WO2006051831A1

WO2006051831A1 - Image creating method and device

Info

Publication number: WO2006051831A1
Application number: PCT/JP2005/020564
Authority: WO
Inventors: Osamu Arai
Original assignee: Hitachi Medical Corporation
Priority date: 2004-11-10
Filing date: 2005-11-10
Publication date: 2006-05-18
Also published as: JPWO2006051831A1; JP4980723B2

Abstract

A method and a device for creating an image enabling a user to easily comprehend the information on temporal variation of a tissue by a contrast medium. A color image where at least a partial area is colored is created by repeating following steps while changing the pixel, i.e. a step for acquiring a plurality of image data of different time phases and then acquiring the luminance value of a pixel at the same position from each of the plurality of image data of different time phases, a step for acquiring one or more feature amounts representatiing temporal variation in luminance value by the contrast medium based on the time variation in luminance value, a step for converting one or more feature amounts into different color information, and a step for coloring the pixel so as to represent the information on temporal variation in luminance value based on one or more color information.

Description

Specification

Image generation method and image generation apparatus

Technical field

[0001] The present invention uses image data acquired by imaging a subject into which a contrast medium has been injected by a medical image diagnostic apparatus such as an X-ray CT apparatus, an MRI apparatus, or an ultrasonic diagnostic apparatus. The present invention relates to an image generation apparatus and an image generation method for generating a color image representing an enhancement effect of a contrast agent.

Background art

[0002] Some medical diagnostic imaging apparatuses such as an X-ray CT apparatus, an MRI apparatus, and an ultrasonic diagnostic apparatus, for example, photograph a subject into which a contrast medium for contrasting blood flow is injected. Some of the acquired images display the enhancement effect (enhancement effect) by the contrast agent that the brightness value of a certain tissue is higher than before the injection of the contrast agent.

[0003] For example, in (Patent Document 1), using an electronic endoscope apparatus which is an example of a medical image diagnostic apparatus, an image obtained by imaging a disease site that changes with time using a contrast agent is obtained. The state of change of the diseased part by the cosmetic agent is displayed with ease and ease. Specifically, the three primary color (R, G, B) image data from an electronic endoscope device is converted into an HSV color system consisting of hue, saturation, and lightness, which is easy to understand for humans, and displayed. is doing.

[0004] As described above, a plurality of images having different time phases after injection of the contrast agent are obtained, and color conversion is performed on each image so that it can be easily understood by humans. By comparing the effects, the operator can easily grasp the change of the diseased part, the blood circulation state or the blood flow dynamics with the contrast medium.

[0005] However, in the conventional medical diagnostic imaging apparatus, the operator can display only one time phase from among multiple time phase images, as in the case where only the image can be displayed due to the size of the display unit. Assuming that an image is selected and displayed, the operator cannot determine whether the tissue with a high luminance value in the selected image is due to the Henno, or the luminance effect, or because the luminance value is originally high. .

[0006] In Patent Document 1, tissue having a high luminance value on one image is enhanced by a contrast agent. Means and methods for making it easy to understand information on changes in the organization over time, such as due to effects or because the luminance value is originally large, are disclosed. Patent Document 1: JP-A 63-79632

Disclosure of the invention

[0007] An object of the present invention is to provide an image generation apparatus and an image generation method for generating an image that allows easy understanding of information on temporal changes in tissue caused by a contrast agent.

[0008] In order to achieve the above object, the image generation method of the present invention uses the image data acquired by imaging the subject into which the contrast medium is injected, and changes the tissue over time by the contrast medium. A method for generating a medical image representing

(a) obtaining a plurality of the image data having different time phases;

(b) obtaining a luminance value of a pixel at the same position from each of the plurality of image data having different time phases;

(c) obtaining one or more feature amounts representing a temporal change in the luminance value due to the contrast agent based on the temporal change in the luminance value;

(d) converting the one or more feature quantities into different color information,

(e) coloring the pixel based on the one or more color information so as to represent information on temporal change of the luminance value;

(f) repeating the steps (b) to (e) for each different pixel in at least a part of the region to generate a color image in which the part of the region is colored. It is characterized by.

[0009] In order to achieve the above object, the image generating apparatus of the present invention includes an input unit that inputs a plurality of image data having different time phases acquired by imaging a subject into which a contrast medium has been injected. Storage means for storing a plurality of image data having different time phases, and calculation means for generating a medical image using the plurality of image data having different time phases, wherein the calculation means comprises the time phases. One or more feature amounts representing temporal changes in the tissue due to the contrast agent are extracted for each pixel from a plurality of different image data and converted into different color information, and at least for each pixel in a partial region It is characterized by generating a color image colored so as to represent the information of the temporal change. [0010] According to the image generation method and the image generation apparatus of the present invention described above, the contrast of whether a tissue having a high luminance value is due to the enhancement effect by the contrast agent or the luminance value is originally high on one image. It becomes easy to understand the information on changes in the tissue over time due to the drug.

Brief Description of Drawings

FIG. 1 is a schematic configuration diagram of an X-ray CT apparatus employing an image generating apparatus in a medical image diagnostic apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing color composition processing of the X-ray CT apparatus shown in FIG. 1.

FIG. 3 is a diagram showing a characteristic curve representing a change in luminance value of each tissue.

4 is a diagram showing a characteristic curve of blood vessel A shown in FIG.

FIG. 5 is a flowchart showing a color composition processing operation of the X-ray CT apparatus shown in FIG.

6 is a flowchart showing a synthesis process that is a main part shown in FIG.

FIG. 7 is a polar coordinate plane showing an example of calculating time T when the luminance value becomes maximum (minimum).

