JP2004121835A - Follow-up control method for interested area, image diagnosing system using the method, and follow-up control program for interested area - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable an interested region on a diagnosing image to be followed while adjusting to the movement of a biological tissue. <P>SOLUTION: One frame image of a motion picture which is formed by picking up a tomographic image of a patient is displayed (S2). A mark which specifies the interested region is displayed by being superposed on the biological tissue of the displayed one frame image, and a reference point is determined by corresponding to the interested region. A sliced image of a size for including the reference point is set on the one frame image (S3 and S4). At the same time, a local image of the same size wherein the matching rate of the local image with the sliced image is highest is extracted by searching other frame images of the motion picture (S5). Moving destination coordinates of the reference point are obtained based on a difference in coordinates between the local image the matching rate of which is highest and the sliced image (S6). From the moving destination coordinates of the reference point, moving destination coordinates of the mark specifying the interested region are obtained and are displayed by being superposed with the other frame image of the motion picture (S7 and S8). Thus, the interested region is made to follow the motion of the biological tissue. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a method for controlling the tracking of a region of interest set in a living tissue having movement of an ultrasonic diagnostic image, a magnetic resonance image, or an X-ray CT image, an image diagnostic apparatus using the method, and a tracking control program for the region of interest. Belongs to technology.

(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)

方法 By the way, there is a demand for a method of measuring blood flow and coronary blood flow in the myocardium of the heart to accurately and accurately diagnose myocardial infarction and the like. For example, after administering a contrast agent to a subject, a region of interest, which is a range to be observed on the screen of the myocardium of the heart, is designated, and luminance, luminance average, luminance change, and the like are determined based on pixel values in the designated region of interest. Get measurement information of Attempts have been made to quantitatively calculate the blood flow and coronary blood flow in the myocardium from the acquired measurement information and to accurately and accurately diagnose myocardial infarction and the like based on the calculated blood flow.

However, for example, the relative position between the myocardium and the region of interest changes due to the movement of the myocardium, and all or part of the myocardium may fall outside the region of interest. As a result, there is a problem that the reliability of the evaluation index such as the luminance, the luminance average, and the luminance change measured in the region of interest is impaired, and the evaluation index does not become an effective evaluation index.

課題 An object of the present invention is to make a region of interest follow a movement of a living tissue.

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

An image diagnostic apparatus according to the present invention is an image diagnostic apparatus including 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, wherein a region of interest is specified in the tomographic image. And a tracking unit that tracks the motion of the tomographic image corresponding to at least a part of the region of interest and causes the region of interest to follow the motion of the tomographic image. In this case, the imaging means can be provided separately. Further, the tracking means can move the display position of the region of interest by tracking the movement of the image part. The tracking means sets one or a plurality of reference points in the region of interest, extracts one or a plurality of image parts corresponding to the reference points, and tracks the movement of the image parts. And control means for following and displaying the region of interest displayed on the display unit in accordance with the movement of the reference point corresponding to the above.

Further, the tracking control method for a region of interest according to the present invention is a control method for following a region of interest displayed superimposed on a moving image obtained by imaging a subject in accordance with the movement of a living tissue on the moving image. A first step of displaying one frame image of the moving image, and a second step of inputting a command to overlap and display a mark defining a region of interest on the living tissue of the displayed one frame image; A third step of determining a reference point corresponding to the region of interest and setting a cut-out image having a size including the reference point as the one frame image; and searching for another frame image of the moving image to obtain the cut-out image. And extracting a local image of the same size having the highest degree of coincidence between the images and obtaining the destination coordinates of the reference point based on the vote difference between the local image having the highest degree of coincidence and the cut-out image. Remember A step of obtaining the destination coordinates of the mark defining the region of interest based on the stored destination coordinates of the reference point, and displaying the obtained destination coordinates overlaid on another frame image of the moving image. Is characterized by the following.

