JP2016154852A - X-ray diagnostic device, image processor and image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray diagnostic device, image processor and image processing method capable of generating an image in which blood flow restoration in a dominant area can easily be confirmed in thrombus removal surgery using a catheter.SOLUTION: According to one embodiment, an X-ray diagnostic device is an X-ray diagnostic device for generating an X-ray image of an attention region and includes an X-ray photographing part for photographing a first X-ray image before injecting a contrast medium, and a second X-ray image and a third X-ray image after injecting the contrast medium, and an image generation part for generating an output image with a ratio between difference between the second X-ray image and the first X-ray image, and difference between the third X-ray image and the first X-ray image defined as a pixel value.SELECTED DRAWING: Figure 2

Description

  Embodiments described herein relate generally to an X-ray diagnostic apparatus, an image processing apparatus, and an image processing method.

  An examination using an X-ray diagnostic apparatus includes X-ray subtraction angiography. In this examination, an image (mask image) before injection of the contrast agent and an image (contrast image) after injection of the contrast agent are taken for the same part of the subject. Then, an image (subtraction image) obtained by calculating the difference between these images is generated.

  This subtraction image is an image in which an image of a blood vessel contrasted with a contrast agent is depicted. For this reason, by observing the subtraction image, the user can easily grasp the state of blood flow of the subject. For example, when performing a thrombectomy operation using a catheter, by observing whether or not an image of a blood vessel downstream of the thrombus (blood vessel dominating region, hereinafter referred to as “dominating region”) appears in the subtraction image after the operation, It is expected that it can be confirmed whether the blood flow in the dominant region has recovered.

  For example, in a thrombectomy operation using a catheter for a patient with cerebral infarction, a thrombus removal operation is attempted pharmacologically by a thrombolytic agent released from the catheter tip or mechanically by a device ejected from the catheter tip. In this case, it is preferable that the user who is a practitioner confirms whether or not the blood flow in the control region has been restored each time the clot is removed. As this confirmation method, for example, by continuously performing X-ray imaging while releasing a contrast agent into the blood vessel from the tip of the catheter, a contrast image is continuously generated to obtain subtraction images, and these subtraction images are obtained. And a method of observing whether or not an image of a blood vessel contrasted in FIG.

  However, with this method, it is difficult to determine from the subtraction image whether or not blood flow has resumed in the entire control region. This is because the contrast medium released from the distal end of the catheter circulates in the bloodstream and images normal brain tissue, and the image is included in the subtraction image.

JP 2011-160978 A

  The problem to be solved by the present invention is an X-ray diagnostic apparatus, an image processing apparatus, and an image processing capable of generating an image capable of easily confirming blood flow recovery in a dominant region in a thrombectomy operation using a catheter. Is to provide a method.

  An X-ray diagnostic apparatus according to an embodiment of the present invention is an X-ray diagnostic apparatus that generates an X-ray image of a region of interest in order to solve the above-described problem, and is a first X-ray image before injection of a contrast agent. An X-ray imaging unit that captures the second X-ray image and the third X-ray image after the injection of the contrast agent, a difference between the second X-ray image and the first X-ray image, the third X-ray image, An image generation unit configured to generate an output image having a difference between the first X-ray images and a pixel value as a ratio.

1 is a block diagram showing an example of an X-ray diagnostic apparatus according to a first embodiment of the present invention. FIG. 3 is a schematic block diagram showing an example of functions realized by a processor of the processing circuit according to the first embodiment. Explanatory drawing which shows an example of a mode that the mask image of the head of a subject is image | photographed. (a) is explanatory drawing which shows an example of a mode that the 1st contrast image of the subject's head is image | photographed, (b) is description which shows an example of the 1st difference image obtained using a 1st contrast image and a mask image. Figure. (A) is explanatory drawing which shows an example of a mode that the other 1st contrast image of the subject's head is image | photographed, (b) is another 1st obtained using another 1st contrast image and a mask image. Explanatory drawing which shows an example of a difference image, (c) is explanatory drawing which shows an example of the ratio image which uses the ratio of the pixel value of another 1st difference image and a 1st difference image as a pixel value. (A) is explanatory drawing which shows an example of a mode that the 2nd contrast image of the subject's head is image | photographed, (b) shows an example of the 2nd difference image obtained using a 2nd contrast image and a mask image. Illustration. Explanatory drawing which shows an example of the ratio image which uses the ratio of the pixel value of a 2nd difference image and another 1st difference image as a pixel value. The flowchart which shows an example of the procedure at the time of producing | generating the image which can confirm easily the blood flow recovery in the downstream (control area | region) of the thrombus in the thrombectomy operation using the catheter by the processor of the processing circuit shown in FIG. The block diagram which shows an example of the X-ray diagnostic apparatus which concerns on 2nd Embodiment of this invention. The schematic block diagram which shows the example of an implementation | achievement function by the processor of the processing circuit which concerns on 2nd Embodiment. Explanatory drawing which shows an example of a mode when a prediction ratio image and a ratio image are displayed in parallel on the display. The flowchart which shows an example of the procedure at the time of displaying a ratio image and a prediction ratio image on a display in parallel by a prediction ratio image generation part and a 2nd image generation part.

  Embodiments of an X-ray diagnostic apparatus, an image processing apparatus, and an image processing method according to the present invention will be described with reference to the accompanying drawings.

An X-ray diagnostic apparatus according to an embodiment of the present invention is an X-ray diagnostic apparatus that generates an X-ray image of a region of interest, and includes an X-ray imaging unit and a processing circuit. The X-ray imaging unit captures the first X-ray image before the injection of the contrast agent and the second X-ray image and the third X-ray image after the injection of the contrast agent. The processing circuit generates an output image having a pixel value as a ratio between the difference between the second X-ray image and the first X-ray image and the difference between the third X-ray image and the first X-ray image.
(First embodiment)

  FIG. 1 is a block diagram showing an example of an X-ray diagnostic apparatus 10 according to the first embodiment of the present invention.

  As shown in FIG. 1, the X-ray diagnostic apparatus 10 includes an X-ray imaging unit (radiography device) 11 and an image processing device 12. The X-ray imaging unit 11 of the X-ray diagnostic apparatus 10 is normally installed in an examination room and generates X-ray projection data related to a part of the patient P (a region of interest of the subject). In many cases, the image processing apparatus 12 is installed in an operation room adjacent to an examination room, and generates and displays an X-ray image based on projection data.