FIG. 8 is another polar coordinate plane showing an example of calculating time T when the luminance value becomes maximum (minimum).

FIG. 9 is a front view showing a display example of the image generation device in the medical diagnostic imaging apparatus shown in FIG. 1.

10 is an explanatory diagram showing a main part of the image generation apparatus in the medical diagnostic imaging apparatus shown in FIG.

FIG. 11 is an explanatory diagram showing another main part of the image generation apparatus in the medical image diagnostic apparatus shown in FIG. 9.

12 is an explanatory view showing another display example in the image generating device in the medical diagnostic imaging apparatus shown in FIG.

FIG. 13 is a schematic configuration diagram of an ultrasonic apparatus employing an image generating apparatus in a medical diagnostic imaging apparatus according to a second embodiment of the present invention.

FIG. 14 is a diagram showing an example of displaying an ultrasonic image and a color composite image in parallel.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of an image generation method and an image generation apparatus according to the present invention will be described with reference to the drawings. [0013] (First embodiment)

FIG. 1 shows an embodiment of the present invention and is a schematic configuration diagram of an example in which the image generation apparatus of the present invention is used in an X-ray CT apparatus as a medical image diagnostic apparatus.

The scanner 1 rotatably supported by the scanner control unit 17 is provided with a bed 2 on which an object is placed in an opening la formed in the center thereof so that the position can be adjusted by the bed control unit 16. 2 The X-ray source 3 and the multi 1J X-ray detector 4 are arranged opposite to each other with the subject on top of it. When the X-ray beam from the X-ray generation source 3 is exposed by the high-voltage switching unit 13, the high-voltage generator 14 and the X-ray control unit 15, it is detected by the multi-row X-ray detector 4 after passing through the subject. Is done. The output from the multiple IJX-ray detector 4 is digitized by an A / D converter via an amplifier and input to the image processing device 5 of the processing device 18, and image reconstruction processing is performed by the image processing device 5. Is done. The reconstructed image data is stored in a storage device (not shown) in the image processing device 5, for example. The reconstructed image is displayed on the display unit 11 on the console 12 by the display processing device 6.

An image generating device 19 and an image display device 6 are connected to the image processing device 5. The image generation device 19 acquires a feature value acquisition unit 7 that acquires a feature value corresponding to a CT value that is a brightness value, and a feature value for the degree of enhancement effect that acquires a feature value corresponding to the degree of the non-sense effect. Part 8, an enhancement effect time feature acquisition unit 9 that acquires a feature quantity corresponding to the time of the enhancement effect, and these three feature quantity acquisition units? ~ Pre-processing arithmetic unit 20 that performs common operations in 9 and these three feature quantity acquisition units? And a color composite image generation unit 10 that generates a color image using feature amounts from .about.9. Each feature amount acquisition unit 7 to 9 is connected to the image processing device 5 via the preprocessing arithmetic unit 20, and image data is input from the image processing device 5, and each feature amount is obtained based on the image data. Acquired and output to the color composite image generation unit 10.

In addition, the preprocessing arithmetic unit 20 has an input unit (not shown) for inputting image data.

The image display device 6 is connected to the image processing device 5, the color composite image generation unit 10, and the display unit 11. The reconstructed image from the image processing device 5 and the color image from the color composite image generation unit 10 are connected. Are displayed on the display unit 11 respectively. The image generating device 19 may be configured to include the image processing device 5, the display processing device 6, the display unit 11, and the console 12.

FIG. 2 is a block explanatory diagram showing the color image generation processing operation in the image generation device 19 described above.

Whereas a conventional CT image is a grayscale representation of an image based only on CT values (that is, luminance values), the image generation device 19 of the present invention obtains it with a luminance value feature amount acquisition unit 7. The luminance value (CT value) data 19 is used as a lightness (Value) component, and the Henhans effect time characteristic acquisition unit 9 obtains the Henhans effect time data 20 acquired from the time when the Jenno effect due to the contrast agent appears. ) Component, and the effect effect degree data 21 obtained by the feature effect degree feature acquisition unit 8 is used as a Saturation component, and each of those components is used by the color composition image generation unit 10 to produce a single color composition. Generated as image 22 (hereinafter referred to as unit power error image) data 22 and displayed in color using the HSV color system.

[0017] It should be noted that the luminance value feature quantity is assigned to the lightness component, and one of the enhancement effect time feature quantity and the enhancement effect degree feature quantity is assigned to either the hue component or the saturation component. May be used to generate a color image with only two components including the brightness component. Alternatively, a color image may be generated using only the hue component and the saturation component, or only one of the components. In either case, the missing component that is not assigned is fixed to an arbitrary constant value, and a color image is generated.

FIG. 3 shows characteristic curves representing temporal changes in the luminance values of blood vessel 47, blood vessel 48, liver 49, and bone 50, respectively.

If the luminance value (CT value) is plotted on the vertical axis and time is plotted on the horizontal axis, the time change of the blood vessel 47 is the characteristic curve 23, the time change of the blood vessels 48 and 49 is the characteristic curve 24, and the time change of the bone 50 Is indicated by a straight line 25. First, at time 1, the blood vessel 47 is enhanced by the contrast agent, and then at time 2, the entire liver 49 and the blood vessel 48 are enhanced by the contrast agent. In addition, since the contrast agent does not flow into the bone 50, the CT value of the bone 50 remains constant regardless of time.