That is, when a region of interest is set in a moving biological tissue, a mark that defines the region of interest is superimposed and displayed on one frame image (still image) of a moving image by operating input means such as a mouse. Set by In this case, as a mark, for example, a frame such as a rectangle, a circle, and an ellipse, or two opposing lines are generally applied. However, the present invention is not limited to these.

Next, at least one point or a plurality of points on the center of gravity, center, or landmark of the region of interest can be set as the reference point determined in correspondence with the region of interest. Then, a cut-out image of a predetermined size including each reference point is set as one frame image automatically or by inputting a frame on the still image. The position to which the cut image has moved in the subsequent frame image is tracked by image correlation processing such as a so-called block matching method for searching for a local image having the same degree of matching between the cut 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. Since the coordinate difference between the cut images before and after the movement corresponds to the coordinate difference before and after the movement of the reference point, the movement direction and the movement amount of the reference point, that is, the movement direction and the movement amount of the region of interest can be measured.

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 reference point of the region of interest can be sequentially obtained. Then, by storing the destination coordinates of the reference point and displaying the mark of the region of interest on the moving image at the coordinate position of the destination, the region of interest can be made to follow the movement of the living tissue. it can. As a result, the moving living tissue can be always positioned within the range of the region of interest, so that highly reliable measurement information on the living tissue can be obtained.

For example, when observing blood flow in the myocardium after administration of a contrast agent to a subject, a region of interest is set in the myocardium, and luminance, luminance average, and luminance as evaluation indices are determined from pixel values in the region of interest. A change or the like is measured. In this case, according to the present invention, since the region of interest moves following the movement of the myocardium, the relative position between the myocardium and the region of interest does not change. As a result, since the reliability of the measurement values such as the luminance, the luminance average, and the luminance change, which are the evaluation indexes calculated from the pixel values in the region of interest, is high, the blood flow of the myocardium is quantitatively determined based on the evaluation indexes. By grasping, the degree of myocardial infarction can be accurately diagnosed. Further, by displaying the change of the measurement information, for example, the luminance change on the display unit in a diagram, the viewer can visually grasp the rate of the luminance change, thereby further improving the accuracy of diagnosis. Can be.

Such a process of causing the region of interest to follow the movement of the living tissue is performed by using the local image having the highest degree of coincidence of the image extracted by the search as a new cutout image with respect to still another frame image of the moving image. By applying the image correlation method, it is possible to sequentially obtain the destination coordinates of the designated region of the region of interest. Then, the destination coordinates of the region of interest can be calculated from the destination coordinates of the designated part. Thereby, the tracking control of the region of interest can be performed in accordance with the movement of the living tissue in the moving image.

In addition, at least two regions of interest are set in the living tissue, destination regions of the two regions of interest are stored, and measurement information such as luminance, average luminance, and change in luminance in the two regions of interest are obtained. Thus, the measurement information of the two regions of interest can be relatively grasped. Therefore, for example, by setting two regions of interest in the myocardium of the heart and calculating the luminance, the luminance average, and the luminance change in the set regions of interest, the blood flow in the myocardium in the two regions of interest is relatively determined. I can figure it out. In this case, by displaying the diagram of the measured values related to the heart and the electrocardiographic waveform in association with the time axis, it is possible to grasp the blood flow of the myocardium in comparison with the cardiac function.

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 at the reference point. 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. An instruction to display one frame image of the moving image stored in the storage unit on the display unit; and an interest in a living tissue of the one frame image displayed according to the instruction. Means for inputting a command to superimpose and display a mark that defines an area, wherein the automatic following section sets a reference point corresponding to the mark of the one frame image displayed on the display section, The extracted image of the size including the point is A cutout image setting means for setting an image, a cutout image tracking means for reading another frame image of the moving image from the storage unit, and extracting a local image of the same size having the highest degree of coincidence between the cutout image and the image, Moving amount calculating means for calculating a coordinate difference between the local image having the highest degree of coincidence and the cut-out image; moving tracking means for calculating and storing destination coordinates of the reference point based on the ticket difference; Display control means for obtaining destination coordinates of the mark defining the region of interest based on the destination coordinates of the reference point, and displaying the destination coordinates on another frame image of the moving image. Can be.

