JP5534704B2 - Image processing apparatus and X-ray diagnostic apparatus - Google Patents

Description

  The present invention relates to an image processing apparatus and an X-ray diagnostic apparatus.

  Conventionally, in the treatment of ischemic heart disease of the heart, a treatment method called intravascular intervention treatment using a catheter has been performed. Specifically, in intravascular interventional treatment, fluoroscopic imaging of a site to be treated is performed by an X-ray diagnostic apparatus, and a doctor referring to an X-ray image displayed on a monitor operates a catheter, thereby causing ischemia. Expansion of the infarct site that causes the disease is performed.

  Here, after treatment of ischemic heart disease, it is important to confirm whether or not myocardial viability has been recovered by reperfusion of blood. In addition, when treating ischemic heart disease, it is important to identify a cardiomyocyte having a reduced viability in determining a treatment policy.

  That is, in the treatment of ischemic heart disease, “whether or not cardiomyocytes are alive” or “recovered” is an important index for the doctor.

  Although it is difficult to know the viability of cardiomyocytes non-invasively, as an indirect technique, a technique of measuring a change in the thickness of the myocardium during contraction exercise using an ultrasonic diagnostic apparatus or an MRI apparatus is known (for example, Patent Document 1 and Patent Document 2).

  In such a technique, if the thickness change of the myocardium is large between the diastole and the systole, the cardiomyocytes are regarded as “alive”.

JP 2005-124636 A JP-A-2005-270478

  By the way, the above-mentioned conventional technique provides a doctor with information indirectly indicating the viability of cardiomyocytes by measuring changes in the thickness of the myocardium using an MRI apparatus or an ultrasonic diagnostic apparatus. Since the apparatus used in the treatment is an X-ray diagnostic apparatus, it is desirable that the X-ray diagnostic apparatus provides information related to cardiomyocyte viability.

  However, at present, there is no known technique for providing information related to the viability of cardiomyocytes from the X-ray image generated by the X-ray diagnostic apparatus.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and an image processing apparatus and an X processing apparatus that can provide information related to the survival rate of cardiomyocytes using an X-ray image. An object is to provide a line diagnostic apparatus.

In order to solve the above-described problems and achieve the object, the present invention captures a cardiac phase acquisition means for acquiring a cardiac phase of a subject and the heart of the subject into which a contrast medium is injected in time series. Based on the cardiac phase of the subject acquired by the cardiac phase acquisition unit from the plurality of X-ray images stored by the image storage unit and the image storage unit that stores the plurality of X-ray images generated by The X-ray image in the first phase and the X-ray image in the second phase extracted in this manner are transformed so that the size and position of the rendered heart match within a predetermined range. The image deformation means for generating the image and the second image, and the ratio value is calculated by dividing the pixel value of the corresponding pixel in the first image and the second image generated by the image deformation means And calculate A ratio image generating unit that generates a ratio image having a ratio value as a pixel value; and a display control unit that controls the ratio image generated by the ratio image generating unit to be displayed on a predetermined display unit. It is characterized by that.

The present invention also stores cardiac phase acquisition means for acquiring the cardiac phase of the subject, and a plurality of X-ray images generated by imaging the subject's heart into which the contrast medium has been injected in time series. An X-ray image at a first phase extracted based on the cardiac phase of the subject acquired by the cardiac phase acquisition unit from the plurality of X-ray images stored by the image storage unit, Image deformation means for generating the first image and the second image by deforming each X-ray image in the second phase so that the size and position of the rendered heart match within a predetermined range. And calculating the ratio value by dividing the pixel value of the corresponding pixel in the first image and the second image generated by the image transformation means, and using the calculated ratio value as the pixel value Ratio that produces a ratio image An image generation unit, characterized by comprising a display control means for controlling to display the ratio image generated on a predetermined display unit by the ratio image generating means.

According to the present invention, it is possible to provide information related to the viability of cardiomyocytes using an X-ray image.

FIG. 1 is a diagram for explaining the configuration of the X-ray diagnostic apparatus according to the first embodiment. FIG. 2 is a diagram for explaining the image generation unit. FIG. 3 is a diagram for explaining the configuration of the image processing unit according to the first embodiment. FIG. 4 is a diagram for explaining the cardiac phase acquisition unit and the image extraction unit in the first embodiment. FIG. 5 is a diagram for explaining a systolic X-ray image and a diastolic X-ray image. FIG. 6 is a diagram for explaining an example of image deformation processing by the image deformation unit. FIG. 7 is a diagram for generating the ratio image generation unit according to the first embodiment. FIG. 8 is a flowchart for explaining processing of the X-ray diagnostic apparatus according to the first embodiment. FIG. 9 is a diagram for explaining the image extraction unit according to the second embodiment. FIG. 10 is a diagram for explaining the configuration of the image processing unit according to the third embodiment. FIG. 11 is a diagram for explaining a model used in the third embodiment. FIG. 12 is a diagram for explaining a calculation formula used to generate a ratio image in the third embodiment. FIG. 13 is a flowchart for explaining processing of the X-ray diagnostic apparatus according to the third embodiment.

