JP4503238B2 - Movement display method and diagnostic imaging apparatus for living tissue - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motion display method for a living tissue such as a myocardium having a motion applied to an ultrasound diagnostic image, a magnetic resonance image, or an X-ray CT image, and an image diagnostic apparatus using the method.
[0002]
[Prior art]
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 relating 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 the organs and the like are observed. Diagnosis is going on.
[0003]
In particular, if the motor function such as the heart can be quantitatively evaluated, it is expected that the accuracy of diagnosis is further improved. For example, conventionally, the contour of the heart wall is extracted from the image obtained by the ultrasonic diagnostic apparatus, and the heart function (heart pump function) is calculated based on the heart wall contour based on the area and volume of the ventricle and the rate of change thereof. Attempts have been made to evaluate or to observe and diagnose local wall motion (Patent Document 1). In addition, the displacement of the tissue is measured based on a measurement signal such as a Doppler signal, and for example, a local contraction or relaxation distribution is imaged. Based on this, the location where the ventricular motion is activated is accurately determined. Or a method for quantitatively measuring tissue motion, such as measuring the thickness (wall thickness) of a ventricular wall during systole (Patent Document 2). Furthermore, a technique has been proposed in which the contours of the atria and ventricles that change from time to time are extracted, the contours are superimposed on the image, and the volume of the ventricles and the like is calculated based on the contours (Patent Document 3).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 9-13145 [Patent Document 2]
JP-T-2001-518342 [Patent Document 3]
US Pat. No. 5,322,067 (USP 5,322,067)
[0005]
[Problems to be solved by the invention]
However, any of the above conventional techniques is only a method for evaluating the overall function of the heart, and no consideration is given to quantitatively evaluating the movement of each tissue such as the myocardium. In particular, the conventional technique for extracting the outline of the heart wall by image processing and measuring the thickness (wall thickness) of the ventricular wall based on the outline or measuring the change in the wall thickness is not necessarily sufficient to obtain sufficient accuracy. Has not reached.
[0006]
In general, for example, if blood does not pass through the myocardium due to a thrombus or the like, the movement of the myocardium is said to decrease. Therefore, if the movement of each tissue of the heart, such as the movement of the myocardium constituting the ventricle and the change in the wall thickness, can be measured quantitatively, it is possible to provide effective diagnostic information when determining the treatment method. 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.
[0007]
In particular, since the heart circulates blood by repeatedly contracting and expanding, a scoring method has been proposed in which the degree of change in myocardial wall thickness is scored for diagnosis. This scoring method is a method in which the heart wall is divided into, for example, six parts in the extending direction of the heart wall, and the degree of wall thickness movement for each divided region is evaluated in five stages while observing a moving image. In addition, this scoring is divided into four modes: a normal state, a load I state in which a patient exercises a load on the heart, a load II state in which a greater load is applied, and a state in which the load is removed and recovered. The diagnosis of the heart is also performed.
[0008]
However, since conventional scoring must be evaluated by subjective judgment of the observer who observed the motion of the heart based on the moving image of the tomogram, the scoring result is not necessarily objective and accurate diagnosis There is a problem that considerable experience is required to do.
[0009]
Therefore, the inventors of the present invention set a pair of tracking points (marks) on the inside and outside of the myocardial wall on the monitor on which the tomographic image of the heart is displayed, and move the cutout image including the tracking points on the moving image. The tip is detected by image processing such as correlation method, and the tracking point is moved and superimposed according to the movement of the myocardial wall, while the distance (wall thickness) between the pair of tracking points is quantified based on the tracking result It proposes to measure automatically (Japanese Patent Application No. 2002-266864).
[0010]
However, since there is not enough consideration about the specific method of displaying the ventricular wall thickness data measured quantitatively, there was a point to be improved when the viewer made an accurate diagnosis.
[0011]
An object of the present invention is to improve a display method of a movement of a predetermined part of a living tissue having movement, such as a ventricular wall thickness measured quantitatively, so that an accurate diagnosis can be performed.
