JP2005087594A - Image diagnostic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To quantatively find and display various information on the movement of a tissue by accurately setting a tracing point and measuring the movement of the tracing point. <P>SOLUTION: The apparatus comprises a display part 2 for displaying moving images obtained by taking tomograms of an organism, a control table 3 for setting a mark 23 on a region of the organic tissue whose movement is to be traced in one still image of the moving images displayed in the display part 2, a tracing means 4 for tracing the movement of the organic tissue of the region on which the mark 23 is set and moving/displaying the mark 23 displayed in the display part 2 according to the movement of the moving images, and an electrocardiograph for measuring the electrocardiographic complex. The tracing image or the result of measurement obtained from the tracing image is displayed as synchronized with the electrocardiographic complex, and the result of measurement is displayed as a numeric value on the tracing image. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a motion tracking display method of a biological tissue applied to an ultrasound diagnostic image, a magnetic resonance image, or an X-ray CT image, and an image diagnostic apparatus using the tracking display method.

  Image diagnostic apparatuses such as an ultrasonic diagnostic apparatus, a magnetic resonance imaging (MRI) apparatus, and an X-ray CT apparatus are all provided for diagnosis by displaying a tomographic image related to the examination site of the subject on a monitor. For example, in the case of a circulatory system such as the heart and blood vessels and other organs with movement, the movement of living tissues (hereinafter referred to as tissues) constituting them is observed by a tomographic image, and the functions of these organs and the like are observed. Diagnosis is going on.

Therefore, there is an ultrasonic diagnostic apparatus that provides both movement tracking (tracking) of a region of interest in a three-dimensional space-time that effectively uses information on a movement vector obtained by pattern matching calculation and a display method thereof. This device displays an image at a certain time phase (in the case of two dimensions, an image of an arbitrary cross section at a certain time phase), and displays all the trajectories in the time phase period from the initial time phase to the end time phase on the image. Are displayed using a line, or the moving speed is displayed, and the position or the speed is associated (Patent Document 1).
JP 2002-177273 A

However, it does not disclose that at least two tracking points are set and the mutual movement amount and movement speed are quantitatively measured, and diagnostic information as described later cannot be obtained.
It is said that the movement of the myocardium decreases when blood does not pass through the myocardium due to blood clots or the like. Therefore, if the movement of each tissue of the heart, such as the movement of the myocardium constituting the ventricle and the change in thickness, can be measured quantitatively, 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, if the movement of the valve annulus can be measured quantitatively, research has been conducted to help evaluate the overall cardiac function in heart diseases such as hypertensive cardiac hypertrophy. The target for quantitatively measuring the movement of such a tissue is not limited to the heart, but is also demanded for blood vessels. That is, if a pulse wave of a large blood vessel wall such as a carotid artery can be measured quantitatively, it is effective for diagnosis of arteriosclerosis.

  An object of the present invention is to quantitatively obtain various pieces of information related to the movement of a tissue by appropriately setting a tracking point and measuring the movement of the tracking point.

  In order to achieve the object of the present invention, a display unit that displays a moving image obtained by imaging a tomogram of a living body, and a living tissue whose movement is to be tracked with respect to one still image of the moving image displayed on the display unit An operation unit for setting a mark on the region, and tracking the movement of the biological tissue of the region where the mark is set on the moving image, and displaying the mark displayed on the display unit in accordance with the movement of the moving image. A tracking unit that generates a tracking image to be moved and an electrocardiograph that measures an electrocardiographic waveform, and the tracking image or a measurement result obtained from the tracking image is displayed in synchronization with the electrocardiographic waveform. It was.

  In addition, a display unit that displays a moving image obtained by imaging a tomogram of a living body, and an operation for setting a mark on a part of a living tissue whose movement is to be tracked with respect to a still image of the moving image displayed on the display unit And the movement of the living tissue of the part where the mark is set are tracked on the moving image, and a tracking image is generated for moving and displaying the mark displayed on the display unit according to the movement of the moving image. A tracking unit, and a measurement result obtained from the tracking image is numerically displayed on the tracking image. Further, the tracking unit displays the moving image and the tracking image on the display unit.