Further, the tracking control program for the region of interest according to 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 input of a command to superimpose and display a mark defining a region of interest on the living tissue of the displayed one frame image, and input setting from the console according to the request. A third step of determining a reference point in association with a region of interest of the living tissue corresponding to the mark, a third step of setting a cut-out image having a size including the reference point in the one frame image, and A fourth step of retrieving another frame image and extracting a local image of the same size having the highest matching degree between the cut-out image and the image; A fifth step of obtaining and storing the destination coordinates of the reference point based on the difference; and obtaining the destination coordinates of the mark defining the region of interest based on the stored destination coordinates of the reference point. And a sixth step of superimposing and displaying the moving image on another frame image.

According to the present invention, the region of interest can be made to follow the movement of the living tissue.

(Embodiment 1)
An image diagnostic apparatus according to an embodiment to which the tracking control method for a region of interest according to the present invention is applied will be described with reference to FIGS. FIG. 1 shows a procedure in a tracking control method for a region of interest according to the present embodiment, and FIG. 2 is a block diagram of an image diagnostic apparatus to which the tracking control method for a region of interest shown in 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 a moving image, and a region of interest. Console 3 for inputting a command to perform, automatic follow-up unit 4 for following the region of interest with the movement of the living tissue of the moving image displayed on display unit 2, and various measurement information of the region of interest to be followed by automatic follow-up unit 4. For example, it is configured to include a region-of-interest measurement information calculation unit 5 for calculating the brightness, average brightness, and change in brightness of a pixel, and a signal transmission path 6 connecting these. 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.

The automatic follow-up unit 4 includes a control unit 8 that controls the entire image diagnostic apparatus, and a cut-out image setting unit 9 that sets a cut-out image of a size including the reference point of the region of interest of one frame image displayed on the display unit 2. A cut-out image tracking unit 10 for reading another frame image of the moving image from the image storage unit 1 and extracting a local image of the same size having the highest matching degree between the cut-out image and the image; a local image having the highest matching degree Moving amount calculating means 11 for calculating a coordinate difference between the image and the cut-out image, moving tracking means 12 for calculating a moving destination coordinate of the reference point 23a of the region of interest 23 based on the coordinate difference, and A display control unit for displaying the obtained region of interest on another frame image of the moving image.

The region-of-interest measurement information calculation unit 5 quantitatively obtains the luminance, the average luminance, the luminance change, and the like based on the measurement information, for example, the pixel value in the region of interest, in the region of interest moved by the automatic tracking unit 4. It has a function of displaying 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 tracking control method for a region of interest is started when a command for selecting a tissue movement tracking mode is input from the console 3 (S1). The control means 8 of the automatic following unit 4 reads the first frame image ft (t = 0) of the moving image from the image storage unit 1 and causes the display unit 2 to display the first frame image ft (t = 0) (S2). For example, it is assumed that the tomographic image of the ventricle 21 of the heart shown in FIG. 3 is displayed as the first frame image f0. In FIG. 3, a specific range of the myocardium 22 is selected as the region of interest 23 of the living tissue that the operator wants to observe. At this time, the operator operates the mouse or the like of the operation unit 3 to input a command to draw a circular, rectangular, or elliptical region of interest 23 on the frame image f0. In one frame image displayed based on the instruction, a mark (mark) as a region of interest of the living tissue is superimposed and displayed. Then, a reference point 23a corresponding to the region of interest on the image is determined. At this time, at least one point or a plurality of points on the center of gravity, center, or landmark of the region of interest, a point separated from the region of interest by a predetermined distance, or the like is manually or automatically set as the reference point 23a. In FIG. 3, reference numeral 24 denotes a mitral valve.

When the reference point 23a of the region of interest 23 is set, the control means 8 takes in the coordinates of the reference point 23a 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 (where A is a natural number) in the vertical and horizontal directions around the image of the reference point 23a 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 reference point 23a. For example, this is because if the size of the cut-out image 25 is too small, many matching local images appear, and the true destination cannot be specified. Conversely, if the size is too large, the cut-out image 25 runs out of the image area of the frame image f0 and is measured. This is because there are cases where it is not possible.