[0012]
In order to solve the above-described problems, an image diagnostic apparatus of the present invention includes an image storage unit that stores moving image data obtained by imaging a tomogram of a tissue having movement, and a display unit that displays a tomogram of the tissue. A display control unit that reads the moving image data stored in the image storage unit and displays a moving image or a still image on the display unit; and a predetermined portion on the still image displayed on the display unit. An operation unit that sets at least a pair of marks facing each other, and a cutout image that includes each mark is set in the still image displayed on the display unit, and the cutout is performed based on the moving image displayed on the display unit Cutout image tracking means for tracking the movement destination of the image, movement amount calculating means for obtaining the movement amount of each mark based on the movement destination of the cutout image, and movement of each mark obtained by the means Based on the above, a motion calculation means for obtaining at least one of the change rate of the distance between the pair of marks and the speed of change of the distance as the momentum of the predetermined portion, and brightness and color of the color according to the momentum obtained by the means An image diagnostic apparatus comprising: an image generation means for generating a motion display image to be displayed on the display area of the display unit by changing at least one pixel value, wherein the motion display image is one axis of a rectangular area Corresponding to the set positions of a plurality of pairs of marks arranged along the predetermined part, the other axis corresponding to the time axis, and the time axis and the set position axis of the motion display image via the operation unit When a line designating at least one of these is input and set, the image generation means displays a graph representing a change in the amount of exercise along the designated line on the display unit.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
An image diagnostic apparatus according to an embodiment to which the heart motion display method of the present invention is applied will be described with reference to FIGS. FIG. 1 shows the procedure of the heart motion display method of this embodiment, and FIG. 2 is a block diagram of an image diagnostic apparatus to which the heart motion display method of FIG. 1 is applied. As shown in FIG. 2, the diagnostic imaging apparatus inputs an image storage unit 1 that stores a moving image obtained by imaging a tomogram of a living body that is a subject, a display unit 2 that displays an image, and various commands. An operation console 3, an automatic tracking unit 4 that tracks the movement of the heart of a moving image displayed on the display unit 2, an image generation storage unit 5 that stores an exercise display image generated by the automatic tracking unit 4, The movement calculation unit 6 calculates various measurement information based on the tracking result of the automatic tracking unit 4 and a signal transmission path 7 formed by connecting them.
[0018]
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 online or offline. 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 can be applied.
[0019]
The console 3 superimposes a mark (mark) on a part of a living tissue whose movement is desired to be tracked on the still image displayed on the still image displayed on the still image displayed 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.
[0020]
The automatic tracking unit 4 includes a control unit 10 that controls the entire image diagnostic apparatus, a display control unit 11 that controls switching of 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 unit 12 that sets a cut-out image having a size including the corresponding tracking part, and another frame image of the moving image is read out from the image storage unit 1 and the cut-out image and the local image of the same size having the highest degree of coincidence between the images. Cutout image tracking means 13 for extracting an image, movement amount calculation means 14 for obtaining the coordinate difference between the local image having the highest degree of coincidence and the cutout image, and movement tracking means for obtaining the movement destination coordinates of the tracking portion based on the coordinate difference 15. The movement destination of the tracking part (mark) obtained by the movement tracking unit 15 may be sequentially stored according to the moving image to generate a tracking image of the moving image.
[0021]
On the other hand, the motion calculation unit 5 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 with a diagram. In particular, the motion calculation unit 5 according to the present embodiment obtains the distance between a pair of marks set to face the inner and outer walls of the myocardium based on the amount of movement of the tracking region as the wall thickness of the myocardium, and the wall of the myocardium. It has a function of obtaining momentum such as change in thickness, rate of change in wall thickness, and rate of change in wall thickness.
[0022]
Further, the image generation storage unit 9 has a function of generating and storing a motion display image in which at least one of luminance and color is changed according to the amount of motion of the myocardium obtained by the motion calculation unit 5. It is configured.
[0023]
The display control unit 11 reads out the moving image data stored in the image storage unit 1 in accordance with a command input from the console 3, and displays the moving image or the still image and the exercise stored in the image generation storage unit 5. It has a function of switching or displaying the displayed images.
[0024]
Next, the detailed functional configuration of the diagnostic imaging apparatus of the present embodiment will be described along with the operation according to the processing procedure shown in FIG. First, the motion tracking operation of the heart muscle starts when a command for selecting the tissue motion tracking mode 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 a tracking part of the biological tissue whose movement is to be tracked, the operator operates the mouse or the like of the operation unit 3 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 to be superimposed on the desired tracking part, and the tracking part is input and set. When measuring the wall thickness of the myocardium, which is a feature of the present invention, as shown in FIG. 6A, a pair of tracking points 23 facing each other with the myocardium 23 in between are input and set. In FIG. 3, reference numeral 24 denotes a mitral valve.