  According to the present invention, by appropriately setting tracking points and measuring the movement of the tracking points, it is possible to quantitatively obtain various information related to the movement of the tissue.

  An image diagnostic apparatus to which the biological tissue motion tracking display method of the present invention is applied will be described with reference to FIGS. FIG. 1 shows the procedure of the biological tissue motion tracking display method of the present embodiment, and FIG. 2 is a block diagram of an image diagnostic apparatus to which the biological tissue motion tracking display method of FIG. 1 is applied. As shown in FIG. 2, the diagnostic imaging apparatus includes an image storage unit 1 that stores a moving image obtained by photographing a tomogram of a living body that is a subject, a display unit 2 that can display a moving image, and various commands. An automatic console 4 for tracking the movement of a living tissue of a moving image displayed on the display unit 2, a tracking image storage unit 5 for storing a tracking image generated by the automatic tracking unit 4, and The movement calculating unit 6 calculates various measurement information based on the tracking result of the automatic tracking unit 5, and the signal transmission path 7 formed by connecting them.

  In the image storage unit 1, a moving image obtained by capturing a tomographic image of a subject from the diagnostic image capturing apparatus 8 indicated by a broken line is stored on-line or off-line. As the diagnostic image imaging apparatus 8, diagnostic apparatuses such as an ultrasonic diagnostic apparatus, a magnetic resonance imaging (MRI) apparatus, and an X-ray CT apparatus are applicable.

  The console 3 superimposes a mark (mark) on the part of the living tissue whose movement is desired to be tracked on the still image displayed on the display unit 2, and a command to display one frame image (still image) on the display unit 2. Various commands such as a command to be displayed and a command to select the type of image to be displayed on the display unit 2 can be input.

  The automatic tracking unit 4 includes a control unit 10 that controls the entire diagnostic imaging apparatus, a display control unit 11 that switches and controls an image displayed on the display unit 2, and a mark position of one frame image displayed on the display unit 2. A cut-out image setting means 12 for setting a cut-out image having a size including the corresponding tracking part, and another frame image of the moving image is read from the image storage unit 1, and the local area of the same size having the highest degree of matching between the cut-out image and the image Extracted image tracking means 13 for extracting an image, movement amount calculating means 14 for obtaining a coordinate difference between the local image having the highest degree of coincidence and the extracted image, and a movement tracking means for obtaining a destination coordinate of the tracking part based on the coordinate difference 15 and tracking image generation means 16 for generating a tracking image in which the mark display position is changed based on the movement destination coordinates. The tracking image generation means 16 has a function of generating a tracking image of a moving image by sequentially storing the movement destination of the tracking portion (mark) according to the moving image and storing the tracking image in the tracking image storage unit 5.

  In addition, the motion calculation unit 6 quantitatively calculates measurement information, which is a physical quantity related to movement such as the movement amount, movement speed, and movement direction of the tracking part, based on the movement destination coordinates of the tracking part obtained by the automatic tracking part 4. It has a function of obtaining and displaying the change of the measurement information on the display unit 2 in a diagram.

  Next, the detailed functional configuration of the diagnostic imaging apparatus according to the present embodiment will be described along with the operation according to the processing procedure shown in FIG. First, the movement tracking operation of the living tissue starts when a command for selecting the movement tracking mode of the tissue is input from the console 3 (S1). The display control means 11 reads 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 heart ventricle 21 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 tracking part of the biological tissue for which movement is to be tracked, the operator operates the mouse of the console 3 etc. to superimpose the tracking part on the frame image f0. The tracking point 23, which is a mark for setting, is displayed. Then, the tracking point 23 is moved and displayed in a superimposed manner on a desired tracking part, and the tracking part is input and set. In FIG. 3, reference numeral 24 denotes a mitral valve.