  Exemplary embodiments of an image processing apparatus and an X-ray diagnostic apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. Hereinafter, a case where the image processing apparatus according to the present invention is incorporated in an X-ray diagnostic apparatus will be described as an example.

  First, the configuration of the X-ray diagnostic apparatus according to the first embodiment will be described. FIG. 1 is a diagram for explaining the configuration of the X-ray diagnostic apparatus according to the first embodiment.

  As shown in FIG. 1, the X-ray diagnostic apparatus according to the present embodiment includes a high voltage generator 11, an X-ray tube 12, an X-ray diaphragm device 13, a top plate 14, a C arm 15, and an X-ray detection. Device 16, C-arm rotation / movement mechanism 17, top-plate movement mechanism 18, C-arm / top-plate mechanism control unit 19, aperture control unit 20, system control unit 21, input unit 22, and display unit 23, an image data generation unit 24, an image data storage unit 25, and an image processing unit 26, and is further connected to an electrocardiograph 30.

  The electrocardiograph 30 acquires an electrocardiographic waveform of the subject P to which a terminal (not shown) is attached, and transmits the acquired electrocardiographic waveform together with time information to the image processing unit 26 described later.

  The high voltage generator 11 generates a high voltage and supplies the generated high voltage to the X-ray tube 12, and the X-ray tube 12 generates X-rays by the high voltage supplied from the high voltage generator 11. That is, the high voltage generator 11 adjusts the voltage supplied to the X-ray tube 12, thereby adjusting the X-ray dose irradiated to the subject P and turning ON / OFF the X-ray irradiation to the subject P. Control.

  The X-ray diaphragm device 13 is a device for narrowing the X-ray generated by the X-ray tube 12 so as to selectively irradiate the region of interest of the subject P. For example, the X-ray diaphragm 13 has four slidable diaphragm blades, and slides these diaphragm blades to narrow down the X-rays generated by the X-ray tube 12 and irradiate the subject P.

  The top 14 is a bed on which the subject P is placed, and is placed on a bed (not shown).

  The X-ray detector 16 is an apparatus in which X-ray detection elements for detecting X-rays transmitted through the subject P are arranged, and each X-ray detection element uses the X-rays transmitted through the subject P as electrical signals. Is converted and stored, and the stored electrical signal is transmitted to the image data generation unit 24 described later.

  The C-arm 15 is an arm that holds the X-ray tube 12, the X-ray diaphragm device 13, and the X-ray detector 16, and the X-ray tube 12, the X-ray diaphragm device 13, and the X-ray detector 16 are Therefore, they are arranged so as to face each other with the subject P interposed therebetween.

  The C-arm rotation / movement mechanism 17 is a device for rotating and moving the C-arm 15, and the top plate moving mechanism 18 is a device for moving the top plate 14.

  The C-arm / top plate mechanism control unit 19 controls the C-arm rotation / movement mechanism 17 and the top-plate movement mechanism 18 to perform rotation adjustment and movement adjustment of the C-arm 15 and movement adjustment of the top plate 14. .

  The diaphragm control unit 20 controls the X-ray irradiation range by adjusting the opening degree of the diaphragm blades of the X-ray diaphragm device 13.

  The image data generation unit 24 generates an X-ray image using an electrical signal converted from the X-rays transmitted through the subject P by the X-ray detector 16 and stores the generated X-ray image in the image data storage unit 25. To do. Specifically, as shown in FIG. 2, the image data generation unit 24 generates a plurality of X-ray images (X-ray image 1, X-ray image 2, X-ray image 3,. ) Each of them is stored in the image data storage unit 25 in association with the time of shooting. FIG. 2 is a diagram for explaining the image generation unit.

  The image data storage unit 25 stores the X-ray image generated by the image data generation unit 24 in association with the imaging time.

  The image processing unit 26 is a processing unit that executes various types of image processing on the X-ray images stored in the image data storage unit 25. For example, the image processing unit 26 generates a moving image by processing a plurality of X-ray images along the time series stored in the image data storage unit 25. The image processing unit 26 will be described in detail later.

  The input unit 22 includes a mouse, a keyboard, a button, a trackball, a joystick, and the like for an operator such as a doctor or engineer who operates the X-ray diagnostic apparatus to input various commands. It transfers to the system control part 21 mentioned later.

  The display unit 23 displays a GUI (Graphical User Interface) for receiving a command from the operator via the input unit 22, or is subjected to image processing by the X-ray image and image processing unit 26 stored in the image data storage unit 25. A monitor for displaying a moving image of the X-ray image.

  The system control unit 21 controls the operation of the entire X-ray diagnostic apparatus. That is, the system control unit 21 controls the high voltage generator 11, the C arm / top plate mechanism control unit 19, and the aperture control unit 20 based on the command from the operator transferred from the input unit 22. Adjustment of X-ray dosage and ON / OFF control of X-ray irradiation, adjustment of rotation / movement of C-arm 15 and movement adjustment of top plate 14 are performed. Accordingly, the X-ray diagnostic apparatus continuously images the heart of the subject P in which the contrast medium is injected into the coronary artery.