FIG. 4 shows a characteristic curve 23 representing the temporal change in the luminance value of the blood vessel 47 in FIG. 3. From this characteristic curve 23, the time T47 when the luminance value in the blood vessel 47 becomes maximum, the maximum luminance value 147, The luminance value change amount D47 can be acquired respectively. Similarly, each S container or pixel Each time, the time Tn at which the brightness value of the organ or pixel becomes the maximum, the maximum brightness value Ιη, and the brightness value change amount Dn can be obtained from the characteristic curve representing the temporal change in the brightness value of the organ or pixel. .

In the examples of FIGS. 2, 3 and 4, the case where the brightness value of the organ is enhanced by the contrast agent and the maximum brightness value exists is described. However, the brightness of the organ is enhanced by the contrast agent. When the value is suppressed and there is a minimum luminance value (for example, in MR perfusion imaging), the same explanation can be obtained by replacing the maximum described above with the minimum. Hereinafter, only the case where the maximum value exists will be described, but the same applies when the minimum value exists.

Therefore, the luminance value feature quantity acquisition unit 7 that acquires the feature quantity corresponding to the CT value shown in FIG. 2 is the maximum (minimum) value that is the maximum (minimum) value of the CT value as the feature quantity of the luminance value I. The luminance value In is acquired. Alternatively, the CT value of any one tomographic image may be the maximum (minimum) luminance value In. In addition, the enhancement effect degree feature amount acquisition unit 8 that acquires a feature amount corresponding to the degree of the non-sense effect is a luminance value change amount that is a change amount of the CT value as a feature amount corresponding to the degree D of the enhance effect. Try to get Dn. Then, the non-sense effect time feature quantity acquisition unit 9 that acquires the feature quantity corresponding to the time when the Enhansse effect appears has a luminance value (that is, CT value) as the feature quantity corresponding to the time T when the Enhansse effect appears. Get the maximum (minimum) time Tn. Alternatively, ijTn may be used when the amount of change in the luminance value is equal to or greater than a predetermined threshold. The threshold value in this case can be set to 1/2 of the maximum (minimum) change amount of the luminance value. Alternatively, the time Tn when the gradient of the luminance value change exceeds a predetermined threshold is acceptable. The threshold in this case can be set to 1/2 of the maximum (minimum) gradient of the luminance value.

[0022] In the above description, at least one of the force S, the enhancement effect degree feature amount, and the enhancement effect time feature amount described to acquire three feature amounts may be used, or four or more You can acquire feature values and select two or three feature values from them.

[0023] After that, the color composite image generation unit 10 generates a color image that simultaneously displays the feature amounts. The operator must compare the display of each feature value to determine whether the luminance value of the organization with a high luminance value is due to the enhancement effect by the contrast agent, or whether the CT value is originally large. Will be able to. [0024] In order to generate a color image that simultaneously displays each feature quantity, the color composite image generation unit 10 combines a color image that is displayed in color by, for example, the HSV color system. That is, the power error composite image generation unit 10 uses the Hue (hue) component as the time T when the Hannhans effect appears, the degree of the Hannhans effect, D as the Saturation component, and the CT value I as Value. Assign to each (lightness) component.

[0025] When the brightness value change amount Dn is used as the feature amount representing the degree of the enhancement effect, D, for example, in the case of a tissue having no enhancement effect such as the bone 50, the brightness value change amount D50 is reduced. When there is an enhancement effect such as blood vessel 47, the luminance value change D47 increases, so this luminance value change Dn is acquired for each organ or pixel and is associated with the saturation component of the HSV color system. be able to.

[0026] For example, the color composite image generation unit 10 compares the acquired luminance value change amount Dn with a preset threshold value, and determines that there is no hen-nos effect when the value is equal to or less than the threshold value, as in the conventional case. Let it be displayed in one scale. On the other hand, if the color composite image generation unit 10 determines that the luminance value change amount Dn is equal to or greater than the threshold value and there is an enhancement effect, the color value change amount Dn is assigned to the saturation component as a color display of the HSV color system. . For example, the threshold value in this case can be set to 1/2 of the maximum (minimum) value of the luminance value change amount Dn.

[0027] Therefore, the operator can easily identify that the tissue displayed in color by the saturation component is due to the enhancement effect. On the other hand, the display of the part where there is no hennosence effect is displayed in grayscale by the lightness component as in the conventional CT value. For this reason, the operator can easily determine that the part has no enhancement effect, and can easily obtain the same information as obtained from the CT value information in the image display device so far. These can be easily done by an operator who is not familiar with color images.

[0028] Similarly, since the time Tn at which the luminance value is maximum (minimum) is assigned to the hue component as the color display of the HSV color system as the time た at which the effect of the Ennos and the effect appears, It is possible to easily identify whether the time when the effect appears is the time of the currently displayed image, the time before or after it.

FIG. 5 is a flowchart showing a specific processing operation of the image generation apparatus 19 described above. In step SI, the volume data force obtained by imaging the subject at time 1, time 2, time 3,... IjN after injection of the contrast agent. For example, the preprocessing operation unit from the storage device in the image processing device 5 A total of N are read into 20.

[0030] In step S2, the volume data are aligned with each other so that the corresponding organizations in the N volume data are located at the same position. This is because the position of the subject in the image varies depending on the time phase when the subject's position changes during dynamic CT imaging, or when the subject's breathing moves due to respiration. This is done to correct the end. Specifically, based on any one volume data among the N volume data, at least 3 reference points are provided on the N volume data, and their positions vary from the reference volume data. The amount of movement and rotation of the tissue is calculated from the amount, and it is only necessary to reversely convert the amount and match all the volume data with the reference volume data. The processing in step S2 is performed by, for example, the preprocessing arithmetic unit 20.

