneration and specifying a treatment site. Furthermore, if the designated point 23 is set on the annulus portion 24 and its movement is tracked, it can be expected to be useful for evaluating the entire cardiac function in a heart disease such as hypertensive cardiac hypertrophy.

FIG. 7 shows a case where a plurality of (in the illustrated example, nine) designated points 23a to 23i are set on the wall portion of the myocardium 22, their movements are tracked, and based on the movement information, FIGS. ). FIG. 3A shows the moving direction of each of the designated points 23a to 23i, and sets the reference point of the moving direction of the heart wall as the center of gravity, and changes the color change in the direction toward the center of gravity and the color in the opposite direction. This is an example of image display. According to this, the movement of the myocardium can be easily grasped by image display. In this case, luminance modulation can be performed according to the moving speed. FIG. 3B shows an example in which the thickness of the line connecting the designated points 23a to 23i is changed according to the movement amount of the designated points 23a to 23i. FIG. 9C shows an example in which the movement locus of each of the designated points 23a to 23i from several frames before is displayed. FIG. 3D shows an example in which the designated points 23a to 23i are connected by lines, and the movement amounts of those points are highlighted. FIG. 11E shows an example in which the change in the area of each quadrilateral surrounded by the designated points 23a to 23i is displayed as shown in FIG. 10C, and FIG. This is an example in which the change over time of the area is displayed as a graph.

FIG. 8 is an example in which a plurality of designated points 23 are set over the entire inside of the myocardium 22, and FIG. 8A is a graph showing the total displacement of the myocardium 22 in the thickness direction. FIG. 4B is a graph of the total displacement in the length direction of the myocardium. FIG. 3C shows an example in which the total displacement is graphed and displayed, where the contraction in the length direction of the myocardium 22 is defined as a plus and the direction in which the myocardium 22 expands in the thickness direction is defined as a plus. FIG. 6D is an example in which the total area change of the region surrounded by the plurality of designated points 23 is graphed.

FIG. 9 sets a plurality of designated points 23 along the inner wall of the myocardium 22. FIG. 9A shows a direction in which each designated point 23 is directed to the center of gravity of a region (ventricle) surrounded by each designated point. Is displayed in, for example, “red”, the direction away from the display is displayed in, for example, “blue”, and the brightness is modulated according to the moving speed. FIG. 2B is a graph showing a time change of the area of the region surrounded by the designated point 23. According to this, it is possible to quantitatively and accurately measure dynamic information (movement information) such as a change in volume of the ventricle.
(Embodiment 2)
In the embodiment of FIG. 1, every time tracking of a designated point for one frame image is completed (S7), various kinds of information on the movement of the tissue are calculated based on the movement of the designated point (S8), and the information is calculated. The example in which the information is displayed on the display unit (S9) has been described. The present invention is not limited to this. As shown in FIG. 10, after the step S10 of FIG. 1 is arranged after the step S7 and the tracking of the designated points for all the frame images is completed, the processes of the steps S8 and 9 are performed. It may be executed.

Here, a specific example of the image tracking processing by the image correlation method will be described with reference to FIG. In the illustrated example, for simplicity of description, the size of the cut-out image 25 is described as a rectangular 9-pixel area, and the search area 26 is also described as a rectangular 25-pixel area. That is, the cut-out image 25 shown in FIG. 7A is an example in which A = 1 pixel is set with the pixel at the designated point 23 as the center, and the search area 26 shown in FIG. This is an example. According to this, as shown in FIG. 7B, the correlation values are obtained for the nine local regions 27, and the position having the largest correlation corresponds to the destination coordinates.
(Embodiment 3)
The present embodiment can be applied to tracking processing of a living tissue using a moving image obtained by imaging by an ultrasonic imaging method. In particular, the movement of a living tissue is tracked by storing the RF signal corresponding to the moving image and correcting the position of the local image having the highest matching degree of the image obtained by the image correlation method using the RF signal. The purpose of the present invention is to make the change in the measured value obtained through the smoothing.

As shown in FIG. 12, a moving image from the ultrasonic diagnostic apparatus 17 and an RF signal (a signal obtained by receiving and processing an ultrasonic echo signal) used for reconstructing the moving image are imaged online or via a recording medium, respectively. It is stored in the storage unit 1 and the RF signal storage unit 18. The RF signal storage unit 18 is connected to the automatic tracking unit 4 via the signal transmission path 6. The automatic tracking section 4 is provided with a movement amount correction section 13.