  The system control unit 21 controls image generation processing in the image data generation unit 24 and image processing in the image processing unit 26 based on a command from the operator. Further, the system control unit 21 displays a GUI for receiving a command from the operator, an X-ray image stored in the image data storage unit 25 and a moving image image-processed by the image processing unit 26 on the monitor of the display unit 23. Control to display.

  As described above, the X-ray diagnostic apparatus according to the present embodiment generates a plurality of X-ray images in time series by continuously imaging the heart of the subject P in which the contrast medium is injected into the cardiac coronary artery. Although stored in the image data storage unit 25, information relating to cardiomyocyte viability is provided using the X-ray image stored in the image data storage unit 25 by the processing of the image processing unit 26 described in detail below. The main feature is that it becomes possible.

  Hereinafter, this main feature will be described with reference to FIGS. 3 is a diagram for explaining the configuration of the image processing unit in the first embodiment, and FIG. 4 is a diagram for explaining the cardiac phase acquisition unit and the image extraction unit in the first embodiment. 5 is a diagram for explaining a systolic X-ray image and a diastolic X-ray image, FIG. 6 is a diagram for explaining an example of image deformation processing by an image deformation unit, and FIG. 6 is a diagram for generating a ratio image generation unit in Example 1. FIG.

  As illustrated in FIG. 3, the image processing unit 26 according to the first embodiment includes a cardiac phase acquisition unit 26a, an image extraction unit 26b, an image deformation unit 26c, and a ratio image generation unit 26d.

  The cardiac phase acquisition unit 26 a acquires the cardiac phase of the subject P at each time point from the electrocardiographic waveform and time information received from the electrocardiograph 30. Specifically, as shown in FIG. 4A, the cardiac phase acquisition unit 26a determines whether each time point after the start of imaging is a time point corresponding to the cardiac systole of the subject P. It is acquired from an electrocardiogram waveform and time information whether it is the time corresponding to the diastole of the heart.

  Based on the cardiac phase of the subject P acquired by the cardiac phase acquisition unit 26a, the image extraction unit 26b is based on a plurality of X-ray images in time series stored in the image data storage unit 25, and the systolic X-ray image. Group and diastolic X-ray image group are extracted.

  For example, when a plurality of X-ray images for 5 heartbeats are generated as a result of continuous imaging for 5 seconds by the X-ray diagnostic apparatus, the image extraction unit 26b acquires the subject P acquired by the cardiac phase acquisition unit 26a. As shown in FIG. 4B, a systolic X-ray image group (ES1 to ES5) and a diastolic X-ray image group (ED1 to ED5) each consisting of five images are extracted based on the cardiac phase.

  Then, the image extraction unit 26b obtains X-ray images in which the myocardial region is highly stained by the contrast agent from the systolic X-ray image group and the diastolic X-ray image group, respectively. Extract as a line image.

  Here, in the contrast image of the heart after the contrast medium is injected into the coronary artery, the appearance of the blood vessels and the myocardium being stained in order is depicted, and then the appearance of the contrast medium exiting from the vein is depicted. . That is, the contrast medium injected into the coronary artery flows from a thick blood vessel into a thin blood vessel, and then flows through the capillary blood vessel, and as a result, flows into the cell stroma of the myocardium. The contrast agent stays in the myocardial cell stroma and then flows out of the myocardial cell stroma into the vein within about 3 heartbeats.

  Therefore, for example, the image extraction unit 26b extracts a blood vessel region from each of the systolic X-ray image group and the diastolic X-ray image group, and generates an image group (blood vessel removal image group) in which the extracted blood vessel region is removed. . Then, the image extraction unit 26b extracts an X-ray image having the highest contrast effect in the generated blood vessel removal image group based on the pixel value. Accordingly, the image extraction unit 26b extracts a systolic X-ray image and a diastolic X-ray image in which the myocardial region is stained with a contrast agent. For example, as illustrated in FIG. 4B, the image extraction unit 26b extracts an X-ray image (ES3) as a systolic X-ray image and extracts an X-ray image (ED3) as a diastolic X-ray image. .

  In the present embodiment, the case where the systolic X-ray image and the diastolic X-ray image are automatically extracted by the image extraction unit 26b has been described. However, the present invention is not limited to this, and the systolic phase is not limited thereto. An X-ray image and a diastole X-ray image may be extracted at the operator's discretion.

  For example, the system control unit 21 displays a moving image generated by the image processing unit 26 from a plurality of time-series X-ray images on the monitor of the display unit 23. Then, the operator designates the systolic X-ray image group and the diastolic X-ray image group based on the cardiac phase of the subject P acquired by the cardiac phase acquisition unit 26a. A request for displaying a still image of each period X-ray image group is notified to the system control unit 21 via the input unit 22. The operator refers to each X-ray image displayed on the monitor of the display unit 23 under the control of the system control unit 21 and visually extracts the X-ray image having the highest myocardial staining state. A systolic X-ray image and a diastolic X-ray image are determined.