  When the tracking point 23 is input and set, the control means 10 takes in the coordinates of the tracking point 23 on the frame image f0 and sends it to the cutout image setting means 12 (S3). As shown in FIG. 4 (a), the cut-out image setting means 12 uses a rectangular area of 2 (A + 1) pixels in length and width (A is a natural number) as a cut-out image 25 with the image of the tracking point 23 as the center. Set (S4). Here, the size of the cut-out image 25 is preferably set to a region having a size including a living tissue different from the living tissue at the tracking point 23.

  The cutout image tracking means 13 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 cutout image 25 and the image (S5). This extraction process is image processing called a so-called block matching method or correlation method. If this extraction process is performed for the entire region of the frame image f1, it takes too much processing time. Therefore, in order to shorten the extraction processing time, in this embodiment, the search area 26 shown in FIG. 4B, which is sufficiently smaller than the frame image f1, is performed. That is, the search area 26 is a rectangular area in which the number B of pixels having a constant swing width is added to the cutout image 25 in the vertical and horizontal directions. The number of pixels B is larger than the amount of movement of the tissue related to the tracking region, and is set to 3 to 10 pixels, for example. This is because the range of movement of the circulatory system such as the heart is limited to a narrow region in a normal visual field. In this way, local images 27 of the same size in the search area 26 are sequentially shifted to obtain the degree of coincidence with the cut image 25. FIG. 5 shows a specific example of image tracking processing by the correlation method. In this example, in order to simplify the 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 cutout image 25 shown in FIG. 11A is an example in which A = 1 pixel is set around the pixel of the tracking point 23, and the search area 26 shown in FIG. This is an example. According to this, as shown in FIG. 5B, the image coincidence is obtained for nine local regions 27. Various known methods can be applied to the method for obtaining the degree of coincidence of images.

  Next, a local image 27max having the highest image matching degree is extracted from the searched plurality of local images 27, and the local image 27max is set as a movement destination of the cut-out image 25 to obtain coordinates of the local image 27max (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 a movement destination coordinate of the tracking point 23 is obtained based on the coordinate difference and stored in the tracking image storage unit 5. Normally, the display control means 11 reads the tracking image from the tracking image storage unit 5 and displays it on the frame image f1 of the display unit 2 (S7). Note that the relative position of the tracking point 23 in the local image 27max and the cutout image 25 is treated as not changing.

The motion calculation unit 6 calculates various measurement information related to the movement of the tracking point 23, that is, the movement of the tissue at the tracking site, based on the movement destination coordinates of the tracking point 23 obtained in S7 (S8). That is, the movement direction and the movement amount can be quantitatively measured based on the coordinates of the tracking part before and after the movement. In addition, measurement information, which is a physical quantity related to movement such as the movement amount, movement speed, and movement direction of the tracking part, can be obtained quantitatively.
Based on the measurement information thus obtained, the motion calculation unit 6 further displays various measurement information related to the movement of the tracking point 23 and changes thereof on the display unit in a graph (S9). Thereby, the viewer can easily observe the movement of the tracking portion.

  Next, the process proceeds to step S10, where it is determined whether or not tracking of the tracking point 23 has been completed for all 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 tracking point 23 is completed for all the frame images, the tracking processing operation is ended. At this time, a tracking image indicating the movement history of the tracking point 23 is stored in the tracking image storage unit 5.

  Here, a specific example of measuring the tracking region of the living tissue will be described with reference to FIG. Figure 6 shows two tracking points 23 set across the heart wall of the myocardium 22, and the distance between the two tracking points 23, that is, the wall thickness, is measured, the change in the wall thickness is measured, and these are graphed. This is an example displayed on the display unit 2. Thereby, the wall thickness of the myocardium and the change in the wall thickness can be grasped quantitatively.