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 B of pixels is larger than the movement amount of the tissue in the region of interest, 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, the destination coordinates of the reference point 23a are obtained from the coordinate difference between the local image 27max and the cut-out image 25, and the destination coordinates of the reference point 23a are obtained and stored based on the coordinates. The display control means 14 moves and moves the region of interest 23 on the basis of the desired region of the living tissue based on the displayed region (S7). It is assumed that the relative position between the local image 27max and the reference point 23a in the cut-out image 25 does not change.

Then, in the region of interest 23 moved based on the destination coordinates of the reference point 23a obtained in S7, various measurement information such as the luminance, average luminance, and luminance change of the pixel value in the region of interest 23 are calculated as the region of interest measurement information. The calculation is performed by the calculation unit 5 (S8). That is, by making the luminance average in the region of interest 23 before and after the movement, the blood flow in the myocardium with movement can be measured accurately and quantitatively. Further, measurement information, which is a physical quantity related to luminance, luminance average, luminance change, and the like, can be quantitatively obtained from the pixel values in the region of interest on the diagnostic image.

Based on the measurement information thus obtained, the region-of-interest measurement information calculation unit 5 further displays the luminance, average luminance, change in luminance, and the like of the pixel values in the region of interest 23 on the display unit 2 in a graph (S9). . Thus, the viewer can visually and quantitatively grasp the blood flow flowing through the living tissue in the region of interest 23, for example, the myocardium.

Next, the process proceeds to step S10, where it is determined whether or not the follow-up of the region of interest 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 region of interest 23 has been completed for all the frame images, the tracking processing operation ends.

As described above, according to this embodiment, by applying the image correlation method, the coordinates of the movement destination of the reference point 23a of the region of interest 23 can be sequentially obtained for the movement of the living tissue. The display can be made to follow the movement of the living tissue. As a result, a change in the relative position between the mark of the region of interest 23 and the biological tissue on the diagnostic image can be avoided, so that the biological tissue to be measured can be reliably positioned within the mark of the region of interest 23. Therefore, the reliability of the evaluation index measured in the region of interest 23 is improved.

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. 5A is an example of an image in which one region of interest 23 shown in FIG. 3 is superimposed and displayed on a myocardial image, and FIG. 5B shows an image on a diagnostic image after a contrast agent is administered to a subject. 9 is an image example in which a luminance average difference is represented in a graph based on a pixel value in a region of interest 23. The horizontal axis of the graph represents time, and the vertical axis represents the average luminance difference. The method of calculating the average luminance difference uses a known method such as a time luminance curve. By referring to this graph, the blood flow in the myocardium in the region of interest 23 can be visually and quantitatively grasped, and a diagnosis of myocardial infarction or the like can be accurately made.

On the other hand, FIG. 6A is an image example in which two regions of interest 23 shown in FIG. 3 are superimposed and displayed with the heart wall of the myocardium 22 interposed therebetween, and FIG. 6B is a diagram in which a contrast agent is administered to the subject. Thereafter, it is an image example in which the average luminance difference is represented by a graph based on the pixel value in the region of interest 23. The horizontal axis of the graph represents time, and the vertical axis represents the average luminance difference. The method of calculating the average luminance difference uses a known method such as a time luminance curve. By referring to this graph, for example, since the blood flow in the myocardium can be relatively grasped by comparing it with the blood flow in other parts, there is a possibility that the onset of myocardial infarction and the like can be accurately grasped. Increase. In this case, it is also preferable to display a graph of the measurement values related to the heart and information such as an ECG waveform and a heart sound waveform on the display unit 2 in association with the time axis. Thereby, the blood flow rate of the myocardium can be grasped while comparing with the cardiac function.