  The systolic X-ray image and the diastolic X-ray image will be described with reference to FIG. As shown in FIG. 5 (A), the heart shape in the systole and the heart shape in the diastole vary with the change in the size of the heart. Specifically, as shown in the model diagram of FIG. 5B, in the systole, the heart contracts to increase the thickness of the myocardium, and in the systole, the heart expands to increase the thickness of the myocardium. Get smaller. Further, as shown in the model diagram of FIG. 5B, the position of the entire heart differs between the systole and the diastole.

  Here, the X-ray image is a projected image by X-rays irradiated from one direction. That is, the photons irradiated from the X-ray tube 12 toward the subject P are partially absorbed by an object located on the path from the X-ray tube 12 to the X-ray detector 16 and then applied to the X-ray detector 16. Reach. In the X-ray detector 16, charges corresponding to the number of transmitted photons are generated, and the generated charges are integrated and counted. Then, the image data generation unit 24 determines the pixel value of each pixel of the X-ray image from the accumulated number of charges counted by the X-ray detector 16.

  In other words, if the myocardium present on the photon path contains a constant concentration of contrast agent, the number of photons absorbed changes depending on the thickness of the myocardium, and as shown in FIG. The pixel values of the systolic X-ray image and the diastolic X-ray image change according to the thickness of the myocardium. Therefore, a change in the thickness of the myocardium can be detected by comparing the pixel values of the systolic X-ray image and the diastolic X-ray image.

  However, in order to compare the pixel values of the systolic X-ray image and the diastolic X-ray image, the size and position of the heart depicted in the X-ray images in the systolic and diastolic phases are matched. It is necessary to perform image transformation.

  For this reason, the image processing unit 26 in this embodiment includes an image deformation unit 26c as shown in FIG.

  That is, the image deformation unit 26c performs image deformation such as affine transformation on the systolic X-ray image and the diastolic X-ray image so that the size and position of the heart of the subject P to be rendered match within a predetermined range. By processing, a systolic deformation image and a diastole deformation image are generated.

  For example, as illustrated in FIG. 6, the image deformation unit 26 c divides each systolic X-ray image and diastolic X-ray image into “10 × 10” grids. Then, the image deformation unit 26c extracts image feature amounts between corresponding grids, performs enlargement / reduction processing and alignment based on the extracted feature amounts, and converts the systolic deformation image and the expansion phase deformation image. Generate.

  Alternatively, the image deforming unit 26c extracts feature points such as a blood vessel branch point and a shape around the heart in each of the systolic X-ray image and the diastolic X-ray image, and enlarges / reduces so that the extracted feature points match. Processing and alignment are performed to generate a systolic deformation image and a diastole deformation image.

  Returning to FIG. 3, the ratio image generation unit 26 d calculates the ratio value by dividing the pixel value of the corresponding pixel in the systolic deformation image and the diastolic deformation image generated by the image deformation unit 26 c. A ratio image having the ratio value as a pixel value is generated.

  That is, as described with reference to FIG. 5, since the myocardial thickness differs between the diastole and the systole, the pixel value changes between corresponding pixels in the systolic deformed image and the diastole deformed image. Therefore, in the region where the myocardial thickness does not change between the diastole and the systole, the pixel value of the ratio image is “1”, and in the region where the myocardial thickness changes twice between the diastole and the systole, the ratio image The pixel value of is greater than “1”.

  Therefore, for example, as illustrated in FIG. 7, the ratio image generation unit 26d generates a ratio image so that the smaller the ratio value, the darker the ratio image. As a result, the ratio image generation unit 26d generates a ratio image that can provide information that the area where the image is dark is the area where the viability of the cardiomyocytes is reduced, as shown in FIG. .

  The ratio image generation unit 26d may generate the ratio image so that the pixels are darker as the ratio value is larger.

  Further, the ratio image generation unit 26d generates or generates a ratio image after removing the blood vessel region from the systolic deformed image and the diastolic deformed image so that the doctor can easily grasp the state of the myocardium. Alternatively, the blood vessel region may be removed from the ratio image.

  Further, the ratio image generation unit 26d generates a ratio image after removing regions other than the heart region from the systolic deformed image and the diastolic deformed image so that the doctor can easily grasp the state of the myocardium. Alternatively, it may be a case where a region other than the heart region is removed from the generated ratio image.

  Further, the ratio image generation unit 26d generates the ratio image by color-coloring, for example, by configuring the pixels so that the portion where the ratio is “1” or more is blue and when the ratio is close to “1”, the pixel is colored. It may be the case.

  Returning to FIG. 3, the system control unit 21 performs control so that the ratio image generated by the ratio image generation unit 26 d is displayed on the monitor of the display unit 23.

  Next, processing of the X-ray diagnostic apparatus according to the first embodiment will be described with reference to FIG. FIG. 8 is a flowchart for explaining processing of the X-ray diagnostic apparatus according to the first embodiment.

  As shown in FIG. 8, when the X-ray diagnostic apparatus according to the first embodiment stores a plurality of X-ray images (contrast images) in time series in the image data storage unit 25 (Yes in step S101), image extraction is performed. The unit 26b extracts a systolic X-ray image group and a diastolic X-ray image group based on the cardiac phase of the subject P acquired by the cardiac phase acquisition unit 26a (step S102).