  Here, when specifying that the tissue is sandwiched between the two tracking points 23, it is desired to confirm and set the movement of the myocardium with the moving image. For example, if the two tracking points 23 are set out of a common expansion / contraction direction, for example, the direction vector is different and the wall thickness of the myocardium to be observed and the change in the wall thickness can be measured quantitatively. It is because it is not possible. Therefore, the display control means 11 for reading the frame image of the moving image from the image storage unit 1 and displaying it on the display unit 2 controls the display form of the moving image and the still image. The display control means 11 reads out the moving image data stored in the image storage unit 1 in response to a command input from the console 3, and displays the moving image and the still image as shown in FIG. The control which performs is performed. When the frame image is read and the tracking point 23 is input, a command to switch to the display mode for displaying the moving image together with the still image for designating the tracking point 23 is specified from the console 3 so that the moving image is read and displayed. input. As a result, the display control means 11 operates to display a moving image of the myocardium 22 and to display a still image for designating the tracking point 23 on the display unit 2 and a moving image for facilitating determination of the myocardium that is the tracking location. Display the image at the same time. As a result, the position of the myocardium can be easily determined, and the tracking point 23 can be designated accurately at the myocardial position. Since the real-time motion of the heart is too fast to recognize the moving image, it may be difficult to set the tracking point 23 on the still image while observing the moving image. Therefore, the frame speed of the moving image can be set arbitrarily by giving a command to the display control means 11 from the console 3 so that the tracking point 23 can be easily set. It is possible to display feed playback. Further, the display control means 11 can also adjust the ratio of luminance between the moving image and the still image, and can superimpose the still image on the moving image. Thereby, the operator can recognize the moving image and the still image without moving the viewpoint, and can set the tracking point 23.

  In this way, when acquiring a cardiac ultrasound image by transthoracic scanning, the myocardium is not sufficient because the ultrasound beam is blocked by the lungs or ribs, and the acoustic window of the probe cannot be sufficiently adhered to the chest wall. If the ultrasound beam is significantly attenuated due to fat layers, etc., and the difference in contrast between the myocardium and other tissues is difficult to depict sufficiently, the myocardial position becomes unclear with only a still image, and the place where the tracking point 23 is placed It becomes difficult to discriminate. In this case, by changing the display mode and displaying the heart motion image simultaneously in addition to the still image for specifying the tracking point 23, the myocardium and the other tissues can be more clearly distinguished and tracked. The position where the point 23 is placed can be easily understood.

  Here, in FIG. 7, when a plurality of tracking points 23 are designated along the myocardium 22, the correspondence between the tracking points 23 and the wall thickness graph becomes difficult to understand. In that case, a command to switch to a display mode for displaying the same label on the tracking point 23 and the wall thickness graph is input from the console 3 as shown in FIG. 8 (a).

  Using the display control means 11, the same label is added to each measurement location of the corresponding tracking point 23 and each graph line of the wall thickness graph, and displayed together with the added label. As a result, the relationship between each trace location and each graph line of the wall thickness is clarified, and it is possible to easily determine which graph line is the wall thickness measured at which location. It is possible to accurately diagnose the unbalanced movement of the heart caused by badness.

  FIG. 8 (b) shows the correlation between the myocardial wall thickness and wall thickness changes and the electrocardiographic waveform. An electrocardiographic probe is attached to the subject, and an electrocardiographic waveform from the subject obtained by the electrocardiographic probe is provided with a biological signal storage unit for converting and recording the time-series pulse synchronized with the heartbeat by the electrocardiogram converter (Not shown). The biological signal storage unit stores an electrocardiogram signal simultaneously with the storage of the image storage unit 1 and the tracking image storage unit 3, and the images stored in the image storage unit 1 and the tracking image storage unit 3 are the heart. A synchronization signal with the electric signal is obtained and stored. Then, an electrocardiographic waveform diagram is formed from the electrocardiographic signal with the horizontal axis taken as time. The time in this case corresponds to the frame switching time in the image storage unit 3 and the tracking image storage unit 3, and can be displayed on the display unit 2. By the display operation of the console 3, the tomogram is reproduced from the image storage unit 1 and the tracking image storage unit 3 and the electrocardiogram waveform and the wall thickness of the myocardium and the change in the wall thickness are displayed at the same time.