In step S3, a desired tomographic image is cut out from each volume data. Specifically, the position and angle information of a section to be cut out is specified using any one volume data, and a tomographic image including a desired section is cut out from all volume data based on these specifications. The images cut out at this time are the same cross-sectional images having different time phases. The processing in step S3 is performed by, for example, the preprocessing arithmetic unit 20.

If the data read in step S1 is not volume data but data of a tomogram including the desired cross section as described above, in step S2, the tomograms are aligned with each other. Step S3 is not necessary.

In step S4, as will be described later using these tomographic images having different time phases, color composition processing in the time axis direction is performed for at least a part of the organs or at least a part of the pixels in a part of the region. Perform (coloring) calculation. The processing in step S4 is performed by the feature amount acquisition units 7, 8, 9 and the color composite image generation unit 10.

[0033] In step S5, the color image generated in step S4 is displayed on the display unit 11 in the medical image display device. It should be noted that before the above-described step SI, there is a step of actually photographing the subject into which the contrast medium has been injected, acquiring volume data of different phases, and storing it in a storage device in the image processing device 5, for example. Even if it is good ,.

As shown in FIG. 6, the color composition process in step S4 is a step of extracting the luminance value of the same organ or the same pixel for at least some of the organs or for every pixel in at least some of the regions. S4a, step S4b for acquiring the maximum (minimum) value In of the luminance value, step S4c for acquiring the luminance value change amount Dn, step S4d for acquiring the time Tn when the luminance value reaches the maximum (minimum), Repeat step S4e for coloring the organ or pixel from the maximum (minimum) value In and the amount of change Dn and the time Tn when the luminance value reaches the maximum (minimum), changing the organ or pixel. . Alternatively, steps S4b, S4c, S4d, and S4e may be repeated independently with different organs or pixels. Figure 6 shows only the pixel and maximum cases. When setting a coloring target organ or region, the organ or region is designated on an arbitrary tomographic image using a mouse or the like before step S4a. Hereinafter, each step of step S4 will be described in detail.

In step S4a, the luminance value of the same organ or the same pixel is extracted for each tomographic image having a different time phase, and the temporal change in the luminance value of the organ or pixel is acquired. In other words, the characteristic curves shown in Fig. 3 and Fig. 4 are obtained. The characteristic curve data extracted in the process of step S4a is data that is commonly used in the subsequent steps S4b to S4d, and is performed by, for example, the preprocessing arithmetic unit 20 in FIG.

In step S4b, the maximum (minimum) value and minimum (maximum) value of the luminance value in the time axis direction are obtained, and the maximum (minimum) luminance value In = [maximum (minimum) value] is set. The process of step S4b is performed by the luminance value feature quantity acquisition unit 7. Note that the luminance value of any one tomographic image may be In as the maximum luminance value.

[0037] In step S4c, the maximum (minimum) value and minimum (maximum) value of the luminance value in the time axis direction are obtained, and the luminance value change amount Dn = [maximum (minimum) value] one (minimum value). Is done. The processing of step S4c is performed by the enhancement effect level and feature quantity acquisition unit 8.

[0038] In step S4d, a time Tn at which the change of the luminance value in the time axis direction becomes the maximum (minimum) value is acquired. The processing of step S4d is performed by the Jenhans effect time feature quantity acquisition unit 9. It is. It should be noted that the time Tn when the change amount of the luminance value becomes equal to or greater than a predetermined threshold is also acceptable. Alternatively, it may be the time Τη when the gradient of the luminance value change becomes a predetermined threshold value or more.

[0039] Here, regarding step S4d, a method of acquiring time T at which the luminance value becomes maximum (minimum) with relatively excellent resolution even when the value of volume data number N is small will be described. . Consider a vector that divides the declination into N parts on the polar coordinate plane as shown in Fig. 7 (here, N = 3 is shown as an example), and the magnitude of each vector is VI, V2, and V3. To do. Here, VI, V2, and V3 are the luminance values at time 1, time 2, and hour 1J3. As shown in FIG. 8, the combined vector of these vectors is calculated, the declination angle Theta of this combined vector is calculated, and this is converted into time to obtain the time T when the luminance value becomes maximum (minimum). . Thus, the maximum (minimum) luminance value In (x, y), the luminance value change Dn (x, y), and the luminance value at the maximum (minimum) of the pixel (x, y) shown in Equation 1 Tn (x, y) can be obtained from the maximum value Max (x, y), minimum value Min (x, y), and maximum (minimum) time Theta of the pixel (x, y).

(Number 1)

In, x, y) = Max, y

Dn (x, y) = Max (x, y) — Min (x, y);

Tn (x, y) = Theta;

[0040] In step S4e, for each organ or pixel, the time Tn at which the luminance value is the maximum (minimum) as the characteristic amount representing the time T at which the enhancement effect appears, the degree of the non-sense effect, and D As shown in Fig. 2, the brightness value change amount Dn as the feature value to be expressed and the maximum (minimum) value In of the brightness value as the CT value as the feature value representing the tissue emphasized by the Enhans effect, respectively, are shown in HSV color. It converts the hue component, saturation component, and brightness component of the system, and colors the organ or pixel.

For example, if two different organs or pixels have the maximum (minimum) luminance value at the same time, they are colored in the same hue, but if the amount of change in luminance value is different, the color of at least one organ or pixel is different It will be colored. The conversion method from the time Tn to the hue component, the luminance value change D to the saturation component, and the maximum (minimum) value I of the luminance value to the lightness component will be described later.