  The X-ray imaging unit 11 includes an X-ray detector 21, an X-ray tube 22 and an X-ray generator 24 having a diaphragm 23 for the X-ray tube 22, a C arm 25, The bed 26 includes a high voltage device 27, a diaphragm driver 28, an arm driver 29, an injector 30, a bed driver 31, and a controller 32. As each of the components 21-32 of the X-ray imaging unit 11, those conventionally known can be used.

  The X-ray detection unit 21 is provided at one end of the C arm 25 so as to be opposed to the X-ray tube 22 with the subject P supported by the top plate (catheter table) 33 of the bed 26 interposed therebetween. The X-ray detection unit 21 is configured by a flat panel detector (FPD), detects X-rays irradiated on the X-ray detection unit 21, and generates X-ray projection data based on the detected X-rays. Output. This projection data is given to the image processing apparatus 12 via the controller 32. Note that the X-ray detection unit 21 may include an image intensifier, a TV camera, and the like.

  The X-ray generator 24 is provided at the other end of the C arm 25 and has an X-ray tube 22 and a diaphragm 23.

  The X-ray tube 22 is applied with a voltage by the high voltage device 27 and generates X-rays. X-rays generated by the X-ray tube 22 are irradiated toward the subject P.

  The diaphragm 23 is, for example, an X-ray irradiation field diaphragm composed of a plurality of lead feathers. The diaphragm 23 is controlled by the controller 32 via the diaphragm driving unit 28 and adjusts the irradiation range of the X-rays irradiated from the X-ray tube 22.

  The C arm 25 holds the X-ray generation unit 24 and the X-ray detection unit 21 together. When the C arm 25 is driven under the control of the controller 32, the X-ray generation unit 24 and the X-ray detection unit 21 move around the subject P as a unit.

  The bed 26 is installed on the floor and supports the top plate 33. The couch 26 is controlled by the controller 32 to move or rotate (roll) the top plate 33 in the horizontal direction and the vertical direction.

  The high voltage device 27 is controlled by the controller 32 to supply the X-ray tube 22 with power necessary for X-ray irradiation.

  The diaphragm driving unit 28 is controlled by the controller 32 to adjust the irradiation range of the X-rays emitted from the X-ray tube 22 according to the imaging protocol by adjusting the aperture of the diaphragm 23.

  The arm driving unit 29 and the bed driving unit 31 are controlled by the controller 32 to drive the C arm 25 and the top plate 33, respectively.

  The injector 30 is a device that is controlled by the controller 32 and injects a contrast medium via a catheter 34 that is held by the operator O and inserted into the affected part of the subject P. The timing of injection and stop of the contrast agent and the concentration and injection rate of the contrast agent are automatically controlled by the controller 32. The injector 30 may be prepared as an external isolated device different from the X-ray diagnostic apparatus 10. In this case, the X-ray diagnostic apparatus 10 does not include the injector 30. The injector 30 does not need to be controlled by the controller 32 regardless of whether it is prepared outside. For example, the injector 30 receives an instruction from the operator O via an input unit provided in the injector 30, and this instruction The contrast agent may be injected at a concentration, speed, and timing according to the above.

  The controller 32 is controlled by the image processing device 12 to control the X-ray detection unit 21, the high voltage device 27, the aperture driving unit 28, the arm driving unit 29, the injector 30, and the bed driving unit 31, thereby performing X-ray imaging. To generate projection data of the region of interest of the subject P, and give it to the image processing apparatus 12.

  On the other hand, the image processing apparatus 12 includes an input circuit 41, a display 42, a network connection circuit 43, a storage circuit 44, and a processing circuit 45, as shown in FIG. Each configuration 41-45 of the image processing apparatus 12 can be configured by an information processing apparatus such as a general personal computer or a workstation.

  The input circuit 41 includes, for example, a general input device such as a mouse, a trackball, a keyboard, a touch panel, and a numeric keypad, a hand switch for instructing the X-ray exposure timing, and the like. The signal is output to the processing circuit 45. Moreover, a microphone for voice input may be used as the input circuit 41. In this case, the microphone converts the voice input by the user into a digital voice signal, and the processing circuit 45 performs an operation according to the voice input by the user by performing voice recognition processing on the digital voice signal. The user may be the same as or different from the operator O.

  The display 42 includes a general display output device such as a liquid crystal display or an OLED (Organic Light Emitting Diode) display, and displays various images such as an X-ray image under the control of the processing circuit 45.

  The network connection circuit 43 implements various information communication protocols according to the form of the network 100. The network connection circuit 43 connects the X-ray diagnostic apparatus 10 and other apparatuses according to these various protocols. Here, the network 100 means an entire information communication network using telecommunications technology. In addition to a wireless / wired LAN such as a hospital basic LAN (Local Area Network) and an Internet network, a telephone communication line network, an optical fiber communication network. Cable communication networks and satellite communication networks. In the present embodiment, the X-ray diagnostic apparatus 10 may not include the network connection circuit 43.

  The storage circuit 44 includes a storage circuit that can be read and written by the processor of the processing circuit 45 such as a magnetic or optical recording medium or a semiconductor memory, and is controlled by the processing circuit 45 to control the mask image M and the mask. The positions and the like based on the X-ray tube 22 and the top plate 33 of the X-ray detector 21 when the image M is captured are stored.

  The processing circuit 45 has at least a processor. The processing circuit 45 is constituted by a storage circuit such as a processor, a RAM, and a ROM, for example. The processing circuit 45 controls the operation of the X-ray diagnostic apparatus 10 including the controller 32 according to the program stored in the storage circuit. The processor of the processing circuit 45 loads an image processing program stored in a storage circuit such as a ROM and data necessary for executing the program into the RAM. Conventionally existing configurations can be used for the configurations described so far.

  In accordance with the image processing program, the processor of the processing circuit 45 according to the present embodiment generates an image that can easily confirm blood flow recovery downstream (dominant region) of the thrombus in the thrombectomy surgery using the catheter 34. Execute the process for

  A conventional RAM for the processing circuit 45 can be used, and provides a work area for temporarily storing programs and data executed by the processor. The storage circuit including the ROM of the processing circuit 45 stores a startup program for the X-ray diagnostic apparatus 10, an image processing program, and various data necessary for executing these programs.