[0025]
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. 4A, the cut-out image setting means 12 cuts out a rectangular area having a size of 2 (A + 1) pixels in length and width (A is a natural number) around the image of each tracking point 23. (S4). Here, the size of the cut-out image 25 is preferably set in a region having a size including a living tissue different from the living tissue of the tracking point 23.
[0026]
The cutout image tracking unit 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 the present 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 of pixels B having a fixed swing width is added to the cutout image 25 in the vertical and horizontal directions. This pixel number 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, the local image 27 having the same size in the search area 26 is 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 explanation, the size of the cut-out image 25 is assumed to be a rectangular 9-pixel area, and the search area 26 is also assumed to be a rectangular 25-pixel area. That is, the cutout image 25 shown in FIG. 10A 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 degree is obtained for nine local regions 27. Various known methods can be applied to the method for obtaining the degree of coincidence of images.
[0027]
Next, the local image 27max having the highest degree of coincidence among the plurality of searched local images 27 is extracted, the local image 27max is set as the movement destination of the cut 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 coordinate difference between the local image 27max and the cut-out image 25 is obtained, and based on this, the movement destination coordinates of the tracking point 23 are obtained and stored. If necessary, the display control means 11 displays the mark of the tracking point 23 on the frame image f1 of the display unit 2 based on the movement destination coordinates of the tracking point 23 (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.
[0028]
The motion calculation unit 6 calculates and stores various measurement information related to the movement of the tracking point 23, that is, the movement of the tissue of the tracking part, 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 point 23 before and after the movement. In this embodiment, the wall thickness of the myocardium 23 is calculated from the distance between the pair of tracking points 23, and the change, rate of change, and rate of change of the wall thickness are calculated according to the command and stored (S9). Instead of or in addition to this, it is possible to quantitatively obtain measurement information that is a physical quantity relating to movement such as the movement amount, movement speed, and movement direction of the tracking region. And the various measurement information regarding the movement of the tracking point 23 calculated | required and its change can be displayed on a display part with a graph. Thereby, the viewer can easily observe the movement of the tracking portion.
[0029]
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 and the processes of S5 to S10 are performed. repeat. When the tracking of the tracking point 23 is completed for all the frame images, the tracking processing operation is ended and the movement history data of the tracking point 23 is stored. Next, the image generation storage unit 5 generates a motion display image of the designated wall thickness change, rate of change, and rate of change, and displays the motion display image on the display unit. A specific example of this display image will be described later. As described above, according to the present embodiment, the coordinates of the movement destination of the tracking point 23 can be obtained sequentially, so that the movement of the tracking portion can be easily measured quantitatively and accurately, and diagnostic information can be obtained. Can be provided accurately.
[0030]
Next, a specific example of the heart motion display method, which is a feature of the present invention, will be described with reference to FIGS. First, a command is input from the console 3, and a tomographic image of the heart is displayed on the display unit 2, and a still image of a desired tomographic image is displayed as shown in FIG. On this still image, a plurality of pairs (1 to n) of tracking points 23 are set along the myocardium 22 across the heart wall, and the tracking process is executed by switching to a moving image. As a result, the automatic tracking unit 4 operates to track the movement of each tracking point 23. The motion calculation unit 6 measures the distance (wall thickness) between the tracking points 23 of each pair (1 to n) based on the measurement result of the movement amount of each tracking point 23, and FIG. As shown in c), the wall thickness change and rate of change at an arbitrary pair of tracking points 23 are measured, a graph of the wall thickness change and rate of change is created in the image generation storage unit 5, and the display unit 2 It can be displayed. Thereby, the movement of the myocardium accompanying the expansion and contraction and expansion of the heart can be grasped quantitatively.
[0031]
However, in order to compare the wall thickness change and rate of change between a plurality of pairs (1 to n) of tracking points 23, a large number of graphs measured for each of n pairs of tracking points 23 must be displayed side by side. It becomes complicated and impractical. That is, when scoring is performed for a region obtained by dividing the heart's motor function into six parts, even if the average value of the wall thickness change in each divided region of the myocardium 22 is displayed as a graph, six graphs are displayed side by side. Therefore, the comparative observation becomes complicated.