  Then, graphs 34 and 35 show the relationship between the cardiac muscle wall thickness and the change in the wall thickness and the electrocardiographic waveform from the storage information of the image storage unit 1, the tracking image storage unit 3 and the biological signal storage unit. The graph 34 is a graph showing the wall thickness of the myocardium and changes in the wall thickness. A graph 35 is a graph of an electrocardiographic waveform, where a waveform 32 indicates an R wave and a waveform 33 indicates a T wave.

  Therefore, the bars 30, 31 following the electrocardiogram waveform are stored in the biological signal storage unit. Since the biological signal storage unit stores the electrocardiogram signal simultaneously with the storage of the image storage unit 1 and the tracking image storage unit 3, by providing a bar 30 at the start point of the R wave, It can be seen that this corresponds to the start of movement. Similarly, by providing a bar 31 at the end point of the T wave, it can be seen from the graph 34 that the tracking point 23 corresponds to the time of moving and focusing. Therefore, it can be seen that the phase of the myocardial wall thickness and the change in the wall thickness is measured in the one-week heartbeat period without looking at the electrocardiograph. That is, it is possible to recognize at which time phase the myocardium is measured by indicating the interrelation between the wall thickness of the myocardium and the change in the wall thickness and the electrocardiogram waveform. The bars 30 and 31 may be scrolled along the horizontal axis together with the electrocardiograph so that, for example, red is displayed at the R wave and blue is displayed at the T wave.

  FIG. 8 (c) shows a result obtained by digitizing the measurement result by reading the values of the graph as shown in FIG. 6 or FIG. 8, and displaying it on the screen. Specifically, the motion calculation unit 6 digitizes the information between the two tracking points 23 and displays the distance, distortion, and distortion rate on the screen. Based on the command from the console 3, the display of distance, distortion, and distortion rate is selected, and numerical values are displayed in the selected display format. The distance, distortion, and distortion rate may be set so as to display the maximum value in one cycle of the heartbeat.

Here, the distance is a distance between the three tracking points 23. This distance can be obtained from the position coordinates of the two tracking points 23. Then, the strain (ε) is obtained by Expression (1) using the measurement result of the distance between the two tracking points 23.
ε = dx / x dx: changed length x: original length (1)
Further, the distortion rate (S) is obtained by the equation (2) using the measurement result of the strain (ε).
S = dε / dt (2)

  A moving image displaying a numerical value can be subjected to loop reproduction such as slow motion reproduction and frame advance reproduction, as required, according to a command from the console 3. It is also possible to detect the maximum point and feature point of distance, distortion, and distortion rate, stop the moving image at that point, and display it as a still image of one frame of the moving image displaying the numerical value. it can. Therefore, diagnosis information can always be obtained from numerical values of distance, distortion, and distortion rate without calculating from the slope and amplitude of the graph. These moving images are created by the tracking image generation means 16 based on a command from the console 3, and stored in the tracking image storage unit 5. When displaying this numerical measurement result, electrocardiographic information may be displayed to confirm which phase is in one heartbeat cycle.

  As described above, the tracking point 23 is designated for the wall thickness part to be measured, the wall thickness change is displayed as a graph, and a label is attached to each measurement line and each graph line of the wall thickness, so that the movement of the heart is Without being confused, the difference in changes in the wall thickness of the myocardium depending on the region can be easily observed by associating the measurement location with the wall thickness graph. In addition, since the movement of each part of the heart can be measured quantitatively, for example, by tracking the myocardial motion or quantitatively measuring the change of the myocardial wall thickness, for example, the ischemic site is identified in ischemic heart disease. be able to. Moreover, it is possible to recognize at which time phase the myocardium is measured by showing the correlation between the wall thickness of the myocardium and the change in the wall thickness and the electrocardiogram waveform. Since the myocardial motion 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. In addition, quantitatively tracking the movement of the valve annulus may be useful in evaluating overall cardiac function in heart diseases such as hypertensive cardiac hypertrophy.