  Then, the image extraction unit 26b extracts the systolic X-ray image from the systolic X-ray image group by extracting the X-ray image having the highest shadow state of the myocardial region, and expands from the diastole X-ray image group. A period X-ray image is extracted (step S103).

  After that, the image deforming unit 26c performs the systolic X-ray image and the diastole so that the size and position of the heart of the subject P to be rendered match within a predetermined range by image deformation processing such as affine transformation. A systolic deformation image and a diastole deformation image are generated from the X-ray image (step S104).

  Subsequently, the ratio image generation unit 26d uses the ratio value calculated by dividing the pixel value of the corresponding pixel in the systolic deformation image and the diastole deformation image generated by the image deformation unit 26c as the pixel value. A ratio image is generated (step S105).

  Then, the system control unit 21 controls to display the ratio image generated by the ratio image generation unit 26d on the monitor of the display unit 23 (step S106), and ends the process.

  As described above, in the first embodiment, the image extraction unit 26b includes a plurality of time-series data stored in the image data storage unit 25 based on the cardiac phase of the subject P acquired by the cardiac phase acquisition unit 26a. A systolic X-ray image group and a diastolic X-ray image group are extracted from the X-ray images. Then, the image extraction unit 26b extracts the systolic X-ray image from the systolic X-ray image group by extracting the X-ray image having the highest shadow state of the myocardial region, and expands from the diastole X-ray image group. A period X-ray image is extracted.

  Then, the image deforming unit 26c contracts from the systolic X-ray image and the diastolic X-ray image so that the size and position of the heart of the object P to be rendered match within a predetermined range by the image deforming process. The period deformation image and the expansion period deformation image are generated. Then, the ratio image generation unit 26d uses the ratio value calculated by dividing the pixel value of the corresponding pixel in the systolic deformation image and the diastole deformation image generated by the image deformation unit 26c as a pixel value. The system controller 21 controls to display the ratio image generated by the ratio image generator 26d on the monitor of the display unit 23.

  Therefore, it is possible to generate and display a ratio image in which changes in the thickness of the myocardium are depicted, and as described above, it is possible to provide information related to the viability of the myocardial cells using the X-ray image. Become. In addition, the doctor can determine the treatment policy after determining the viability of the myocardial cells by referring to the ratio image generated from the X-ray image, and the intravascular intervention treatment can be performed only by the X-ray diagnostic apparatus. Can be performed.

  In the first embodiment described above, the case where the systolic X-ray image and the diastolic X-ray image are extracted from each X-ray image group has been described, but in the second embodiment, the systolic X-ray image and the diastolic X-ray image are extracted. The case of combining from each X-ray image group will be described with reference to FIG. FIG. 9 is a diagram for explaining an image extraction unit according to the second embodiment.

  The X-ray diagnostic apparatus according to the second embodiment and the image processing unit 26 according to the second embodiment have the same configuration as the X-ray diagnostic apparatus according to the first embodiment and the image processing unit 26 according to the first embodiment described with reference to FIGS. It becomes. However, in the second embodiment, the processing content of the image extraction unit 26b is different from the first embodiment. Hereinafter, this will be mainly described.

  The image extraction unit 26b according to the second embodiment generates a systolic X-ray image by extracting and synthesizing a pixel in which the myocardial region is stained with the contrast agent from each systolic X-ray image group. Similarly, the image extraction unit 26b according to the second embodiment generates a diastole X-ray image by extracting and synthesizing a pixel in which the myocardial region is stained with a contrast agent from each diastole X-ray image group. To do.

  For example, as illustrated in FIG. 9, the image extraction unit 26b according to the second embodiment generates a blood vessel removal image group from each of the systolic X-ray image group (ES1 to ES5) and the diastolic X-ray image group (ED1 to ED5). Then, among the same pixels, a peak value that is “a value at which the myocardium is most stained with a contrast agent” is adopted as a pixel value, thereby generating a systolic X-ray image and a diastolic X-ray image.

  Note that the processing contents of the image deformation unit 26c and the ratio image generation unit 26d are the same as those in the first embodiment except that the systolic X-ray image and the diastolic X-ray image synthesized from the peak values are processed. Description is omitted.

  Further, the processing procedure of the X-ray diagnostic apparatus according to the second embodiment employs peak values from the systolic X-ray image group and the diastolic X-ray image group in step S103 in FIG. Except for synthesizing the diastolic X-ray image, the processing procedure in the X-ray diagnostic apparatus according to the first embodiment described with reference to FIG.

  As described above, in the second embodiment, a ratio image can be generated by synthesizing a systolic X-ray image and a diastolic X-ray image in which the myocardium is most stained with a contrast agent. It becomes possible to provide related information more accurately.

  In Example 3, a case where a ratio image is generated using an index value calculated when a myocardial perfusion image is generated will be described with reference to FIGS. 10 is a diagram for explaining the configuration of the image processing unit in the third embodiment, FIG. 11 is a diagram for explaining a model used in the third embodiment, and FIG. 3 is a diagram for explaining a calculation formula used for generating a ratio image in FIG.