[0041] Steps S4a to S4e described above are performed for at least some of the organs or in at least some of the regions. By repeating for each pixel, at least some organs or at least some areas are colored. As a result, different coloring is performed on organs or pixels having temporal changes in luminance values. In addition, even in the same organ, different coloring is performed on pixels with different temporal changes in luminance values. In addition, the same coloring or different coloring is performed on each pixel in different organs.

Then, the color image power synthesized based on the HSV color system is displayed on the display unit 11, for example, in step S5 as shown in FIG.

FIG. 9 is a diagram showing a display example on the display unit 22 of the image display device.

A color bar 27 is placed near the bottom of the color image 26. Saturation S and lightness V are constants. For example, saturation S = 255, lightness V = 255), hue level (that is, hue component) H is 0. The color gradation is displayed when the color is changed from to 255. Below that, the time phase corresponding to the hue (hour 1J) is marked as a scale. It is now possible to understand the relationship with the time T when the Hanns-Hans effect appears, in which case the saturation S and the brightness V should be constant, for example, the saturation and brightness of the point on the image specified by the operator. In addition, this color bar 27 is not limited to expressing the time T of the Hannhans effect, but is emphasized by the degree D of the Hannhans effect, the Jenno effect, CT value (ie, brightness value) I representing tissue For example, when the operator selects any one of the radio buttons 28a, 28b, and 28c corresponding to the three feature amounts of CT value I, time T of the enhancement effect T, and degree of the enhancement effect D, respectively. Switch to the color bar corresponding to the selected radio button, and display the 2D color bar or 3D color bar in a combination of these three features without being limited to the 1D color bar. It may be.

When the color image 26 and the color bar 27 are displayed side by side in this way, the operator can easily determine in association with what the display color in the color image 26 means.

[0043] Further, the time T when the Hanns effect appears in the hue component of the HSV color system, the degree D of the Hanns effect as the chroma component, and the CT value I as the lightness component are not allotted. It differs from the time T when the effect appears, the degree D of the non-sense effect D, and the CT value I. Even if the components are assigned, the identification becomes easy. For example, the time T when the Hanns effect appears in the saturation component, the degree D of the ensemble effect D as the lightness component, and the CT value I as the hue component. Alternatively, not only the arrangement of hue components in the HSV color system, but the time T when the effect of the Ennos and Sons effect appears is subdivided into a plurality of periods, a plurality of colors are prepared in advance, and the correspondence between each color and each period is determined in advance. Decide it and get it.

[0044] Furthermore, using not only the HSV color system but also the RGB color system or other color systems, the time T when the Hannshang effect appears in one of the different components of those color systems, You can assign either the degree D or the luminance value I. For example, when using the RGB color system, the time T when the enhancement effect appears in the R (red) component, the degree of the enhancement effect in the G (green) component, D, and the brightness value in the B (blue) component You can assign each I.

[0045] Further, when displaying the color image 26 on the display unit 22 of the image display device, in order to make it easy to see a specific part, organ, or time visually, a display window (Window) for displaying the feature amount is arbitrarily set. It can be adjusted. For example, as shown in FIG. 9, the operator selects each of the three feature quantities of CT value I, time of effect effect T, and degree of effect effect D with radio buttons 28a, 28b, and 29c. After that, the operator can independently set the window level of each feature amount with the scroll bar 30a as the Windows level adjustment means 30, and the window width of each feature amount with the scroll bar 31a as the Windows width adjustment means 31. Can be adjusted. As a result, the display window of each feature value is adjusted. Here, the Window level is the center value of the display window, and the Window width means the width of the display window, that is, the difference between the maximum value and the minimum value.

Next, an image processing method related to the display window will be described.

When the display window for feature amount display is set, the conversion from the time T of the Hannhans effect to the hue is performed by the first conversion method 32 shown in FIG. 10 as follows. Adjusting the window level 30 (that is, the center position of the display window indicated by the interval between two dashed lines parallel to the vertical axis) (that is, changing the level), the conversion formula Η = ίΗ (Τ) intercept Is adjusted (i.e., the position of the intersection of the conversion formula and the vertical axis is up and down), and the window width 31 (i.e., the width of the display window indicated by the distance between two dashed lines parallel to the vertical axis) is adjusted ( In other words, the inclination of the conversion formula H = ίΗ (変換) is adjusted when the width of the display window is increased or decreased. In other words, this first conversion method 32 uses the conversion formula Η = ίΗ (Τ) This is a method of changing the shape according to the display window. If time T is inside the display window, Hoc T (proportional relationship) is set. If time T is smaller than the display window, H = 0. If time T is larger than the display window, H = 255. By doing this, the organization where the hennosse effect appears at the time inside the display window is displayed in a color gradation of red → green → blue, and the tissue where the henhans effect appears at a time before the display window is red. Tissues that have an enhanced effect at a later time than the display window are displayed in blue. At this time, according to the change in the relationship between the hue H and the time T, the position of the time scale on the color bar is changed and displayed. Or, the position of the scale on the color bar is fixed, and the display is changed by changing the color dura.

[0047] Further, regarding the conversion from the luminance value change amount Dn to saturation as the feature amount representing the degree of enhancement effect D, and the conversion from the luminance value I to brightness as the feature amount representing the organization emphasized by the enhancement effect, Based on the respective predetermined conversion formulas, the above-mentioned conversion from the time T to the hue of the Enhansse effect is performed.

[0048] In the above-described conversion process from the time T of the Hannhans effect to the hue, the structure in which the Hannhs effect appears at a time before the display window and the Hannhs effect at a time later than the display window. Force that is displayed in a color with a hue different from that of the tissue Only the tissue that shows the Hanhuns effect is displayed in color in the time zone inside the display window, and the tissue that shows the Hannhans effect at other times is grayscale It may be displayed. In this case, in addition to the above-described processing, the following processing shown in Equation 2 is performed.