FIG. 7 shows an example of a display mode of the region of interest in FIG. FIG. 7A is a display example in which the region of interest 23A is defined by an elliptical frame, and FIG. 8B is a display example in which the region of interest 23B is defined by a circular frame. FIG. 14C is a display example in which the region of interest 23C is defined by a rectangular frame, and FIG. 14D is a display example in which the region of interest 23D is defined by two opposing lines. is there. These regions of interest 23A to 23D are superimposed and displayed on the display unit 2 based on commands from a mouse or the like of the console 3, respectively. In this case, the display mode of the mark is not limited to these, and an arbitrary display mode can be set.
(Embodiment 2)
In the embodiment of FIG. 1, each time the tracking of the reference point 23a of the region of interest 23 for one frame image ends (S7), the region of interest 23 is moved on the screen based on the movement of the reference point 23a. An example has been described in which various types of information relating to the tissue defined in the moved region of interest 23 are calculated (S8), and the information is displayed on the display unit (S9). The present invention is not limited to this. As shown in FIG. 8, after the step S10 of FIG. 1 is arranged after the step S7 and the tracking of the reference point 23a is completed for all the frame images, the processing of the steps S8 and 9 is performed. 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 reference point 23a 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 RF signal corresponding to the moving image is stored, and the position of the local image having the highest matching degree of the image obtained by the image correlation method is corrected using the RF signal to follow the movement of the living tissue. The destination of the reference point 23a of the region of interest 23 to be moved can be obtained with higher accuracy.

As shown in FIG. 10, 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 following unit 4 via the signal transmission path 6. Further, the automatic follow-up unit 4 is provided with a movement amount correction unit 13.

FIG. 11 shows a processing procedure of a main part of the present embodiment. The basis of the tracking processing of the present embodiment is to capture the destination coordinates of the cut-out image obtained in step S6 of FIG. 8 and calculate the destination coordinates of the reference point 23a (S21). Next, the RF signal related to the image around the coordinates of the reference point 23a of the cut-out image 25 and the coordinates of the reference point 23a 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 reference point 23a of the region of interest 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). Then, the movement amount of the reference point 23a obtained by using the RF signal is added to the movement amount of the reference point 23a previously obtained by the image correlation method to correct the movement amount of the reference point 23a (S25).

Here, 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 reference point 23a, and by correcting the movement amount of the reference point 23a, the position measurement accuracy is improved. The reason will be described with reference to FIG. In FIG. 12A, the time axes of the RF signal 41 around the reference point before the movement and the RF signal 42 around the reference 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 region of interest on the diagnostic image can be made to follow the movement of the living tissue with high accuracy, and the relative movement between the living tissue and the region of interest can be determined by the movement of the living tissue. The position can be prevented from changing. That is, since the living tissue with movement can always be located in the region of interest, the reliability of the measurement information measured in the region of interest is improved.

For example, when observing blood flow in the myocardium, after administering a contrast agent to the subject, a region of interest is set in the myocardium, and the luminance and luminance average as evaluation indices are determined from the pixel values in the mark of the region of interest. Diagnosis of myocardial infarction or the like is performed by measuring a change in luminance, etc., and grasping the blood flow in the myocardium based on the measured evaluation index. In this case, according to the present invention, since the region of interest always moves following the movement of the myocardium, it is possible to reliably obtain the luminance, luminance average, luminance change, and the like, which are evaluation indices, from the pixel values in the landmark of the region of interest. It is possible to improve the reliability of the evaluation index. By quantitatively grasping the myocardial blood flow based on the evaluation index, the possibility of accurately and accurately diagnosing the location and the degree of symptoms of myocardial infarction increases. Further, by displaying the measurement information on the display unit in a diagram, the observer can visually grasp the measurement information, so that diagnosis can be easily performed.

Also, it is apparent that the present invention is not limited to measuring the blood flow in the heart muscle of the heart, but can be applied to any part of the living tissue as long as the living tissue moves. For example, the present invention can be applied to measurement of blood flow in a large blood vessel wall such as a carotid artery. In this case, the region of interest including the boundary of the carotid artery is superimposed and displayed, the displayed mark of the region of interest is made to automatically follow the movement of the carotid artery, and the blood value is calculated based on the luminance of the pixel values in the region of interest, the luminance average, and the luminance change. The flow rate can be measured.