  Compared with the image processing unit 26 according to the first and second embodiments described with reference to FIG. 3, the image processing unit 26 according to the third embodiment includes an index value calculation unit 26 e and a myocardial perfusion image generation unit as illustrated in FIG. 10. The point which has 26f newly differs from Example 1 and 2. Hereinafter, these will be mainly described.

  The index value calculation unit 26e uses the systolic X-ray image group extracted by the image extraction unit 26b and the index value calculated to generate the “myocardial perfusion image” representing the blood perfusion state in the myocardial capillaries. It calculates from each diastolic X-ray image group.

  First, before describing the index value calculation unit 26e, the inflow / outflow model of the contrast medium into the myocardium used in this embodiment will be described with reference to FIG. Here, as shown in FIG. 11, blood (contrast medium) that has flowed into the capillaries from the coronary artery permeates through the capillaries and flows into the interstitial space from the interstitial space of the myocardium. Out to the capillary through the interstitial space.

Therefore, in the model shown in FIG. 11, the relative concentration per unit volume of the contrast medium in the myocardium is defined as “C _m (t)” at time “t”, and the contrast medium in the coronary artery at time “t”. The relative concentration per unit volume is defined as “C _a (t)”. Further, in the model shown in FIG. 11, when the time concentration curve indicating the temporal change of the contrast agent concentration in the coronary artery is an input function, and the time concentration curve indicating the time change of the contrast agent concentration in the local region of the myocardium is the output function, The “index value indicating the blood inflow state in the myocardium” is defined as “K ₁ ”, and the “index value indicating the blood outflow state in the myocardium” is defined as “K ₂ ”.

  When each value is defined as described above, the three-dimensional coordinates (x, y, z) of the heart at time “t” are as shown in the following formula (1) between the myocardial part and the coronary artery. Concentration balance of contrast agent is established.

Here, under the condition where the contrast agent begins to flow into the myocardium, the amount of inflow is extremely small, so that `` K ₂ C _m (x, y, z, t) << K ₁ C _a (x, y, z , t) ". Thereby, Formula (1) can be approximated as Formula (2) shown below.

Further, by transforming Equation (2), Equation (3) shown below is derived. According to Equation (3), “K ₁ ” is “C _m (t)” on the Y axis and “C _a ( It is shown that it is calculated as a slope when a value obtained by time integration of “t)” is plotted.

When the model shown in FIG. 11 is applied to the X-ray image generated by the X-ray diagnostic apparatus, the X-ray image projects the subject P by X-rays emitted from the X-ray tube 12 at a specific position. In the following, the coordinates (u, v) of the orthogonal coordinate system are used. Here, the pixel value corresponding to the pixel of the coronary artery in the projection direction at time “t” is defined as “I _a (u, v, t)”, and the thickness of the coronary artery in the projection direction is defined as “D _a (u , v) ”, and the relative concentration per unit volume of the contrast agent in the coronary artery portion of“ t ”is defined as“ C _a (u, v, t) ”, the relationship shown in the following equation (4) is obtained. To establish. Note that “I _a (u, v, 0)” indicates a pixel value corresponding to a pixel in the coronary artery portion without contrast medium in the projection direction at the start of contrast medium injection.

Further, the pixel value corresponding to the myocardial pixel in the projection direction at time “t” is defined as “I _m (u, v, t)”, and the myocardial thickness in the projection direction is defined as “D _m (u, u, v) ”and the relative concentration per unit volume of the contrast medium in the myocardium of“ t ”is defined as“ C _m (u, v, t) ”, the relationship shown in the following equation (5) is established. To do. “I _m (u, v, 0)” indicates a pixel value corresponding to a myocardial pixel having no contrast agent in the projection direction at the start of contrast agent injection.

  Furthermore, when the relational expressions of the expressions (4) and (5) are applied to a relational expression obtained by converting the expression (3) into a two-dimensional coordinate system, the following expression (6) is established.

In Expression (6), “K ₁ ” is the natural logarithm of the pixel value reflecting the contrast agent concentration of the coronary artery with the amount of change of the natural logarithm of the pixel value reflecting the contrast agent concentration of the myocardial portion as the Y axis. Is the slope when the value obtained by integrating the amount of change over time is plotted on the X-axis. Here, a new index value that reflects the thicknesses of the coronary portion of the myocardial portion to the "K _1", "K ₁ '', defined by the following equation (7).

Here, conventionally, when the myocardial perfusion image is generated, the index value “K ₁ ′” shown in Expression (7) represents the actual inflow state of blood into the myocardial local region proportional to the myocardial blood flow. Calculated as a value. Then, from “K ₁ ′”, an image showing the maximum value of blood flow (contrast agent) in the myocardial region and an image showing change in blood flow (contrast agent) concentration in the myocardial region are generated as myocardial perfusion images.

However, in the present embodiment, the index value calculation unit 26e not only calculates “K ₁ ′” from a plurality of time-series X-ray images, but also the systolic X-ray image extracted by the image extraction unit 26b. "K _1ES '" and "K _1ED '" corresponding to "K ₁ '" are calculated from the group and the diastolic X-ray image group, respectively.

That is, the thickness of the myocardial portion in the projection direction, "D _mES (u, v)" in systole and, when in diastole and "D mED _(u, v)", "K _1ES '" and "K _1ed' "Is represented as the following formula (8) and formula (9), respectively.