  As the storage circuit including the ROM, a conventional one can be used, and has a configuration including a storage circuit readable by a processor, such as a magnetic or optical recording medium or a semiconductor memory, Some or all of the programs and data in these storage circuits may be downloaded via an electronic network. Further, the processing circuit 45 may be constituted by a plurality of processors.

  FIG. 2 is a schematic block diagram illustrating an example of functions realized by the processor of the processing circuit 45 according to the first embodiment.

  As shown in FIG. 2, the processor of the processing circuit 45 functions as at least a photographing control function 51, a first image generation function 52, a second image generation function 53, and a movement processing function 54 by an image processing program. Each of these functions is stored in the storage circuit in the form of a program.

  As the imaging control function 51, an existing one can be used, and by controlling the X-ray imaging unit 11 via the controller 32, X-ray imaging is performed before and after the injection of the contrast agent.

  The first image generation function 52 generates a digital image with the logarithm of the X-ray intensity transmitted through the subject P as a pixel value based on the projection data. For example, the first image generation function 52 generates a mask image based on projection data obtained by X-ray imaging before removing blood flow obstacles such as plaque and thrombus and before injecting contrast medium. The first image generation function 52 generates a first contrast image based on projection data obtained by X-ray imaging before blood flow obstacle removal and after injection of a contrast medium. The first image generation function 52 generates a second contrast image based on projection data obtained by X-ray imaging after removing blood flow obstacles and after injecting contrast medium.

  Here, a conventional subtraction image will be briefly described. In the following description, the subject P has developed cerebral infarction, the blood flow obstacle is a thrombus, the region of interest including the blood flow obstacle is the head of the subject P, and the blood flow obstacle An example where the removal operation is a thrombus removal operation using the catheter 34 will be described. However, cerebral infarction is a condition in which an artery in the brain is clogged with an embolus such as a thrombus, and blood does not flow to a tissue downstream (dominant area) of the artery, or the blood flow rate is significantly reduced.

  The first treatment option for patients with cerebral infarction is the intravenous administration of a thrombolytic agent. However, there is a restriction that the administration must be performed within a certain time limit after the onset (standards differ depending on the region in the world), and the success rate (thrombus dissolves, blood flow in the control region is sufficient) (Probability of recovery (restart)) is low.

  In cases where venous thrombolytic agents could not be administered within the time limit, cases where the onset time was unknown, or cases where thrombolytic agents were administered but were not successful, cerebral infarction As a second option of treatment for the patient, a thrombectomy operation using the catheter 34 is performed.

  The thrombus removal operation using the catheter 34 is an operation for removing the thrombus by allowing the catheter 34 to enter the cerebral blood vessel while continuously X-raying the head of the subject P (that is, under fluoroscopy). . In thrombus removal surgery using the catheter 34, a thrombus removal operation is attempted pharmacologically with a thrombolytic agent released from the distal end of the catheter 34 or mechanically with a device ejected from the distal end of the catheter 34.

  When using a thrombolytic agent, the thrombolytic agent is released from the distal end of the catheter 34 and waits for a while.

  When the thrombus is mechanically removed, a device for entwining the thrombus is taken out from the distal end of the catheter 34, and the contrast medium is released while continuously imaging the head of the subject P with X-rays. Make sure that the device is inserted into the thrombus and entangled with the device. Next, many parts of the thrombus are removed by removing the device.

  As another means for mechanically removing the thrombus, a device for crushing the thrombus is taken out from the distal end of the catheter 34, and the contrast agent is released while continuously imaging the head of the subject P to remove the thrombus. Confirm position and insert device into thrombus. The device pulverizes the thrombus by emitting ultrasonic waves or the like. The broken pieces are sucked out through the catheter.

  When performing a thrombectomy operation using the catheter 34, it is important to check whether the blood flow in the control region has been restored each time the thrombus removal operation is performed. For this reason, the head of the subject P is continuously X-rayed while releasing the contrast medium from the distal end of the catheter 34 into the artery, and it is observed whether an image of the blood vessel contrasted in the dominant region appears. Is preferred. If the thrombus is sufficiently removed, an image of the arterial branch, capillary network, and venous system in the dominant region will appear.

  In addition, the arterial branch or capillary network in the dominant region may be clogged with another thrombus. This may have been originally such a condition, or may also be caused by clogging of clot fragments (debris) produced by thrombectomy surgery downstream. In this case, an image obtained by contrasting only a part of the arterial branch / capillary network in the dominant region is obtained.

  When generating an image for observing this kind of blood flow, a subtraction image (difference image) is used to remove an image generated by a tissue such as a skull or a contrast medium that has already diffused in the blood. It is known to generate.

  In order to generate a difference image, the first image generation function 52 first generates a mask image M based on projection data obtained by X-ray imaging before the removal of the thrombus and before the injection of the contrast agent. Since it is before the removal of the thrombus, the region 61 where there is no blood flow in the artery in the brain is considered to coincide with the dominant region.

  FIG. 3 is an explanatory diagram illustrating an example of a state in which the mask image M of the head of the subject P is captured. FIG. 4A is an explanatory diagram showing an example of a state in which the first contrast image P1 of the head of the subject P is photographed, and FIG. 4B is obtained using the first contrast image P1 and the mask image M. It is explanatory drawing which shows an example of the subtraction image (1st difference image) 71 (P1-M).

  When the contrast medium is injected before the removal of the thrombus, the region 62 upstream of the dominant region is stained with the contrast medium (see the hatched area in FIG. 4A). The first image generation function 52 generates a first contrast image P1 based on projection data obtained by, for example, X-ray imaging while releasing a contrast medium from the distal end of the catheter 34 into the artery. The first contrast image P1 may be generated based on projection data obtained by performing X-ray imaging after a time during which the contrast medium is distributed substantially uniformly in the tissue after administration of the contrast medium.

  The second image generation function 53 generates a first difference image 71 (P1-M) having a pixel value as a difference between the pixel value of each pixel of the first contrast image P1 and the pixel value of each pixel of the mask image M. (See FIG. 4 (b)).

  As shown in FIG. 4B, the pixels in the portion corresponding to the dominant region in the first difference image 71 (P1-M) do not have uniform pixel values. This is because the X-ray transmission length for the contrast agent distributed in the subject P differs depending on the position of the pixel.