(Equation 2)

If T = (outside the display window)

Then Saturation (S) = 0;

[0049] That is, the saturation component of the pixel in which the enhancement effect appears at time T outside the display window is set to zero. By doing this, when the display window is adjusted, only the organs or pixels corresponding to the inside of the display window are displayed in color, and the outside is displayed in grayscale. A color image suitable for viewing images can be obtained. At this time, the color bar 27 is displayed in color only on the inside of the display window and grayscale on the outside. [0050] In the image processing method relating to the display window, the conversion from the time T of the Hanengs effect to the hue is performed by converting the time from the time Hannjé effect to the hue as in the second conversion method 33 shown in FIG. May be. This second conversion method 33 is a method of changing the position and width of the display window on this conversion equation without changing the conversion equation H = fH (T). In other words, even if the Window width and Window level are adjusted, the intercept and slope of the conversion formula are made constant. Then, the position of the display window is adjusted by the window level, and the width of the display window is adjusted by the window width. As a result, the display window only moves on the conversion line indicated by the dotted line. Therefore, the hue of each tissue does not change when the display window is adjusted compared to the first conversion method 32. In addition, the color gradation on the power rubber 27 and the position of the time scale are fixedly displayed. Note that, as shown in Equation 2, the saturation component of the pixel where the enhancement effect appears at time T outside the display window is set to zero, so that the inner side of the display window is the same as in the first conversion method 32. At this time, it is possible to display in color only the structures that show the Hanhans effect at 1 JT, and to display the tissues that show the Hannhans effect at other times in gray scale.

[0051] Further, as an application technique of this display window, when the window level is changed with the window width at the time T of the Hannhs effect set to a constant value, the time change of the part where the Hannhs effect appears can be seen as a moving image. It becomes like this. FIG. 12 shows moving images 35a to 35e when the window level is changed from 34a to 34e while the window width at time T is narrowed. With such moving images 35a to 35e, the operator can easily observe how the contrast agent flows every moment.

Alternatively, the window width may be changed with the window level set to a constant value, or a movie may be generated by changing both the window level and the window width.

[0052] At this time, when displaying each of the moving images 35a to 35e, the brightness of a specific part or organ where the ennence effect appears at a specific time can be increased and emphasized to make it visually easy to see. For example, in Fig. 12, when the hue Hue of a specific part in the video 35a at Window level force ¾4a is 0 <Hue <0.3 for the color bar 27 corresponding to the red color of the HVS color system, Hue It is also possible to increase the brightness of a specific part displayed in Hue and emphasize it.

[0053] In the above-described image generating apparatus in the medical diagnostic imaging apparatus, a conventional CT image is a CT. While only the value I is expressed, not only the CT value I as described above, but also the information of the time T when the enhancement effect by the contrast agent appears, the information of the degree D of the non-sense effect D and the force Newly incorporated into the CT image and displayed in color, the information is represented on a single image. Traditionally, X-ray CT systems have displayed CT values I in grayscale.

On the other hand, the image generation apparatus of the present invention adds the information of the time T when the Hannhans effect appears, the degree of the Hannhans effect, and the D information to the grayscale information without changing the grayscale display. By displaying in color, it is possible to display new information and information that can be easily discriminated while inheriting the previous experience with CT value I.

[0054] In particular, in order to express the above-described three feature amounts, the three feature amounts are displayed in color using the HSV color system. In other words, the hue component is assigned the time T when the Hannsheng effect appears, the saturation component is assigned the degree D of the Hannes effect, and the brightness component is assigned the luminance value (ie CT value) I. As a result, an image display device that displays a color image that is easier for the operator to easily identify and judge can be provided.

[0055] Further, in the above-described image generation apparatus in the medical diagnostic imaging apparatus, since the luminance value change amount Dn is used as the feature amount representing the degree of the enhancement effect, the Hannhans like a bone is used. If the tissue has no effect, the change in luminance value Dn is small and displayed in grayscale, while if there is an enhanced effect such as a blood vessel, the change in luminance value Dn is large and displayed in power. It becomes easy for a person to distinguish between the two and grasp the presence or absence of blood flow. In addition, the maximum (minimum) luminance value In is adopted as a feature value representing the organization emphasized by the Enhans effect, and the luminance value is the maximum (minimum) value as a feature value representing the time T at which the Nennence effect appears. The time Tn is adopted, and each is converted into color information and reflected in the image display. For this reason, depending on the time at which the Enhansse effect appears on the image, the hue changes to red, yellow, green, and blue, and the contrast agent progresses from moment to moment on the image. Will be displayed. This makes it easier for the operator to grasp the blood circulation state.

[0056] (Second Embodiment)

FIG. 13 shows another embodiment of the present invention, and an ultrasonic diagnosis as a medical image diagnostic apparatus. It is a schematic block diagram of the example which used the image generation apparatus of this invention for the cutting device.

The ultrasonic diagnostic apparatus 38 receives the volume data transfer described in the first embodiment from the medical image diagnostic apparatus 37 such as an X-ray CT apparatus and an MRI apparatus using a network or other portable storage medium, and receives data. It is stored in the storage unit 43. The main parts of the ultrasonic diagnostic apparatus 38 are roughly classified into a system for reconstructing an ultrasonic image and a system for reconstructing a tomographic image corresponding to the reconstructed ultrasonic image. The former includes an ultrasonic image acquisition unit 42 that reconstructs an ultrasonic image based on the reflected echo signal output from the probe 39. The latter includes a data storage unit 43, various detection means 40 including a position sensor and a body position sensor for detecting a magnetic field attached to the probe 39, and a magnetic field generator and a respiration sensor as a main body in cooperation with these, A position associating unit 44 and a tomographic image acquiring unit 45 are provided. The ultrasonic image of the same section and the color image of the tomographic image output from the ultrasonic image acquisition unit 42 and the slice image acquisition unit 45 are drawn on the display unit 11 by the display processing device 46, and here the ultrasonic image and the tomographic image are displayed. The images are displayed side by side on the same screen.