[0032]
Therefore, as shown in FIG. 7A, it is conceivable to display the change in wall thickness in a three-dimensional graph. In the figure, the horizontal axis represents time, the vertical axis represents the wall thickness, and the depth axis represents the measurement site along the myocardium 22, and the measurement is started when the heart is most dilated. It is the result measured about one period until it expands again from. In this way, if it can be displayed as a three-dimensional image, it will be easier to see to some extent, but in this embodiment, the change in the wall thickness of the myocardium (momentum) is not changed along the time axis. It is characterized by generating and displaying a colored exercise display image.
[0033]
As an example of the exercise display image, as shown in FIG. 7B, a rectangular display area 30 is set on the display screen of the display unit 2, the horizontal axis is a time axis, and the vertical axis is a measurement part. Changes in the wall thickness (momentum) of the myocardium at each measurement site are displayed in the display area with luminance changes or colorization along the time axis. This figure is schematically shown. In the figure, auxiliary lines d1 to d3 correspond to equal thickness lines, and d1 (thin wall thickness) <d2 (medium thickness wall thickness) <d3. (Thickest wall thickness) relationship. As is clear from the figure, it can be seen at a glance that the cardiac contraction and expansion phase of the myocardium in the vicinity of the middle of the measurement site surrounded by the broken line in the figure are delayed compared to the other sites. For example, when the wall thickness is thin, the luminance is set to the minimum value (for example, black), and the luminance is increased as the wall thickness is increased. This exercise display image is created and stored by the image generation storage unit 5 based on the measurement result of the exercise calculation unit 6.
[0034]
FIG. 7 is an example of a motion display image of the change in the wall thickness of the myocardium. However, the change rate of the wall thickness or the change rate of the wall thickness can be similarly imaged and displayed. For example, when imaging the rate of change of wall thickness, a motion display image of the rate of change of wall thickness is generated and displayed with “red” as the direction of change in wall thickness and “blue” as the direction of decrease in thickness. can do. Further, the wall thickness change rate is obtained based on the measurement result of the motion calculation unit 6 as shown in FIG. 8A, and the wall thickness change rate data is obtained, and based on this data, the motion shown in FIG. 8B is obtained. A display image can be generated and displayed in the display area 30. In FIG. 8B, the region with “0” in the figure is a region with little wall thickness change, the region with “+” is a region with a positive wall thickness change rate, and “−” is attached. This area is a negative wall thickness change rate area.
[0035]
Further, as shown in FIG. 9, by operating the console 3 and inputting arbitrary designation lines 31 and 32 that are orthogonal to the time axis or the axis of the measurement site to the display area 30, A difference in wall thickness or wall thickness change speed due to a difference in measurement site, or a change or change speed in wall thickness on the designated line 32 can be displayed as a graph.
[0036]
Further, as shown in FIG. 10, a schema that is a tomographic image of the myocardium or a simulated image of the myocardium can be displayed on the display unit, and the above-described motion display image can be displayed on the image. In this case, the measurement site corresponds to the tomographic image of the myocardium, and the temporal change of the momentum is displayed as a moving image.
[0037]
As described above, according to the above-described embodiment, the following effects can be obtained. First, if the heart movement is biased to only one side after the heart surgery, or if you want to inspect the part where the blood circulation is poor by observing the part where the change in the wall thickness of the myocardial wall is small, mark the tracking point. Even if the movement display is performed following the movement of the myocardium, it is difficult to observe the subtle difference in the change in the wall thickness because the whole heart wall is confused. In this regard, according to the above embodiment, the momentum such as the change in wall thickness of each measurement site of the myocardium corresponding to the position of the mark is displayed by the difference in brightness, color, etc. It is possible to detect a symptom in which the motion of the heart is biased, or a site where blood circulation is poor, which is a site where the change in wall thickness is small.
[0038]
For example, when evaluating the function of the heart by scoring, the heart wall is generally divided into six along the heart wall of the heart, and the degree of change in wall thickness is divided into five stages for each divided region. “5”, “1” when there is no movement, and “2” to “4” according to the degree of movement in the middle. In addition, scoring is performed for four modes: the normal state, the load I state in which the patient is exercised to load the heart, the load II state in which a greater load is applied, and the state in which the load is removed and recovered. Then, the heart is being diagnosed. In this case, there is a problem that the scoring result varies when the degree of movement is determined by the subjective judgment of the viewer and given a score. In this regard, according to the present embodiment, the change in wall thickness, that is, the movement of the myocardium can be quantitatively discriminated based on the difference in brightness or the difference in color. Evaluation can be performed, and the same evaluation result can be obtained even by a viewer with little experience.