FIG. 13 shows a processing procedure of a main part of the present embodiment. The basis of the tracking process of the present embodiment is to capture the destination coordinates of the cut-out image obtained in step S6 in FIG. 10 and calculate the destination coordinates of the designated point 23 (S21). Next, the RF signal relating to the image around the coordinates of the designated point 23 of the cut-out image 25 and the coordinates of the designated point 23 of the local image 27max having the highest matching degree is extracted from the RF signal storage unit 18 (S22). That is, the RF signal of the peripheral image of the designated point 23 before and after the movement is extracted. Then, the cross-correlation between the RF signals before and after the movement is obtained, and the correlation value is obtained (S23). In this case, first, any one of the RF signals before and after the movement is shifted on the time axis by an amount corresponding to the movement amount (the number of pixels) obtained by the image correlation method, and the cross-correlation (for example, a product-sum operation) between the two is taken. , Any one of the RF signals before and after the movement. Then, the shift amount τ at which the obtained cross-correlation value becomes the maximum value is obtained as a correction value of the movement amount by the RF signal (S24). The movement amount of the designated point is corrected by adding the correction value of the movement amount of the designated point obtained by using the RF signal to the movement amount of the designated point previously obtained by the image correlation method (S25).

Here, the reason that the maximum value of the cross-correlation value of the RF signal before and after the movement is correlated with the movement amount of the designated point, and that the position measurement accuracy is improved by correcting the movement amount of the designated point thereby. This will be described with reference to FIG. In FIG. 14A, the time axes of the RF signal 41 around the designated point before the movement and the RF signal 42 around the designated point after the movement are shifted based on the movement amount obtained by the image correlation method. The state is shown. Then, for example, when the cross-correlation with the RF signal 42 is calculated while shifting the time axis of the RF signal 41 in either the positive or negative direction, a cross-correlation value 43 indicating the maximum value shown in FIG. If the shifted phase difference between the RF signal 41 and the RF signal 42 is τ, the moving amount τ corresponds to the moving amount to be corrected in addition to the moving amount in the image correlation method. Thereby, the measurement accuracy of the movement amount of the image correlation method can be improved.

As described above, according to each embodiment of the present invention, the following effects can be obtained.

First, since the movement of each part of the heart can be quantitatively measured, for example, by tracking myocardial dynamics or quantitatively measuring changes in myocardial thickness, it is possible to specify, for example, an ischemic site in ischemic heart disease. it can. In addition, since the myocardial dynamics can be quantified, the degree of ischemia can be known, and can be used as an index for selecting a treatment method such as coronary artery regeneration and specifying a treatment site.

定量 Quantitative tracking of the movement of the annulus may help to assess overall cardiac function in heart disease such as hypertensive cardiac hypertrophy.

Also, it is clear that the present invention is not limited to measuring the movement of each part of the heart, and can be applied to any part of the living tissue where the movement of the living tissue is desired to be observed. For example, the present invention can be applied to pulse wave measurement of a wall of a large blood vessel such as a carotid artery. In this case, the degree of arteriosclerosis can be determined by setting a plurality of designated portions in the longitudinal direction of the blood vessel wall, quantitatively measuring the movement amounts of these designated portions, and comparing them.

In the above-described embodiment, an example in which the processing is performed offline has been described. However, if the processing speed of the block matching method is improved, the present invention can be applied to online or real-time moving images.

The above embodiment has been described by taking a two-dimensional tomographic image as an example, but it goes without saying that the present invention can be applied to a three-dimensional tomographic image.

In addition, a known technique can be used for the image correlation method as long as it is a method of calculating the degree of coincidence between the cut image and the corresponding image of the local image. For example, a generally known product of a pixel value for each corresponding pixel of a cut-out image and a local image is obtained, and a two-dimensional cross-correlation method in which the sum of the absolute values is used as a correlation value, each pixel value of the cut-out image and the local image Is subtracted from the pixel value of each pixel, the product is obtained, and the two-dimensional normalized cross-correlation method, in which the sum of the absolute values is used as the correlation value, calculates the absolute value of the difference between the pixel values for each pixel, and calculates the absolute value. An SAD method in which the sum of the values is used as a correlation value, an SSD method in which a square value of a difference between pixel values of pixels is obtained, and the sum of the square values is used as a correlation value, and the like can be applied. At this time, in order to select the local image having the maximum correlation, the local image having the largest correlation value in the two-dimensional cross-correlation method and the two-dimensional normalized cross-correlation method, and the local image having the smallest correlation value in the SAD method and the SSD method. What is necessary is just to let it be the local image with the highest image matching degree. There is a feature of the image correlation method in selecting a local image having the maximum correlation (the maximum or minimum correlation value).