Then, a ratio (Ratio) obtained by dividing “K _1ES ′” by “K _1ED ′” is expressed as Expression (10) shown below from Expression (8) and Expression (9).

  Then, by deleting the common term of Expression (10), the following Expression (11) is derived.

By the way, if the contrast medium is distributed in the cell space of the myocardium and there is almost no inflow or outflow of the contrast medium into the capillaries due to heartbeat movement, “K _1ES ” and “K _1ED ” are regarded as almost the same value. Equation (11) can be transformed into Equation (12) shown below.

As a result, the ratio of the change in the thickness of the myocardium can be expressed as the ratio of “K _1ES ′” and “K _1ED ′” as shown in the following equation (13).

That is, in the X-ray image group in the systole, the amount of change per unit time of “C _mES ”, which is the relative concentration per unit volume of the contrast medium in the myocardium in the systole, is “K _1ES ” and “C 1 _mES ”(see (1) in FIG. 12), and the change per unit time in the diastole of“ C _mED ”, which is the relative concentration per unit volume of the contrast medium in the myocardium in the diastole The quantity is represented by the product of “K _1ED ” and “C _mED ” (see (2) in FIG. 12). According to the above description using the equations (1) to (13), “K _1ES ” and “K _1ED ” reflect the thickness of the myocardium in “K _1ES ” and “K _1ED ”. If the ratio is calculated, the ratio of the thickness of the myocardium generated between the systole and the diastole is calculated (see (3) in FIG. 12).

For this reason, the index value calculation unit 26e generates “K _1ES ” corresponding to “K ₁ ′” and “K ₁ ′” from the systolic X-ray image group and the diastolic X-ray image group in order to generate the ratio image. “K _1ED '” is calculated for each pixel.

Then, the image deforming unit 26c according to the third embodiment outputs a systolic X-ray image and a diastolic X-ray image in which “K _1ES ′” and “K _1ED ′” calculated for each pixel by the index value calculating unit 26e are pixel values. After the generation, similar to the first and second embodiments, the image deformation process is performed to generate the systolic deformed image and the diastole deformed image.

  Then, the ratio image generation unit 26d according to the third embodiment generates a ratio image by dividing the pixel value between corresponding pixels of the systolic deformed image and the diastolic deformed image.

The myocardial perfusion image generation unit 26 f generates a myocardial perfusion image from “K ₁ ′” calculated from the plurality of X-ray images along the time series by the index value calculation unit 26 e.

  Then, the system control unit 21 performs control so that the ratio image generated by the ratio image generation unit 26d is displayed on the monitor of the display unit 23 together with the myocardial perfusion image generated by the myocardial perfusion image generation unit 26f.

In the present embodiment, the case where the image deformation unit 26c generates a systolic X-ray image and a diastolic X-ray image from “K _1ES ′” and “K _1ED ′” has been described, but the present invention is not limited to this. The image extraction unit 26b may generate a systolic X-ray image and a diastolic X-ray image from “K _1ES ′” and “K _1ED ′”.

  In this embodiment, the case where the myocardial perfusion image is generated and displayed together with the ratio image has been described. However, the present invention is not limited to this, and only the ratio image is generated and displayed. Also good.

  Next, processing of the X-ray diagnostic apparatus according to the third embodiment will be described with reference to FIG. FIG. 13 is a flowchart for explaining processing of the X-ray diagnostic apparatus according to the third embodiment.

  As shown in FIG. 13, when the X-ray diagnostic apparatus according to the third embodiment stores a plurality of time-series X-ray images (contrast images) in the image data storage unit 25 (Yes in step S201), image extraction is performed. The unit 26b extracts a systolic X-ray image group and a diastolic X-ray image group based on the cardiac phase of the subject P acquired by the cardiac phase acquisition unit 26a (step S202).

Then, the index value calculation unit 26e calculates a systolic index value “K _1ES ′” for each pixel from the systolic X-ray image group and generates a ratio image for each pixel from the diastolic X-ray image group. The diastolic index value “K _1ED '” is calculated (step S203).

After that, the image deformation unit 26c generates a systolic X-ray image and a diastole X-ray image from “K _1ES '” and “K _1ED '” (step S204), and the generated systolic X-ray image and diastole An X-ray image is subjected to image deformation processing to generate a systolic deformation image and a diastole deformation image (step S205).

  Subsequently, the ratio image generation unit 26d uses the ratio value calculated by dividing the pixel value of the corresponding pixel in the systolic deformation image and the diastole deformation image generated by the image deformation unit 26c as the pixel value. A ratio image is generated (step S205).

Then, the system control unit 21 controls to display the ratio image generated by the ratio image generation unit 26d on the monitor of the display unit 23 (step S206), and ends the process.

Although not shown in FIG. 13, the index value calculation unit 26e calculates “K ₁ ′” from a plurality of time-series X-ray images, and the myocardial perfusion image generation unit 26f calculates the index value calculation unit 26e. Generates a myocardial perfusion image from the calculated “K ₁ ′”, and the system control unit 21 controls to display the myocardial perfusion image generated by the myocardial perfusion image generation unit 26f on the monitor of the display unit 23 together with the ratio image. To do.