  For example, when a contrast medium is injected from a catheter in an artery, the blood vessel, the blood vessel branch downstream thereof, the capillary network in the control region downstream thereof, and the venous system downstream thereof are imaged. At this time, since the capillary network is very fine and extremely numerous, it looks like a cloud that is not clearly visible but is contrasted with a blur. When the capillary network in the dominant region is uniformly imaged, if the captured image of the X-ray CT apparatus is used, the pixel corresponding to the first difference image 71 (P1-M) in the dominant region Becomes a uniform pixel value. However, the image captured by the X-ray diagnostic apparatus 10 has different X-ray transmission lengths with respect to the contrast agent distributed in the subject P depending on the pixel position, and therefore the influence of attenuation due to the contrast agent differs depending on the pixel position. For this reason, even if the capillary network in the dominant region is uniformly imaged, the portion corresponding to the dominant region in the first difference image 71 (P1-M) generated by the X-ray diagnostic apparatus 10 Is not uniform (see FIG. 4B).

  FIG. 5A is an explanatory view showing an example of a state in which another first contrast image P2 of the head of the subject P is photographed, and FIG. 5B shows another first contrast image P2 and a mask image M. It is explanatory drawing which shows an example of the subtraction image (other 1st difference image) 72 (P2-M) obtained by using. FIG. 5C shows an image 81 (hereinafter referred to as a ratio image) having a pixel value ratio between the other first difference image 72 (P2-M) and the first difference image 71 (P1-M). It is explanatory drawing which shows an example of ((P2-M) / (P1-M)).

  For example, since the contrast medium at the time of capturing the first contrast image P1 is distributed in the blood, if the first contrast image P2 is captured again, the contrast agent concentration (contrast contained in the living tissue of the unit volume) is higher than P1. The image is taken in a state where the amount of the agent is increased. In this case, in the other first difference image 72 (P2-M), as in the first difference image 71 (P1-M), the pixels in the portion corresponding to the dominant region do not have uniform pixel values (FIG. 5 (b)).

  For this reason, the blood flow is resumed by thrombus removal surgery (the clogging of blood vessels is removed and the blood flow is sufficiently recovered), so that the contrast agent concentration (the amount of the contrast agent contained in the living tissue of the unit volume) increases. Even if these difference images 71 and 72 are observed, it is difficult to identify the region because of the non-uniformity of the pixel values in the portion corresponding to the dominant region, and the thrombectomy operation is successful. It is very difficult to determine whether or not Further, a difference image ((P1-M)-(P2-M)) = (P1-P2) between the first difference image 71 (P1-M) and the other first difference image 72 (P2-M) is generated. Even so, since the contrast agent concentration (the amount of contrast agent contained in the biological tissue of the unit volume) in the difference images 71 and 72 is different, the difference image (P1-P2) corresponding to the control region The pixels also do not have uniform pixel values.

  Therefore, the second image generation function 53 of the X-ray diagnostic apparatus 10 according to the present embodiment generates a ratio image in which the pixel value ratio between the difference images is a pixel value. The ratio image generated from the difference images is an image reflecting the ratio of the contrast agent concentration (the amount of contrast agent contained in the living tissue of the unit volume) at the time of capturing the contrast image of each difference image. For this reason, the pixel values of the pixels corresponding to the dominant region in the ratio image are substantially uniform.

  For example, as shown in FIG. 5C, the ratio between the pixel value of each pixel of the other first difference image 72 (P2-M) and the pixel value of each pixel of the first difference image 71 (P1-M). A ratio image 81 ((P2-M) / (P1-M)) having a pixel value as an image is an image reflecting only an increase in contrast agent concentration (amount of contrast agent contained in a unit volume of biological tissue), The portion corresponding to the dominating region becomes a substantially uniform image (see FIG. 5C).

  FIG. 6A is an explanatory diagram showing an example of a state in which the second contrast image P3 of the head of the subject P is photographed, and FIG. 6B is obtained using the second contrast image P3 and the mask image M. It is explanatory drawing which shows an example of the 2nd difference image 73 (P3-M).

  FIG. 7 shows a ratio image 82 ((P3-M) / (P2) in which the pixel value is the ratio between the pixel values of the second difference image 73 (P3-M) and the other first difference image 72 (P2-M). -M)) is an explanatory diagram showing an example. An image 66 in FIG. 7 shows an example of an image generated by X-rays transmitted through the region 63, the region 62, and the region 61 (see FIG. 6A). Further, the image 67 in FIG. 7 shows only an area 63, and the image 68 in FIG. 7 shows an example of an image generated by X-rays transmitted through the area 63 and the area 62, respectively. Note that the first difference image 71 (P1-M) may be used instead of the other first difference image 72 (P2-M) in FIGS. 6B and 7.

  Consider the case where blood flow resumes through a part of the controlled area due to the removal of the thrombus. In this case, when the contrast agent is injected after the removal of the thrombus, the region 63 in FIG. 6A where the blood flow resumes is stained with the contrast agent, while the region 61 in FIG. 6A where the blood flow does not resume. Does not contain contrast media.

  At this time, the second image generation function 53 firstly uses the second difference image 73 (P3-M) in which the pixel value is the difference between the pixel value of each pixel of the second contrast image P3 and the pixel value of each pixel of the mask image M. ) Is generated (see FIG. 4B). However, the second difference image 73 (P3-M) is similar to the other first difference image 72 (P2-M) and the first difference image 71 (P1-M), in the portion corresponding to the dominant region. This is an image with nonuniform pixel values (see FIG. 6B).

  Subsequently, the second image generation function 53 uses the pixel value of each pixel of the second difference image 73 (P3-M) and the other first difference image 72 (P2-M) (or the first difference image 71 (P1-M1)). M)), a ratio image 82 ((P3-M) / (P2-M) (or (P3-M) / (P1-M))) having the pixel value as the pixel value ratio is generated.

  The second difference image 73 (P3-M) illustrated in FIG. 6B is an image in which the pixel values of the pixels corresponding to the dominant region are not uniform. For this reason, just comparing FIG. 6 (b) and FIG. 5 (b), the contrast agent concentration (the amount of contrast agent contained in the biological tissue of the unit volume) is increased even when the blood flow resumes. Even if the region 63 exists, it is very difficult to determine the region 63 due to the influence of the nonuniformity of the pixel values of the pixels corresponding to the dominant region.