FIG. 1 is a diagram showing a processing procedure of an embodiment of a living tissue motion tracking method according to the present invention. FIG. 2 is a block diagram of an image diagnostic apparatus to which the movement tracking method of the living tissue shown in FIG. 1 is applied. FIG. 3 is a diagram for explaining the motion tracking of the living tissue of the present invention applied to a tomographic image of a heart. 4A and 4B are diagrams illustrating an embodiment of the block matching method according to the present invention, wherein FIG. 4A illustrates an example of a cut-out image, and FIG. 4B illustrates an example of a search area. FIG. 5 is an example of a display image of measurement information regarding movement of a living tissue measured by the tracking method of the present invention. FIG. 6 is an example in which the distance between two designated points set across the heart wall and the change in the distance are measured and displayed as a graph. FIG. 7 is an example in which a plurality of designated points are set on the heart wall, and various types of movement information obtained by tracking their movements are displayed as images. FIG. 8 is a display example of various information obtained by setting a plurality of designated points throughout the myocardium and measuring based on the movement of the designated points. FIG. 9 is an example of a display image in which a plurality of designated points are set along the inner wall of the myocardium and information of the movement is set. FIG. 10 is a diagram of a tracking processing procedure according to the second embodiment of the present invention in which the processing procedure of FIG. 1 is modified. FIG. 11 is a diagram illustrating an image tracking process by the image correlation method using a specific example. FIG. 12 is a block diagram of an image diagnostic apparatus according to one embodiment in which the present invention is applied to an ultrasonic diagnostic apparatus. FIG. 13 is a diagram illustrating a processing procedure of an RF signal correction method in which the image correlation method of FIG. 10 is improved. FIG. 14 is a diagram illustrating the RF signal correction method.

Explanation of reference numerals

REFERENCE SIGNS LIST 1 image storage unit 2 display unit 3 console 4 automatic tracking unit 5 dynamic information calculation unit 6 signal transmission path 7 diagnostic image pickup device 8 control unit 9 cutout image setting unit 10 cutout image tracking unit 11 movement amount calculation unit 12 movement tracking unit

Claims (32)