[0039]
In addition, since the motion of the myocardium can be recognized quantitatively, it is possible to identify, for example, the ischemic site or the degree of ischemia in ischemic heart disease. Can be used as an indicator.
[0040]
Further, in the above-described embodiment, in order to observe the movement of the myocardium finely, the number of tracking points 23 that are marks of the tracking site is input and set from the console 3, and the setting work is complicated. Therefore, when the tracking point 23 is set along the myocardial wall, an interval is appropriately provided for a portion where the tissue shape changes gently according to the operator's judgment, and an interval is provided for a portion where the tissue shape changes greatly. You may make it set narrowing. In this case, it is preferable that the tracking point 23 is automatically complemented and set at a close interval by the control means 10.
[0041]
Moreover, although the above-mentioned embodiment demonstrated the example performed offline, if the speed concerning an image tracking process is improved, it can be applied also to an online or real-time moving image. In addition, 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.
[0042]
【The invention's effect】
As described above, according to the present invention, since the method for displaying the ventricular wall thickness measured quantitatively has been improved, it is possible to assist so that an accurate diagnosis can be performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a processing procedure of an embodiment of a biological tissue motion tracking display method of the present 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.
FIG. 3 is a diagram for explaining the application of motion tracking of a living tissue of the present invention to a tomographic image of the heart.
FIGS. 4A and 4B are diagrams for explaining an embodiment of an image tracking processing method according to the present invention, in which FIG. 4A is an example of a cut-out image, and FIG. 4B is an example of a search area; .
FIG. 5 is a diagram for explaining image tracking processing by a correlation method using a specific example;
FIG. 6 is an example in which a distance between a plurality of pairs of marks set across a heart wall and a change in the distance are measured and displayed as a graph.
FIG. 7 is a graph showing wall thickness data measured by moving a pair of tracking points set on the inner and outer walls of the myocardium in accordance with the movement of the myocardium, and changes in the wall thickness of the myocardium over time It is a figure which shows an example of the exercise | movement display image displayed by changing a brightness | luminance or coloring along.
FIG. 8 is a graph showing data on the rate of change of the wall thickness of the myocardium, and a diagram showing an example of a motion display image that displays the change rate of the wall thickness with luminance change or coloration along the time axis. is there.
FIG. 9 is a diagram illustrating an example of displaying a graph of myocardial momentum on a line by setting an arbitrary designated line on the exercise display image shown in FIG. 7 or FIG. 8;
FIG. 10 is a diagram showing an example in which a schema that is a tomographic image of the myocardium or a simulated image of the myocardium is displayed on the display unit, and the motion display image of the present invention is superimposed on the image.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Image memory | storage part 2 Display part 3 Console 4 Automatic tracking part 5 Image generation 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

Claims (1)

Image storage means for storing moving image data obtained by imaging a tomographic tissue having movement;
A display unit for displaying a tomographic image of the tissue;
Display control means for reading out the moving image data stored in the image storage means and displaying a moving image or a still image on the display unit;
An operation unit for setting at least a pair of marks facing each other across a predetermined part on the still image displayed on the display unit;
A cutout image tracking unit that sets a cutout image including each mark in the still image displayed on the display unit, and tracks a movement destination of the cutout image based on the moving image displayed on the display unit;
A moving amount calculating means for determining a moving amount of each mark based on a moving destination of the cut image;
A motion calculating means for determining at least one of a rate of change of the distance between the pair of marks and a speed of change of the distance as the amount of motion of the predetermined part based on the amount of movement of each mark determined by the means;
An image diagnostic apparatus comprising: an image generation unit configured to generate an exercise display image to be displayed in a display area of the display unit by changing at least one pixel value of luminance and color according to the amount of exercise obtained by the unit. And
Said movement display image, one of the axes of the rectangular area so as to correspond to the set position of the mark pairs arranged along said predetermined portion, Ri Na in correspondence to the other axis to the time axis,
When a line designating at least one of the time axis and the setting position axis of the motion display image is input and set via the operation unit, the image generation means is a graph representing a change in the momentum along the designated line Is displayed on the display unit.

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