  On the other hand, as shown in FIG. 7, in the ratio image 82, an image 67 generated by X-rays transmitted through the region 62 in FIG. 6A upstream of the thrombus is different from the second difference image 73 (P3-M) and others. Since the first difference image 72 (P2-M) of FIG. 1 has no increase in blood flow and there is only a change in contrast agent concentration (amount of contrast agent contained in the biological tissue of a unit volume), the image 67 is within the region. The pixel values a are almost the same throughout. On the other hand, the pixel value of the pixel corresponding to the image 68 generated by the X-ray transmitted through the region 63 of FIG. 6A through which the blood flow has resumed is the other first difference in the second difference image 73 (P3-M). Compared with the image 72 (P2-M), the value reflects an increase in contrast agent concentration due to an increase in blood flow. Therefore, the pixel of the image 68 has a pixel value b different from that of the image 67.

  The ratio between the pixel value a and the pixel value b is approximately proportional to the size obtained by multiplying the thickness of the part where the blood flow has resumed by the amount of the contrast medium in the blood contained in the part. For example, if the dominating area covers almost half of the brain, the pixel value b is almost twice the pixel value a if the entire dominating area resumes.

  For this reason, the ratio image 82 represents a region where blood flow has been restored by thrombus removal performed between the imaging of the first contrast image P1 or another first contrast image P2 and the imaging of the second contrast image P3. It becomes an image. Therefore, the user can grasp the reopening region of the blood flow easily and reliably by observing the ratio image 82. Further, by comparing and observing the image of the dominant region obtained by other modalities such as an X-ray CT (Computed Tomography) apparatus and a magnetic resonance imaging (MRI) apparatus and the ratio image 82, the user can more It is possible to obtain information on the area that has been resumed in detail.

  The mask image M, the first contrast images P1, P2 and the second contrast image P3 are images from the same viewpoint because each pixel value is calculated as reflecting the X-ray transmission intensity at the same position. It is preferable.

  Therefore, the movement processing function 54 causes the storage circuit 44 to store the positions of the X-ray tube 22 and the X-ray detection unit 21 with respect to the top 33 at the time of capturing the mask image M, and the mask image M. The movement processing function 54 is configured to capture the first contrast images P1, P2 and the second contrast image P3 so that the first contrast images P1, P2 and the second contrast image P3 are images from the same viewpoint as the mask image M. The X-ray tube 22 and the X-ray detection unit 21 are moved to the positions stored in the storage circuit 44.

  Further, the movement processing function 54 performs the matching process between the X-ray fluoroscopic image and the mask image M at the position after the movement so as to reduce the influence of the body movement of the subject P, and the X-ray fluoroscopic image becomes the mask image M. The positions of the X-ray tube 22 and the X-ray detection unit 21 are finely adjusted so that an image from the same viewpoint is obtained. Note that various types of matching processing are conventionally known in the technical field of image processing, and any of these can be used. The imaging control function 51 captures the first contrast images P1 and P2 and the second contrast image P3 after this fine adjustment. With the movement processing function 54, the first contrast images P1, P2, the second contrast image P3, and the mask image M can be made images from the same viewpoint.

  It should be noted that the movement processing function 54 detects the X-ray tube 22 and the X-rays with reference to the top 33 in accordance with an instruction to “store” via the input circuit 41 by the user when the mask image M is captured. The position of the unit 21 and the mask image M may be stored in the storage circuit 44. Further, when the user gives an instruction to “reproduce” via the input circuit 41 when the first contrast images P1, P2 and the second contrast image P3 are taken, the first contrast image P1, The positions of the X-ray tube 22 and the X-ray detector 21 may be adjusted so that the P2 and the second contrast image P3 are images from the same viewpoint as the mask image M.

  Next, an example of the operation of the X-ray diagnostic apparatus 10 according to this embodiment will be described.

  FIG. 8 shows a procedure for generating an image by which the CPU of the processing circuit 45 shown in FIG. 1 can easily confirm blood flow recovery in the downstream (dominant region) of the thrombus in the thrombectomy operation using the catheter 34. It is a flowchart which shows an example. In FIG. 8, reference numerals with numbers added to S indicate steps in the flowchart.

  First, in step S1, the first image generation function 52 generates a mask image M. Next, in step S <b> 2, the movement processing function 54 receives an instruction to “store” from the user via the input circuit 41. Note that steps S1 and S2 may be performed in parallel or in reverse order.

  Next, in step S <b> 3, the movement processing function 54 stores in the storage circuit 44 the positions of the X-ray tube 22 and the X-ray detection unit 21 with respect to the top plate 33 when the mask image M is captured, and the mask image M. Let

  Next, in step S <b> 4, the imaging control function 51 injects a contrast agent into the subject P via the injector 30. Next, in step S <b> 5, the movement processing function 54 receives an instruction to “reproduce” from the user via the input circuit 41. Note that steps S4 and S5 may be performed in parallel or in reverse order.

  Next, in step S <b> 6, the movement processing function 54 positions the X-ray tube 22 and the X-ray detection unit 21 with reference to the top 33 so that an image from the same viewpoint as the mask image M can be generated. Adjust.

  Next, in step S7, the first image generation function 52 generates a first contrast image P1.

  Next, in step S <b> 8, the operator O performs a blood flow obstacle removing operation using the catheter 34.

  Next, in step S <b> 9, the movement processing function 54 receives an instruction to “reproduce” from the user via the input circuit 41.

  In response to this instruction, in step S10, the movement processing function 54 generates the image from the same viewpoint as the mask image M, and the X-ray tube 22 and the X-ray detection unit with the top 33 as a reference. 21 is adjusted.

  Next, in step S <b> 11, the imaging control function 51 injects a contrast agent into the subject P via the injector 30. Then, the first image generation function 52 generates a second contrast image P3.

  Next, in step S12, the second image generation function 53 uses the pixel value of each pixel of the second difference image 73 (P3-M) and the first difference image 71 (P1-M) (or another first difference image 72). (P2-M)) Ratio image 82 ((P3-M) / (P1-M) (or (P3-M) / (P2-M))) having a pixel value as the ratio of each pixel to the pixel value. Is generated and displayed on the display 42 (see FIG. 7).