An imaging unit that captures a tomographic image of a subject, and an image diagnostic apparatus that includes a display unit that displays a moving image obtained by the imaging unit, an operation unit that specifies a part to be tracked of the tomographic image with a mark, An image diagnostic apparatus, comprising: a tracking unit that extracts the tomographic image corresponding to a part specified by the mark and tracks the movement of the tomographic image by the mark. A display unit that displays a moving image obtained by capturing a tomographic image of a subject; an operation unit that specifies a part to be tracked of the tomographic image by a mark; and an image corresponding to the part specified by the mark from the tomographic image An image diagnostic apparatus comprising a tracking unit for extracting a part, tracking the movement of the image part, and moving the display position of the mark. A display unit that displays a moving image obtained by capturing a tomographic image of a subject; an operation unit that specifies a part to be tracked of the tomographic image by a mark; and an image corresponding to the part specified by the mark from the tomographic image An image diagnostic apparatus comprising: a tracking unit that tracks a movement of a part; and a control unit that moves and displays the mark displayed on the display unit in accordance with the movement of the moving image. A first step of displaying a frame image of a moving image obtained by capturing a tomographic image of a subject, and superimposing a mark on a designated portion of a living tissue whose movement is to be tracked in the displayed frame image A second step of inputting a command to set the designated region, a third step of setting a cutout image of a size including the designated region as the one frame image, and searching for another frame image of the moving image Extracting a local image of the same size having the highest degree of coincidence between the cut-out image and the image; and moving the destination of the designated region based on the coordinate difference between the local image having the highest degree of coincidence and the cut-out image. And a fifth step of obtaining coordinates. The method according to claim 4, wherein the fourth step performs a correlation process between the cut-out image and the image data of the local image to extract a local image having the highest image correlation. . The moving image is photographed by an ultrasonic imaging method, and an RF signal corresponding to the moving image is stored,
In the fourth step, a destination coordinate of the designated part is obtained based on a coordinate difference between the local image having the highest matching degree and the cut-out image, and a plurality of RF signals corresponding to the periphery of the destination coordinate are extracted. 5. The method according to claim 4, wherein a cross-correlation of the plurality of extracted RF signals is obtained, and the destination coordinates are corrected according to a position of a maximum value of the cross-correlation. . The extracted local image is used as the cutout image, and the fourth step and the fifth step are repeatedly performed on still another frame image of the moving image to sequentially obtain the destination coordinates of the designated portion. The method for tracking motion of a living tissue according to any one of claims 1 to 5, characterized in that: The method according to any one of claims 4 to 7, wherein the size of the cut-out image is a region including a living tissue different from the living tissue of the designated portion. The method according to claim 4, wherein in the fourth step, a search range for extracting a local image of the same size having the highest degree of matching between the cut-out image and the image is set to an area having a larger number of pixels than the cut-out image. 6. The method for tracking movement of a living tissue according to any one of 1 to 5. The method according to any one of claims 4 to 9, wherein the mark is displayed on the moving destination of the designated part so as to overlap the moving image. 11. The method according to claim 10, wherein the destination coordinates of the designated part are stored, and the movement trajectory of the mark is displayed on the moving image. 10. The method according to claim 4, further comprising: storing a destination coordinate of the designated part, and obtaining at least one of a moving amount, a moving speed, and a moving direction of the designated part. The method for tracking movement of a living tissue according to the above. The method according to claim 12, wherein at least one change in the movement amount, the movement speed, and the movement direction of the designated part is displayed in a diagram. A plurality of the designated parts are set on the heart wall of the myocardium, the moving direction of each designated part is determined, the reference point of the moving direction is set as the center of gravity, and the color of the direction toward the center of gravity and the color in the opposite direction are changed. The method according to any one of claims 4 to 9, wherein the movement is displayed. The method according to claim 14, wherein luminance modulation is performed according to the moving speed. At least two designated parts are set, destination coordinates of the two designated parts are stored, and a distance between the two designated parts, a change in the distance, a change speed of the distance, and a The method according to any one of claims 4 to 9, further comprising a sixth step of calculating at least one of the change rates. 10. The method according to claim 4, further comprising the step of: setting at least two of the designated portions with the myocardium interposed therebetween, and calculating at least one of a thickness, a thickness change, a thickness change speed, and a thickness change rate of the myocardium. The movement tracking method of a biological tissue according to any one of the above. 10. The method according to claim 4, wherein the plurality of designated portions are provided along an inner wall of the ventricle, and a volume of the ventricle and a change in the volume are obtained based on a straight line connecting the plurality of designated portions or an approximate curve of the straight line. The movement tracking method of a biological tissue according to any one of the above. A storage unit in which a moving image obtained by capturing a tomographic image of the subject is stored, a display unit capable of displaying the moving image, an operation unit for inputting a command, and an operation unit for displaying the moving image displayed on the display unit An automatic tracking unit that tracks the movement of the biological tissue, comprising a signal transmission path connecting the storage unit, the display unit, the operation unit, and the automatic tracking unit,
The operation unit includes a command to display one frame image of the moving image stored in the storage unit on the display unit, and a biological tissue whose movement is to be tracked in the one frame image displayed according to the command. Means for inputting a command to superimpose and display a mark on the designated part of