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 an image diagnostic apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram of an image diagnostic apparatus to which the tracking control method for a region of interest shown in FIG. 1 is applied. FIG. 3 is a diagram for explaining the tracking of the region of interest according to the present invention applied to a tomographic image of the 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 mode of a region of interest and a display image of measurement information measured by the tracking control method of the present invention. FIG. 6 is an example of a display mode of a region of interest and a display image of measurement information measured by the tracking control method of the present invention. FIG. 7 shows an example of a display mode of the region of interest. FIG. 8 is a diagram of a follow-up control procedure according to the second embodiment of the present invention, which is a modification of the procedure of FIG. FIG. 9 is a diagram illustrating an image tracking process using the image correlation method using a specific example. FIG. 10 is a block diagram of an image diagnostic apparatus according to an embodiment in which the present invention is applied to an ultrasonic diagnostic apparatus. FIG. 11 is a diagram illustrating a processing procedure of an RF signal correction method in which the image correlation method of FIG. 8 is improved. FIG. 12 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 moving amount calculation unit 12 movement tracking unit 14 Display control means

Claims (27)

In an image diagnostic apparatus including 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 that specifies a region of interest in the tomographic image, An image diagnostic apparatus comprising: a tracking unit that tracks the movement of the tomographic image corresponding to at least a part of the tomography and causes the region of interest to follow the movement of the tomographic image. A display unit that displays a moving image obtained by capturing a tomographic image of the subject, an operation unit that specifies a region of interest in the tomographic image, and an image part of the tomographic image corresponding to at least a part of the region of interest. An image diagnostic apparatus comprising a follower for extracting and tracking the movement of the image part to move the display position of the region of interest. Tracking means for setting one or more reference points in the region of interest, extracting one or more image parts corresponding to the reference points, and tracking the movement of the image parts, 3. The image diagnostic apparatus according to claim 2, further comprising: control means for following and displaying the region of interest displayed on the display unit in accordance with the movement of the reference point corresponding to (a). A control method in which a region of interest displayed superimposed on a moving image obtained by capturing an image of an object is followed in accordance with movement of a living tissue on the moving image, wherein a first frame image of the moving image is displayed. One step, a second step of inputting a command to superimpose and display a mark defining a region of interest on the biological tissue of the displayed one frame image, and defining a reference point corresponding to the region of interest; A third step of setting a cut-out image having a size including a reference point as the one frame image; and searching for another frame image of the moving image to search for another frame image and a local image having the same degree of matching between the cut-out image and the image. A fifth step of extracting the coordinates of the reference point based on the vote difference between the local image having the highest degree of coincidence and the cut-out image, and storing the coordinates of the reference point. Point Another sixth step and follow-up control method of the region of interest comprising the displayed over the frame image of the moving image in search of destination coordinate of the mark that defines the region of interest based on Dosaki coordinates. 5. 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 fifth step, a destination coordinate of the reference point 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 tracking control method for a region of interest 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 local image extracted in the fourth step is used as the cut-out image, and the fourth to sixth steps are repeatedly performed on still another frame image of the moving image to define the region of interest. The tracking control method for a region of interest according to any one of claims 4 to 6, wherein the mark is superimposed and displayed so as to follow the movement of the living tissue on the moving image. 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 region of interest. 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. The tracking control method for a region of interest according to any one of claims 4 to 8. 10. The mark according to claim 4, wherein the mark that defines the region of interest is one of a rectangular, circular, and elliptical frame, or two opposing linear bodies. A tracking control method for a region of interest. 11. The method according to claim 4, wherein the reference point is at least one point on a center of gravity, a center, and the mark of the region of interest. The method according to any one of claims 4 to 11, further comprising a step of measuring information on a biological tissue in the region of interest. The method according to claim 12, wherein the information about the living tissue is at least one of luminance, a luminance average, and a luminance change in the region of interest. Setting at least two regions of interest, storing destination regions of the two regions of interest, and calculating at least one of luminance, luminance average, and luminance change in the two regions of interest. The method according to claim 12, wherein the tracking control is performed on a region of interest. The method according to claim 13 or 14, wherein the change in luminance is displayed in a diagram. 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 follow-up unit that follows the movement of the living tissue, comprising a signal transmission path connecting the storage unit, the display unit, the operation unit, and the automatic follow-up unit,