  Through the above procedure, it is possible to generate and display a ratio image 82 that allows easy confirmation of blood flow recovery in the downstream (dominant region) of the thrombus in the thrombectomy operation using the catheter 34.

  The X-ray diagnostic apparatus 10 including the image processing apparatus 12 according to the present embodiment can generate the ratio image 82. The ratio image 82 is an image 67 generated by X-rays transmitted only through the region 62 upstream of the thrombus. In the second difference image 73 (P3-M) and the first difference image 71 (P1-M), the blood flow increases. Since there is only a change in the contrast agent concentration (the amount of contrast agent contained in the biological tissue of a unit volume), the image 67 has almost the same pixel value a everywhere in the region. On the other hand, the image 68 generated by the X-rays transmitted through the region 63 through which the blood flow is resumed has an increased blood flow in the second difference image 73 (P3-M) compared to the first difference image 71 (P1-M). Therefore, the pixels of the image 68 have various pixel values b different from the pixels of the image 67.

  Therefore, according to the X-ray diagnostic apparatus 10, the user can grasp the reopening region of the blood flow very easily and reliably by observing the ratio image 82.

  Generally, in the thrombectomy operation using the catheter 34, X-ray imaging is performed while releasing the contrast medium from the catheter 34 for the operation of causing the catheter 34 to enter the thrombus and the operation for removing the thrombus. This needs to be repeated over and over again.

  Since the contrast medium dissolves in the blood and circulates throughout the body, and a part of the contrast medium in the blood is gradually filtered and excreted by the kidney, the concentration of the contrast medium in the blood decreases very slowly. However, in the thrombectomy operation using the catheter 34, since the release of the contrast medium is frequently repeated, the increase in the contrast medium concentration in the blood far exceeds the decrease by filtration. On the other hand, contrast agents have the side effect of adversely affecting renal function. For this reason, even in patients with normal renal function, the upper limit of the total amount of contrast agent that can be used is limited. In particular, in patients with renal dysfunction, contrast agents cause side effects that significantly worsen renal dysfunction.

  Therefore, the upper limit of the total amount of contrast agent that can be used should be strictly limited. In other words, the surgeon O abandons thorough treatment of cerebral infarction, and even if he can save his life, he / she suffers from a disorder such as movement and sensation and needs to be rehabilitated over a long period of time. You will be forced to choose whether to exacerbate the disorder and require permanent dialysis or kidney transplantation.

In this regard, according to the X-ray diagnostic apparatus 10 according to the present embodiment, the user can grasp whether or not the blood flow in the dominant region has been recovered very easily by observing the ratio image 82. For this reason, compared with the conventional technique which only compares the 1st difference image 71 and the 2nd difference image 73, the usage-amount of a contrast agent can be suppressed significantly.
(Second Embodiment)

  Next, a second embodiment of the X-ray diagnostic apparatus, image processing apparatus, and image processing method according to the present invention will be described.

  FIG. 9 is a block diagram showing an example of an X-ray diagnostic apparatus 10A according to the second embodiment of the present invention.

  The X-ray diagnostic apparatus 10A shown in the second embodiment is different from the X-ray diagnostic apparatus 10 shown in the first embodiment in that a prediction ratio image 90 of the ratio image 82 is generated by simulation. Since other configurations and operations are not substantially different from those of the X-ray diagnostic apparatus 10 shown in FIG. 1, the same components are denoted by the same reference numerals and description thereof is omitted.

  The X-ray diagnostic apparatus 10A acquires volume data (medical three-dimensional image data) of the region of interest of the subject P from the modality 101 and the image server 102 connected via the network 100, and stores them in the storage circuit 44 in advance. deep. Further, a part or all of the data stored in the storage circuit 44 may be configured to be downloaded via the network 100, or may be stored via a portable storage medium such as an optical disk. .

  The modality 101 is, for example, a medical image diagnostic apparatus such as an X-ray CT (Computed Tomography) apparatus, an MRI (Magnetic Resonance Imaging) apparatus, an ultrasonic diagnostic apparatus, an X-ray diagnostic apparatus, and the like by imaging a subject P (patient). An apparatus that can generate volume data (medical three-dimensional image data) based on the obtained projection data can be used.

  The image server 102 is a server for long-term storage of images provided in, for example, a PACS (Picture Archiving and Communication System), and a reconstructed image generated by the modality 101 connected via the network 100. And volume data.

  FIG. 10 is a schematic block diagram illustrating a configuration example of a function implementing unit by the CPU of the processing circuit 45A according to the second embodiment. In addition, this function realization part may be comprised by hardware logics, such as a circuit, without using CPU.

  The volume data acquisition function 56 acquires volume data of a region of interest of the subject P that is stored in advance in the storage circuit 44 or acquired from the modality 101 or the image server 102 via the network connection circuit 43 and the network 100.

  The prediction ratio image generation function 57 generates a prediction image (prediction first difference image) of the first difference image 71 by performing simulation using the volume data of the attention area. Further, the prediction ratio image generation function 57 simulates using the volume data of the region of interest, thereby predicting the second difference image 73 predicted to be obtained when the blood flow obstacle is completely removed ( A predicted second difference image) is generated.

  In addition, the prediction ratio image generation function 57 generates a prediction ratio image 90 (E) in which the pixel value ratio between the predicted second difference image and the predicted first difference image is a pixel value.

  FIG. 11 is an explanatory diagram illustrating an example of a state when the prediction ratio image 90 (E) and the ratio image 82 are displayed in parallel on the display 42.

  The second image generation function 53A according to the present embodiment generates a ratio image 82 (see FIG. 7) generated based on projection data obtained by X-ray imaging of the region of interest of the subject P, and a predicted ratio image generation. The prediction ratio image 90 (E) generated by the function 57 is displayed in parallel on the display 42 (see FIG. 11).

  The predicted ratio image 90 (E) is a ratio image 82 predicted to be obtained when the blood flow obstacle is completely removed. For this reason, the user can easily know the recommunication location and resumption state of the blood flow by comparing and observing the ratio image 82 and the predicted ratio image 90 (E).