The image generation apparatus according to the present embodiment includes at least the data storage unit 43 and the tomographic image acquisition unit 45, and may further include a display processing unit 46 and the display unit 11.

[0057] The probe 39 transmits and receives ultrasonic waves to and from the subject 41, and includes a plurality of transducers that generate ultrasonic waves and receive reflected echoes. The ultrasonic image acquisition unit 42 inputs the reflected echo signal output from the probe 39 and converts it into a digital signal, and for example, a black and white tomographic image (B mode image) or a color flow mapping image (CFM image) of the diagnostic part. Is generated.

The position associating unit 44 acquires various pieces of information from the various detection means 40 in order to obtain a tomographic image including substantially the same cross section as the ultrasonic image. The various detection means 40 are information for correcting a shift in the coordinate system between the tomographic image and the ultrasonic image due to a change in the posture of the subject 41 and a change in the coordinate system of the subject 41 due to movement of the internal organs due to respiration. Acquire by adding. The tomographic image acquisition unit 45 uses the volume data in the data storage unit 43 based on the various types of information acquired by the position association unit 44 to obtain a slice image including substantially the same cross section as the ultrasonic image. As described above, there are various methods for obtaining a tomographic image having the same cross section as that of the ultrasonic image. A calculation method can be employed (for example, WO2004 / 098414).

Further, the tomographic image acquisition unit 45, as shown in FIG. 2, data 19 of the luminance value (that is, CT value) I in the data storage unit 43 and data 20 of time T when the enhancement effect by the contrast agent appears. The color image data 22 described in the first embodiment is generated from the data 21 of the degree D of the Hannhans effect.

FIG. 14 is a diagram showing a display example on the display unit 11. An ultrasonic image 70 and a CT color image 71 of the same cross section are displayed. In addition, a 3D body mark 72 is displayed by superimposing the current ultrasonic scan surface on a 3D image that visualizes the body surface and internal organs of the subject.

[0061] The 3D image is generated by the volume rendering method using the volume data of the color image data 22. The volume rendering method is a typical process for generating a three-dimensional visualization image, and the display target can be selected and the internal structure can be seen through by adjusting the opacity. (For details, see §ΰ, for example, “Barthold Lichtenbelt, et al, Introduction to Volume rendering, Hewlett-Packard Professional Books”)

[0062] The present image generation apparatus is configured so that the opacity can be set according to at least one feature amount among the time when the enhancement effect appears, the luminance value I, the degree of the enhancement effect, and D. deep. For example, as in (Equation 3), the opacity 0 is defined as a function of the IJT when the Hannhans effect appears, the degree D of the Nennons effect, and the CT value I. The opacity 0 may be a function of one or two of the time 時刻 when the Hannhans effect appears, the degree D of the Hannhans effect, and the CT value I.

(Equation 3)

0 = f (T, D, I)

The step of obtaining the opacity 0 is inserted, for example, between step S4d and step S4e in FIG. 6 described above, and the opacity is obtained for each organ or each pixel. Alternatively, it may be inserted between step S4 and step S5 to obtain the opacity 0 for each organ or each pixel. Then, after the coloring and opacity of all the organs or pixels are obtained, a color 3D composite image is generated using the volume rendering method. After that, in the display step S5 described above, the display unit 11 A color 3D image is displayed on the screen. [0064] On the display unit 11, for example, an opacity curve 73 is displayed in which the relationship between the opacity 0 and the time T at which the enhancement effect appears is shown as a graph. The operator should be able to change the opacity curve using a mouse. As a result, the operator can select a display target or perform a fluoroscopic view of the internal structure every time the enhancement effect appears.

[0065] For example, if the opacity value of time phase 2 is set large and the opacity value other than time phase 2 is set small, a 3D image is generated in which the region where the enhancement effect is obtained in time phase 2 is extracted. Will be.

[0066] The opacity curve 73 may display a relationship between the opacity 0 and the degree of enhancement effect D, or may display a relationship between the opacity 0 and the luminance value I. Yo! The display should be switched in response to the operator's selection of radio buttons 28a, 28b, 28c.

[0067] According to such an image generation apparatus in the ultrasonic diagnostic apparatus, an ultrasonic image and a tomographic image having the same cross section can be displayed simultaneously. Further, as described in the first embodiment, the tomographic image is emphasized by color display, so that the operator can more easily make a comprehensive diagnosis while comparing the two.

[0068] Moreover, since the luminance value change amount Dn is used as the feature amount representing the degree D of the enhancement effect as in the first embodiment described above, the tissue has no enhancement effect such as a bone. The brightness value change amount Dn is small and displayed in grayscale. On the other hand, when there is an ensemble effect such as a blood vessel, the luminance value change amount Dn is displayed in a large color. Because of these differences, it is easier for the operator to distinguish between the two and grasp the presence or absence of blood flow. In addition, the maximum (minimum) value In of the luminance value is adopted as the feature value that represents the organization emphasized by the Jenno and Gons effect, and the luminance value is used as the feature value that represents the time at which the Enhans effect appears. The maximum (minimum) time Tn is used so that it is reflected in the color image, so depending on the time when the Enhansse effect appears, the hue will be displayed as red, yellow, green, and blue. It is possible to display the progress of the contrast medium from moment to moment on a single image.