  As described above, in the third embodiment, a ratio image can be generated simply by calculating index values conventionally used in generating a myocardial perfusion image in each of the systole and diastole. It becomes possible to easily provide information relating to the degree of survival. In addition, since the myocardial perfusion image can be generated and displayed together with the ratio image, the morphological information on whether or not there is a stenosis site and the perfusion information on whether or not blood has reached the myocardium can be obtained by a single contrast imaging. It is possible to provide it with information on the survival of

  In the first to third embodiments, the case where the image processing unit 26 is incorporated in the X-ray diagnostic apparatus has been described. However, the present invention is not limited to this, and the image processing unit 26 is not limited to the X-ray. It may be a case where a ratio image is generated from a plurality of X-ray images that are installed independently of the diagnostic apparatus and are taken in time series by the X-ray diagnostic apparatus.

  As described above, the image processing apparatus and the X-ray diagnosis apparatus according to the present invention are useful when treating ischemic heart disease of the heart, and are particularly related to the survival of cardiomyocytes using X-ray images. Suitable for providing information.

DESCRIPTION OF SYMBOLS 11 High voltage generator 12 X-ray tube 13 X-ray aperture apparatus 14 Top plate 15 C arm 16 X-ray detector 17 C arm rotation and movement mechanism 18 Top plate movement mechanism 19 C arm and top plate mechanism control part 20 Aperture control part DESCRIPTION OF SYMBOLS 21 System control part 22 Input part 23 Display part 24 Image data generation part 25 Image data memory | storage part 26 Image processing part 26a Heart phase acquisition part 26b Image extraction part 26c Image deformation part 26d Ratio image generation part 30 Electrocardiograph

Claims (6)

Cardiac phase acquisition means for acquiring the cardiac phase of the subject;
Image storage means for storing a plurality of X-ray images showing the heart of the subject into which a contrast medium has been injected;
The X-ray image in the first phase and the X in the second phase extracted from the plurality of X-ray images stored in the image storage means based on the cardiac phase of the subject acquired by the cardiac phase acquisition means Image deformation means for generating a first image and a second image by deforming each line image so that the size and position of the rendered heart match within a predetermined range;
A ratio image obtained by dividing a pixel value of a corresponding pixel in the first image and the second image generated by the image transformation unit to calculate a ratio value, and using the calculated ratio value as a pixel value A ratio image generating means for generating
The ratio image generated by said ratio image generating means and display control means for controlling so as to display the table radical 113,
An image processing apparatus comprising: X-ray images corresponding to the first phase and the second phase from the plurality of X-ray images stored by the image storage unit based on the cardiac phase of the subject acquired by the cardiac phase acquisition unit A group is extracted, and among the extracted X-ray image groups, X-ray images having the maximum contrast effect of the myocardium by the contrast agent are respectively obtained in the X-ray image in the first phase and the second phase. It further comprises image extraction means for extracting as an X-ray image,
2. The image deformation means performs image deformation processing on the X-ray image in the first phase and the X-ray image in the second phase extracted by the image extraction means. An image processing apparatus according to 1.   The image extraction means generates an X-ray image in the first phase by extracting and synthesizing pixels having the maximum myocardial contrast effect by the contrast agent from each of the X-ray image groups in the first phase. Then, an X-ray image in the second phase is generated by extracting and synthesizing a pixel having a maximum myocardial contrast effect by the contrast agent from each of the X-ray image groups in the second phase. The image processing apparatus according to claim 2. The X-ray image group in the first phase extracted from the plurality of X-ray images stored in the image storage unit based on the cardiac phase of the subject acquired by the cardiac phase acquisition unit, and the second phase In each of the X-ray image groups in the phase, it further comprises index value calculation means for calculating, for each pixel, a first index value and a second index value representing the blood perfusion state in the myocardial capillaries,
The image deformation means is an X-ray in the first phase generated by using each of the first index value and the second index value calculated for each pixel by the index value calculation means as a pixel value. The image processing apparatus according to claim 1, wherein the first image and the second image are generated by performing image deformation processing on the image and the X-ray image in the second phase.   5. The image processing apparatus according to claim 1, wherein the first phase is a systole of the heart, and the second phase is a diastole of the heart. Cardiac phase acquisition means for acquiring the cardiac phase of the subject;
Image storage means for storing a plurality of X-ray images showing the heart of the subject into which a contrast medium has been injected;
The X-ray image in the first phase and the X in the second phase extracted from the plurality of X-ray images stored in the image storage means based on the cardiac phase of the subject acquired by the cardiac phase acquisition means Image deformation means for generating a first image and a second image by deforming each line image so that the size and position of the rendered heart match within a predetermined range;
A ratio image obtained by dividing a pixel value of a corresponding pixel in the first image and the second image generated by the image transformation unit to calculate a ratio value, and using the calculated ratio value as a pixel value A ratio image generating means for generating
The ratio image generated by said ratio image generating means and display control means for controlling so as to display the table radical 113,
An X-ray diagnostic apparatus comprising:

Images