  Further, the second image generation function 53A generates a comparison support image having a pixel value as a ratio between the pixel value of each pixel of the prediction ratio image 90 (E) and the pixel value of each pixel of the ratio image 82, and displays the display 42. May be displayed. The comparison support image is an image in which only the non-resuming part of the blood flow is extracted. Therefore, the user can easily know the blood flow resumption location and the resumption degree by observing the comparison support image. Of course, the second image generation function 53A may display all of the ratio image 82, the predicted ratio image 90 (E), and the comparison support image on the display 42 in parallel.

  Here, a simulation using volume data by the prediction ratio image generation function 57 will be described. The prediction ratio image generation function 57 calculates the prediction first difference image and the prediction first image by calculation based on the volume data of the attention area so that the prediction ratio image 90 (E) is an image from the same viewpoint as the ratio image 82. Note that each of the two difference images should be generated.

  First, the prediction ratio image generation function 57 extracts a lesion portion of cerebral infarction by appropriate image processing or manual operation from the volume data generated by the X-ray CT apparatus or MRI apparatus acquired by the volume data acquisition function 56. As a result, for each voxel, if the position (x, y, z) where the voxel exists corresponds to the infarcted region, “true (1)”, and if not, “false (0)” is set to that voxel. Volume data L made up of voxels such that has as a value is generated.

      L (x, y, z) = (1 (true) if point (x, y, z) corresponds to the infarcted area, 0 (false) otherwise)

  Further, a portion corresponding to the brain parenchyma is extracted from the same volume data. As a result, for each voxel, if the position (x, y, z) where the voxel exists corresponds to the brain parenchyma, “1”, If not applicable, volume data B composed of voxels whose value is “0” is generated.

      B (x, y, z) = (1 if the point (x, y, z) corresponds to the brain parenchyma, 0 otherwise)

  A set operation is performed using these volume data L and B. If the position where each voxel exists is “0” in L and “1” in B, “1”, otherwise For example, volume data (B∧L) composed of voxels whose value is “0” is generated.

      (B∧¬L) (x, y, z) = B (x, y, z) (1-L (x, y, z))

The amount of blood in normal brain tissue is almost the same everywhere, but precisely, it is less in white matter and more in gray matter. Therefore, obtaining volume data S imaged without contrast medium using an X-ray CT apparatus or MRI apparatus, and subsequently obtaining contrast volume data T imaged by distributing the contrast medium substantially uniformly in the blood, Volume data representing the contrast medium concentration distribution in the brain is created from the difference image of S, and this is represented by X.
At this time, the logical product of (B∧¬L) and X voxels is

      U (x, y, z) = (B∧¬L) (x, y, z) X (x, y, z)

Then, U is approximately proportional to the contrast medium concentration distribution before the cerebral infarction is resumed.
Also, the logical product of B and X for each voxel is

      V (x, y, z) = B (x, y, z) X (x, y, z)

  Then, V is substantially proportional to the contrast agent concentration distribution when cerebral infarction is completely resumed.

  As a simpler method, there is a method in which X is a constant value everywhere without considering that the amount of blood in normal brain tissue is small in white matter and large in gray matter. In this case, it is only necessary to create B, L, and (B い て ¬L) based on the volume data imaged by the X-ray CT apparatus or MRI apparatus without using the contrast agent.

  If a simulation is performed to calculate what kind of image is obtained when X-rays are taken from the same direction as the subject P is photographed using U, the image of the first difference image (P2-M) is predicted. An image (predicted first difference image) can be generated. Further, if V is used in the same manner, an image (predicted second difference image) predicting what the second difference image (P3-M) will be when the cerebral infarction is completely restarted can be generated. Based on these predicted images, the prediction ratio image 90 (E) can be calculated.

      E = "(P3-M) predicted image" / "(P2-M) predicted image"

  Next, an example of the operation of the X-ray diagnostic apparatus 10A according to the present embodiment will be described.

  FIG. 12 is a flowchart illustrating an example of a procedure for displaying the ratio image 82 and the prediction ratio image 90 (E) in parallel on the display 42 by the prediction ratio image generation function 57 and the second image generation function 53A. This procedure starts when a ratio image 82 (see FIG. 7) is generated based on projection data obtained by X-ray imaging of the region of interest of the subject P by a series of procedures shown in FIG.

  In step S21, the prediction ratio image generation function 57 simulates by calculation what kind of image is obtained when X-rays are taken from the same direction as the subject P is taken using the volume data U. Thus, an image (predicted first difference image) obtained by predicting the image of the first difference image (P2-M) is generated.

  Next, in step S22, the prediction ratio image generation function 57 calculates what kind of image is obtained when X-rays are taken from the same direction as the subject P is taken using the volume data V. By performing simulation, an image (predicted second difference image) obtained by predicting the image of the second difference image (P3-M) is generated.

  Next, in step S23, the prediction ratio image generation function 57 generates a prediction ratio image 90 (E) having a pixel value as a ratio between each pixel of the prediction first difference image and each pixel of the prediction second difference image. .

  In step S24, the second image generation function 53A uses a ratio image 82 (see FIG. 7) generated based on projection data obtained by X-ray imaging of the region of interest of the subject P, and a predicted ratio image. The prediction ratio image 90 (E) generated by the generation function 57 is displayed in parallel on the display 42 (see FIG. 11).

  Through the above procedure, the ratio image 82 and the predicted ratio image 90 (E) can be displayed on the display 42 in parallel.

  The X-ray diagnostic apparatus 10A including the image processing apparatus 12 according to the second embodiment also has the same effects as the X-ray diagnostic apparatus 10 according to the first embodiment.

  In addition, the X-ray diagnostic apparatus 10A according to the second embodiment generates a prediction ratio image 90 (E) that is a ratio image 82 predicted to be obtained when the blood flow obstacle is completely removed, and displays 42 can be displayed in parallel with the ratio image 82. For this reason, according to the X-ray diagnostic apparatus 10A, the user can easily know the recommencement location and the resumption status of the blood flow. Furthermore, when a comparison support image having a pixel value that is a difference between each pixel of the predicted ratio image 90 (E) and each pixel of the ratio image 82 is generated and displayed on the display 42, the user can more easily resume blood flow. You can know the communication place and reopening condition.

  According to at least one embodiment described above, it is possible to generate an image in which blood flow recovery in the control region can be easily confirmed in the thrombectomy operation using the catheter 34.