Claims

The scope of the claims

[1] A method for generating a medical image representing a temporal change of a tissue by the contrast agent using image data obtained by imaging a subject into which a contrast agent has been injected,

(a) obtaining a plurality of the image data having different time phases;

(f) repeating the steps (b) to (e) for each different pixel in at least a part of the region to generate a color image in which the part of the region is colored. An image generation method characterized by the above.

[2] In the image generation method according to claim 1,

In the coloring step, the first pixel is colored to the first color based on the first information of the temporal change of the luminance value in the first pixel, and the first temporal change of the luminance value in the second pixel is performed. 2. An image generation method characterized in that the second pixel is colored in a second color based on information.

[3] The image generation method according to claim 2,

In the coloring step, based on the first information and the second information, at least one force S of the first pixel and the second pixel is colored to a third color. Image generation method.

[4] The image generation method according to claim 2,

The image generating method, wherein the first pixel and the second pixel are included in one organ.

[5] The image generation method according to claim 2,

The first pixel is contained in a first organ, the second pixel is contained in a second organ; An image generation method, wherein the first organ is colored in the first color and the second organ is colored in the second color.

[6] The image generation method according to claim 1,

In the coloring step, the first pixel and the second pixel, which are different in temporal change information of the luminance value with reference to a desired time phase, are colored in different colors, respectively. Image generation method.

[7] The image generation method according to claim 2,

In the conversion step, at least one of color type and color vividness is used as the color information,

In the coloring step, the first pixel and the second pixel are colored with a color that differs in at least one of the color type and the vividness of the color.

[8] In the image generation method according to claim 1, in the feature amount acquisition step,

As the one or more feature quantities, at least one of a feature quantity representing a time at which an enhancement effect by the contrast medium appears and a feature quantity representing an ensemble effect by the contrast medium is acquired. An image generation method.

[9] The image generation method according to claim 8,

The image generation method characterized in that the feature amount representing the enhancement effect by the contrast agent is an increase amount or a decrease amount of the luminance value of the pixel by the contrast agent.

[10] The image generation method according to claim 8,

An image generation method characterized in that the feature amount indicating the time when the ensemble effect due to the contrast agent appears is the time when the luminance value of the pixel becomes maximum or minimum in the plurality of image data .

[11] The image generation method according to claim 8,

In the conversion step,

HSV color system consisting of Hue component, Saturation component, and Value component is used.

A feature amount indicating the time when the enhancement effect by the contrast agent appears is the hue component, A feature amount representing the enhancement effect by the contrast agent is converted into the saturation component,

In the color image generation step, the color image is generated using at least one of the hue component and the saturation component.

[12] The image generation method according to claim 11,

In the feature amount acquisition step, a feature amount based on a luminance value is further acquired as one of the one or more feature amounts,

In the conversion step, a feature amount based on the luminance value is converted into the lightness component, and in the color image generation step, the color image is further generated using the lightness component. .

[13] The image generation method according to claim 12,

The image generation method characterized in that the feature amount based on the luminance value is a maximum or minimum luminance value among the same pixels in the plurality of image data.

[14] The image generation method according to claim 1,

After the color image generation step,

Displaying the color image;

Adjusting the coloring in the color image;

Have

In the adjustment step, the coloring in the color image is adjusted by adjusting at least one of the range and level of the feature amount converted into the color information.

[15] The image generation method according to claim 14,

In the adjustment step, the color image is generated as a moving image by continuously changing at least one of a range and a level of the feature amount converted into the color information. Method.

[16] The image generation method according to claim 1,

The step of acquiring image data is

A step of reading a plurality of volume data having different time phases; Aligning a plurality of volume data having different time phases, and

In the luminance value acquisition step, a luminance value of a pixel at the same position is acquired for each of the plurality of volume data having different time phases,

Between the coloring step and the color image generating step,

Determining an opacity of the pixel based on at least one of the one or more feature quantities;

The color image generation step includes a step of generating a three-dimensional color image in which at least a part of the area is colored based on the one or more color information and the opacity.

An image generation method comprising:

[17] An input means for inputting a plurality of image data having different time phases obtained by imaging a subject into which a contrast medium has been injected,

Storage means for storing a plurality of image data having different time phases;

A calculation means for generating a medical image using a plurality of image data having different time phases, and

The computing means extracts one or more feature amounts representing temporal changes in the organization due to the contrast agent from the plurality of image data having different time phases, and converts them into different color information. An image generating apparatus characterized by generating a color image colored so as to represent information of temporal change for each pixel in a part area.

[18] An input means for inputting a plurality of image data having different time phases obtained by imaging a subject into which a contrast medium has been injected,

The computing means extracts one or more feature amounts representing temporal changes in the organization due to the contrast agent from the plurality of image data having different time phases, and converts them into different color information. Color to represent the temporal change information for each pixel in the area Generating an attached color image.

[19] The image generation device according to claim 18,

Display means for displaying the color image;

The display means displays the color image and a color bar representing a correspondence relationship in conversion of the feature quantity into color information.

[20] The image generating device according to claim 18,

The input means inputs first tomographic image data acquired by imaging a desired cross section of the subject,

Means for obtaining position information of the desired cross section;

The computing means is

Based on the position information, a plurality of second tomographic image data having different time phases including the desired cross section are acquired from the plurality of image data having different time phases,

The color image is generated by using the plurality of second tomographic image data having different time phases.