The operation unit has a command to display one frame image of the moving image stored in the storage unit on the display unit, and a region of interest in a biological tissue of the one frame image displayed according to the command. A means for inputting a command to superimpose and display the prescribed mark,
The automatic tracking unit determines a reference point corresponding to the mark of the one frame image displayed on the display unit, and sets a cut image having a size including the reference point as the one frame image. A setting unit, a cutout 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 matching degree between the cutout image and the image, and Movement amount calculating means for calculating a coordinate difference between the high local image and the cut-out image; movement tracking means for calculating and storing a destination coordinate of the reference point based on the ticket difference; An image diagnostic apparatus comprising: display control means for obtaining destination coordinates of the mark defining the region of interest based on the destination coordinates, and displaying the destination coordinates on another frame image of the moving image. 17. The diagnostic imaging apparatus according to claim 16, 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 reference point based on the coordinate difference, extracts a plurality of RF signals corresponding to the vicinity of the destination coordinate of the reference point, and extracts the plurality of extracted RF signals. 17. The image diagnostic apparatus according to claim 16, wherein the cross-correlation is obtained, and 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, the moving amount calculating means obtains a coordinate difference between the local image having the highest degree of coincidence sequentially extracted and the cut-out image, and the movement tracking means calculates the coordinate difference based on the coordinate difference obtained by the moving amount calculating means. Based on the destination coordinates of the reference point, the display control means causes the mark defining the region of interest to follow the movement of the biological tissue on the moving image based on the destination coordinates of the reference point. 19. The diagnostic imaging apparatus according to claim 16, wherein the diagnostic imaging apparatus displays images in a superimposed manner. 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 16 to 19. Measurement information for measuring information on the living tissue from pixel values in at least one of the region of interest before the movement and the region of interest after the movement, and displaying a change in the measurement information on the display unit in a diagram. The image diagnostic apparatus according to any one of claims 16 to 20, further comprising a calculating unit. 22. The diagnostic imaging apparatus according to claim 21, wherein the measurement information is at least one of luminance, luminance average, and luminance change. The measurement information calculation unit stores destination coordinates of at least two regions of interest input and set from the operation unit, and calculates at least one of luminance, luminance average, and luminance change in the two regions of interest. 22. The diagnostic imaging apparatus according to claim 16, wherein the diagram is 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 an input of a command to superimpose and display a mark defining a region of interest on the living tissue of the subject, and relating to the region of interest of the living tissue corresponding to the mark set from the console in response to the request. A third step of setting a reference point by setting the cutout image having the size including the reference point as the one frame image; and searching the other frame images of the moving image for the cutout image. A fourth step of extracting a local image of the same size having the highest degree of coincidence of the image, and obtaining a destination coordinate of the reference point based on a difference between the local image having the highest degree of coincidence and the cut-out image. A fifth step of obtaining the destination coordinates of the mark defining the region of interest based on the stored destination coordinates of the reference point, and displaying the destination coordinates on the other frame image of the moving image. And a step of controlling the tracking of the region of interest. 25. The computer-readable storage medium according to claim 24, 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 reference point 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. The cross-correlation of the plurality of extracted RF signals is obtained, and the destination coordinates of the reference point are corrected according to the position of the maximum value of the cross-correlation. Tracking control program. The local image extracted in the fourth step is used as the cut-out image, and the fourth to sixth steps are repeatedly performed on still another frame image of the moving image to define the region of interest. 27. The region of interest tracking control program according to claim 24, wherein the mark is displayed so as to overlap with the movement of the living tissue on the moving image.

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