  The first image generation function 52 and the second image generation function 53 in the embodiment are examples of the image generation unit in the claims. The input circuit 41, the storage circuit 44, the movement processing function 54, and the prediction ratio image generation function 57 are examples of an input unit, a storage unit, a movement processing unit, and a prediction ratio image generation unit in the claims. The mask image M in the above embodiment is an example of the first X-ray image in the claims, and the first contrast image P1 or the other first contrast image P2 is an example of the second X-ray image in the claims. The second contrast image P3 is an example of a third X-ray image in the claims. In addition, the ratio image 82 in the above embodiment is an example of an output image in the claims, and the prediction ratio image 90 is an example of a prediction output image in the claims.

  In addition, the term “processor” according to the above-described embodiment is, for example, a dedicated or general-purpose CPU (Central Processing Unit), a GPU (Graphics Processing Unit), or an application specific integrated circuit (ASIC). Circuits such as programmable logic devices (for example, Simple Programmable Logic Device (SPLD), Complex Programmable Logic Device (CPLD), and Field Programmable Gate Array (FPGA)) means. The processor implements various functions by reading and executing a program stored in the storage circuit.

  Further, instead of storing the program in the storage circuit, the program may be directly incorporated in the processor circuit. In this case, the processor implements various functions by reading and executing a program incorporated in the circuit. In addition, a processing circuit may be configured by a single processor, and a single processor may realize all functions, or a processing circuit may be configured by combining a plurality of independent processors, and each processor executes a program. Each function may be realized by the above. In addition, when a plurality of processors are provided, a storage circuit that stores a program may be provided for each processor individually, or one storage circuit stores a program corresponding to the functions of all the processors in a lump. Also good.

  In addition, although some embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

10, 10A X-ray diagnostic apparatus 21 X-ray detection unit 22 X-ray tube 33 Top plate 34 Catheter 41 Input unit 42 Display unit 44 Storage unit 52 First image generation unit 53, 53A Second image generation unit 54 Imaging position adjustment unit 57 Prediction ratio image generation unit 71 First difference image (P1-M)
72 Other first difference image (P2-M)
73 Second difference image (P3-M)
81 ratio image ((P2-M) / (P1-M))
82 Ratio image ((P3-M) / (P1-M))
90 Predictive ratio image (E)
M mask image P subject P1-M first difference image P2-M other first difference image P3-M second difference image

Claims (12)

An X-ray diagnostic apparatus for generating an X-ray image of a region of interest,
An X-ray imaging unit that images the first X-ray image before injection of the contrast agent and the second X-ray image and the third X-ray image after injection of the contrast agent;
An image generation unit that generates an output image having a pixel value as a ratio between the difference between the second X-ray image and the first X-ray image and the difference between the third X-ray image and the first X-ray image;
An X-ray diagnostic apparatus comprising: The output image represents a region where blood flow has been recovered by thrombus removal performed between the imaging of the second X-ray image and the imaging of the third X-ray image.
The X-ray diagnostic apparatus according to claim 1. A storage unit for storing a first imaging position related to the X-ray tube and the X-ray detection unit at the time of imaging the first X-ray image;
A movement processing unit configured to move the X-ray tube and the X-ray detection unit to the first imaging position based on a user instruction;
The X-ray diagnostic apparatus according to claim 1, further comprising: The second X-ray image is
It is an image taken after the time that the contrast medium is distributed almost uniformly in the tissue after administration of the contrast medium.
The X-ray diagnostic apparatus according to any one of claims 1 to 3. The third X-ray image is
It is an image taken after the clot removal work is performed after taking the second X-ray image,
The X-ray diagnostic apparatus according to any one of claims 1 to 4. The movement processing unit
The first X-ray image and the first X-ray image of the X-ray tube and the X-ray detection unit with respect to the top plate according to an instruction from the input unit by a user when the first X-ray image is captured The second X-ray image and the third X-ray image are stored in the storage unit, and when the second X-ray image and the third X-ray image are captured, the second X-ray image and the third X-ray image are converted into the first X-ray according to an instruction from the user via the input unit Moving the X-ray tube and the X-ray detector to the first imaging position so that the image is from the same viewpoint as the image;
The X-ray diagnostic apparatus according to claim 3. Obtained when the difference image between the second X-ray image and the first X-ray image is predicted by calculation using the medical three-dimensional image data of the region of interest and the blood flow obstacle is completely removed. By predicting and generating a difference image between the third X-ray image and the first X-ray image that are predicted to be calculated, the blood flow obstacle is predicted to be obtained when it is completely removed. A prediction ratio image generation unit that generates a predicted output image that is an output image;
Further comprising
The image generation unit
Displaying the output image generated based on projection data obtained by X-ray imaging of the region of interest and the predicted output image in parallel on a display;
The X-ray diagnostic apparatus according to any one of claims 1 to 6. The image generation unit
Generating a comparison support image having a pixel value as a ratio between a pixel value of each pixel of the output image and a pixel value of each pixel of the predicted output image and displaying the comparison support image on the display;
The X-ray diagnostic apparatus according to claim 7. The prediction ratio image generation unit
Obtained when the difference image between the second X-ray image and the first X-ray image and the blood flow obstacle are completely removed so that the predicted output image is an image from the same viewpoint as the output image. Predicting and generating each of the difference images of the third X-ray image and the first X-ray image predicted by
The X-ray diagnostic apparatus according to claim 7 or 8. The thrombus removal is tried multiple times,
The image generation unit
Generating and updating the output image for each thrombus removal;
The X-ray diagnostic apparatus according to claim 2. An image processing apparatus for generating an X-ray image of a region of interest,
A first image generation unit that generates a first X-ray image before injection of a contrast agent and a second X-ray image and a third X-ray image after injection of the contrast agent;
A second image generation unit that generates an output image having a pixel value as a ratio between the difference between the second X-ray image and the first X-ray image and the difference between the third X-ray image and the first X-ray image;
An image processing apparatus. An image processing method of an image processing apparatus for generating an X-ray image of a region of interest,
Generating a first X-ray image before injection of a contrast agent and a second X-ray image and a third X-ray image after injection of the contrast agent;
Generating an output image having a pixel value as a ratio between the difference between the second X-ray image and the first X-ray image and the difference between the third X-ray image and the first X-ray image;
An image processing method.