The automatic tracking unit includes a cutout image setting unit configured to set a cutout image of a size including the designated region corresponding to the position of the mark of the one frame image displayed on the display unit, and the moving image from the storage unit. A cut-out image tracking means for reading another frame image of the image and extracting a local image of the same size having the highest matching degree between the cut-out image and the image; and a coordinate difference between the local image having the highest matching degree and the cut-out image. An image diagnostic apparatus comprising: a movement amount calculating means for obtaining a moving distance; and a movement tracking means for obtaining a moving destination coordinate of the designated part based on the coordinate difference. 20. The diagnostic imaging apparatus according to claim 19, wherein the cut-out image tracking unit performs a correlation process between the cut-out image and the image data of the local image to extract a local image having the highest image correlation. The moving image stored in the storage unit is captured by an ultrasonic imaging method, and an RF signal corresponding to the moving image is stored in the storage unit,
The movement tracking means obtains a destination coordinate of the designated part based on the coordinate difference, extracts a plurality of RF signals corresponding to a periphery of the destination coordinate, and performs a cross-correlation of the extracted plurality of RF signals. 20. The image diagnostic apparatus according to claim 19, wherein the destination coordinates are corrected according to the position of the maximum value of the cross-correlation. The cut-out image tracking means repeatedly executes the extracted local image as the cut-out image on still another frame image of the moving image to obtain a local image of the same size having the highest degree of matching between the cut-out image and the image. Are sequentially extracted, and the movement amount calculating means and the movement tracking means obtain a coordinate difference between the local image and the cut-out image which are sequentially extracted with the highest degree of coincidence, and move the designated portion based on the obtained coordinate difference. 22. The image diagnostic apparatus according to claim 19, wherein a preceding coordinate is obtained. The cut-out image tracking means performs a search for extracting a local image of the same size having the highest degree of coincidence between the cut-out image and the image, with respect to a search range set in an area having a larger number of pixels than the cut-out image. An image diagnostic apparatus according to any one of claims 19 to 22. The image according to any one of claims 19 to 23, wherein the automatic tracking unit stores destination coordinates of the designated part, and displays a movement locus of the mark over the moving image. Diagnostic device. The automatic tracking unit stores a destination coordinate of the designated part, obtains at least one of a moving amount, a moving speed, and a moving direction of the designated part, and displays the change on the display unit in a diagram. The image diagnostic apparatus according to any one of claims 19 to 24, wherein: The automatic tracking unit stores destination coordinates of at least two designated parts input and set from the operation unit, and calculates a distance between the two designated parts, a change in the distance, and a change speed of the distance. 25. The image diagnostic apparatus according to claim 19, wherein at least one of a change rate of the distance is calculated and a diagram thereof is displayed on the display unit. The automatic tracking unit calculates at least one of a thickness, a thickness change, a thickness change rate, and a thickness change rate of the myocardium based on at least two of the designated parts input and set with the myocardium interposed therebetween from the operation unit. 25. The image diagnostic apparatus according to claim 19, wherein the diagram is displayed on the display unit. The automatic tracking unit obtains a destination of the plurality of designated sites along the inner wall of the ventricle input and set from the operation unit, and calculates a destination of the ventricle based on a straight line connecting the plurality of designated sites or an approximate curve of the straight line. 25. The diagnostic imaging apparatus according to claim 19, wherein a volume and a change in the volume are obtained and displayed on the display unit. A first step of reading a frame image of a moving image obtained by capturing a tomographic image of a subject from a storage unit in response to a command from a console and displaying the frame image on a display unit; and the displayed one frame image A second step of requesting a command input for superimposing and displaying a mark on the designated portion of the living tissue whose movement is to be tracked, and the coordinates of the designated portion of the living tissue corresponding to the mark set from the console in response to the request And a fourth step of setting a cut-out image of a size including the designated region as the one frame image, and searching for another frame image of the moving image to match the cut-out image with the image. Extracting a local image of the same size having the highest value, and obtaining a destination coordinate of the designated portion based on a coordinate difference between the local image having the highest matching degree and the cut-out image. Motion tracking program of biological tissue comprising a 6 steps. The program according to claim 33, wherein the fifth step performs a correlation process between the cut-out image and the image data of the local image to extract a local image having the highest correlation between the images. . The moving image is photographed by an ultrasonic imaging method and an RF signal corresponding to the moving image is stored in the storage unit,
In the fifth step, a destination coordinate of the designated portion is obtained based on a coordinate difference between the local image having the highest matching degree and the cut-out image, and a plurality of RF signals corresponding to the vicinity of the destination coordinate are extracted. 30. The biological tissue motion tracking program according to claim 29, wherein a cross-correlation of the plurality of extracted RF signals is obtained, and the movement destination coordinates are corrected according to a position of a maximum value of the cross-correlation. . The extracted local image is used as the cutout image, and the fifth step and the sixth step are repeatedly performed on still another frame image of the moving image to sequentially obtain the destination coordinates of the designated portion. 32. The motion tracking program for a living tissue according to claim 29, wherein:

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