  Further, the present invention is not limited to measuring the movement of each part of the heart, but is obviously applicable to any part of the biological tissue as long as the movement of the biological tissue is desired to be observed. For example, it can be applied to pulse wave measurement of a large blood vessel wall such as a carotid artery. In this case, the degree of arteriosclerosis can be determined by setting a plurality of tracking parts in the longitudinal direction of the blood vessel wall and quantitatively measuring and comparing the movement amounts of these tracking parts.

  Further, in the above-described embodiment, in order to observe the movement of the myocardium in detail, the number of tracking points 23 that are marks of the tracking region is set to be input from the console 3, and the setting work is complicated. Therefore, when setting the tracking point 23 along the myocardial wall, an appropriate interval is provided for a part where the tissue shape changes gently according to the operator's judgment, and an interval is provided for a part where the tissue shape changes greatly. You may make it set narrowing. In this case, it is preferable that the tracking points 23 are automatically complemented and set at a close interval by the control means 10.

  In the above-described embodiment, an example of performing offline has been described. However, if the speed related to the image tracking process is improved, it can be applied to an online or real-time moving image. Further, although a two-dimensional tomographic image has been described as an example, it goes without saying that the present invention can also be applied to a three-dimensional tomographic image.

It is a figure which shows the process sequence of one Embodiment of the movement tracking display method of the biological tissue of this invention. FIG. 2 is a block configuration diagram of an image diagnostic apparatus to which the biological tissue motion tracking display method of FIG. 1 is applied. It is a figure for demonstrating by applying the motion tracking of the biological tissue of this invention to the tomogram of a heart. It is a figure explaining one Embodiment of the image tracking processing method which concerns on this invention, (a) is an example of a cut-out image, (b) is a figure which shows an example of a search area | region. It is a figure explaining the image tracking process by a correlation method using a specific example. In this example, the distance between two marks set across the heart wall and the change in the distance are measured and displayed as a graph. It is a figure which shows the example which superimposes and displays the tracking point set to the inner and outer wall of the heart on the moving image of the heart. It is a figure which shows the example which displays a graph synchronizing with an electrocardiogram, and a label and a measurement result.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image memory | storage part 2 Display part 3 Console 4 Automatic tracking part 5 Tracking image memory | storage part 6 Motion calculation part 7 Signal transmission path 8 Diagnostic image imaging device 10 Control means 11 Display control means 12 Cutout image setting means 13 Cutout image tracking means 14 Movement amount calculation means 15 Movement tracking means 16 Tracking image generation means 23 Tracking point 32 R wave 33 T wave

Claims (3)

A display unit that displays a moving image obtained by imaging a tomogram of a living body, and an operation unit that sets a mark on a portion of a living tissue whose movement is to be tracked with respect to a still image of the moving image displayed on the display unit. Tracking means for generating a tracking image for tracking a movement of a living tissue of a part where the mark is set on the moving image and moving and displaying the mark displayed on the display unit in accordance with the movement of the moving image. And an electrocardiograph that measures an electrocardiographic waveform, and displays the tracking image or a measurement result obtained from the tracking image in synchronization with the electrocardiographic waveform. A display unit that displays a moving image obtained by imaging a tomogram of a living body, and an operation unit that sets a mark on a portion of a living tissue whose movement is to be tracked with respect to a still image of the moving image displayed on the display unit. Tracking means for generating a tracking image for tracking a movement of a living tissue of a part where the mark is set on the moving image and moving and displaying the mark displayed on the display unit in accordance with the movement of the moving image. An image diagnostic apparatus characterized in that a measurement result obtained from the tracking image is numerically displayed on the tracking image. The image diagnosis apparatus according to claim 1, wherein the tracking unit displays the moving image and the tracking image on the display unit.

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